Geography 11 Suggestion 2023
কোন একক দ্বারা সুস্থিত শব্দের মাত্রা পরিমাপ করা হয় ?
মুম্বাই বন্দরের পরিপুরক বন্দর কোনটি ?
প্রশস্ততার ভিত্তিতে ভারতীয় রেলপথকে কয়ভাগে ভাগ করা যায় ও কী কী ?
ভারতের কোথায় ভূ-তাপ শক্তি প্লান্ট স্থাপনের অনুমোদন রয়েছে ?
ভারতের কোন রাজ্যে নীরু-মীরু কর্মসূচিটি গৃহিত হয়েছে : শস্য প্রগাঢ়তা নির্ণয়ের সূত্রটি লিখ।
বিক্ষিপ্ত বসতি দেখা যায় এমন একটি অঞ্চলের নাম লিখ।
পরিব্রাজনের কোন ধারায় পুরুষ পরিব্রাজনের পরিমাণ অধিক ?
WTO এর পুরো নাম কী ?
পানামা খালপথ কোন মহাসাগরগুলোকে যুক্ত করে এ
কোন শ্রেণির অর্থনৈতিক ক্রিয়াকলাপ স্বর্ণালী পোষাক জীবিকা নামে পরিচিত ?
কোন অঞ্চলটি "আমেরিকা যুক্তরাষ্ট্রের মরিচা পাত্র' নামে পরিচিত ?
কে মানব উন্নয়নের ধারণাটি উপস্থাপন কারেন ?
কোন দেশে পৃথিবীর সর্বাধিক লিঙ্গানুপাত রয়েছে ?
সম্ভাবনাবাদ কী ?
ভূগোলের কোন উপক্ষেত্রটি সমাজ বিজ্ঞানের বিষয় মনোবিজ্ঞানের সঙ্গে যুক্ত ?
সংক্ষেপে উত্তর দাও :- 2×5
সম্প্রসারিত জনসংখ্যা বলতে কী বোঝ ? ডিজিটাল বিভাজন কাকে বলে ?
আন্তঃমহাদেশীয় রেলপথ বলতে কী বোঝায় ?
জনসংখ্যার ঘনত্ব কী ?
সড়কপথ ব্যবহারের সুবিধাগুলো লেখ।
উত্তর দাও 3×2
ভারতের কয়লা উৎপাদক অঞ্চলগুলো সম্পর্কে লেখ।
বন্দরকে কেন আন্তর্জাতিক বাণিজ্যের প্রবেশদ্বার বলে ?
উত্তর দাও 4×2
যাযাবর পশুপালন এবং বাণিজ্যিক পশুপালনের পার্থক্য লেখ।
ভারতের অর্থনৈতিক উন্নয়নে সড়কের ভূমিকা আলোচনা কর।
উত্তর দাও 5×2
ভারতের বস্তিগুলোর সমস্যা বর্ণনা কর।
জনসংখ্যার বন্টন ও ঘনত্বকে প্রভাবিত করে এমন কারণগুলো আলোচনা কর।
CBSE Board
অধ্যায় 1 একটি শৃঙ্খলা হিসাবে ভূগোল
অধ্যায় 2 পৃথিবীর উৎপত্তি এবং বিবর্তন
অধ্যায় 3 পৃথিবীর অভ্যন্তর
অধ্যায় 4 মহাসাগর এবং মহাদেশের বন্টন
অধ্যায় 5 খনিজ ও শিলা
অধ্যায় 6 জিওমরফিক প্রসেস
অধ্যায় 7 ল্যান্ডফর্ম এবং তাদের বিবর্তন
অধ্যায় 8 বায়ুমণ্ডলের গঠন এবং গঠন
অধ্যায় 9 সৌর বিকিরণ, তাপের ভারসাম্য এবং তাপমাত্রা
অধ্যায় 10 বায়ুমণ্ডলীয় প্রচলন এবং আবহাওয়া সিস্টেম
অধ্যায় 11 বায়ুমণ্ডল জল
অধ্যায় 12 বিশ্ব জলবায়ু এবং জলবায়ু পরিবর্তন
অধ্যায় 13 জল (মহাসাগর)
অধ্যায় 14 মহাসাগরের জলের গতিবিধি
অধ্যায় 15 পৃথিবীতে জীবন
অধ্যায় 16 জীববৈচিত্র্য এবং কথোপকথন
Chapter 1 Geography as a Discipline
Chapter 2 Origin and Evolution of the Earth
Chapter 3 Earth's Interior
Chapter 4 Distribution of oceans and continents
Chapter 5 Minerals and Rocks
Chapter 6 Geomorphic Processes
Chapter 7 Landforms and their evolution
Chapter 8 Structure and composition of the atmosphere
Chapter 9 Solar radiation, heat balance and temperature
Chapter 10 Atmospheric Circulation and Weather Systems
Chapter 11 Atmosphere Water
Chapter 12 World Climate and Climate Change
Chapter 13 Water (Ocean)
Chapter 14 Movement of Ocean Water
Chapter 15 Life on Earth
Chapter 16 Biodiversity and Conversation
Solutions Chapter 2 The Origin and Evolution of the Earth
Class 11 Geography Chapter 2 NCERT Textbook Questions Solved
1. Multiple choice questions.
Question 1(i).
Which one of the following figures represents the age of the earth?
(a) 4.6 million years
(b) 13.7 billion years
(c) 4.6 billion years
(d) 13.7 trillion years.
Answer:
(b) 4.6 billion years
Question 1(ii).
Which one of the following has the longest duration?
(a) Eons
(b) Period
(c) Era
(d) Epoch.
Answer:
(a) Eons
Question 1(iii).
Which one of the following is not related to the formation or modification of the present atmosphere?
(a) Solar winds
(b) Differentiation
(c) Degassing
(d) Photosynthesis.
Answer:
(b) Differentiation
Question 1(iv).
Which one of the following represents the inner planets?
(a) Planets between the sun and the earth
(b) Planets between the sun and the belt of asteroids
(c) Planets in gaseous state
(d) Planets without satellite(s).
Answer:
(d) Planets without satellite(s)
Question 1(v).
Life on the earth appeared around how
many years before the present?
(a) 13.7 billion
(b) 3.8 million
(c) 4.6 billion
(d) 3.8 billion.
Answer:
(d) 3.8 billion.
2. Answer the following questions in about 30 words.
Question 2(i).
Why are the terrestrial planets rocky? Answer: Terrestrial planets are rocky because:
The terrestrial planets were formed in the close vicinity of the parent star where it was too warm for gases to condense to solid particles.
The solar wind was most intense nearer the sun; so, it blew off lots of gas and dust from the terrestrial planets.
The terrestrial planets are smaller and their lower gravity could not hold the escaping gases.
Question 2(ii).
What is the basic difference in the arguments related to the origin of the earth given by (a) Kant and Laplace (b) Chamberlain and Moulton.
Answer:
1. Kant and Laplace’s Principle: The hypothesis considered that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating. According to this principle which emerged in 1796, the interior of the earth must be gaseous because the earth has originated from gas form.
2. Chamberlain and Moulton: In 1900, Chamberlain and Moulton considered that a wandering star approached the sun. As a result, a cigar-shaped extension of material was separated from the solar surface. As the passing star moved away, the material separated from the solar surface continued to revolve around the sun and it slowly condensed into planets. Later on, the arguments considered of a companion to the sun to have been coexisting. These arguments are called binary theories.
Question 2(iii).
What is meant by the process of differentiation?
Answer:
Starting from the surface to the central parts, we have layers like the crust, mantle, outer core and inner core. From the crust to the core, the density of the material increases. This process of the earth forming material got separated into different layers is called differentiation.
Question 2(iv).
What was the nature of the earth surface initially?
Answer:
The planet earth initially was a barren, rocky and hot object with a thin atmosphere of hydrogen and helium. This is far from the present day picture of the earth. It is said that in initial stage the earth was in liquid form. Certainly, there must have been some events- processes, which may have caused this change from rocky, barren and hot earth to a beautiful planet with ample amount of water and conducive atmosphere favouring the existence of life.
Question 2(v).
What were the gases which initially formed the earth’s atmosphere?
Answer:
Hydrogen’ and helium were the gases which initially formed the earth’s surface. The early atmosphere with hydrogen and helium is supposed to have been stripped off as a result of intense solar wind. This happened not only in the case of earth, but also in all the terrestrial planets which were supposed to have lost their primordial atmosphere through the impact of solar winds. During the cooling of the earth, gases and water vapour were released from the interior solid earth. Continuous volcanic eruptions contributed water vapour and gases at atmosphere. It was the first „ stage of atmosphere development.
3. Answer the following questions in about 150 words.
Question 3(i).
Write an explanatory note on the ‘Big Bang Theory’.
Answer:
The Big Bang Theory, also called as expanding universe hypothesis. Edwin Hubble in 1920 provided the evidence that the universe is expanding. The galaxies move farther as the time passes. It says that galaxies are moving away from each other. The universe appears to be growing larger.
The Big Bang Theory:-
1. In the beginning, ail matter forming the universe existed in one place in the form of a ‘tiny ball” with an unimaginably small volume, infinite temperature and infinite density.
2. At the Big Bang “tiny ball” exploded violently. This led to a huge expansion. It is now/ generally accepted that the event of big bang took place 13,7 billion years before the present. The expansion continues even to the present day. As it grew7, some energy was converted into matter. There was particularly rapid expansion within fractions of a second after the bang. Thereafter, the expansion has slowed down. Within first three minutes from the Big Bang event, the first atom began to form.
3. Within 300,000 years from the Big Bang, temperature dropped to 4,500k and gave rise to atomic matter. The universe became transparent.
4. The expansion of universe means increase in space between the galaxies. An alternative to this was Hoyle’s concept of steady state. It considered the universe to be roughly the same at any point of time. However, with greater evidence becoming available about the expanding universe, scientific community at present favours argument of expanding universe.
Question 3(ii).
List the stages in the evolution of the earth and explain each stage in brief.
Answer:
The earth was mostly in a volatile state during its primordial stage. Due to gradual increase in density the temperature inside has increased. As a result the material inside started getting separated depending on their densities. This allowed heavier materials (like iron) to sink towards the centre of the earth and the lighter ones to move towards the surface. With passage of time it cooled further and solidified and cpndensed into a smaller size. This later led to the development of the outer surface in the form of a crust. It is through the process of differentiation that the earth forming material got separated into different layers. Starting from the surface to the central parts, we have layers like the crust, mantle, outer core and inner core. From the crust to the core, the density of the material increases.
The origin of life as a kind of chemical reaction, which first generated complex organic molecules and assembled them, This assemblage was such that they could duplicate themselves concerting inanimate matter into living substance. The record of life that existed on this planet in different periods is found in rocks in the form of fossils. The microscopic structures closely related to the present form of the blue algae have been found in geological formations much older than some 3,000 million years. It can be assumed that life began to evolve sometime 3,800 million years ago,
Project work
Collect information about the project “Stardust” (website: v.’ww.sci.edu/public.htinl and www. nasm.edu) along the following lines.
(i) Which is the agency that has launched this project?
(ii) Why are scientists interested in collecting Stardust?
(iii) Where from the Stardust is being • collected?
Answer:
Attempt yourself.
Class 11 Geography Chapter 1 NCERT Extra Questions
Class 11 Geography Chapter 1 Multiple Choice Questions
Question 1.
How many planets are there in solar system?
(a) 5
(b) 7
(c) 8
(a) 9.
Answer:
(c) 8
Question 2.
What is the distance between the earth and the sun?
(a) 149.6 million kms
(b) 15.98 million kms
(c) 169.34 million kms
(d) 179.67 million kms.
Answer:
(a) 149.6 million kms
Question 3.
Which expert gave the nebular hypothesis?
(a) Immurial Kant
(b) Lalpace
(c) Chamberlain
(d) Moulton.
Answer:
(b) Laplace
Question 4.
Which expert gave the Collision hypothesis?
(a) Immanuel Kant
(b) Lalpace
(c) Chamberlain
(d) Sir James and Harold Jeffrey.
Answer:
(d) Sir James and Harold Jeffrey
Question 5.
Which theory is most widely accepted regarding origin of the universe at present?
(a) Collision hypothesis
(b) Big Bang Theory
(c) Nebular hypothesis
(d) Binary Theory.
Answer:
(b) Big Bang Theory
Question 6.
About how many years back did stars originate?
(a) About 3 to 4 billion years before
(b) About 5 to 6 billion years before
(e) About 6 to 7 billion years before
(d) About 4 to 5 billion years before.
Answer:
(b) About 5 to 6 billion years before
Question 7.
What is the diameter of milky way?
(a) Between 80 thousand to 1,50,000 light years
(b) Between 1 lakh to 2 lakh light years
(c) Between 2 lakh to 3 lakh light years
(d) Between 2,50,000 to 3,00,000 light years.
Answer:
(a) Between 80 thousand to 1,50,000 light years
Question 8.
Which of the following is not an inner planet?
(a) Jupiter
(b) Mercury
(c) Venus
(d) Earth.
Answer:
(a) Jupiter
Question 9.
Which of the following is not an outer- planet?
(a) Jupiter
(b) Saturn
(e) Uranus
(d) Mars.
Answer:
(d) Mars
Question 10.
By which elements is the terrestrial planets formed?
(а) Rocks and Metals
(б) Hydrogen and helium
(c) Liquid elements
(d) All of the above.
Answer:
(a) Rocks and metals.
Class 11 Geography Chapter 2 Very Short Answer Type Questions
Question 1.
What do you mean by the big splat?
Answer:
The origin of the moon as a satellite of the earth is the result of big collision which is called “the big splat”.
Question 2.
Which hypothesis was given by Hoyle?
Answer:
Hoyle gave concept of steady .state. It considered the universe to be roughly the same at any point of time. However, with greater evidence becoming available about the expanding universe, scientific community at present favours argument of expanding universe.
Question 3.
What do you mean by dwarf planets?
Answer:
According to International Astronomical. Union (LAU) on August 24,2006, a planet is a celestial body that
orbits around the sun
has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape.
The non-satellites bodies fulfilling these two rules are called dwarf planets. Pluto is now considered a dwarf planet. Ceres, Eris, Makemake, Haumea are some other dwarf planets.
Question 4.
What are different stages of development of atmosphere?
Answer:
In the early stage the atmosphere with hydrogen and helium is supposed to have been stripped off as a result of intense solar winds. In the second stage during the cooling of the earth, gases and water vapour were released from the interior solid earth. Continuous volcanic eruptions contributed water vapour and gases to the atmosphere. As the earth cooled, the water vapour released started getting condensed. Third stage was the stage of photosynthesis.
Question 5.
What do you mean by degassing?
Answer:
The early atmosphere largely contained water vapour, nitrogen, carbon dioxide, methane, ammonia and very little of free oxygen. The process through which the gases were outpoured from the interior is called degassing.
Question 6.
Name different hypothesis associated with the formation of the earth.
Answer:
Nebular Hypothesis: It was given by Laplace.
Collision Hypothesis: It was given by Sir James and Harold Jeffrey.
Accretion Hypothesis: It was given by Schmidt and Carl Weizascar.
The Big Bang Theory: It was given by Edwin Hubble.
Question 7.
Who gave their opinions about the formation of the moon? What did they opine?
Answer:
In 1838, Sir George Darwin suggested that initially the earth and the moon formed a single rapidly rotating body. The whole mass became a dumb-bell shaped body and eventually it broke. The material separated from the earth was formed as Moon and the place became the Pacific Ocean. It is not accepted now. The present theory is “the giant impact theory” or “big splat theory”. A large size body of Mars collided with the earth and that portion was separated from the earth. The same portion became as a moon which revolves around the earth.
Question 8.
What do you mean by light year?
Answer:
A light year is equal to the number of kilometers travelled by light per second. It is a measure of distance and not of time. Light travels at a speed of 300,000 km/second. Therefore, the distances the light will travel in one year is taken to be one light year.
Question 9.
What do we get to know by the study of celestial bodies?
Answer:
We get to know about the origin, evolution and function of each and every celestial bodies.
Question 10.
What do you mean by terrestrial planets?
Answer:
The terrestrial planets were formed in the close vicinity of the parent star where it was too warm for gases to condense to solid particles. Mercury, Venus, Earth and Mars are called terrestrial planets.
Question 11.
Which gases were found in excess in earlier atmosphere?
Answer:
In the earlier atmosphere there was mainly hydrogen and helium.
Question 12.
How did atmosphere originate?
Answer:
Gases were released from the earth’s interior such as water vapour and other gases. There were water vapour, nitrogen, carbon dioxide, methane, ammonia and little free oxygen. The process of outpouring the gases from the interior of the earth is called degassing. The process of differentiation created the present atmosphere.
Question 13.
How were stars formed?
Answer:
The distribution of matter and energy was not even in the early universe. These initial density differences gave rise to differences in gravitational forces and it caused the matter to get drawn together. These formed the bases for development of galaxies which contains millions of stars.
Question 14.
What are jovian planets?
Answer:
Jupiter, Saturn, Uranus and Neptune are called Jovian or Gas Giant planets. Jovian means jupiter-like. Most of them are much larger than the terrestrial planets and have thick atmosphere, mostly of helium and hydrogen.
Question 15.
Name the experts who modified nebular hypothesis.
Answer:
In 1950, Otto Schmidt in Russia and Carl Weizascar in Germany revised the ‘nebular hypothesis’, though differing in details. They considered that the sun was surrounded by solar nebula containing mostly the hydrogen and helium along with what may be termed as dust. The friction and collision of particles led to formation of a disk-shaped cloud and the planets were formed through the process of accretion. However, scientists in later period took up the problems of origin of universe rather than that of just the earth or the planets.
Question 16.
What kind of evidences have been given by Edwin Hubble?
Answer:
Edwin Hubble, in 1920, provided evidence that the universe is expanding. As time passes, galaxies move further and further apart.
Class 11 Geography Chapter 2 Short Answer Type Questions
Question 1.
What is the opinion of present day
scientists about the origin of moon?
Answer:
In 1838, Sir George Darwin suggested that initially the earth and the moon formed a single rapidly rotating body. The whole mass became a dumb-bell shaped body and eventually it broke. The material separated from the earth was formed as moon and the place became the Pacific Ocean. It is not accepted now.
The present theory is the “giant impact theory” or “big splat theory”. A large size body of Mars collided with the earth and that portion was separated from the earth. The same portion became as a moon which revolves around the earth. The moon was formed about 4.44 billion years ago.
Question 2.
What are the difference between terrestrial planet and jovian planets?
Answer:
The main differences between the two are summarized below:
The terrestrial planets were formed in the close vicinity of the planet star where it was too warm for gases to condense solid particles. Jovian planets were formed at a quite distant location.
The solar wind was most intense nearer the sun, so it blew off lots of gas and dust from the terrestrial planets. The solar winds were not all that intense to cause similar removal of gases from the Jovian planets.
The terrestrial planets are smaller and their lower gravity could not hold the escaping gases. Jovian planets are bigger and have high gravity.
Question 3.
Inner planets are terrestrial while outer planets are Jovian. Why?
Answer:
Inner planets are terrestrial while outer planets are Jovian because the terrestrial planets are smaller and their lower gravity could not hold the escaping gases. Jovian planets are bigger and have high gravity. Moreover, the solar wind was most intense nearer the sun, so it blew off lots of gas and dust from the terrestrial planets. The solar winds were not all that intense to cause similar removal of gases from the Jovian planets.
Question 4.
How did earth develop its different layers?
Answer:
During the formation of the moon, due to the giant impact, the earth was further heated up. It is through the process of differentiation that the earth forming material got separated into different layers. Starting from the surface to the central parts, we have layers like the crust, mantle, outer core and inner core. From the crust to the core, the density of the material increases.
Question 5.
Differentiate between inner planets and outer planets.
Answer:
The difference between inner planets and outer planets inner planets outer planets
Inner Planets Outer Planets
1. Mercury, Venus, Earth and Mars are called Inner Planets 1. Jupiter, Saturn, Uranus, Neptune and Pluto are called Outer Planets
2. They are found between belt of asteroids and the sun 2. They are found after the belt of asteroids
3. They are also called terrestrial planets 3. They are called Jovian planets
4. Smaller in size 4. Larger in size
5. High density 5. Low density
6. Solid rocky state 6. Gaseous state
7. They are warm 7. They are cold
Class 11 Geography Chapter 2 Long Answer Type Questions
Question 1.
Explain how did life evolve on the earth?
Answer:
The origin of life as a kind of chemical reaction, which first generated complex organic molecules and assembled them. This assemblage was such that they could duplicate themselves converting inanimate matter into living substance. The record of life that existed on this • planet in different periods is found in rocks in the form of fossils. The microscopic structures closely related to the present form of the blue algae have been found in geological formations m uch older than some 3,000 million years. It can be assumed that life began to evolve sometime 3,800 million years ago.
Question 2.
Explain different phases of evolution of planets.
Answer:
Evolution of planets can be understood in three stages:
1. Formation of Disc; The stars are localised lumps of gas within a nebula. The gravitational force within the lumps leads to the formation of a core to the gas cloud and a huge rotating disc of gas and dust develops around the gas core.
2. Formation of Planetesimals: In the next stage, the gas cloud starts and getting condensed and the matter around the core develops into small rounded objects. These small rounded objects by the process of collision develop into what is called planetesimals. Larger bodies start forming by collision and gravitational attraction causes the materials to stick together. Planetesimals are a large number of smaller bodies.
3. Formation of Planets: In the final stage, these large number of small planetesimals accrete to form fewer large bodies in the form of planets.
Question 3.
Explain the earliest theory associated with the origin of the earth.
Answer:
A large number of hypotheses were put forth by different philosophers and scientists regarding the origin of the earth. One of the earlier and popular arguments was by German philosopher Immanuel Kant. Mathematician Laplace revised it in 1796. It is known as Nebular Hypothesis. According to this theory there was a hot and rotating gas cloud called Nebula in the space. From Nebula there was a gradual loss of heat due to its rotation which resulted in cooling of its outer surface. This gradual cooling caused contraction in size of Nebula, but its speed increased due to angular momentum. The outer layer was separated from the remaining part of Nebula.
The centre of Nebula became ‘Sun’ and the planets were formed of the smaller units. The lighter material gases and the heavier dust particle gave the fact of inner and outer planets. In 1950, Otto Schmidt in Russia and Carl Weizasear in Germany somewhat revised the ‘nebular hypothesis’, though differing in details. They considered that the sun was surrounded by solar nebula containing mostly the hydrogen and helium along with what may be termed as dust. The friction and collision of particles led to formation of a disk-shaped cloud and the planets were formed through the process of accretion.
Question 4.
Explain the modern theory associated with evolution of the earth.
Answer:
In modern theory the evolution of the earth is associated with Big Bang Theory. It was put forth by Edwin Hubble in 1920. In the beginning, all matter forming the universe existed in one place in the form of a ‘tiny ball” \yith an unimaginably- small volume infinite temperature and infinite density. At the Big Bang “tiny ball” exploded violently. This led to a huge” expansion. it is now generally? accepted that the event of big. bang took place 13.7 billion years before the present. The expansion continues even to the present day. As it grew, some energy’ was converted into matter. There was particularly rapid expansion within fractions of a second’ after the bang. Thereafter, the expansion has slowed down. Within first Big Bang event, the first atom began to form.
Within 300,000 years from the Big Bang, temperature dropped to 4,500k and gave rise to atomic matter. The universe became transparent. The expansion of universe means increase in space between the galaxies. An alternative to this was Hoyle’s concept of steady state. It considered the universe to be roughly the same at any point of time. However, with greater evidence becoming available about the expanding universe, scientific community at present favours argument of expanding universe.
Question 5.
Explain the collision and accretion I hypothesis associated with the evolution of the earth.
Answer:
Collision hypothesis and accretion hypothesis are described below in short.
1. Collision Hypothesis: It was given by Sir James and Harold Jeffrey.
According to this theory, a large nebula ’wandering in the space came very close to smaller nebula (Sun) and its huge upsurge of matter on the surface of smaller nebula. The matter was detected from the smaller nebula and on cooling condensed into planets.
2. Accretion Hypothesis: It was given by? Schmidt and Carl Weizascar.
According to them, solar system started out as a cloud of gas and dust drifting in a space called nebula. This gaseous cloud
exploded violently to form supernova. The exploitation left the vast spinning cloud and gases and thus to collapse under its own gravity and develop as denser core.
The denser core became larger and hotter and began to burge. Later it developed into protostar which finally evolved as ‘infant Sun.
Away from its central surface, particles of dust began to clump together and converted into first smaller fragments of rocks and then becoming larger bodies which were called planetesimals which collided with one another to form rocky inner planets like Mercury, Venus, Earth and Mars and the remaining were outer planets.
Class 11 Geography Chapter 2 Hots Questions
Question 1.
How’ was the layered structure of the earth developed?
Answer:
The planet earth initially was a barren, rocky arid hot object with a thin atmosphere of hydrogen and helium. This is far from the present day picture of the earth. It is said that in initial stage the earth was in liquid form. Certainly, there must have been some events- processes, which may? have caused this change from rocky, barren and hot earth to a beautiful planet with ample amount of water and conducive atmosphere favouring the existence of life.
The earth was mostly in a volatile state during its primordial stage. Due to gradual increase in density the temperature inside has increased. As a result the material inside started getting separated depending on their densities. This allowed heavier materials (like iron) to sink towards the centre of the earth and the lighter ones to move towards the surface. With passage of time it cooled further and solidified and condensed into a smaller size. This later led to the development of the outer surface in the form of a crust. It is through the process of differentiation that the earth forming material got separated into different layers.
Question 2.
What role did carbon dioxide pipy in the formation of oceans?
Answer:
The carbon dioxide in the atmosphere got dissolved in rainwater and the
temperature further decreased causing more condensation and more rains. The rainwater falling onto the surface got collected in the depressions to give rise to oceans. The earth’s oceans were formed within 500 million years from the formation of the earth.
Class 11 Geography Chapter 3 NCERT Textbook Questions Solved
1. Multiple choice questions
Question 1(i).
Which one of the following earthquake waves is more destructive?
(a) P-waves
(b) S-waves
(c) Surface waves
(d) None of the above.
Answer:
(a) P-waves
Question 1(ii).
Which one of the following is a direct source of information about the interior of the earth?
(а) Earthquake waves
(b) Volcanoes
(c) Gravitational force
(d) Earth magnetism.
Answer:
(а) Earthquake waves
Question 1(iii).
Which type of volcanic eruptions have caused Deccan Trap formations?
(a) Shield
(b) Flood
(c) Composite
(d) Caldera.
Answer:
(b) Flood
Question 1(iv).
Which one ofthe following describes the lithosphere?
(a) Upper and lower mantle
(b) Crust and upper mantle
(c) Crust and core
(d) Mantle and core.
Answer:
(b) Crust and upper mantle
2. Answer the following questions in about 30 words.
Question 2(i).
What are body waves?
Answer:
Body waves are generated due to the release of energy at the focus and move in all directions travelling through the body of the earth. Therefore, it has been named as body waves. These are of two types: P-waves and S-waves.
Question 2(ii).
Name the direct sources of information about the interior of the earth.
Answer:
Some of the direct sources are:-
Mining: It is a process by which commercially variable valuable mineral resources are extracted from Earth’s surface which includes precious stones, rocks and solid fuels.
Drilling: Scientists world over are working on two major projects such as “Deep Ocean Drilling Projects” and “Integrated Ocean Drilling Project”. The deepest drill at Kola, in Arctic Ocean, has so far reached a depth of 12 km.
Volcanic Eruptions: When molten material is thrown onto the surfaced earth during volcanic eruption it becomes available for analysis
Question 2(iii).
Why do earthquake waves develop shadow zone?
Answer:
Earthquake waves get recorded in seismographs located at far offlocations. But there exist some specific areas where the waves are not reported. Such a zone is called the ‘shadow zone’. The study of different events reveals that for each earthquake, there exists an altogether different shadow zone. It was observed that seismographs located at any distance within 105° from the epicentre, recorded the arrival of both P and S-waves.
However, the seismographs located beyond 145° from epicentre, record the arrival of P-waves, but not that of S-waves. Thus, a zone between 105° and 145° from epicentre was identified as the shadow zone for both the types of waves. The entire zone beyond 105° does not receive S-waves. The shadow zone of S-wave is much larger than that of the P-waves. The shadow zone of P-waves appears as a band around the earth between 105° and 145° away from the epicentre. The shadow zone of S-waves is not only larger in extent but it is also a little over 40 per cent of the earth surface.
Question 2(iv).
Briefly explain the indirect sources of information of the interior of the earth other than those of seismic activity.
Answer:
Analysis of properties of matter indirectly provides information about the interior
Meteors
Gravitation
Magnetic field
Seismic Activity.
3. Answer the following questions in about 150 words.
Question 3(i).
What are the effects of propagation of earthquake waves on the rock mass through which they travel?
Answer:
Earthquake waves are basically of two types: Body waves and surface waves. Body waves are generated due to the r elease of energy at the focus and move in all directions travelling through the body of the earth. Therefore these are called body weaves. The body wraves interact with the surface rocks and generate new set of waves called surface waves. These waves move along the surface. The velocity of waves changes as they travel through materials with different densities. The denser the material, the higher is the velocity. The direction of vibrations of S-waves is perpendicular to the wave direction in the vertical plane. Hence, they create troughs and crests in the material through which they pass. Surface waves are considered to be the most damaging waves.
Seismographs . located at any distance within 105° from the epicentre, recorded the arrival of both P and S-waves, However, the seismographs located beyond 145° from epicentre, record the arrival of P-waves, hut not that of S-waves. Thus, a zone between 105° and 145° from epicentre was identified as the shadow zone for both the types of waves. The entire zone beyond 105° does not receive S-waves. The shadow zone of S-wave is much larger than that of the P-waves. The shadow zone of P-waves appears as a band around the earth between 105° and 145° away from the epicentre. The shadow zone of S-waves is not only larger in extent but it is also a little over 40 per cent of the earth surface.
Question 3(ii).
What do you understand by intrusive forms? Briefly describe various intrusive forms.
Answer:
The lava that cools within the crustal portions assumes different forms. These forms are called intrusive forms. Important intrusive forms are described below:
Batholiths: A large body of magmatic material that cools in the deeper depth of the crust develops in the form of large
domes. Batholiths are the cooled portion of magma chambers.
Lacoliths: These are large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below. It resembles the surface volcanic domes of composite volcano, only these are located at deeper depths.
Lapolith: As and when the lava moves upwards, a portion of the same may tend to move in a horizontal direction wherever it finds a weak plane. It may get rested in different forms. In case it develops into a saucer shape, concave to the sky body, it is called lapolith.
Phaeolith: A wavy mass of intrusive rocks, at times, is found at the base of synclines or at the top of anticline in folded igneous country. Such wavy materials have a definite conduit to source beneath in the form of magma chambers (subsequently developed as batholiths). These are called the phacoliths.
Sills: The near horizontal bodies of the intrusive igneous rocks are called sill or sheet, depending on the thickness of the material. The thinner ones are called sheets while the thick horizontal deposits are called sills.
Dykes: When the lava makes its way through cracks and the fissures developed in the land, it solidifies almost perpendicular to the ground. It gets cooled in the same position to develop a wall-like structure. Such structures are called dykes.
Class 11 Geography Chapter 3 NCERT Extra Questions
Class 11 Geography Chapter 3 Multiple Choice Questions
Question 1.
How do we measure magnitude of earthquake?
(a) Richter Scale
(b) Mercalli Scale
(c) Measuring Scale
(d) Seismograph.
Answer:
(a) Richter Scale
Question 2.
How do we measure intensity of earthquake?
(a) Richter Scale
(b) Mercalli Scale
(c) Measuring Scale
(d) Seismograph.
Answer:
(b) Mercalli Scale
Question 3.
Fast moving waves which reach the earth earliest are called:
(a) Alpha Waves
(b) S-Waves
(c) P-Waves
(d) Beta Waves.
Answer:
(c) P-Waves
Question 4.
The upper portion of mantle is called:
(a) Asthenosphere
(b) Crust
(c) Lithosphere
(d) Fossil Sphere.
Answer:
(a) Asthenosphere
Question 5.
What is the approximate depth of mantle?
(a) 2400 km
(b) 2900 km
(c) 3200 km
(d) 3500 km.
Answer:
(b) 2900 km
Question 6.
Core is made of which metals?
(a) Iron and Magnesium
(b) Iron and Silicon
(c) Nickel and Iron
(d) Nickel and Magnesium.
Answer:
(d) Nickel and Magnesium.
Question 7.
What is the density of the rocks between the adjoining line on mantle and core?
(а) 3-4 gm per sq cm
(b) 5 gm per sq cm
(c) 4-5 gm per sq cm
(d) 6 gm per sq cm.
Answer:
(b) 5 gm per sq cm
Question 8.
What is the thickness of the crust?
(a) 10 km to 200 km
(b) 50 km to 300 km
(c) 30 km to 400 km
(d) 100 km to 200 km.
Answer:
(a) 10 km to 200 km
Question 9.
What is the density of the rocks of mantle?
(a) 3-4 gm per sq cm
(b) 5 gm per sq cm
(c) 4-5 gm per sq cm
(d) 6 gm per sq cm.
Answer:
(a) 3-4 gm per sq cm
Question 10.
Crust and upper portion of mantle taken together is called:
(a) Asthenosphere
(b) Magma
(c) Lithosphere
(d) Core.
Answer:
(c) Lithosphere
Question 11.
What is the mean thickness of oceanic crust?
(a) 5 km
(b) 30 km
(c) 10 km
(d) 70 km.
Answer:
(a) 5 km
Question 12.
What is the mean thickness of continental crust?
(a) 5 km
(b) 30 km
(c) 10 km
(d) 70 km.
Answer:
(b) 30 km.
Class 11 Geography Chapter 3 Very Short Answer Type Questions
Question 1.
By which metals is core made of?
Answer:
Core is made up of nickel and iron.
Question 2.
Name the deepest mine of the world.
Answer:
Gold mines in South Africa are as deep as 3 – 4 km.
Question 3.
How do we measure magnitude, of an earthquake?
Answer:
We measure magnitude of an earthquake using Richter Scale.
Question 4.
What is the thickness of the crust in oceans, continents and mountains?
Answer:
The mean thickness of oceanic crust is 5 km whereas that of the continental is around 30 km. The continental crust is thicker in the areas of major mountain systems. It is as much as 70 km thick in the Himalayan region.
Question 5.
What do you mean by dykes?
Answer:
When the lava makes its way through cracks and the fissures developed in the land, it solidifies almost perpendicular to the ground. It gets cooled in the same position to develop a wall-like structure. Such structures are called dykes.
Question 6.
What do we get to know about the interior of the earth through mining?
Answer:
We get to know through the mining activity that temperature and pressure increase with the increasing distance from the surface towards the interior in deeper depths. Moreover, it is also known that the density of the material also increases with depth.
Question 7.
What do you mean by gravitational anomaly?
Answer:
The difference in readings from the expected values is called gravity anomaly. Gravity anomaly give us information about the distribution of mass of the material in the crust of the earth.
Question 8.
What do you mean by caldera?
Answer:
These are the most explosive of the earth’s volcanoes. They are usually so explosive that when they erupt they tend to collapse on themselves rather than building any tall structure. The collapsed depressions are called calderas.
Question 9.
When can an earthquake cause tsunami?
Answer:
An earthquake can take form of tsunami if its epicentre is below ocean and its magnitude is very high. An earthquake of magnitude more than 5 on Richter scale can prove to be very dangerous.
Question 10.
What are different types of forces?
Answer:
There are two types of forces:-
Exogenic forces: These are the forces on the surface of the earth like weathering, erosion, mining, etc.
Endogenic forces: These are the forces under the surface of the earth, like volcanic eruption, earthquake and any other seismic activity, tectonic plates.
Question 11.
Name the interior most part of the earth. What is its depth?
Answer:
Core is the interior most part of the earth. Its depth is between 2900 km to 6373km.
Question 12.
What is a volcano?
Answer:
A volcano is a place where gases,’ ashes and/or molten rock material – lava – escape to the ground.
Question 13.
What are intrusive forms?
Answer:
The lava that cools within the crustal portions assumes different forms. These forms are called intrusive forms.
Question 14.
What are batholiths?
Answer:
A large body of magmatic material that cools in the deeper depth of the crust develops in the form of large domes. Batholiths are the cooled portion of magma chambers.
Question 15.
What do you mean by hypocentre?
Answer:
The point where the energy is released is called the focus of an earthquake, alternatively, it is called the hypocentre.
Question 16.
What are surface waves?
Answer:
The body waves interact with the surface rocks and generate new set of waves called surface waves. These waves move along the surface. These waves are very destructive.
Question 17.
What do you mean by lapoliths?
Answer:
As and when the lava moves upwards, a portion of the same may tend to move in a horizontal direction wherever it finds a weak plane. It may get rested in different forms. In case it develops into a saucer shape, concave to the sky body, it is called lapoliths.
Question 18.
What do you mean by lacoliths?
Answer:
These are large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below. It resembles the surface volcanic domes of composite volcano, only these are located at deeper depths.
Question 19.
What do you mean by phacoliths?
Answer:
A wavy mass of intrusive rocks, at times, is found at the base of synclines or at the top of anticline in folded igneous country. Such wavy materials have a definite conduit to source beneath in the form of magma chambers (subsequently developed as batholiths). These are called the phacoliths.
Question 20.
What do you mean by sills?
Answer:
The near horizontal bodies of the intrusive igneous rocks are called sill or sheet, depending on the thickness of the material. The thinner ones are called sheets while the thick horizontal deposits are called sills.
Question 21.
What is magma?
Answer:
As long as liquid rocks are in the upper portion of the mantle, it is called magma.
Question 22.
Give meaning of mid-ocean ridge volcanoes.
Answer:
These volcanoes occur in the oceanic areas. There is a system of mid-ocean ridges more than 70,000 km long that stretches through all the ocean basins. The central portion of this ridge experiences frequent eruptions.
Class 11 Geography Chapter 3 Short Answer Type Questions
Question 1.
Write a note on composite volcanoes.
Answer:
These volcanoes are characterised by eruptions of cooler and more viscous lavas than basalt. These volcanoes often result in explosive eruptions. Along with lava, large quantities of pyroclastic material and ashes find their way to the ground. This material accumulates in the vicinity of the vent openings leading to formation of layers, and this makes the mounts appear as composite volcanoes.
Question 2.
Give a brief description of caldera.
Answer:
These are the most explosive of the earth’s volcanoes. Their features are as follows:
They are usually so explosive that when they erupt they tend to collapse on themselves rather than building any tall structure. The collapsed depressions are called calderas.
Their explosiveness indicates that the magma chamber supplying the lava is not only huge but is also in close vicinity.
The hills produced by them are similar to the one made by composite volcanoes.
Question 3.
Write a short note on flood basalt provinces.
Answer:
These volcanoes outpour highly fluid lava that flows for long distances.
Some parts of the world are covered by thousands of sq. km of thick basalt lava flows.
There can be a series of flows with some flows attaining thickness of more than 50 m.
Individual flows may extend for hundreds of km.
The Deccan Traps from India, presently covering most of the Maharashtra plateau, are a much larger flood basalt province.
It is believed that initially the trap formations covered a much larger area than the present.
Question 4.
Explain the uppermost layer of the earth- crust.
Answer:
It is the outermost solid part of the earth. It is brittle in nature.
Thickness: The thickness of the crust varies under the oceanic and continental areas. Oceanic crust is thinner as compared to the continental crust. The mean thickness of oceanic crust is 5 km whereas that of the continental is around 30 km. The continental crust is thicker in the areas of major mountain systems. It is as much as 70 km thick in the Himalayan region.
Composition: It is made up of heavier rocks.
Density: It is having density of 3 g/cm3.
In Oceans: This type of rock found in the oceanic crust is basalt. The mean density of material in oceanic crust is 2.7 g/cm3.
Question 5.
Explain the innermost layer of the earth- core.
Answer:
The Core is the innermost layer of the earth.
Information: The earthquake wave velocities helped in understanding the existence of the core of the earth.
Depth: The core- mantle boundary is located at the depth of 2,900 km.
Form: The outer core is in liquid state while the inner core is in solid state.
Density: The density of material at the mantle core boundary is around 5 g/cm3
and at the centre of the earth at 6,300 km, the density value is around 13g/cm3.
Composition: The core is made up of very heavy material mostly constituted by nickel and iron.
Other name: It is sometimes referred to as the nife layer.
Question 6.
Explain the middle layer of the earth- mantle.
Answer:
The Mantle: The portion of the interior beyond the crust is called the mantle.
Depth: The mantle extends from Moho’s discontinuity to a depth of 2,900 km.
Asthenosphere: The upper portion of the mantle is called asthenosphere. The word astheno means weak. It is considered to be extending upto 400 km. It is the main source of magma that finds its way to the surface during volcanic eruptions.
Density: It has a density higher than the crust’s (3.4 g/cm3).
Upper Mantle: The crust and the uppermost part of the mantle are called lithosphere. Its thickness ranges from 10-200 km.
Lower Mantle: The lower mantle extends beyond the asthenosphere. It is in solid state.
Question 7.
Write a short note on shield volcanoes.
Answer:
Shield Volcanoes:
Composition: These volcanoes are mostly made up of basalt, a type of lava that is very fluid when erupted. For this reason, these volcanoes are not steep. They become explosive if somehow water gets into the vent; otherwise, they are characterised by low-explosivity.
Largest of all: Barring the basalt flows, the shield volcanoes are the largest of all the volcanoes on the earth.
Examples: The Hawaiian volcanoes are the most famous examples.
Movement of Lava: The upcoming lava moves in the form of a fountain and throws out the cone at the top of the vent and develops into cinder cone.
Question 8.
What are the effects of earthquake?
Answer:
The following are the immediate hazardous effects of earthquake
Loss of life and property: Ground shaking takes place in earthquake. It leads to loss of life and property. Many buildings fall off and take life of people who were in and around the building.
Change in land: Due to earthquake we can see many changes in the land. Many areas get converted into pits. There are cracks in mountains.
Causes landslides and tsunami: It leads to landslides in mountainous regions and tsunami in oceans. It may further aggravate the calamity and loss of human and property.
Destruction of means of communication and transportation: It leads to destruction of means of communication and transportation. It creates problem in sending help and relief to victims.
Other effects: Earthquake may also lead to breaking or damage of dams which mav lead to floods. .
Question 9.
What is earthquake? Discuss focus/ hypocentre and epicentre. How do we measure its magnitude and intensity?
Answer:
An earthquake is shaking of the earth. It’s a nature event. It is caused due to release of energy, which generates waves that travel in all directions.
Focus/Hypocentre: The point where the energy is released is called the focus/ Hypocentre of an earthquake.
Epicentre: The point on the surface which is nearest to the focus of energy is called epicentre. It is the first one to experience the waves. It is a point directly above the focus.
Measurement of earthquake:
Magnitude: It is measured by Richter Scale
Intensity: It is measured by Mercalli Scale.
Question 10.
Differentiate between Body waves and Surface waves?
Answer:
Main differences between body waves and surface waves are given below:
Body waves:
These are generated due to the release of energy at the focus.
They move in all directions travelling through the body of the earth.
These are less destructive than the surface waves.
Surface waves:
The body waves interact with the surface rocks and generate new set of waves called surface waves.
These waves move along the surface.
These waves are more destruction.
| P-Waves | S-Waves | |
| Other name | These are called primary waves. | These are called secondary waves. |
| Speed | These move faster and are the first to arrive at the surface. | These arrive at surface with sometime later. |
| Shadow Zone | The shadow zone of P-wave is much smaller than that of the S-waves. | The shadow zone of S-wave is much larger than that of the P-waves. |
| Source of travelling | They travel through gaseous, liquid and solid materials. | S-waves can travel only through solid materials. |
Class 11 Geography Chapter 3 Long Answer Type Questions
- Tectonic earthquake: The most common ones are the tectonic earthquakes. These are generated due to sliding of rocks along a fault plane.
- Volcanic earthquake: A special class of tectonic earthquake is sometimes recognised as volcanic earthquake. However, these are confined to areas of active volcanoes.
- Collapse earthquake: In the areas of intense mining activity, sometimes the roofs of underground mines collapse causing minor tremors. These are called collapse earthquakes.
- Explosion earthquake: Ground shaking may also occur due to the explosion of chemical or nuclear devices. Such tremors are called explosion earthquakes.
- Reservoir Induced earthquake: The earthquakes that occur in the areas of large reservoirs are referred to as reservoir induced earthquakes. Sometimes earthquakes also occur in mines due to mining processes. Sometimes earthquakes also occur below the oceans on surface of the ocean causing tsunamis.
- Mining: It is a process by which commercially variable valuable mineral resources are extracted from Earth’s surface which includes precious stones, rocks and solid fuels.
- Drilling: Scientists world over are working on two major projects such as “Deep Ocean Drilling projects” and “integrated ocean drilling project”. The deepest drill at kola, in Arctic Ocean, has so far reached a depth of 12 km.
- Volcanic Eruptions: When molten material is thrown onto the surface of the earth during volcanic eruption it becomes available for analysis.Some of the indirect sources of information: Analysis of properties of matter indirectly provides information about the interior. Knowing the total thickness of the earth, scientists have estimated the values of temperature, pressure and the density of materials at different depths.
- Meteors that at times reach the earth: However, it may be noted that the material that becomes available for analysis from meteors, is not from the interior of the earth. The material and the structure observed in the meteors are similar to that of the earth. They are solid bodies developed out of materials same as, or similar to, our planet. Hence, this becomes yet another source of information about the interior of the earth.
- Gravitation: The gravitation force (g) is not the same at different latitudes on the surface. It is greater near the poles and less at the equator. This is because of the distance from the centre at the equator being greater than that at the poles. The gravity values also differ according to the mass of material.
- Magnetic surveys: Magnetic surveys also provide information about the distribution of magnetic materials in the crustal portion, and thus, provide information about the distribution of materials in this part.
- Body waves: These are generated due to the release of energy at the focus. They move in all directions in all directions travelling through the body of the earth. These are less destructive than the surface waves.
- Surface waves: The body waves interact with the surface rocks and generate new set of waves called surface waves. These waves move along the surface. These waves are more destruction. The surface waves are the last to report on seismograph. These waves are more destructive. They cause displacement of rocks, and hence, the collapse of structures occurs.There are two types of body waves. They are called P- and S-waves,
- P-waves: They move faster and are the first to arrive at the surface. These are also called ‘primary waves’. The P-waves are similar to sound waves. They travel through gaseous, liquid and solid materials.
- S-Waves: S-waves arrive at the surface with some time lag. These are called secondary waves. An important fact about S-waves is that they can travel only through solid materials. This characteristic of the S-waves is quite important. It has helped scientists to understand the structure of t he interior of the earth. Reflection causes was es to rebound whereas refraction makes waves move in different directions. The variations in the direction of waves are inferred with the help of their record on seismograph.
2. Mantle: The portion of the interior beyond the crust is called the mantle. The mantle extends from Moho’s discontinuity to a depth of 2,900 km. The upper portion of the mantle is called asthenosphere. The word astheno means weak. It is considered to be extending upto 400 km. It is the main source of magma that finds its way to the surface during volcanic eruptions. It has a density higher than the crust’s (3.4 g/ cm3). The crust and the uppermost part of the mantle are called lithosphere. Its thickness ranges from 10-200 km. The lower mantle extends beyond the asthenosphere. It is in solid state.
3. Core: The earthquake wave velocities helped in understanding the existence of the core of the earth. The core- mantle boundary is located at the depth of 2,900 km. The outer core is in liquid state while the inner core is in solid state. The density of material at the mantle core boundary is around 5 g/cm3 and at the centre of the earth at 6,300 km, the density value is around 13g/cm3. The core is made up of very heavy material mostly constituted by nickel and iron. It is sometimes also called the nife layer.
1. Shield Volcanoes: These volcanoes are mostly made up of basalt, a type of lava that is very fluid when erupted. For this reason, these volcanoes are not steep. They become explosive if somehow water gets into the vent; otherwise, they are characterised by low-explosivity. Barring the basalt flows, the shield volcanoes are the largest of all the volcanoes on the earth. The Hawaiian volcanoes are the most famous examples. The upcoming lava moves in the form of a fountain and throws out the cone at the top of the vent and develops into cinder cone.
2. Composite Volcanoes: These volcanoes are characterised by eruptions of cooler and more viscous lavas than basalt. These volcanoes often result in explosive eruptions. Along with lava, large quantities of pyroclastic material and ashes find their way to the ground. This material accumulates in the vicinity of the vent openings leading to formation of layers, and this makes the mounts appear as composite volcanoes.
3. Calderas: These are the most explosive of the earth’s volcanoes. They are usually so explosive that when they erupt they tend to collapse on themselves rather than building any tall structure. The collapsed depressions are called calderas. Their explosiveness indicates that the magma chamber supplying the lava is not only huge but is also in close vicinity. The hills produced by them are similar to the one made by composite volcanoes.
4. Basalt Flood Provinces: These volcanoes outpour highly fluid lava that flows for long distances. Some parts of the world are cohered by thousands of sq. km of thick basalt lava flows. There can be a series of flows with some flows attaining thickness of more than 50 m. Individual flows may extend for hundreds of km. The Deccan Traps from India, presently covering most of the Maharashtra plateau, are a much larger flood basalt province. It is believed that initially the trap formations covered a much larger area than the present.
5. Mid-Ocean Ridge Volcanoes: These volcanoes occur in the oceanic areas. There is a system of mid-ocean ridges more than 70,000 km long that stretches through all the ocean basins. The central portion of this ridge experiences frequent eruptions.
Class 11 Geography Chapter 3 Hots Questions
Although it is not illustrated think what would happen to an S-wave that just entered the outer liquid core. S-waves cannot travel through a liquid so from 105° to 105° degrees on either side of the epicentre no S-waves are recorded. This is the S-Wave Shadow Zone.
:
Question 3.
Explain the distribution of earthquake and volcanic plate on the earth,
Answer:
Earthquake and Volcanic plate:
1. It goes from Atlantic Ocean almost parallel to the coastlines. It further extends into the Indian Ocean. It bifurcates a little south of the Indian subcontinent with one branch moving into East Africa and the other meeting a similar line from Myanmar to New Guiana.
2. Another area of concentration coincides with the Alpine-Himalayan system and the rim of the Pacific Ocean. In general, the foci of the earthquake in the areas of mid-oceanic ridges are at shallow depths whereas along the Alpine-Himalayan belt as well as the rim of the Pacific, the earthquakes are deep-seated ones. The map of volcanoes also shows a similar pattern. The rim of the Pacific is also called rim of fire due to the existence of active volcanoes in this area.
Question 4.
What information do we get from the mapping of the ocean floor and palaeomagnetic studies of rocks from oceanic regions?
Answer:
The mapping of the ocean floor and palaeomagnetic studies of rocks from oceanic regions gave following information:
- Along the mid-oceanic ridges, volcanic eruptions are common and they bring huge amounts of lava to the surface in this area.
- The rocks equidistant on either sides of the crest of mid-oceanic ridges show remarkable similarities in terms of period of formation, chemical compositions and magnetic properties.
- The ocean crust rocks are much younger than the continental rocks. The age of rocks in the oceanic crust is nowhere more than 200 million years old. Some of the continental rock formations are as old as 3,200 million years.
- The sediments on the ocean floor are unexpectedly very thin. Scientists expected that if the ocean floors were as old as the continent, to have a complete sequence of sediments for a period of much longer duration. However, nowhere was the sediment column found to be older than 200 million years.
- The deep trenches have deep-seated earthquake occurrences while in the mid-oceanic ridge areas, the quake foci have shallow’ depths.
Question 5.
Explain the basic concept of continental drift theory.
Answer:
Alfred Wegener, a German meteorologist, put forth a comprehensive argument in the form of “the continental drift theory” in 1912. This was regarding the distribution of the oceans and the continents. According to Wegener, all the continents formed a single continental mass and mega ocean surrounded the same. He called the super continent as PANGAEA, meaning all earth. He named mega ocean as PANTHALASSA, meaning all water. According to him. around 200 million years ago, the super continent, Pangaea, began to split. Pangaea first broke into two large continental masses as Laurasia and Gondwanaland forming the northern and southern components respectively. Subsequently, Laurasia and Gondwanalan d continued to break into various smaller continents that exist today. A variety of evidence was offered in support of the continental drift.
Question 6.
Explain different types of boundaries that form as a result of tectonic plates.
Answer:
Three types of boundaries are formed as a result of tectonic plates:
- Convergent Boundaries: Where the crust is destroyed as one plate dived under another, it is called convergent boundaries.
- Divergent Boundaries: Where new crust is generated as the plates pull away from each other, these are called divergent boundaries.
- Transform Boundaries: Where the
crust is neither produced nor destroyed as the plates slide horizontally past each other. ,
Class 11 Geography Chapter 4 Long Answer Type Questions
Question 1.
According to tectonic plates theory in how many plates has the earth been divided? Explain.
Answer:
The theory of plate tectonics proposes that the earth’s lithosphere is divided into seven major and some minor plates. The major plates are as follows:
- Antarctica and the surrounding oceanic plate
- North American plate
- South American plate
- Pacific plate
- India-Australia-New Zealand plate
- Africa with the eastern Atlantic floor plate
- Eurasia and the adjacent oceanic plate. Some important minor plates are:
- Cocos plate: It is between Central America and Pacific plate
- Nazca plate: It is between South America and Pacific plate
- Arabian plate: It includes mostly the Saudi Arabian landmass
- Philippine plate: It is between the Asiatic and Pacific plate
- Caroline plate: It is between the Philippine and Indian plate (North of New Guinea)
- Fuji plate: It includes North-east of Australia.
- Pacific plate is largely an oceanic plate whereas the Eurasian plate may be called a continental plate. Plates are not static. Plates may converge or diverge. Plates may break as well.
Question 2.
Explain tectonic plate theory and its j working.
Answer:
These plates have been constantly moving over the globe throughout the history of the earth.
- The theory of plate tectonics was introduced by Mckenzie, Parker and , Morgan in 1967.
- A tectonic plate is also called as lithosphere plate.
- It is a massive irregularly shaped slab of solid rock.
- Consists of oceanic and continental sphere.
- Plates move horizontally over the asthenosphere.
- Average thickness is 100 km of oceanic part and 200 km of continental part.
- It may be oceanic or continental.
- Pacific plate is largest oceanic plate whereas Eurasian plate is the largest continental plate.
- These plates are moving constantly throughout geological time not the continent, believed by Wegener.
It creates three types of boundaries.
- Divergent boundaries
- New crust is generated
- Plates move away from each other
- These are called spreading sites
- Ex. Mid atlantic ridge
- Convergent boundaries |
- Crust is destroyed
- Sinking of plate is called “subduction zone”. There are three ways in which subduction occurs (i) between an oceanic and continental plates; (ii) between two oceanic plates; and (iii) between two continental plates.
- Transform boundaries: Where the crust is neither produced nor destroyed as the plates slide horizontally past each other.
Question 3.
Explain important theories associated with the movement of continents.
Answer:
Continental drift: Abraham Ortelius a Dutch map maker in 1596 first proposed the possibility of joining the continents such as America with Europe and Africa. Antonio Pellegrini drew a map showing the three continents together. Alfred Wegener, a German meteorologist put forth the continental drift theory. According to him, all continents formed a single continental mass called Pangaea.
All oceans formed a single universal ocean called Panthalassa around 200 million years ago. The Pangaea began to split into two large continental masses called Laurasia and Gondwanaland. By further splitting Laurasia formed northern continents and Gondwanaland formed southern continents.
Sea Floor Spreading: The deep trenches have deep-seated earthquake occurrences while in the mid- oceanic ridge areas, the quake foci have shallow depths. These facts and a detailed analysis of magnetic properties of the rocks on either sides of the mid-oceanic ridge led Hess in 1961 to propose his hypothesis. It was called the “sea floor spreading”. Hess argued that constant eruptions at the crest of oceanic ridges cause the rupture of the oceanic crust forces and the new lava wedges into it, pushing the oceanic crust on either side. The ocean floor, thus spreads. Two facts made Hess think about the consumption of the oceanic crust.
- The younger age of the oceanic crust.
- The spreading of one ocean does not cause the shrinking of the other.
He further maintained that the ocean floor that gets pushed due to volcanic eruptions at the crest, sinks down at the oceanic trenches and gets consumed. Plate Tectonics: It was in 1967, McKenzie and Parker and also Morgan, independently collected the available ideas and came out with another concept termed Plate Tectonics. The theory of plate tectonics proposes that the earth’s lithosphere is divided into seven major and some minor plates. These plates have been constantly moving over the globe throughout the history of the earth. It is not the continent that moves as believed by Wegener. Continents are part of a plate and what moves is the plate. All the plates, without exception, have moved in the geological past, and shall continue to move in the future as well.
Question 4.
The ocean floor may be segmented into how many divisions based on the depth as well as the forms of relief?
Answer:
The ocean floor may be segmented into three major divisions based on the depth as well as the forms of relief. These divisions are:
(i) Continental margins,
(ii) Abyssal plains and
(iii) Mid-oceanic ridges.
- Continental margins
- Form transitional zone between continental shore and deep sea basins
- They include continental slope , shelf, continental rise and deep oceanic trenches
- Abyssal plains
- Extensive plains
- Found between continental margin and mid oceanic ridge
- Continental sediments get deposited
- Mid-oceanic ridges
- Distribution of volcanoes and earthquakes
- All volcanoes and earthquakes are parallel to the coast
- This line also co-incides with mid- Atlantic ridge and Alpine Himalayan system
- Around the Pacific Ocean it is called ring of fire mid oceanic ridges.
Class 11 Geography Chapter 4 Hots Questions
Question 1.
The rate of plate movement varies considerably. Justify.
Answer:
It is very rightly said. The strips of normal and reverse magnetic field that parallel the mid-oceanic ridges help scientists determine the rates of plate movement. These rates vary considerably.
- Slowest Rate: The Arctic Ridge has the slowest rate. It is less than 2.5 cm/yr.
- Fastest Rate: The East Pacific rise near Easter Island, in the South Pacific about 3,400 km west of Chile, has the fastest rate. It is more than 15 cm/yr.
Map Skill
Question 1.
Show on the physical map of the world,
- The Tectonic Plates
- Volcanic Eruptions
- Ring of Fire
- Hot Spots.
Answer:
Class 11 Geography
Answer:
(i) Minerals and rocks
| S.no | Minerals | Rocks |
| 1. | Naturally occurring substances with the definite chemical and physical composition. | Solid or the soften portion of the earth crust. |
| 2. | May be composed of two or more elements. | Are of three types and comprises of various metals. |
| 3. | More than 2, 000 minerals exist. | Classified as Igneous, sedimentary and Metamorphic rocks. |
(ii) Sedimentary and igneous rocks
| S.no | Sedimentary rocks | Igneous rocks |
| 1. | Made up of sediments. | Made up of solidified lava. |
| 2. | Loose sediments get sedimented into rocks. | Liquid lava gets solidified by gradual cooling. |
| 3. | Form in layers. | They are compact. |
| 4. | Contains fossils. | Do not have fossils. |
| 5. | Are organic and inorganic in nature. | They are extrusive or intrusive. |
| 6. | Permeable and allow water to seep. | In permeable and do not allow water to seep. |
| 7. | They are known as secondary rocks, these are of two types: Intrusive- granite, Diorite; Extrusive-basalt. | They are known as primary rocks e.g. organic rock-coal, limestone Inorganic- sandstone, shale. |
(iii) Igneous and metamorphic rocks
| S.no | Igneous rocks | Metamorphie rocks |
| 1. | Magma cools and solidifies. | Igneous and sedimentary rocks and are changed into metamorphie rock due to heat and temperature. |
| 2. | Igneous rocks are normally crystalline and are of two types- Intrusive and Extrusive. | Metamorphism can be of two types contact metamorphism and regional metamorphism. |
| 3. | Hard, Impermeable in nature. | They are also hard but have formed due to change in igneous and sedimentary rocks for e.g. Limestone changes into marble, sandstone into quartzite and coal into graphite. |
| 4. | In igneous rocks no bands are seen. | In metamorphie rocks banding is a normal. |
| 5. | In the intensive igneous rocks the cooling and solidification decides the size of the particles. | The arrangement of the minerals of granules is called lineation. |
(iv) Extrusive Igneous and intrusive igneous.
| S.no | Extrusive Igneous | Intrusive Igneous |
| 1. | Lava cools rapidly on the surface of earth. | Cooling and solidification occurs inside the earth surface and is a slow process. |
| 2. | Minerals crystals of extrusive igneous rocks change their structure and can became very small in size e.g. Basalt. | They are the coarse granule structure e.g. Granite Doloride. |
Class 11 Geography Chapter 5 Long Answer Type Questions
Question 1.
Explain any six physical characteristics?
Answer:
Brief information about some important minerals in terms of their nature and physical characteristics is given below :
- External crystal form: Determined by internal arrangement of the molecules- cubes octahedrons, hexagonal prism, etc.
- Fracture: Internal molecular arrangement so complex there are two planes of molecules; the crystal will break in an irregular manner, not along planes of cleavage.
- Lustre: Appearance of a material without regard to color; each mineral has a distinctive lustre like metallic, silky, glossy, etc.
- Streak: Colour of the ground powder of any mineral. It may be of the same colour as the mineral or may differ malachite is green and gives green streak.
- Structure: Particular arrangement of the individual crystal; fine, medium or coarse grained; fibrous separable, divergent and radiating.
- Specific gravity: The ratio between the weight of a given object and the weight of an equal volume of water; object weighted in air and then weighed in water and divide weight in air by the difference of the two weights.
Question 2.
Explain some important minerals and their characteristics.
Answer:
Some major minerals and their characteristics
- Feldspar: Silicon and oxygen are common elements in all types of feldspar and sodium, potassium, calcium, aluminium etc. are found in specific feldspar variety.
- Question uartz: It is one of the most important components of sand and granite. It consists of silica. It is a hard mineral virtually insoluble in water.
- Pyroxene: Pyroxene consists of cak ium, aluminum, magnesium, iron and silica. Pyroxene forms 10 percent of the earth’s crust.
- Amphibole: Aluminium, calcium, silica, iron, magnesium are the major elements of amphiboles. They form 7 per cent of the earth’s crust.
- Mica: It comprises of potassium, aluminium, magnesium, iron, silica etc. It forms 4 per cent of the earth’s crust.
- Olivine: Magnesium, iron and silica are major elements of olivine. It is used in jewellery. It is usually a greenish crystal, often found in basaltic rocks.
Question 3.
Rocks do not remain in their original form for long but may undergo transformation. Explain.
Answer:
Rocks do not remain in their original form for long but may undergo transformation. Rock cycle is a continuous process through which old rocks are transformed into new ones. Igneous rocks are primary rocks and other rocks form from these primary rocks. Igneous rocks can be changed into metamorphic rocks. The fragments derived out of igneous and metamorphic rocks form into sedimentary rocks. Sedimentary rocks themselves can turn into fragments and the fragments can be a source for formation of sedimentary rocks. The crustal rocks (igneous, metamorphic and sedimentary) once formed may be carried down into the mantle through subduction process and the same melt down due to increase in temperature in the interior and turn into molten magma, the original source for igneous rocks
Class 11 Geography Chapter 3 HOTS Questions
Question 1.
Igneous rocks act as a source of all other types of rocks. Justify.
Answer:
Yes, it is right to say that igneous rocks act as a source of all other rocks. Therefore these are also called primary rocks.
Igneous rocks are primary rocks and other rocks i.e. sedimentary and metamorphic formed from these primary rocks. Igneous rocks can be changed into metamorphic rocks. The fragments derived out of igneous and metamorphic rocks form into sedimentary rocks. Sedimentary rocks themselves can turn into fragments and the fragments can be a source for formation of sedimentary rocks. The crustal rocks (igneous, metamorphic and sedimentary) once formed may be carried down into the mantle (interior of the earth) through subduction process (parts or whole of crustal plates going down under another plate in zones of plate convergence) and the same melt down due to increase in temperature in the interior and turn into molten magma, the original source for igneous rocks.
Question 2.
Metallic minerals are more useful as compared to non metallic minerals. Do you agree? Justify your answer.
Answer:
No, I do not agree. Minerals both metallic and non metallic have their own importance.
1. Metallic minerals: These minerals contain metal content and can be sub-divided into three types:
- Precious metals: Gold, Sivler, Platinum, etc
- Ferrous metals: Iron, Nickel, Chromite, Maganese
- Non-ferrous metals: Copper, Lead, Zinc, Tin etc.
2. Non metallic minerals: These minerals do not have a metal content. Sulphur, phosphates and nitrates are some of the examples. Cement is a mixture of non metallic mineral. These minerals have their own utility. We can’t manage without these minerals.
Class 11 Geography
- .
Question 14.
Differentiate between:
1. Stalactites and Stalagmites
2. Sinkholes and Urallas
3. Gorge and Canyon
Answer:
1. Stalactites and Stalagmites
| S.No. | Stalactites | Stalagmites |
| 1. | Stalactites hang as icicles of different diameters. | Stalagmites rise up from the floor of the caves. |
| 2. | They are broad at their bases and taper towards the free ends showing up in a variety of forms. | It may take the shape of a disc, a column with either a smooth, rounded bulging end. |
2. Sinkholes and Urallas
| Sinkholes | Urallas |
| A sinkholes is an opening more or less circular at the top and funnel-shaped towards the bottom. | When sink holes and dolines join together because of slumping of material along their margins the Urallas are formed. |
3. Gorge and Canyon
- A gorge is a deep valley with very steep to straight sides and a canyon is characterized by steep step-like side slopes and may be as deep as a gorge.
- A gorge is almost equal in width at its top as well as its bottom. In contrast, a canyon is wider at its top than at its bottom. In fact, canyon is a variant of gorge.
- Example, canyons commonly form in horizontal bedded sedimentary rocks and gorge form in hard rocks.
Class 11 Geography Chapter 7 Long Answer Type Questions
Question 1.
Explain the landforms that are seen in upper part of the river.
Answer:
In upper part of the river, many beautiful and attractive landforms are formed. Some of them are as follows:
- V-shaped valleys: Valleys start as small and narrow rills; the rills will gradually develop into long and wide gullies; the gullies will further deepen, widen and lengthen to give rise to valleys. Depending upon dimensions and shape, many types of valleys like V-shaped valley, gorge, canyon, etc. can be recognised.
- Gorge: A gorge is a deep valley with very steep to straight sides.
- Canyon: A canyon is characterised by steep step-like side slopes and may be as deep as a gorge. A gorge is almost equal in width at its top as well as its bottom. In contrast, a canyon is wider at its top than at its bottom. In fact, a canyon is a variant of gorge.
- Waterfall: When the rivers start falling in pits in mountainous regions, it makes waterfall.
- Plunge pools: Once a small and shallow depression forms, pebbles and boulders get collected in those depressions and get rotated by flowing water and consequently the depressions grow in dimensions. A series of such depressions eventually join and the stream valley gets deepened. At the foot of waterfalls also, large potholes, quite deep and wide, form because of the sheer impact of water and rotation of boulders. Such large and deep holes at the base of waterfalls are called plunge pools.
Question 2.
Explain the landforms made by erosion caused by groundwater.
Answer:
Important landforms made by erosion are as follows:
1. Pools: These are conical shaped pits whose depth is three to nine metres. The width of the mouth is more than one metre. Due to solubility in water, when cracks in limestone increase, then pools take birth.
2.Swallow holes: Small to medium sized round to sub-rounded shallow depressions called swallow holes form on the surface of limestones through soil.
3. Sinkholes: A sinkhole is an opening more or less circular at the top and funnel -shaped towards the bottom with sizes varying in area from a few square metre to a hectare and with depth from a less than half a metre to thirty metres or more.
4. Uvalas: When sinkholes and dolines join together because of slumping of materials along their margins or due to roof collapse of caves, long, narrow to wide trenches called uvalas are formed.
5. Collapse sinks: If the bottom of the sinkholes forms the roof of a void or cave underground it might collapse leaving a large hole opening into a cave or a collapse sinks.
6. Lapies: Gradually, most of the surface of the limestone is eaten away by these pits and trenches, leaving it extremely irregular with a maze of points, grooves and ridges or lapies. Especially, these
ridges or lapies form due to differential solution activity along parallel to sub¬parallel joints. The lapie field may eventually turn into somewhat smooth limestone pavements.
7. Caves: In areas where there are alternating beds of rocks (shales, sandstones, quartzites) with limestones or dolomites in between or in areas where limestones are dense, massive and occurring as thick beds, cave formation is prominent. Water percolates down either through the materials or through cracks and joints and moves horizontally along bedding planes. It is along these bedding planes that the limestone dissolves and long and narrow to wide gaps called caves result. There can be a maze of caves at different elevations depending upon the limestone beds and intervening rocks. Caves normally have an opening through which cave streams are discharged. Caves having openings at both the ends are called tunnels.
Question 3.
Explain the depositional landforms made by rivers.
Answer:
Depositional Landfoi, made by rivers:
1. Alluvial Fans: Alluvia ms are formed when streams flowing from higher levels break into foot slope plains of low gradient. Normally very coarse load is carried by streams flowing over mountain slopes. This load becomes too heavy for the streams to be carried over gentler gradients and gets dumped and spread as a broad low to high cone shaped deposit called alluvial fan. Usually, the streams which flow over fans are not confined to their original channels for long and shift their position across the fan forming many channels called distributaries. Alluvial fans in humid areas show normally low cones with gentle slope from head to toe.
2. Deltas: Delta is like alluvial fans but develop at a different location. The load carried by the rivers is dumped and spread into the sea. If this load is not carried away far into the sea or distributed along the coast, it spreads and accumulates. Such areas over flood plains built up by abandoned or cut-off channels contain coarse deposits. The flood deposits of spilled waters carry relatively finer materials like silt and clay. The flood plains in a delta are called delta plains.
3. Floodplains: Floodplain is a major landform of river deposition. Large sized materials are deposited first when stream channel breaks into a gentle slope. Thus, normally, fine sized materials like sand, silt and clay are carried by relatively slow moving waters in gentler channels usually found in the plains and deposited over the bed and when the waters spill over the banks during flooding above the bed.
4. Natural Levees: Natural levees are found along the banks of large rivers. They are low, linear and parallel ridges of coarse deposits along the banks of rivers, quite often cut into individual mounds. During flooding as the water spills over the bank, the velocity of the water comes down and large sized and high specific gravity materials get dumped in the immediate vicinity of the bank as ridges. They are high nearer the banks and slope gently away from the river. The levee deposits are coarser than the deposits spread by flood waters away from the river. When rivers shift laterally, a series of natural levees can form.
5. Point Bars: Point bars are also known as meander bars. They are found on the convex side of meanders of large rivers and are sediments deposited in a linear fashion by flowing waters along the bank. They are almost uniform in profile and in width and contain mixed sizes of sediments. If there more than one ridge, narrow and elongated depressions are found in between the point bars.
Question 4.
Explain the erosional landforms created by waves and currents.
Answer:
Cliffs, Terraces, Caves and Stacks are important landforms created by erosion caused by waves and currents.
- Wave-cut cliffs: Almost all sea cliffs are steep and may range from a few m to 30 m or even more. At the foot of such cliffs there may be a flat or gently sloping platform covered by rock debris derived from the sea cliff behind. Such platforms occurring at elevations above the average height of waves is called a wave-cut terrace.
- Terraces: The lashing of waves against the base of the cliff and the rock debris that gets smashed against the cliff along with lashing waves create hollows and these hollows get widened and deepened to form sea caves. The roofs of caves collapse and the sea cliffs recede further inland.
- Sea stacks: Retreat of the cliff may leave some remnants of rock standing isolated as small islands just off the shore. Such resistant masses of rock, originally parts of a cliff or hill are called sea stacks.
Like all other features, sea stacks are also temporary and eventually coastal hills and cliffs will disappear because of wave erosion giving rise to narrow coastal plains, and with onrush of deposits from over the land behind m ay get covered up by alluvium or may get covered up by shingle or sand to form a wide beach.
Question 5.
Explain the different stages of a river.
Answer:
A river passes through three stages like a human being: youth, mature and old.
1. Youth Stage: Youth streams are less in number. In this stage with poor integration and flow over original slopes showing shallow V-shaped valleys with no floodplains or with very narrow floodplains along trunk streams. Streams divides are broad and flat with marshes, swrnmp and lakes. If meanders are present, they develop over these broad upland surfaces. These meanders may eventually entrench themselves into the uplands. Waterfalls and rapids may exist where local hard rock bodies are exposed.
2. Mature Stage: During this stage streams are plenty with good integration. The valleys are still V-shaped but deep; trunk streams are broad enough to have wider floodplains within which streams may flow in meanders confined within the valley. The flat and broad inter stream areas and swamps and marshes of youth disappear and the stream divides turn sharp. Waterfalls and rapids disappear.
3. Old Stage: Smaller tributaries during old age are few with gentle gradients. Streams meander freely over vast floodplains showing natural levees, oxbow lakes, etc. Divides are broad and flat with lakes, swamps and marshes. Most of the landscape is at or slightly above sea level.
Class 11 Geography Chapter 7 HOTS Questions
Question 1.
Distinguish between river alluvial plains and glacial outwash plains.
Answer:
River Alluvial Plains: The alluvial plain is an erosional plain that occurs from weathering caused by water currents in the sea, river or stream. Fluvial (water) movement comes from higher land regions and wear away landmasses to produce low relief plains. This is known as the alluvial plain. These landforms are made up of the deposition of sediment over a long period of time from the fluvial movement to form alluvial soil.
An alluvial plain is characterized by its relatively flat -and gently sloping landform and is normally formed at the base of a range of hills. Continuous fluvial weathering of these hills is what causes sediments to move and spread across lower levels to produce this type of plain. These plains are formed mostly by slow running rivers, as slower fluvial movement picks up less sediment off the river floor causing more particles to settle and develop into an alluvial plain. Areas where more particles are dropped off are sometimes referred to as flood plains, and the particles that settle are called alluvium.
Glacial Outwash Deposits: The large quantities of water that flowed from the melting ice deposited is called glacial outwash. Outwash plains made up of outwash deposits are characteristically flat and consist of layers of sand and other fine sediments. Such plains with their sandy soils are often used for specialized kinds of agriculture, such as the potato production in Montcalm County.
As the margins of the ice lobes retreated, glacial meltwater and precipitation drained southward to the Gulf of Mexico because higher land or glacial ice blocked flow in other directions. Ice-marginal lakes (or proglacial lakes) form when the land in front of the ice margin slopes toward the ice, allowing meltwater to pond directly in contact with the ice.
Question 2.
Distinguish between till and alluvium.
Answer:
Alluvium:
It refers to material, such as sand, silt, or clay, deposited on land by streams. Till: It refers to unsorted, nonstratified glacial deposits consisting of clay, silt, sand, and boulders transported and deposited by glacial ice.
Both are brought by streams but one by water stream and other by glacier. Therefore, in the former, boulders are not there and in latter these are found.
Question 3.
What kinds of landforms are made by wind action and action of sheet floods?
Answer:
Three landforms created by wind are; sand dunes, yardangs (half-teardrop shaped formations hill sized, and deflation hollows (wind swept depressions good examples are in death valley, California, U.S.) Wind also contributes to significant sculpting of sandstone rock including arches.
Sheet flood can create flood plains, natural levees, point bars and delta.
Map Skill
Question 1.
Answer:
Class 11 Geography
| Constituent | Formulae | % by Volume |
| Nitrogen | N2 | 78.08 |
| Oxygen | O. | 20.95 |
| Argon | Ar | 0.93 |
| Carbon dioxide | CO2 | 0.036 |
| Neon | Ne | 0.002 |
| Helium | He | 0.0005 |
| Krypton | Kr | 0.001 |
| Xenon | Xe | 0.00009 |
| Hydrogen | H2 | 0.00005 |
The atmosphere is composed of gases, water vapour and dust particles. Nitrogen constitutes 78.8%, oxygen contributes 20.94% and argon contributes 0.93% in atmosphere. Other gases include carbon dioxide, helium, ozone, methane, hydrogen, krypton, xenon and neon, etc. Nitrogen and oxygen together constitute 99% of the atmosphere. Neon, krypton, xenon are scarce gases. The proportion of gases changes in the higher layers of the atmosphere in such a way that oxygen will be almost in negligible quantity at the height of 120 km. Similarly, carbon dioxide and water vapour are found only up to 90 km from the surface of the earth.
Carbon dioxide is meteorologically a very important gas as it is transparent to the incoming solar radiation but opaque to the outgoing terrestrial radiation. It absorbs a part of terrestrial radiation and reflects back some part of it towards the earth’s surface. It is largely responsible for the green house effect. Ozone is another important component of the atmosphere. It is found between 10 and 50 km above the earth’s surface and acts as a filter. It absorbs the ultra-violet rays radiating from the sun. It prevents them from reaching the surface of the earth.
Water vapour is such a variable gas in the atmosphere, which decreases with altitude. In the warm and wet tropics, it may account for four per cent of the air by volume, while in the dry and cold areas of desert and polar regions, it may be less than one per cent of the air. Atmosphere has a sufficient capacity to keep small solid particles, which may originate from, different sources and include sea salts, fine soil, smoke-soot, ash, pollen, dust and disintegrated particles of meteors.
Question 3(ii).
Draw a suitable diagram for the structure of the atmosphere and label it and describe it.
Answer:
The atmosphere consists of different layers with varying density and temperature. Density is highest near the surface of the earth and decreases with increasing altitude. The atmosphere is divided into five different layers depending upon the temperature condition.
They are: troposphere, stratosphere, mesosphere, thermosphere and exosphere.
1. Troposphere: The troposphere is the lowermost layer of the atmosphere. Its average height is 13 km and extends roughly to a height of 8 km near the poles and about 18 km at the equator. Thickness of the troposphere is greatest at the equator because heat is transported to great heights by strong convectional currents. This layer contains dust particles and water vapour. All changes in climate and weather take place in this layer. The temperature in this layer decreases at the rate of 1°C for every 165m of height.
2. Stratosphere: The stratosphere is found above the tropopause and extends up to a height of 50 km. One important feature of the stratosphere is that it contains the ozone layer. This layer absorbs ultra-violet radiation and shields life on the earth from intense, harmful form of energy.
3. Mesosphere: The mesosphere lies above the stratosphere, which extends up to a height of 80 km. In this layer, temperature starts decreasing with the increase in altitude and reaches up to minus 100°C at the height of 80 km.
4. Ionosphere; The ionosphere is located between 80 and 400 km above the mesopause. It contains electrically charged particles known as ions, and hence, it is known as ionosphere. Radio waves transmitted from the earth are reflected back to the earth by this layer.
Temperature here starts increasing with height.
5. Exosphere: The uppermost layer of the atmosphere above the thermosphere is known as the exosphere. This is the highest layer but very little is known about it.
Class 11 Geography Chapter 8 NCERT Extra Questions
Class 11 Geography Chapter 8 Multiple Choice Questions
Question 1.
Which of the following is an important component of atmosphere?
(a) Water vapours
(b) Dust particles
(c) Gases
(d) All of the above.
Answer:
(d) All of the above
Question 2.
What is the upper layer of mesosphere called?
(a) Mesosphere
(b) Ionosphere
(c) Troposphere
(d) Stratosphere.
Answer:
(a) Mesosphere
Question 3.
Which layer of atmosphere has electronically charged particles?
(a) Mesosphere
(b) Ionosphere
(c) Troposphere
(d) Stratosphere.
Answer:
(b) Ionosphere
Question 4.
Which of the following is the uppermost layer of the atmosphere?
(a) Exosphere
(b) Ionosphere
(c) Troposphere
(d) Stratosphere.
Answer:
(a) Exosphere
Question 5.
Which of the following is the lowest layer of the earth?
(a) Mesosphere
(b) Ionosphere
(c) Troposphere
(d) Stratosphere.
Answer:
(c) Troposphere
Question 6.
The air is an integral part of the earth’s mass and 99 per cent of the total mass of the atmosphere is confined to the height of how many km from the earth’s surface?
(a) 10 km
(b) 12 km
(c) 24 km
(d) 32 km.
Answer:
(d) 32 km
Question 7.
To what height carbon dioxide and water vapours are found in atmosphere?
(a) 60 km
(b) 75 km
(c) 90 km
(d) 100 km.
Answer:
(c) 90 km
Question 8.
To what height is ozone found?
(a) 10 to 50 km
(b) 5 to 60 km
(c) 30 to 80 km
(d) 40 to 90 km.
Answer:
(a) 10 to 50 km
Question 9.
Which of the following layer of atmosphere is most important for life?
(a) Nitrogen
(b) Oxygen
(c) Ozone
(d) Carbon dioxide.
Answer:
(c) Ozone
Question 10.
What are causes behind increasing density of carbon dioxide?
(а) Burning of fossil fuels
(b) Killing animals
(c) Exploitation of minerals
(d) Ozone layer depletion.
Answer:
(a) Burning of fossil fuels.
Class 11 Geography Chapter 8 Very Short Answer Type Questions
Question 1.
By which elements is atmosphere made up of?
Answer:
Atmosphere is made up of gases, water vapours and dust particles.
Question 2.
What percent of earth mass is constituted by air and it is confined to what height?
Answer:
The air is an integral part of the earth’s mass and 99 percent of the total mass of the atmosphere is confined to the height of 32 km from the earth’s surface.
Question 3.
How does the composition of air keep changing in upper layers of the earth?
Answer:
The proportion of gases changes in the higher layers of the atmosphere in such a way that oxygen will be almost in negligible quantity at the height of 120 km. Similarly, carbon dioxide and water vapour are found only up to 90 km from the surface of the earth.
Question 4.
Ozone is an important constituent of atmosphere How?
Answer:
Ozone is another important component of the atmosphere. It is found between 10 and 50 km above the earth’s surface and acts as a filter. It absorbs the ultra-violet rays radiating from the sun. It prevents them from reaching the surface of the earth.
Question 5.
What do you mean by tropopause?
Answer:
The zone separating the troposphere from stratosphere is known as the tropopause.
Question 6.
What is an important feature of stratosphere?
Answer: The stratosphere is found above the tropopause and extends up to a height of 50 km. One important feature of the stratosphere is that it contains the ozone layer. This layer absorbs ultra-violet radiation and shields life on the earth from intense, harmful form of energy.
Question 7.
What is an important feature of troposphere?
Answer:
The troposphere is the lowermost layer of the atmosphere. Its average height is 13 km and extends roughly to a height of 8 km near the poles and about 18 km at the equator. Thickness of the troposphere is greatest at the equator because heat is transported to great heights by strong convectional currents. This layer contains dust particles and water vapour. All changes in climate and weather take place in this layer. The temperature in this layer decreases at the rate of 1 C for every 165m of height.
Question 8.
Name the gases found in atmosphere.
Answer:
The atmosphere is composed of gases, water vapour and dust particles. Nitrogen constitutes 78.8%, oxygen contributes 20.94% and argon contributes 0.93% in atmosphere. Other gases include carbon dioxide, helium, ozone, methane, hydrogen, krypton, xenon and neon, etc.
Question 9.
Explain important features of ionosphere.
Answer:
The ionosphere is located between 80 and 400 km above the mesopause. It contains electrically charged particles known as ions, and hence, it is known as ionosphere. Radio waves transmitted from the earth are reflected back to the earth by this layer. Temperature here starts increasing with height.
Class 11 Geography Chapter 8 Short Answer Type Questions
Question 1.
Write a short note on water vapours.
Answer:
Water vapour:
- The amount of water vapour decreases with the altitudes. In warm and wet tropics, it accounts for 4% of the air by volume whereas in dry and cold areas of deserts and polar regions, it may be less then 1% of the air.
- It also decreases from the equator towards the poles.
- It absorbs parts of the insolation received from the sun and preserves the earth’s radiated heat and thus acts as a blanket by allowing the earth neither to become too hot nor too cold.
Question 2.
Explain about dust particles.
Answer:
Dust particles:
- Dust particles are concentrated in the lower layers of the atmosphere but sometimes conventional currents take them to the higher height.
- Dust particles includes sea salts, fine soil, smoke, ashes, pollens, dust, disintegrated particles of meteors.
- Dust particles and salt particles act as a hygroscopic nuclei around which water condenses into water vapour to produce clouds.
- Dust particles produce optical phenomenon which makes the sky look beautiful at dawn and dusk.
- Sky looks blue due to the presence of dust particles and water vapour which are scattered in the atmosphere.
Class 11 Geography Chapter 8 Long Answer Type Questions
Question 1.
Write about elements of weather and climate in detail.
Answer:
The main elements of atmosphere which are subject to change and which influence human life on earth are temperature, pressure, winds, humidity, clouds and precipitation. These elements act and react on each other. These elements determine the direction and speed of wind, amount of sunlight received, cloud formation and amount of rainfall. These in turn affect weather and climate. These factors behave differently in different places. All these elements are affected by a number of factors in turn. For example, temperature is affected by latitude and height; humidity is affected by distance from the sun and pressure is affected by height from sea level.
Question 2.
Write about the structure of atmosphere in detail.
Answer:
Structure of Atmosphere: The layers of atmosphere differ from one another with respect to density and temperature. On the basis of chemical composition the atmosphere is mainly divided into
- Homosphere
- Hetrosphere
1. Homosphere:
- It extends upto 90 km.
- It is uniform in chemical composition.
- It consists of three layers
- Troposphere
- Stratosphere
- Mesosphere
Troposphere:
- Lower most layer of atmosphere
- Average height is 13 km although it is roughly 8 km.
- The thickness of troposphere is greater at equation due to upward transportations of heat by conventional currents. This layer consists of dust particles and water vapours.
- The temperature decrease with height in this layer at a rate ldegree for every 165 m. this is known as Normal Lapse Rate.
- It is layer is important for all biological activities besides that all climatic and weather conditions takes place in this layer.
Tropopause:
- The upper limit of troposphere separating it from stratosphere is called tropopause. It is very unstable at a thin layer and very thin layers of 1.5 km thickness.
- The temperature of tropopause is -80degree centigrade censius at equator and -40 degree centigrade at poles.
- The jet planes at the other activities occur in this layer.
Stratosphere:
- It extends upto 50km.
- It is thicker at poles then at equator.
- The temperature is almost constant in its lower portion upto 20 km and their it gradually increases upto 50 km due to the presence of Ozone which absorbs UV rays.
- The temperature rises in the upper limits of the stratosphere as there are no clouds, no conventional currents, no dust particles and the air moves in the horizontal direction. The upper’ limit of stratosphere is called stratosphere which has concentration of Ozone gas.
Mesosphere:
- It extends from 50* to 90 km.
- Temperature decreases with height in this layer and false upto minus 100 degree centigrade at a height of 80-90 km. this is due to the clouds in high latitudes.
- The upper limit of Mesosphere is called as Mesopause.
2. Hetrosphere:
- It has heterogeneous chemical.
- It consist of two layers
- Ionosphere
- Exosphere
Ionosphere
- It extends from 80 to 400 km above the mesopause.
- It contains electrically charged particles known as ions.
Exosphere
- It is the uppermost layer of the atmosphere above the thermosphere.
Class 11 Geography Chapter 8 HOTS Questions
Question 1.
What would happen if there is no ozone in the atmosphere?
Answer:
It is the special variety of oxygen gas which is found in small quantity in atmosphere between 10 to 15 km above the earth surface. It acts as a filter and absorbs UV radiation from the sun and prevents them from reaching the earth surface. If ozone is not there, then UV rays will reach the surface of the earth. There will be extreme skin problems, instances of cancer and in all probabilities life would not have been possible on the earth.
Question 2.
What is the role of dust particles in atmosphere?
Answer:
The atmosphere has sufficient capacity to keep small solid particles which may originate from different sources and includes sea salts, fine soil, smoke soot, ash, polan, dust and disintegrated particles of meteors. Dust and solid particles act as hygroscopic nuclei around which water vapour condenses to produce clouds.
MAP SKILL
Question 1.
Use a diagram to show summer solstice on a globe.
Answer:
Class 11 Geography
.
| (a) Insolation | (i)The difference between the mean temperature of the warmest and the coldest months |
| (b) Albedo | (ii)The lines joining the places of equal temperature |
| (c) Isotherm | (iii) The incoming solar radiation |
| (d) Annual range | (iv) The percentage of visible light reflected by an object. |
Answer:
(a) (iii)
(b) (iv)
(c) (ii) and
(d) (i)
Question 1(v).
The main reason that the earth experiences highest temperatures in the subtropics in the northern hemisphere rather than at the equator is:
(a) Subtropical areas tend to have less cloud cover than equatorial areas.
(b) Subtropical areas have longer day hours in the summer than the equatorial.
(c) Subtropical areas have an enhanced “green house effect” compared to equatorial areas.
(d) Subtropical areas are nearer to the oceanic areas than the equatorial locations.
Answer:
(b) Subtropical areas have longer day hours in the summer than the equatorial.
2. Answer the following questions in about 30 words.
Question 2(i).
How does the unequal distribution of heat over the planet earth in space and time cause variations in weather and climate?
Answer:
Weather and climate gets affected by the unequal distribution of temperature on the earth. The areas where there is high temperature, wind blows from low temperature areas. Therefore, wind move upward from equatorial regions and blow towards two poles.
Due to this wind, pressure on both the poles increases. In winter season, wind blows from land regions to oceanic regions. Therefore these wind are dry. On the other hand, during summers, wind blow from ocean towards land. Therefore, these winds are humid. Unequal distribution of temperature is main case of blowing of wind. Rainfall and cyclone also arise due to unequal distribution of temperature. In this way, unequal distribution of temperature affects climate and weather.
Question 2(ii).
What are the factors that control temperature distribution on the surface of the earth?
Answer:
Factors controlling temperature distribution: The temperature of air at any place is influenced by
the latitude of the place;
the altitude of the place;
distance from the sea, the air- mass circulation;
the presence of warm and cold ocean currents;
local aspects.
1. The latitude: The temperature of a place depends on the insolation received. It has been explained earlier that the insolation varies according to the latitude hence the temperature also varies.
2. The altitude: The atmosphere is indirectly heated by terrestrial radiation from below. Therefore, the places near
the sea-level record higher temperature than the places situated at higher elevations.
3. Distance from the sea: Another factor is the location of a place with respect to the sea. Compared to land, the sea gets heated slowly and loses heat slowly. Land heats up and cools down quickly. Therefore, the differences in the temperature over the sea is less compared to land. And this places near the sea has a moderate temperature.
4. Air-mass and ocean currents: Air- masses affects the temperature. The places which come under the influence of warm air- masses experience higher temperature and the place that comes under the influence of cold air-masses experience low temperature.
Question 2(iii).
In India, why is the day temperature maximum in May and why not after the summer solstice?
Answer:
The main cause behind temperature being highest in May is due to summer solstice. At that time sun shines on the Tropic of Capricorn. Tropic of Capricorn passes through middle of India. But it remains till end of May in India. It is because rain starts on Malabar coast at the end of the May. Due to this, temperature does not increase in South India. Although increase in temperature continues in India till 21 June and we find highest temperature in first week of June in India.
Question 2(iv).
Why is the annual range of temperature high in the Siberian plains?
Answer:
Siberian plains are quite far off from sea. Uneven climate is found in areas located away from oceans and seas. The mean monthly temperature for January is between -18° C to -48° C in the Siberian plains. In summers, it is up to 20°celcius. Therefore, the annual range of temperature is -68 (-48-20) which is extremely high. The pressure of warm ocean currents, Gulf Stream and north Atlantic drift, make the northern Atlantic Ocean warmer and the isotherms bend towards the north. Over the land, the temperature decreases sharply and the isotherms bend towards south in Europe.
3. Answer the following questions in about 150 words.
Question 3(i).
How do the latitude and the tilt in the axis of rotation of the earth affect the amount of radiation received at the earth’s surface?
Answer:
Sunrays fall vertical on equator through the year. From 0° to 23.5° north and south, the sun keeps fluctuating. From 1st march to 21st march, the sun is southern and sunrays fall vertical on tropic of cancer. This time there is summer in northern hemisphere. From 23rd September to 22nd December, the sun is southern. During this time, the sunrays fall vertical on tropic of capricorn. On 21st march and 23rd September, sunrays fall vertical on equator. As we move towards poles from tropic of cancer and tropic of Capricorn, temperature keeps on decreasing. Therefore, after 6614 degree north and south there is cold zone. Throughout the year, the temperature remains low here. In this region, throughout the year, there is frigid snow. It is because the sun’s rays fall tilted on it. In this way, the latitude and the tilt in the axis of rotation of the earth affect the amount of radiation received at the earth’s surface.
Question 3(ii).
Discuss the processes through which the earth-atmosphere system maintains heat balance.
Answer:
1. Conduction:
The earth after being heated by insolation transmits the heat to the atmospheric layers near to the earth in long wave form. The air in contact with the land gets heated slowly and the upper layers in contact with the lower layers also get heated.
It takes place when two bodies of unequal temperature are in contact with one another, there is a flow of energy from the warmer to cooler body. The transfer of heat continues until both the bodies attain the same temperature or the contact is broken. Conduction is important in heating the lower layers of the atmosphere.
2. Convection:
The air in contact with the earth rises vertically on heating in the form of currents and further transmits the heat
of the atmosphere. This vertical heating of atmosphere is known as convection.
The convection transfer of energy is confined only to the troposphere.
3. Advection:
The transfer of heat through horizontal movement of air is called advection. Horizontal movement of the air is relatively more important than the vertical movement.
In tropical regions particularly in northern India during summer season local winds called ‘loo’ is the outcome of advection process.
Question 3(iii).
Compare the global distribution of temperature in January over the northern and the southern hemisphere of the earth.
Answer:
In January, there is summer in southern hemisphere and winter in northern hemisphere. The main reason behind it is that sun has northern face and sunrays fall vertical in northern hemisphere. The areas which are closer to equator have temperature up to 27°C and over the land the temperature decreases sharply and the isotherms bend towards south in Europe. It is much pronounced in the Siberian plain. The mean January temperature along 60° E longitude is minus 20° C both at 80° N and 50° N latitudes. The mean monthly temperature for January is over 27° C, in equatorial oceans over 24° C in the tropics and 2° C – 0° C in the middle latitudes and -18° C to -48° C in the Eurasian continental interior.
Class 11 Geography Chapter 9 NCERT Extra Questions
Class 11 Geography Chapter 9 Multiple Choice Questions
Question 1.
What percent of sunrays that is received by the upper layer of the atmosphere reach the earth surface?
(a) 43%
(b) 51%
(c) 53%
(d) 40%.
Answer:
(b) 51%
Question 2.
The process of heating up of land through horizontal movement of heat is called:
(a) Conduction
(b) Convection
(c) Advection
(d) Air drainage.
Answer:
(a) Conduction
Question 3.
With increase in height the temperature decreases at a normal rate. It is called:
(a) Air drainage
(b) Earth radiation
(c) Normal lapse rate
(d) Inversion of temperature.
Answer:
(c) Normal lapse rate
Question 4.
Being heavy and dense, the cold air acts almost like water and moves down the slope to pile up deeply in pockets and valley bottoms with warm air above. This is called what?
(a) Air drainage
(b) Earth radiation
(c) Normal lapse rate
(d) Inversion of temperature.
Answer:
(a) Air drainage
Question 5.
The air in contact with the earth rises vertically on heating in the form of currents and further transmits the heat of the atmosphere. This process of vertical heating of the atmosphere is called what?
(a) Conduction
(b) Convection
(c) Advection
(d) Air drainage.
Answer:
(b) Convection
Question 6.
What is normal lapse rate at 1000 metre?
(a) 4 degree Celsius
(b) 2 degree Celsius
(c) 1 degree Celsius
(d) 6.5 degree Celsius.
Answer:
(d) 6.5 degree Celsius
Question 7.
On 4th July, the earth is farthest from sun. What is its distance?
(a) 152 million km
(b) 147 million km
(c) 148 million km
(d) 198 million km.
Answer:
(a) 152 million km
Question 8.
On 3rd January, the earth is nearest from sun. What is its distance?
(a) 152 million km
(b) 147 million km
(c) 148 million km
(d) 198 million km.
Answer:
(b) 147 million km
Question 9.
Which continent has highest temperature range?
(a) Asia
(b) Australia
(c) Africa
(d) Eurasia.
Answer:
(d) Eurasia
Question 10.
Which of the following has longest day and nights?
(a) Poles
(b) Equator
(c) Tropic of Cancer
(d) Tropic of Capricorn.
Answer:
(a) Poles
Question 11.
Which of the following causes inversion of temperature in mountainous regions?
(a) Due to air drainage
(b) Due to dust particles
(c) Due to gravitation
(d) Due to water vapours.
Answer:
(a) Due to air drainage.
Class 11 Geography Chapter 9 Very Short Answer Type Questions
Question 1.
What factors cause variation in insolation?
Answer:
The factors that cause these variations in insolation are :
the rotation of earth on its axis;
the angle of inclination of the sun’s rays;
the length of the day;
the transparency of the atmosphere;
the configuration of land in terms of its aspect.
Question 2.
What is aphelion?
Answer:
During its revolution around the sun, the earth is farthest from the sun (152 million km) on 4th July. This position of the earth is called aphelion.
Question 3.
What is perihelion?
Answer:
On 3rd January, the earth is the nearest to the sun (147 million km). This position is called perihelion.
Question 4.
What does Plank’s law state?
Answer:
Plank’s law states that hotter a body, the more energy it will radiate and shorter the wavelength of that radiation.
Question 5.
What factors affect the temperature of a place?
Answer:
The temperature of air at any place is influenced by
the latituae of the place;
the altitude of the place;
distance from the sea, the air- mass circulation;
the presence of warm and cold ocean currents;
local aspects.
Question 6.
What is terrestrial radiation?
Answer:
The insolation received by the earth is in short wave orms and heats up its surface. The i arth after being heated itself becomes a radiating body and it radiates energy to the atmosphere in long wave form. This energy heats up the atmosphere from below. This process is known as terrestrial radiatio”
Question 7.
What are the causes behind loo in tropical regions?
Answer:
In tropical regions particularly in northern India during summer season local winds called ‘loo’ is the outcome of advection process.
Question 8.
Why does sun look red during rising and setting and why does sky look blue?
Answer:
Within the troposphere water vapour, ozone and other gases absorb much of the near infrared radiation. Very small- suspended particles in the troposphere scatter visible spectrum both to the space and towards the earth surface.
This process adds colour to the sky. The red colour of the rising and the setting sun and the blue colour of the sky are the result of scattering light of the atmosphere.
Question 9.
How does some amount of energy is reflected to the atmosphere? or what is albedo?
Answer:
While passing through the atmosphere some amount of energy is reflected, scattered and absorbed. Only the remaining part reaches the earth surface. The reflected amount of radiation is called the albedo of the earth.
Question 10.
How do sunrays while passing through atmosphere gets absorbed?
Answer:
Out of 100% received, 65 units are absorbed, 14 units within the atmosphere and 51 units by the earth’s surface. The earth radiates back 51 units in the form of terrestrial radiation. Of these, 17 units are radiated to space directly and the remaining 34 units are absorbed by the atmosphere (6 units absorbed directly by the atmosphere, 9 units through convection and turbulence and 19 units through latent heat of condensation).
Question 11.
Atmosphere gets heated up indirectly by terrestrial radiation and not directly by s nrays. Explain.
Answer:
Tne long wave radiation is absorbed by the atmospheric gases particularly by carbon dioxide and the other green house gases. Thus, the atmosphere is indirectly b ^ated by the earth’s radiation. The atmosphere in turn radiates and transmits heat to the space. Finally, the amount of heat received from the sun is returned to space, thereby maintaining constant temperature at the earth’s surface and in the atmosphere.
Question 12.
What is meant by insolation?
Answer:
The earth’s surface receives most of its energy in short wavelengths. The energy received by the earth’s is known as incoming solar radiation which in short is termed as insolation.
Question 13.
Differentiate between Perihelion and Aphelion.
Answer:
During its revolution around the sun, tho earth is farthest from the sun, on 4th July. This position of earth is called Aphelion.
And on 3rd January, the earth is the nearest to the sun. This position is called Perihelion.
Question 14.
Why the annual insolation received by the earth on 3rd January is more than that of 4th July?
Answer:
The solar output received at the top of atmosphere varies slightly in a year due to the variations in the distance between the earth and the sun. Therefore, the annual insolation received by the earth on 3rd January is more than the amount received on 4th July.
Class 11 Geography Chapter 9 Short Answer Type Questions
Question 1.
What is inversion of temperature? When | and in what regions does it take place?
Answer:
At times, the situations are reversed and the normal lapse rate is inverted. It is called Inversion of temperature. Inversion is usually of short duration but quite common nonetheless. A long winter night with clear skies and still air is ideal situation for inversion. The heat of the day is radiated off during the night, and by early morning hours, the earth is’ cooler than the air above. Over polar areas, temperature inversion is normal throughout the year. Surface inversion promotes stability in the lower layers of the atmosphere.
Smoke and dust particles get collected beneath the inversion layer and spread horizontally to fill the lower strata of the atmosphere. Dense fogs in mornings are common occurrences especially during winter season. This inversion commonly lasts for few7 hours until the sun comes up and beings to warm the earth. The inversion takes place in hills and mountains due to air drainage.
Question 2.
How does the energy received in upper layer of the atmosphere keep changing at different times of the year?
Answer:
The solar output received at the top of the atmosphere varies slightly in a year due to the variations in the distance between the earth and the sun. During its revolution around the sun, the earth is farthest from the sun (152 million km) on 4th July. This position of the earth is called aphelion.On 3rd January, the earth is the nearest to the sun (147 million km). This position is called perihelion. Therefore, the annual insolation received by the earth on 3rd January is slightly more than the amount received on 4th July.
However, the effect of this variation in the solar output is masked by other factors like the distribution of land and sea, and the atmospheric circulation. Hence, this variation in the solar output does not have great effect on daily weather changes on the surface of the earth.
Question 3.
How does the amount of insolation received depends on the angle of inclination of the rays?
Answer:
The amount of insolation received depends on the angle of inclination of the rays. It depends on the latitude of a place. The higher the latitude the less is the angle they make with the surface of the earth resulting in slant sunrays. The area covered by vertical rays is always less than the slant rays. If more area is covered, the energy gets distributed and the net energy received per unit area decreases. Moreover, the slant rays are required to pass through greater depth of the atmosphere resulting in more absorption, scattering and diffusion.
Question 4.
Explain about spatial distribution of insolation on the earth’s surface.
Answer:
The insolation received at the surface varies from about 320 Watt/m2 in the tropics to about 70 Watt/m2 in the poles. Maximum latitude insolation is received over the subtropical deserts, where the cloudiness is the least. Equator receives comparatively less insolation than the tropics. Generally, at the same latitude the insolation is more over the continent than over the oceans. In winter, the middle and higher latitudes receive less radiation than in summer.
Question 5.
Explain the distribution of temperature in July.
Answer:
Distribution of temperature in July
During this period the sun shines vertically over head near the tropic of cancer. It is summer for the northern hemisphere and winters for the southern hemisphere.
In the northern hemisphere the isotherm bends equator wards while crossing the oceans and pole wards ‘while crossing the landmass. In the southern hemisphere it is vice-versa.
The isotherms are most irregular and zig-zig in northern hemisphere on the other hand the isotherms are relatively more regular and straight in southern hemisphere.
Maximum temperature of about 30 degree centigrade occurs entirely in the northern hemisphere between 10° and 40° north latitude however the lowest temperature below 0° C is recorded over northern hemisphere in the central parts of green land.
Question 6.
Explain the factors affecting insolation at the surface of earth.
Answer:
The factors affecting insolation at the surface of earth are:-
1. The rotation of earth on its axis: The fact that the earth on its axis makes an angle of 6614 with the plane of it’s orbit round the sun has a greater influence on the amount of insolation received at different latitudes.
2. The angle of inclination of the sunrays: The higher the latitude the greater is the angle they make with the surface of the’earth resulting in slant sunrays. The areas covered by vertical rays is always less than the slant rays. If more areas is covered the energy gets distributed and the net energy received per unit area decreases. Thus, the slant rays are required to pass through greater depth of the atmosphere resulting in more absorption, scattering and diffusion.
3. The transparency of the atmosphere:
The atmosphere is largely transparent to the short wave solar radiation. The incoming solar radiation passes through the atmosphere before striking the earth’s surface. Within the troposphere water vapour, ozone and other gases absorb much of the near infrared radiation.
4. The configuration of land in terms of its aspect: The insolation received at the surface varies from about 320 watt/ m2 in the poles. Maximum insolation is received over the subtropical deserts, when the cfoudness is the least. Equator receives less rainfall as compared to tropics
Question 7.
Distribution of temperature in the month of July.
Answer:
During this period the sun shines vertically over head near tropic of cancer it is the summer for northern hemisphere and winter for southern hemisphere.
The isotherms are relatively more regular and straight in southern hemisphere.
Maximum temperature of over 30°C occurs entirely in northern hemisphere between 10° and 40° temperature below 0° C is recorded over northern hemisphere in the central parts of Greenland.
Question 8.
Explain the distribution of temperature in January.
Answer:
1. In January the isotherms deviate to north over the ocean and to the south over the continent. This can be seen on the North Atlantic Ocean.
2. The pressure of warm ocean currents, Gulf Stream and north Atlantic drift, make the northern Atlantic Ocean warmer and the isotherms bend towards the north.
3. Over the land the temperature decreases sharply and the isotherms bend towards south in Europe.
4. It is much pronounced in the Siberian plan. The mean January temperature along 60° E longitude is minus 20° both at 80° N and 50° N latitude. The mean monthly temperature for January is over 27° C in equatorial oceans over 24°C in the tropics and 2° C- 0° C in middle latitudes and -18° C to -48° C in Eurasian continental interior.
5. The effect of the ocean in well pronounced in southern hemisphere. Here, the isotherms are more or less parallel to latitudes and the variations in temperature is more gradual than in the northern hemisphere. The isotherm of 20°C, 10°C, and 0°C run parallel to 35°S, 45° and 60°S latitudes respectively.
Class 11 Geography Chapter 9 Long Answer Type Questions
Question 1.
Explain about inversion of temperature.
Answer:
At times, the situations are reversed and the normal lapse rate is inverted. It is called inversion of temperature. Inversion is usually of short duration but quite common nonetheless. A long winter night with clear skies and still air is ideal situation for inversion. The heat of the day is radiated off during the night, and by early morning hours, the earth is cooler than the air above.
Over polar areas, temperature inversion is normal throughout the year. Surface inversion promotes stability in the lower layers of the atmosphere. Smoke and dust particles get collected beneath the inversion layer and spread horizontally to fill the lower strata of the atmosphere. Dense fogs in mornings are common occurrences especially during winter season. This inversion commonly lasts for few hours until the sun comes up and beings to warm the earth. The inversion takes place in hills and mountains due to air drainage.
Question 2.
Explain the heating and the cooling mechanism of atmosphere.
Or
Discuss the process through which earth and the atmosphere system maintain heat balance.
Answer:
(a) Conduction:
The earth after being heated by insolation transmits the heat to the atmospheric layers near to the earth in long wave form. The air in contact with the land gets heated slowly and the upper layers in contact with the lower layers also get heated.
Conduction takes place when two bodies of unequal temperature are in contact with one another, there is a flow of energy from the warmer to cooler body. The transfer of heat continues until both the bodies attain the same temperature or the contact is broken. Conduction is important in heating the lower layers of the atmosphere.
(b) Convection:
The air in contact with the earth rises vertically on heating in the form of currents and further transmits the heat of the atmosphere. This vertical heating of atmosphere is known as convection.
The convection transfer of energy is confined only to the troposphere.
(c) Advection:
The transfer of heat through horizontal movement of air is called advection. Horizontal movement of the air is relatively more important than the vertical movement.
In tropical regions particularly in northern India during summer season local winds called ‘loo’ is the outcome of advection process.
Class 11 Geography Chapter 9 Hots Questions
Question 1.
Explain about heat budget of the earth.
Answer:
The earth receives almost all of its energy from the sun. The earth in turn radiates back to space the energy received from the sun. As a result, the earth neither warms up nor does it get cooled over a period of time. Thus, the amount of heat received by different parts of the earth is not the same. This variation causes pressure differences in the atmosphere. This leads to transfer of heat from one region to the other by winds. The insolation received at the top of the atmosphere is 100 per cent. While passing through the atmosphere some amount of energy is reflected, scattered and absorbed. Only the remaining part reaches the earth surface.
Roughly 35 units are reflected back to space even before reaching the earth’s surface. Of these, 27 units are reflected back from the top of the clouds and 2 units from the snow and ice- covered areas of the earth. The reflected amount of radiation is called the albedo of the earth. The remaining 65 units are absorbed, 14 units within the atmosphere and 51 units by the earth’s surface. The earth radiates back 51 units in the form of terrestrial radiation. Of these, 17 units are radiated to space directly and the remaining 34 units are absorbed by the atmosphere (6 units absorbed directly by the atmosphere, 9 units through convection and turbulence and 19 units through latent heat of condensation). 48 units absorbed by the atmosphere (14 units from insolation +34 emits from terrestrial radiation) are radiated back into space.
MAP SKILL
Question 1.
On an outline map of the world, locate the distribution of surface air temperature in the month of January.
Answer:
:
Class 11 Geography
Question 3(iii).
Why does tropical cyclone originate over the seas? In which part of the tropical cyclone do torrential rains and high velocity winds blow and why?
Answer:
At the equator, the Coriolis foroe is zero and the wind blows perpendicular to the isobars. The low pressure gets filled instead of getting intensified. That is the reason why tropical cyclones are not formed near the equator.
Torrential rain occurs in the eye of the cyclone. The strong spirally circulating wind around the centre is called the eye. The diameter of the circulating system can vary between 150 and 250 km. The eye is a region of calm with subsiding air. Around the eye is the eye wall, where there is a strong spiralling ascent of air to greater height reaching the tropopause. The wind reaches maximum velocity in this region, reaching as high as 250 km per hour.
Class 11 Geography
Class 11 Geography Chapter 11 NCERT Textbook Questions Solved
1. Multiple choice questions.
Question 1(i).
Which one of the following is the most important constituent of the atmosphere for human beings?
(a) Water vapour
(b) Nitrogen
(c) Dust particle
(d) Oxygen.
Answer:
(a) Water vapour
Question 1(ii).
Which one of the following process is responsible for transforming liquid into vapour?
(a) Condensation
(b) Transpiration
(c) Evaporation
(d) Precipitation.
Answer:
(c) Evaporation
Question 1(iii).
The air that contains moisture to its full capacity:
(a) Relative humidity
(b) Specific humidity
(c) Absolute humidity
(d) Saturated air.
Answer:
(d) Saturated air.
Question 1(iv).
Which one of the following is the highest cloud in the sky?
(a) Cirrus
(b) Stratus
(c) Nimbus
(d) Cumulus.
Answer:
(a) Cirrus
2. Answer the following questions in about 30 words.
Question 2(i).
Name the three types of precipitation.
Answer:
There are many forms of precipitation like dew, fog, rainfall, snowfall, hailstones etc.
- Rainfall: The precipitation in the form of water is called rainfall.
- Snowfall: When the temperature is lower than the 0°C, precipitation takes place in the form of fine flakes of snow and is called snowfall.
- Hailstones: Sometimes, drops of rain after being released by the clouds become solidified into small rounded solid pieces of ice and which reach the surface of the earth are called hailstones.
Question 2(ii).
Explain relative humidity.
Answer:
The percentage of moisture present in the atmosphere as compared to its full capacity at a given temperature is known as the relative humidity. It is highest over oceans and lowest over continents. With the change of air temperature, the capacity to retain moisture increases or decreases and the relative humidity is also affected.
Question 2(iii).
Why does the amount of water vapour decreases rapidly with altitude?
Answer:
The quantity of water vapour existing in the air depends upon the rate of evaporation and the temperature of the air which determines its holding capacity of water vapour. Both temperature and evaporation decreases with altitude and as a result water vapour also decreases rapidly with altitude.
Question 2(iv).
How are clouds formed? Classify them.
Answer:
Cloud is a mass of minute water droplets or tiny crystals of ice formed by the condensation of the water vapour in free air at considerable elevations. As the clouds are formed at some height over the surface of the earth, they take various shapes. According to their height, expanse, density and transparency or opaqueness clouds are grouped under four types :
- cirrus
- cumulus
- stratus
- nimbus.
3. Answer the following questions in about 150 words.
Question 3(i).
Discuss the salient features of the world distribution of precipitation.
Answer:
Salient features of the world distribution of precipitation are given below:
1. Different places on the earth’s surface receive different amounts of rainfall in a year and that too in different seasons. In general, as we proceed from the equator towards the poles, rainfall
goes on decreasing steadily. The coastal areas of the world receive greater amounts of rainfall than the interior of the continents. The rainfall is more over the oceans than on the landmasses of the world.
2. Between the latitudes 35° and 40° N and S of the equator, the rain is heavier on the eastern coasts and goes on decreasing towards the west. But, between 45° and 65° N and S of equator, the rainfall is first received on the western margins of the continents and it goes on decreasing towards the east.
3. In some regions rainfall is distributed evenly throughout the year such as in the equatorial belt and in the western parts of cool temperate regions. .
4. On the basis of the total amount of annual precipitation, major precipitation regimes of the world are identified as follows.
- The equatorial belt, the windward slopes of the mountains along the western coasts in the cool temperate zone and the coastal areas of the monsoon land receive heavy rainfall of over 200 cm per annum.
- Interior continental areas receive moderate rainfall varying from 100-200 cm per annum.
- The coastal areas of the continents receive moderate amount of rainfall.
- The central parts of the tropical land and the eastern and interior parts of the temperate lands receive rainfall varying between 50-100 cm per annum.
- Areas lying in the rain shadow zone of the interior of the continents and high latitudes receive very low rainfall-less than 50 cm per annum.
Question 3(ii).
What are forms of condensation? Describe the process of dew and frost formation.
Answer:
Condensation: The transformation of water vapour into water is called condensation. Condensation is caused by the loss of heat. When the water vapour or the moisture in the atmosphere takes one of the following forms — dew, frost, fog and clouds. Forms of condensation can be classified on the basis of temperature and location. Condensation takes place when the dew point is lower than the freezing point as well as higher than the freezing point.
- Dew: When the moisture is deposited in the form of water droplets on cooler surfaces of solid objects (rather than nuclei in air above the surface) such as stones, grass blades and plant leaves, it is known as dew.
- Frost: Frost forms on cold surfaces when condensation takes place below freezing point (CPC), i.e. the dew point is at or below the freezing point.
- Fog and Mist: When the temperature of an air mass containing a large quantity of water vapour falls all of a sudden, condensation takes place within itself on fine dust particles. So, the fog is a cloud with its base at or very near to the ground.
- Smog: Such a condition when fog is mixed with smoke, is described as smog.
- Clouds: Cloud is a mass of minute water droplets or tiny crystals of ice formed by the condensation of the water vapour in free air at considerable elevations. As the clouds are formed at some height over the surface of the earth, they take various shapes.
Class 11 Geography Chapter 11 NCERT Extra Questions
Class 11 Geography Chapter 11 Multiple Choice Questions
Question 1.
What do we say to the amount of water vapours present in atmosphere?
(a) Saturation
(b) Humidity
(c) Dew Points
(d) Dew.
Answer:
(b) Humidity
Question 2.
The temperature at which saturation occurs in a given sample of air is known as what?
(a) Saturation
(b) Humidity
(c) Dew Point
(d) Dew.
Answer:
(c) Dew point
Question 3.
Conversion of water vapours into water is called:
(a) Fog
(b) Condensation
(c) Dew
(d) Humidity.
Answer:
(b) Condensation
Question 4.
What do we call to a situation where fog with smoke is found?
(a) Fog
(b) Smog
(c) Dew
(d) Humidity.
Answer:
(b) Smog
Question 5.
What is the absolute amount of water vapours present in atmosphere called?
(a) Absolute humidity
(b) Relative humidity
(c) Condensation
(d) Fog.
Answer:
(a) Absolute humidity
Question 6.
At what height are cirrus clouds formed?
(a) 8000-12000 metres
(b) 3000-5000 metres
(c) 6000-9000 metres
(d) 4000-7000 metres.
Answer:
(a) 8000-12000 metres
Question 7.
At what height are cumulus clouds formed?
(а) 8000-12000 metres
(б) 3000-5000 metres
(c) 6000-9000 metres
(d) 4000-7000 metres.
Answer:
(d) 4000-7000 metres
Question 8.
When the saturated air mass comes across a mountain, it is forced to ascend and as it rises, it expands; the temperature falls, and the moisture is condensed. It is also known as what?
(a) Relief rain
(b) Cyclonic rain
(c) Hailstones
(d) Rainfall.
Answer:
(a) Relief rain
Question 9.
In atmosphere density of water vapour varies. To what per cent does it vary?
(a) 0 – 4%
(b) 5-10%
(c) 7-12%
(d) 9-15%.
Answer:
(a) 0-4%
Question 10.
The temperature at which the water starts evaporating is referred to as:
(a) Dew point
(b) The latent heat of vapourisation
(c) High temperature
(d) Condensation.
Answer:
(b) The latent heat of vapourisation
Question 11.
Interior continental areas receive:
(a) Heavy rainfall
(b) Moderate rainfall
(c) Low rainfall
(d) Cyclonic rainfall.
Answer:
(b) Moderate rainfall.
Class 11 Geography Chapter 11 Very Short Answer Type Questions
Question 1.
What is smog?
Answer:
Such a condition when fog is mixed with smoke, is described as smog.
Question 2.
How is humidity received in atmosphere?
Answer:
The moisture in the atmosphere is derived from water bodies through evaporation and from plants through transpiration.
Question 3.
What is relative humidity?
Answer:
The percentage of moisture present in the atmosphere as compared to its full capacity at a given temperature is known as the relative humidity.
Question 4.
What is absolute humidity?
Answer:
The actual amount of the water vapour present in the atmosphere is known as the absolute humidity. It is the weight of water vapour per unit volume of air and is expressed in terms of grams per cubic metre.
Question 5.
By what processes there a continuous exchange of water between the atmosphere, the oceans and the continents?
Answer:
There is a continuous exchange of water between the atmosphere, the oceans and the continents through the processes of evaporation, transpiration, condensation and precipitation.
Question 6.
How are clouds classified?
Answer:
According to their height, expanse, density and transparency or opaqueness clouds are grouped under four types :
- cirrus;
- cumulus;
- stratus;
- nimbus.
A combination of these four basic types can give rise to the following types of clouds: high clouds cirrus, cirrostratus, cirrocumulus; middle clouds—altostratus and altocumulus; low clouds—stratocumulus and nimbostratus and clouds with extensive vertical development cumulus and cumulonimbus.
Question 7.
When does condensation take place?
Answer:
The transformation of water vapour into water is called condensation. Condensation is caused by the loss of heat.
Question 8.
What are the suitable conditions for making of dew?
Answer:
The ideal conditions for its formation are clear sky, calm air, high relative humidity, and cold and long nights. For the formation of dew, it is necessary that the dew point is above the freezing point.
Question 9.
What are hailstones?
Answer:
Sometimes, drops of rain after being released by the clouds become solidified into small rounded solid pieces of ice and which reach the surface of the earth are called hailstones.
Question 10.
What is rain shadow area?
Answer:
The area situated on the leeward side, which gets less rainfall is known as the rain-shadow area.
Question 11.
What is precipitation?
Answer:
After the condensation of water vapour, the release of moisture is known as precipitation. This may take place in liquid or solid form.
Question 12.
What is convectional rain?
Answer:
Convectional Rain: The air on being heated, becomes light and rises up in convection currents. As it rises, it expands and loses heat and consequently, condensation takes place and cumulous clouds are formed. With thunder and lightening, heavy rainfall takes place but this does not last for long.
Question 13.
What factors influence the process of condensation?
Answer:
Condensation is influenced by the volume of air, temperature, pressure and humidity. Condensation takes place:
- when the temperature of the air is reduced to dew point with its volume remaining constant;
- when both the volume and the temperature are reduced;
- when moisture is added to the air through evaporation.
Class 11 Geography Chapter 11 Short Answer Type Questions
Question 1.
Name and define three important types of rainfall.
Answer:
On the basis of origin, rainfall may be classified into three main types:
- The convectional rain
- Orographic or relief rain and
- Cyclonic or frontal rainfall
1. Convectional rain: The air on being heated, becomes light and rises up in convection currents. As it rises, it expands and loses heat and consequently, condensation takes place and cumulous clouds are formed. With thunder and lightening, heavy rainfall takes place but this does not last for long.
Such rain is common in the summer or in the hotter part of the day. It is very common in the equatorial regions and interior parts of the continents, particularly in the northern hemisphere.
2. Orographic rain: When the saturated air mass comes across a mountain, it is forced to ascend and as it rises, it expands; the temperature falls, and the moisture is condensed. In this sort of rain the windward slopes receive greater rainfall. After giving rain on the windward side, when these winds reach the other slope, they descend, and their temperature rises. Then their capacity to take in moisture increases and hence, these leeward slopes remain rainless and dry. The area situated on the leeward side, which gets less rainfall is known as the rain-shadow area. It is also known as the relief rain.
3. Cyclonic rainfall: These rains take place in low pressure areas where air moves from low pressure area to high pressure are a and this movement brings rainfall.
Question 2.
Explain the process of evaporation.
Answer:
Evaporation is a process by which water is transformed from liquid to gaseous state. Heat is the main cause for evaporation. The temperature at which the water starts evaporating is referred to as the latent heat of vapourisation. Increase in temperature increases water absorption and retention capacity of the given parcel of air. Similarly, if the moisture content is low, air has a potentiality of absorbing and retaining moisture. Movement of air replaces the saturated layer with the unsaturated layer. Hence, the greater the movement of air, the greater is the evaporation.
Question 3.
Explain cyclonic rain.
Answer:
Air expands when heated and gets compressed when cooled. This results in variations in the atmospheric pressure. The result is that it causes the movement of air from high pressure to low pressure, setting the air in motion. Air in horizontal motion is wind. Atmospheric pressure also determines when the air will rise or sink. The wind redistributes the heat and moisture across the planet, thereby, maintaining a constant temperature for the planet as a whole. The vertical rising of moist air cools it down to form the clouds and bring precipitation. It is called cyclonic rain.
Question 4.
Differentiate between
Answer:
(i) Precipitation and Condensation.
| Basis | Precipitation | Condensation |
| Meaning | After the condensation of water vapour, the release of moisture is known as precipitation. This may take place in liquid or solid form. | The transformation of water vapour into water is called condensation. Condensation is caused by the loss of heat. |
| Sequence | Precipitation takes place after condensation. | Condensation takes place before precipitation. |
| Forms | It may take form of rainfall, snowfall, hailstorms, sleet etc. | It may take form of dew, smog, clouds, fog and mist etc. |
(ii) Absolute humidity and Relative humidity.
| Basis | Absolute Humidity | Relative Humidity |
| Meaning | The actual amount of the water vapour present in the atmosphere is known as the absolute humidity. | The percentage of moisture present in the atmosphere as compared to its full capacity at a given temperature is known as the relative humidity. |
| Unit | It is the weight of water vapour per unit volume of air and is expressed in terms of grams per cubic metre. | It is measured in percentage and hence is unit free. |
(iii) Convection rain and Relief rain.
| Basis | Convection Rain | Relief Rain |
| Meaning | The, air on being heated, becomes light and rises up in convection currents. As it rises, it expands and loses heat and consequently, condensation takes place and cumulous clouds are formed. With thunder and lightening, heavy rainfall takes place but this does not last for long. | When the saturated air mass comes across a mountain, it is forced to ascend and as it rises, it expands; the temperature falls, and the moisture is condensed. In this sort of rain is that the windward slopes receive greater rainfall. After giving rain on the windward side, when these winds reach the other slope, they descend, and their temperature rises. Then their capacity to take in moisture increases and hence, these leeward slopes remain rainless and dry. |
| Timing | Such rain is common in the summer or in the hotter part of the day. | Such rain is common in winters. |
| Prevalent | It is very common in the equatorial regions and interior parts of the continents, particularly in the northern hemisphere. | It is very common in terrestrial regions. |
(iv) Fog and Mist.
| Basis | Fog | Mist |
| Meaning | Fogs are drier than mist. | The mist contains more moisture than the fog. |
| Prevalent | They are prevalent where warm currents of air come in contact with cold currents. | Mists are frequent over mountains as the warm air rising up the slopes meets a cold surface. |
| Structure | In mist each nuclei contains a thicker layer of moisture. | Fogs are mini clouds in which condensation takes place around nuclei provided by the dust, smoke, and the salt particles. |
Class 11 Geography Chapter 11 Long Answer Type Questions
Question 1.
Explain about condensation in detail.
Answer:
1. Meaning: The transformation of water vapour into water is called condensation. Cause: Condensation is caused by the loss of heat.
2. Sublimation: When moist air is cooled, it may reach a level when its capacity to hold water vapour ceases. Then, the excess water vapour condenses into liquid form. If it directly condenses into solid form, it is known as sublimation.
3. Process: In free air, condensation results from cooling around very small particles termed as hygroscopic condensation nuclei. Particles of dust, smoke and salt from the ocean are particularly good nuclei because they absorb water. Condensation also takes place when the moist air comes in contact with some colder object and it may also take place when the temperature is close to the dew point. Condensation, therefore, depends upon the amount of cooling and the relative humidity of the air.
Factors affecting condensation:
- When the temperature of the air is reduced to dew point with its volume remaining constant;
- When both the volume and the temperature are reduced;
- When moisture is added to the air through evaporation.
However, the most favourable condition for condensation is the decrease in air temperature. After condensation the water vapour or the moisture in the atmosphere takes form of dew, frost, fog and clouds.
Question 2.
Explain about fog and mist.
Answer:
When the temperature of an air mass containing a large quantity of water vapour falls all of a sudden, condensation takes place within itself on fine dust particles. So, the fog is a cloud with its base at or very near to the ground.
- Because of the fog and mist, the visibility becomes poor to zero. In urban and industrial centres smoke provides plenty of nuclei which help in the formation of fog and mist.
- Such a condition when fog is mixed with smoke, is described as smog.
- The only difference between the mist and fog is that mist contains more moisture than the fog.
- In mist each nuceli contains a thicker layer of moisture. Mists are frequent over mountains as the warm air rises up the slopes and meets a cold surface.
- Fogs are drier than mist and they are prevalent where warm currents of air come in contact with cold currents. Fogs are mini clouds in which condensation takes place around nuclei provided by the dust, smoke, and the salt particles.
Class 11 Geography Chapter 11 HOTS Questions
Question 1.
On the basis of rainfall received, in how many groups can we classify the world?
Answer:
On the basis of rainfall received, we can classify the world into five groups.
- The equatorial belt, the windward slopes of the mountains along the western coasts in the cool temperate zone and the coastal areas of the monsoon land receive heavy rainfall of over 200 cm per annum.
- Interior continental areas receive moderate rainfall varying from 100 – 200 cm per annum.
- The coastal areas of the continents receive moderate amount of rainfall.
- The central parts of the tropical land and the eastern and interior parts of the temperate lands receive rainfall varying between 50-100 cm per annum.
- Areas lying in the rain shadow zone of the interior of the continents and high latitudes receive very low rainfall-less than 50 cm per annum.
Question 2.
Use a diagram to explain the process of evaporation.
Answer:
Evaporation is a process by which water is transformed from liquid to gaseous state. Heat is the main cause for evaporation. Movement of air replaces the saturated layer with the unsaturated layer. Hence, the greater the movement of air, the greater is the evaporation.
Class 11 Geography
:
| Af | Tropical Wet | No dry season. The driest month has at least 60 mm (2.4”) of rain. Rainfall is generally evenly distributed throughout the year. All average monthly temperatures are greater than 18°C (64°F). |
| Am | Tropical Monsoon | Pronounced wet season. Short dry season. There are one or more months with less than 60 mm (2.4”). All average monthly temperatures are greater than 64°F (18°C). Highest annual temperature occurs just prior to the rainy season. |
| Aw | Tropical Wet and Dry Climate | Winter dry season. There are more than two months with less than 60 mm (2.4”). All average monthly temperatures are greater than 18°C (64°F). |
| BSh | Subtropical Dry Semiarid (Steppe) | Low-latitude dry. Evaporation exceeds precipitation on average but is less than potential evaporation. Average temperature is more than 18°C (64°F). |
| BSk | Mid-latitude Dry Semiarid (Steppe) | Mid-latitude dry. Evaporation exceeds precipitation on average but is less than potential evaporation. Average temperature is less than 18°C (64°F). |
| BWh | Subtropical Dry Arid (Desert) | Low-latitude desert. Evaporation exceeds precipitation on average but is less than half potential evaporation. Average temperature is more than 18°C (64°F). Frost is absent or infrequent. |
| BWk | Mid-latitude Dry Arid (Desert) | Mid-latitude desert. Evaporation exceeds precipitation on average but is less than half potential evaporation. Average temperature is less than 18°C (64°F). Winter has below freezing temperatures. |
Question 3(ii).
What type of vegetation would you find in the “C” and “A” type(s) of climate?
Answer:
Group A: Tropical Humid Climates Tropical humid climates exist between Tropic of Cancer and Tropic of Capricorn. The sun being overhead climate hot and humid. Annual range of temperature is very low and annual rainfall is high. The tropical group is divided into three types, namely:
- Af- Tropical wet climate;
- Am – Tropical monsoon climate;
- Aw- Tropical wet and dry climate.
Group C: Warm temperate (mid-throughout the year and the presence of Inter Tropical Convergence Zone (ITCZ) make the
latitude) climates extend from 30° – 50° of latitude mainly on the eastern and western margins of continents. These climates generally have warm summers with mild winters. They are grouped into four types:
- Humid subtropical, i.e. dry in winter and hot in summer (Cwa);
- Mediterranean (Cs);
- Humid subtropical, i.e. no dry season and mild winter (Cfa);
- Marine west coast climate (Cfb).
Question 3(iii).
What do you understand by the term “Greenhouse Gases”? Make a list of greenhouse gases.
Answer:
The term greenhouse is derived from the analogy to a greenhouse used in cold areas for preserving heat. A greenhouse is made up of glass. The glass which is transparent to incoming short wave solar radiation is opaque to outgoing long wave radiation. The glass, therefore, allows in more radiation and prevents the long wave radiation going outside the glass house, causing the temperature inside the glasshouse structure warmer . than outside.
Greenhouse gases are those gases which cause global warming and result in rise in atmospheric temperature. These gases absorb long wave radiation. The processes that warm the atmosphere are often collectively referred to as the greenhouse effect.
Greenhouse Gases(GHGs): The primary GHGs of concern today are carbon dioxide (C02), Chlorofluorocarbons (CFCs), methane (CH4), nitrous oxide (N20) and ozone (03). Some other gases such as nitric oxide (NO) and carbon monoxide (CO) easily react with GHGs and affect their concentration in the atmosphere. The effectiveness of any given GHG molecule will depend on the magnitude of the increase in its concentration, its life time in the atmosphere and the wavelength of radiation that it absorbs.
PROJECT WORK
1. Collect information about Kyoto declaration related to global climate changes.
Answer:
Kyoto protocol is the most important protocol which was proclaimed in 1997. This protocol went into effect in 2005, ratified by 141 nations. Kyoto protocol bounds the 35 industrialised countries to reduce their emissions by the year 2012 to 5 percent less than the levels prevalent in the year 1990. The increasing trend in the concentration of GHGs in the atmosphere may, in the long run, warm up the earth. Once the global warming sets in, it will be difficult to reverse it. The effect of global warming may not be uniform everywhere. Nevertheless, the adverse effect due to global warming will adversely affect the life supporting system. Rise in the sea level due to melting of glaciers and ice-caps and thermal expansion of the sea may inundate large parts of the coastal area and islands, leading to social problems.
Class 11 Geography Chapter 12 NCERT Extra Questions
Class 11 Geography Chapter 12 Multiple Choice Questions
Question 1(i).
What kind of climate is expressed by the letter code- BSh?
(а) Tropical Dry
(b) Tropical Monsoon
(c) Subtropical Dry Steppe
(d) Mid Latitude Climate
Answer:
(c) Subtropical Dry Steppe
Question 1(ii).
What kind of climate is expressed by the letter code- ET?
(a) Humid subtropical
(b) Mediterranean
(c) Marine west coast
(d) Tundra
Answer:
(d) Tundra
Question 1(iii).
According to Koeppen, what is the average temperature of dry tropical climate?
(a) More than 20°C
(b) More than 18°C
(c) More than 40°C
(d) More than 10°C
Answer:
(b) More than 18°C
Question 1(iv).
During the 1930s, severe drought occurred in southwestern Great Plains of the United States.
What is it called?
(a) Famine area
(b) Barren area
(c) Dust bowl
(d) Dust flower
Answer:
(c) Dust bowl
Question 1(v).
Which of the following area come under tropical wet climate?
(a) Amazon Basin in South America
(b) Western equatorial Africa
(c) Islands of East Indies.
(d) All of the above
Answer:
(d) All of the above
Question 1(vi).
Which protocol was held for reducing the emission of GHGs into the atmosphere in 1997?
(a) Reid Jenero Earth Summit
(b) Johnsonburg meet
(c) Kyoto Protocol
(d) Copenhagen Meet
Answer:
(c) Kyoto Protocol
Question 1(vii).
In 8000 BC how was the climate of Rajasthan?
(a) Humid and cold
(b) Dry and warm
(c) Dry and cold
(d) Humid and warm
Answer:
(a) Humid and cold
Question 1(viii).
In the geological past, how was the earth’s climate about 500-300 million years ago, through the Cambrian, Ordovician and Silurian periods?
(a) Humid
(b) Warm
(c) Cold
(d) Dry
Answer:
(b) Warm
Question 1(ix).
Which of the following is not a greenhouse gas?
(a) Carbon dioxide
(b) Chlorofluorocarbons
(c) Methane
(d) Oxygen
Answer:
(d) Oxygen
Question 1(x).
What absorbs ultra-violet rays in stratosphere?
(a) Ozone
(b) Ions
(c) Methane
(d) Nitrogen
Answer:
(a) Ozone
Question 1(xi).
Europe witnessed what kind of experiences from 1550 to about 1850?
(а) Excess summer season
(b) Little Ice age
(c) Long dry age
(d) Long humid age
Answer:
(b) Little ice age
Question 1(xii).
What is thrown in atmosphere by volcanic eruptions?
(a) Aerosols
(b) Solid waste
(c) Alcohol
(d) Carbonmonoxide
Answer:
(a) Aerosols
Question 1(xiii).
Which type of climate exist in Plateau Station , Antarctica ,79°S according to Koeppen?
(a) Tundra climate
(b) Ice cap climate
(c) Taiga climate
(d) Cold climate with roots
Answer:
(b) Ice cap climate
Question 1(xiv).
The most important anthropogenic effect on the climate is the increasing trend in the concentration of greenhouse gases in the atmosphere. What can happen because of it?
(а) Global warming
(b) Air pollution
(c) Water pollution
(d) Land degradation
Answer:
(a) Global warming
Question 1(xv).
At which place the highest shade temperature of 58° C was recorded in Libya on 13 September 1922?
(a) Tripoli
(b) A1 Aziziyah
(c) Taiwan
(d) Tikari.
Answer:
(b) Al Aziziyah
Class 11 Geography Chapter 12 Very Short Answer Type Questions
Question 1.
In how many categories can we classify type- A climate according to Koeppen?
Answer:
The tropical group i.e. group- A is divided into three types, namely
- Af- Tropical wet climate;
- Am – Tropical monsoon climate;
- Aw- Tropical wet and dry climate.
Question 2.
In how many groups has Koeppen classified the climate?
Answer:
Koeppen has classified climate into five groups: four are based on temperature and one is based on humidity. The capital letters: A, C, D and E delineate humid climates and B dry climates.
Question 3.
In which areas is tropical climate found? What are its features?
Answer:
Tropical humid climates exist between Tropic of Cancer and Tropic of Capricorn. The sun being overhead throughout the year and the presence of Inter Tropical Convergence Zone (ITCZ) make the climate hot and humid. Annual range of temperature is very low and annual rainfall is high.
Question 4.
What is the astronomical theory of Millankovitch oscillations?
Answer:
It is an astronomical theory of Millankovitch oscillations, which infer cycles in the variations in the earth’s orbital characteristics around the sun, the wobbling of the earth and the changes in the earth’s axial tilt. All these alter the amount of insolation received from the sun, which in turn, might have a bearing on the climate.
Question 5.
How does volcano affect the climate?
Answer:
Volcanic eruption throws up lots of aerosols into the atmosphere. These aerosols remain in the atmosphere for a considerable period of time reducing the sun’s radiation reaching the Earth’s surface. After the recent Pinatoba and El Cion volcanic eruptions, the average temperature of the earth fell to some extent for some years.
Question 6.
Explain about tundra climate.
Answer:
The tundra climate (ET) is so called after the types of vegetation, like low growing mosses, lichens and flowering plants. This is the region of permafrost where the sub soil is permanently frozen. The short growing season and water logging support only low growing plants. During summer, the tundra regions have very long duration of day light.
Question 7.
Explain about humid subtropical climate.
Answer:
Humid subtropical climate occurs poleward of Tropic of Cancer and Capricorn, mainly in North Indian plains and South China interior plains. The climate is similar to Aw climate except that the temperature in winter is warm.
Question 8.
What is Kyoto Protocol?
Answer:
International efforts have been initiated for reducing the emission of GHGs into the atmosphere. Kyoto protocol is the most important and was proclaimed in 1997. This protocol went into effect in 2005, ratified by 141 nations. Kyoto protocol bounds the 35 industrialised countries to reduce their emissions by the year 2012 to 5 per cent less than the levels prevalent in the year 1990.
Question 9.
In how many groups has warm temperate climates been divided?
Answer:
They are grouped into four types:
- Humid subtropical, i.e. dry in winter and hot in summer (Cwa);
- Mediterranean (Cs);
- Humid subtropical, i.e. no dry season and mild winter (Cfa);
- Marine west coast climate (Cfb).
Class 11 Geography Chapter 12 Short Answer Type Questions
Question 1.
In which areas do we find tropical humid (Af) climate? What are its features?
Answer:
Tropical wet climate is found near the equator. The major areas are the Amazon Basin in South America, western equatorial Africa and the islands of East Indies.
Features:
- Significant amount of rainfall occurs in every month of the year as thunder showers in the afternoon.
- The temperature is uniformly high and the annual range of temperature is negligible.
- The maximum temperature on any day is around 30 C while the minimum temperature is around 20 C.
- Tropical evergreen forests with dense canopy cover and large biodiversity are found in this climate.
Question 2.
Explain about tropical wet and dry climate (Aw).
Answer:
Tropical Wet and Dry Climate (Aw): Tropical wet and dry climate occurs north and south of Af type climate regions. It borders with dry climate on the western part of the continent and Cf or Cw on the eastern part. Extensive Aw climate is found to the north and south of the Amazon forest in Brazil and adjoining parts.
Question 3.
Explain about Mediterranean Climate
Answer:
Mediterranean climate occurs around Mediterranean sea, along the west coast of continents in subtropical latitudes between 30 – 40 latitudes. Central California, Central Chile, along the coast in south eastern and south western Australia are examples of this type of climate. These areas come under the influence of subtropical high in summer and westerly wind in winter.
Features:
- The climate is characterised by hot, dry summer and mild, rainy winter.
- Monthly average temperature in summer is around 25 C and in winter below 10 C.
- The annual precipitation ranges between 35 – 90 cm.
Question 4.
Explain about humid sub tropical climate (Cfa).
Answer:
Humid subtropical climate lies on the eastern parts of the continent in subtropical latitudes. In this region the air masses are generally unstable and cause rainfall throughout the year.
They occur in eastern United States of America, southern and eastern China, southern Japan, northeastern Argentina, coastal south Africa and eastern coast of Australia.
Features:
- The annual average of precipitation vary from 75-150 cm.
- Thunderstorms in summer and frontal precipitation in winter are common.
- Mean monthly temperature in summer is around 27 C, and in winter it varies from 5 -12 C.
- The daily range of temperature is small.
Question 5.
In which areas do we find Marine west coast climate? Explain about the features of this climate?
Answer:
Marine west coast climate (Cfb) is located poleward from the Mediterranean climate on the west coast of the continents. The main areas are: North western Europe, west coast of North America, north of California, southern Chile, Southeastern Australia and New Zealand.
Features:
- Due to marine influence, the temperature is moderate and in winter, it is warmer than for its latitude.
- The mean temperature in summer months ranges from 15 -20 C and in winter 4 -10 C.
- The annual and daily ranges of temperature are small.
- Precipitation occurs throughout the year. Precipitation varies greatly from 50-250cm.
Class 11 Geography Chapter 12 Long Answer Type Questions
Question 1.
Explain the major climate categories by Koeppen.
Answer:
The first level recognises six major climatic types with each group being designated by a capital letter. These major climate categories have the following broad characteristics:
- Tropical moist climates: These are very warm climates found in the tropics that experience high quantities of precipitation. The primary distinguishing characteristic of these climates is that all months have average temperatures above 18 C (64 F).
- Dry climates: These are climates that experience little precipitation during most of the year. Further, potential losses of water from evaporation and transpiration greatly exceed atmospheric input.
- Moist mid-latitude climates with mild winters: In these climates, summer temperatures are warm to hot and winters are mild. The primary distinguishing characteristic of these climates is that the coldest month has an average temperature between 18 C (64 F) and -3 C (27 F).
- Moist mid-latitude climates with cold winters: In these climates, summer temperatures are warm and winters are cold. The primary distinguishing characteristic of these climates is the average temperature of warmest month exceeds 10 C (50 F), and average temperature of coldest is below -3 C (27 F).
- Polar climates: These climates have very cold winters and summers, with no real summer season. The primary distinguishing characteristic of these climates is the warmest month has an average temperature below 10 C (50 F).
- Highland climates: These are climates that are strongly influenced by the effects of altitude. As a result, the climate of such locations is rather different from places with low elevations at similar latitudes.
Question 2.
Explain the climatic changes that has taken place since ancient times. Also explain its causes.
Answer:
The type of climate we experience now might be prevailing over the last 10,000 years with minor and occasionally wide fluctuations. The planet earth has witnessed many variations in climate since the beginning. Geological records show alteration of glacial and inter-glacial periods. The sediment deposits in glacial lakes also reveal the occurrence of warm and cold periods. The rings in the trees provide clues about wet and dry periods. Historical records describe the diversities in climate. All these evidences indicate that change in climate is a natural and continuous process. Archaeological findings show that the Rajasthan desert experienced wet and cool climate around 8,000 B.C. During the Pleistocene epoch, glacial and inter-glacial periods occurred, the last major peak glacial period was about 18,000 years ago. The present inter-glacial period started 10,000 years ago. Variability in climate occurs all the time. The nineties decade of the last century witnessed extreme weather events. The 1990s recorded the warmest temperature of the century and some of the worst floods around the world. Europe witnessed “Little Ice Age” from 1550 to about 1850. From about 1885¬1940 world temperature showed an upward trend. After 1940, the rate of increase in temperature slowed down.
Causes of Climate Change: The causes for climate change can be grouped into astronomical and terrestrial causes.
1. The astronomical causes: These are the changes in solar output associated with sunspot activities. Sunspots are dark and cooler patches on the sun which increase and decrease in a cyclical manner. According to some meteorologists, when the number of sunspots increase, cooler and wetter weather and greater storminess occur. A decrease in sunspot numbers is associated with warm and drier conditions.
2. Volcanism: It is considered as another cause for climate change. Volcanic eruption throws up lots of aerosols into the atmosphere. These aerosols remain in the atmosphere for a considerable period of time reducing the sun’s radiation reaching the Earth’s surface. After the recent Pinatoba and El Cion volcanic eruptions, the average temperature of the earth fell to some extent for some years.
3. Greenhouse gases: The most important anthropogenic effect on the climate is the increasing trend in the concentration of greenhouse gases in the atmosphere which is likely to cause global warming.
Question 3.
Explain about Polar climate (E).
Answer:
Polar Climates (E) exist poleward beyond 70 latitude. Polar climates consist of two types:
- Tundra (ET);
- Ice Cap (EF).
1. Tundra Climate (ET): The tundra climate (ET) is so called after the types of vegetation, like low growing mosses, lichens and flowering plants. This is the region of permafrost where the sub soil is permanently frozen. The short growing season and water logging support only low growing plants. During summer, the tundra regions have very long duration of day light.
2. Ice Cap Climate (EF): The ice cap climate (EF) occurs over interior Greenland and Antarctica. Even in summer, the temperature is below freezing point. This area receives very little precipitation. The snow and ice get accumulated and the mounting pressure causes the deformation of the ice sheets and they break. They move as icebergs that float in the Arctic and Antarctic waters. Plateau Station, Antarctica ,79 S, portray this climate.
Question 4.
Explain about Cold snow forest climates (D).
Answer:
Cold Snow Forest Climates (D) occur in the large continental area in the northern hemisphere between 40 -70 north latitudes in Europe, Asia and North America. Cold snow forest climates are divided into two types:
- Df- cold climate with humid winter;
- Dw- cold climate with dry winter.
The severity of winter is more pronounced in higher latitudes.
1. Cold climate with humid winters (Df): Cold climate with humid winter occurs poleward of marine west coast climate and mid latitude steppe. The winters are cold and snowy. The frost free season is short. The annual ranges of temperature are large. The weather changes are abrupt and short. Poleward, the winters are more severe.
2.Cold climate with dry winters (Dw): Cold climate with dry winter occurs mainly over Northeastern Asia. The development of pronounced winter anti cyclone and its weakening in summer sets in monsoon like reversal of wind in this region. Poleward summer temperatures are lower and winter temperatures are extremely low with many locations experiencing below freezing point temperatures for up to seven months in a year. Precipitation occurs in summer. The annual precipitation is low from 12-15 cm.
Question 5.
Write a detailed note on Tropical monsoon climate (Am).
Answer:
Tropical monsoon climate, occasionally also known as a tropical wet climate or tropical monsoon and trade-wind littoral climatein climate classification, is a relatively rare type of climate that corresponds to the Koppen climate classification category “Am”.
Tropical monsoon climates have monthly mean temperatures above 18 C in every month of the year and feature wet and dry seasons, as Tropical savanna climates do. Unlike tropical savanna climates however, a tropical monsoon climate’s driest month sees less than 60 mm of precipitation but more than (100 [total annual precipitation [mm}/25]). Also, a tropical monsoon climate tends to see less variance in temperatures during the course of the year than a tropical savanna climate. This climate has a driest month which nearly always occurs at or soon after the “winter” solstice for that side of the equator. Tropical monsoon climates are most commonly found in South and Central America. However, there are sections of South Asia, Southeastsia, Africa (particularly West and Central Africa), the Caribbean, and North America that also features this climate.
Class 11 Geography Chapter 12 Hots Questions
Question 1.
Explain about that region where there is no permanent settlements for human beings.
Ans:
Polar Climates (E) exist poleward beyond 70° latitude. There are no permanent human settlements. Only some scientists live there temporarily for their research and tasks related to manmade satellites.
Polar climates consist of two types:
- Tundra (ET);
- Ice Cap (EF).
1. Tundra Climate (ET): The tundra climate (ET) is so called after the types of vegetation, like low growing mosses, lichens and flowering plants. This is the region of permafrost where the sub soil is permanently frozen. The short growing season and water logging support only low growing plants. During summer, the tundra regions have very long duration of day light.
2. Ice Cap Climate (EF): The ice cap climate (EF) occurs over interior Greenland and Antarctica. Even in summer, the temperature is below freezing point. This area receives very little precipitation. The snow and ice get accumulated and the mounting pressure causes the deformation of the ice sheets and they break. They move as icebergs that float in the Arctic and Antarctic waters. Plateau Station, Antarctica, 79°S, portray this climate.
Question 2:
Give the letter codes used by Koeppen for following types of climates.
- Tropical Wet
- Sub tropical steppe
- Humid Subtropical
- Humid Continental
- Polar Ice cap
- Mid Latitude desert
- Subarctic
- Highlands with snow cover
Answer:
- Af
- BSh
- Cfa
- Df
- EF
- BWk
- Dw
- H.
Question 3:
Which letter code did Koeppen use for following temperature ranges?
- Average temperature of the coldest month is 18° or higher.
- Average temperature for all months is below 10° C.
- Average temperature of the coldest month is -3° or lower.
- Average temperature of the coldest month is higher than -3° but less than 18°.
Answer:
- A – Tropical climates
- E – Cold Climates
- D – Cold Snow Forest Climates
- C – Warm Climates.
Map Skill
Question 1.
Answer:
Class 11 Geography
| Water on the Earth’s surface | ||
| Reservoir | Volume (Million of the Total Cubic km ) | Percentage of the total |
| Oceans | 1,370 | 97.25 |
| IceCaps and Glaciers | 29 | 2.05 |
| Groundwater | 9.5 | 0.68 |
| Lakes | 0.125 | 0.01 |
| Soil Moisture | 0.065 | 0.005 |
| Atmosphere | 0.013 | 0.001 |
| Streams and Rivers | 0.0017 | 0.0001 |
| Biosphere | 0.0006 | 0.00004 |
The hydrological cycle, is the circulation of water within the earth’s hydrosphere in different forms i.e. the liquid, solid and the gaseous phases. About 71 percent of the planetary water is found in the oceans. The remaining is held as freshwater in glaciers and ice caps, groundwater sources, lakes, soil moisture, atmosphere, streams and within life. Nearly 59 percent of the water that falls on land returns to the atmosphere through evaporation from over the oceans as well as from other places. The remainder runs-off on the surface, infiltrates into the ground or a part of it becomes glacier.
Question 4.
Explain the components and process of hydrological cycle.
Answer:
Components of water cycle includes water storage in oceans, atmosphere, ice and snow, groundwater and water bodies. The processes of the water cycle vary in different components. In water stored in oceans evaporation, evapotranspiration and sublimation takes place. In water, in the atmosphere condensation and precipitation takes place. In water stored in ice and snow there is snowmelt runoff to streams. In surface runoff, there is stream flow freshwater storage and infiltration. In groundwater storage, groundwater discharge springs occurs.
Question 5.
Differentiate between continental shelf and continental slope.
Answer:
Continental shelf:
- It is an extended margin of each continent occupied by shallow sea, gulfs, etc. It is a submerge part of the land adjoining the coast.
- It is shallow and is about 800m deep with an average gradient 1° or even less.
- Its edges extended upto the denth of 150-200 m. ‘
- It contains the sediments deposited with land its average width is 80km.
- The largest continental shelf is a Siberian shelf in Arctic Ocean which stretches upto 1500 km of width.
- About one-fourth of the petroleum is produced from oil wells on the continental shelfs.
- It is important for coastal transport and trade.
Continental slopes:
- It represents the edge of continental block.
- It connects continental shelf and ocean basin.
- The depth varies from 200-300 m.
- Its average gradient is 2-5°.
- It has a steep slope linking continental shelf and deep sea flow lying at an average depth of 3600 m.
- Canyons are formed here.
Question 6.
Write a short note on variation in salinity.
Answer:
The salinity for normal open ocean ranges between 33% and 37%. In the land locked Red Sea, it is as high as 41%, while in the estuaries and the Arctic, the salinity fluctuates from 0 – 35 %, seasonally. In hot and dry regions, where evaporation is high, the salinity sometimes reaches to 70%. Salinity decreases from 35% – 31% on the western parts of the northern hemisphere because of the influx of melted water from the Arctic region. In the same way, after 15° – 20° south, it decreases to 33%.
The average salinity of the Atlantic Ocean is around 36%. The highest salinity is recorded between 15° and 20° latitudes. Maximum salinity (37%) is observed between 20° N and 30° N and 20° W—60° W. It gradually decreases towards the north. The North Sea, in spite of its location in higher latitudes, records higher salinity due to more saline water brought by the North Atlantic Drift. Baltic Sea records low salinity due to influx of river water in large quantity. Highest salinity is found in water bodies as Lake Van in Turkey, Dead Sea, Great Salt Lake.
Class 11 Geography Chapter 13 Long Answer Type Questions
Question 1.
The average temperature of water on oceans floor keeps on falling from equator to poles systematically. Explain.
Answer:
The average temperature of surface water of the- oceans is about 27°C and it gradually decreases from the equator towards the poles. The rate of decrease of temperature with increasing latitude is generally 0.5°C per latitude. The average temperature is around 22°C at 20° latitudes, 14° C at 40° latitudes and 0° C near poles.
The oceans in the northern hemisphere record relatively higher temperature than in the southern hemisphere. The highest temperature is not recorded at the equator but slightly towards north of it.
The average annual temperatures for the northern and southern hemisphere are around 19° C and 16° C respectively. This variation is due to the unequal distribution of land and water in the northern and southern hemispheres.
Question 2.
Explain about horizontal distribution of salinity.
Answer:
Horizontal distribution of salinity:
- The salinity for normal Open Ocean ranges between 33% and 37%. In the land locked Red Sea records higher salinity due to high evaporation.
- Salinity is, however, very low in Black Sea due to enormous fresh water influx by rivers.
- The average salinity of the Indian Ocean is 35 %.
- The low salinity trend is observed in the Bay of Bengal due to influx of river water.
- On the contrary, the Arabian Sea shows higher salinity due to high evaporation and low influx of fresh water.
Question 3.
Explain about vertical distribution of salinity.
Answer:
Vertical distribution of salinity
- Salinity changes with depth, but the way it changes depends upon the location of the sea. Salinity at the surface increases by the loss of water to ice or evaporation, or decreased by the input of fresh waters, such as from the rivers.
- Salinity at depth is very much fixed, because there is no way that water is ‘lost’, or the salt is ‘added.’
- There is a marked difference in the salinity between the surface zones and the deep zones of the oceans. The lower salinity water rests above the higher salinity dense water.
- Salinity, generally, increases with depth and there is a distinct zone called the halocline, where salinity increases sharply.
- Other factors being constant, increasing salinity of seawater causes its density to increase. High salinity seawater, generally, sinks below the lower salinity water. This leads to stratification by salinity.
Question 4.
Explain about vertical distribution of temperature.
Answer:
The temperature structure of oceans over middle and low latitudes can be described as a three-layer system from surface to the bottom.
- The first layer represents the top layer of warm oceanic water and it is about 500 m thick with temperatures ranging between 20° and 25° C. This layer, within the tropical region, is present throughout the year but in mid-latitudes it develops only during summer.
- The second layer called the thermocline layer lies below the first layer and is characterised by rapid decrease in temperature with increasing depth. The thermocline is 500 – 1,000 m thick.
- The third layer is very cold and extends upto the deep ocean floor. In the Arctic and Antarctic circles, the surface water temperatures are close to 0 C and so the temperature change with the depth is very slight.
Question 5.
Explain the features of the deep sea plains, submarine ridges, ocean deeps and seamount.
Answer:
Abyssal plains (the deep sea plains):
- These are the world’s flattest and smoothest regions.
- About 40% of the oceanic floor is flat.
- It is formed accumulation of sediments on the sea floor.
- Its depth varies from 3000-6000 m.
Submarine ridges:
- Oceanic floors have submarine narrow and elongated ridges.
- They resemble mountain ridges on the earth surface.
- Peak of these ridges may rise above the sea level to form islands.
- Eg-Philippines Ice land is a mid-Atlantic ridge.
Oceanic deeps of submarine trenches:
- Deep narrow steep sided depression is found along the abyssal plain.
- The depth of these trenches may vary from 6,000 to 11,000 m. Example, Marina trenches is the deepest trench in Pacific Ocean.
- Trenches are formed as a result of tectonic forces and normally occur along the marines of Pacific Ocean.
- They occur at the base of the continental slopes and along the island area. Normally associated with volcanoes and strong earthquake.
- There are 32 trenches in Pacific Ocean, 19 in Atlantic Ocean and just 6 in Indian Ocean.
Seamount:
- It is the mount with a pointed submit rising from the sea floor but do not reach the surface of ocean. For example
- Emperor seamount, an extension of Hawaiian islands in Pacific Ocean
- The tallest seamount between Soman and New Zealand.
- Seamounts are volcanic in origin and can be 3000 to 4500 m tall.
Class 11 Geography Chapter 13 Hots Questions
Question 1.
“Ocean seems to be water body but it has many types of landforms within it”. Justify the statements by giving some examples.
Answer:
The statement is absolutely right. Like the surface of the earth ocean flow is neither level or flat, it is undulating and varying. It comprises of different types of landforms below it. Some of these are:
- Continental shelf: It is an extended margin of each continent occupied by shallow sea, gulfs, etc. It is a submerge part of the land adjoining the coast.
- Continental slopes: It represents the edge of continental block. It connects continental shelf and ocean basin. The depth varies from 200-300 m.
- Abyssal Plains (The Deep Sea Plains): These are the world’s flattest and smoothest regions. About 40% of the oceanic floor is flat. It is formed accumulation of sediments on the sea floor. Its depth varies from 3000-6000m.
- Sub Marine Ridges: Oceanic floors have sub-marine narrow and elongated ridges. They resemble mountain ridges on the earth surface. Peak of these ridges may rise above the sea level to form islands. Eg- Philippines Ice land is a mid-Atlantic ridge.
- Oceanic deeps of sub-marine trenches: Deep narrow steep sided depression found along the abyssal plain. The depth of these trenches may vary from 6,000 to 11,000 m. Example, Marina trenches is the deepest trench in Pacific Ocean.
Question 4.
Explain hydrological cycle.
Answer:
The hydrological cycle is a conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere, and the hydrosphere. Water on our planet can be stored in any one of the
following major reservoirs: atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, and groundwater. Water moves from one reservoir to another by way of processes like evaporation, condensation, precipitation, deposi-tion, runoff, infiltration, subli¬mation, transpiration, melting, and groundwrater flow. The oceans supply most of the evaporated water found in the atmosphere. Of this evaporated water, only 91% of it is returned to the ocean basins by way of precipitation. The remaining 9% is transported to areas over landmasses where climatologically factors induce the formation of precipitation. The resulting imbalance between rates of evaporation and precipitation over land and ocean is corrected by runoff and groundwater flow to the oceans.
Map Skills
Question 1.
Show7 spatial distribution of surface temperature in degree celsius on a physical map of the world.
Answer:
Question 2.
Show on a physical map of the world, surface salinity of the different oceans.
Answer:
Question 3.
Show on a physical map of the world, mid oceanic ridges.
Answer:
Question 4.
Locate trenches on the map of the world.
Answer:
Question 5.
Show different types of ocean floors.
Answer:
Class 11 Geography
| S.no. | Spring Tides | Neap Tides |
| 1. | It occurs twice each month new moon day because the sun, moon and earth are in the straight line. | They occur at first and third quarter of the moon. Because during these days the sun, moon form a right angle with each other. |
| 2. | When the rise and fall is more than the normal then it is called the spring tides. | The rise and the fall is considerably low than the normal level. |
| 3. | It is due to complimentary gravitational effect and cause sun, moon and earth are in the same. | Here the tidal forces do not supplement each other because the moon and earth are in right angles and so the velocity of tidal current slows down. |
Class 11 Geography Chapter 14 Long Answer Type Questions
Question 1.
In how many categories can tides be classified on the basis of their height and frequency?
Answer:
- Semi-diurnal tide: It is the most common tidal pattern, featuring two high tides and two low tides each day. The successive high or low tides are approximately of the same height.
- Diurnal tide: There is only one high tide and one low tide during each day. The successive high and low tides are approximately of the same height.
- Mixed tide: Tides having variations in height are known as mixed tides. These tides generally occur along the west coast of North America and on many islands of the Pacific Ocean.
- Spring tides: The position of both the sun and the moon in relation to the earth has direct bearing on tide height. When the sun, the moon and the earth are in a straight line, the height of the tide will be higher. These are called spring tides.
- Neap tides: Wlien the sun and moon are at right angles to each other and the forces of the sun and moon tend to counteract one another. The moon’s attraction, though more than twice as strong as the sun’s, is diminished by the counteracting force of the sun’s gravitational pull. These are called neap tides.
Question 2.
White the characteristics of waves in the oceanic water.
Answer:
Characteristics of waves in the oceanic water are given below:
- The highest and lowest points of a wave are called the crest and trough.
- Wave height is the vertical distance from the bottom of a trough to the top of a crest of a wave.
- Wave amplitude is one-half of the wave height.
- Wave period is merely the time interval between two successive wave crests.
- Wavelength is the horizontal distance between two successive crests.
- Wave speed is the rate at which the wave moves through the water, and is measured in knots.
- Wave frequency is the number of waves passing a given point during a one- second time interval.
Question 3.
Explain how do heating of solar energy, wind, gravitation and coriolis force affect the ocean currents.
Answer:
Heating by solar energy: Heating by solar energy causes the water to expand, that is why, near the equator the ocean water is about 8 cm higher in level than in the middle latitudes. This causes a very slight gradient and water tends to flow down the slope.
- Wind: Wind blowing on the surface of the ocean pushes the water to move. Friction between the wind and the water surface affects the movement of the water body in its course.
- Gravity: Gravity tends to pull the water down the pile and create gradient variation.
- The Coriolis force: The coriolis intervenes and cause the water to move to the right in the northern hemisphere and to the left in the southern hemisphere.
Question 4.
Differentiate between warm currents and cold currents.
Answer:
| S.no. | Warm currents | Cold currents |
| 1. | They flow from equatorial regions to high latitudes. | They flow from polar region to low latitudes. |
| 2. | Its temperature is higher than the surrounding water. | Its temperature is below than the surrounding water. |
| 3. | It raises the temperature of coastal areas and are observed normally on the east coast of lower and middle latitude. | It reduces the temperature of the coastal area and are observed on the west of continent in lower and middle latitudes. |
| 4. | Winds passing over warm currents absorb a good amount of moisture and bring heavy rainfall on the coastal areas. | Winds passing over cold currents becomes dry and little rainfall on the coaarea. |
| 5. | Warm currents are of great help to navigation because they melt ice bergs. | Cold currents hinder navigation because they create ice bergs. |
| 6. | Warm currents keep the ports open in the polar regions free from ice. | Cold currents make the parts unoperational in lower latitudes as they are ice bound. |
Class 11 Geography Chapter 14 Hots Questions
Question 1.
Make a list of currents which are found in Pacific, Atlantic and Indian Ocean.
Answer:
This is a listing of the seventeen major surface ocean currents.
| Agulhas Current | Indian | Warm |
| Alaska Current | North Pacific | Warm |
| Benguela Current | South Atlantic | Warm/Cool |
| Brazil Current | South Atlantic | Warm |
| California Current | North Pacific | Cool |
| Canaries Current | North Atlantic | Cool |
| East Australian Current | South Pacific | Warm |
| Equitorial Current | Pacific | Warm |
| Gulf Stream | North Atlantic | Warm |
| Humboldt (Peru)Current | South Pacific | Cool |
| Kuroshio (Japan)Current | North Pacific | Warm |
| Labrador Current | North Atlantic | Cool |
| North Atlantic Drift | North Atlantic | Warm |
| North Pacific Drift | North Pacific | Warm |
| Oyashio (Kamchatka)Current | North Pacific | Cool |
| West Australian Current | Indian | Cool |
| West Wind Drift | South Pacific | Cool |
Question 2.
How is the movement of currents influenced by prevailing winds? Give examples.
Answer:
The prevailing winds, or winds that usually blow in the same direction, influence ocean currents because the wind causes friction on the water surface causing the water to move in the same direction as the wind. Some prevailing winds are called “trade winds” because merchants on sailboats used these regular winds to sail across the Indian Ocean or Atlantic Ocean to trade their goods. The wind made sailing to some places very easy and other places very difficult. Some of these regular winds change direction during certain months. This is called monsoon. Monsoon winds blow one direction from May to October, then change directions from November to April, which allowed the merchants to sail home in Monsoon areas of the world. The monsoon winds mainly effects South Asia (India). Indian traders sailed west to Africa in the summer and east back to India in the winter.
Question 3.
Why some currents are warm or cold?
Answer:
There are several warm ocean currents that move warm water away from the equator. These currents of water have warm air above the water. The warm air raises the temperature of the land it touches. These areas enjoy a much warmer climate than other places at the same latitude. Areas such as England would be much colder without the warm Gulf Stream. Warm ocean currents flow on the eastern side of a continents. They only reach the western side in high latitude areas. Another characteristic is that they flow away from the equator. Warm currents have higher temperatures, so they are less dense than cold water. Usually warm water has a higher salinity, but it remains less dense than cold water, so cold water is heavier and flows under warm water. The water is warmed on the surface, so warm currents flow across the surface of the ocean. As a warm current cools down, it drops down and becomes a cold water currents.
Question 4.
What are under currents?
Answer:
Under currents deep in the ocean flow in the opposite direction from the surface current above them. They replace the surface waters that are moving out. A major under current circles the globe at about 30 mph. The main under current is called the Great Conveyor Belt. It is truly like an underwater river. In fact, under currents are called “submarine rivers”.
Map Skill
Question 1.
Show on a world map the currents of the oceans.
Answer:
Class 11 Geography
Class 11 Geography Chapter 15 NCERT Textbook Questions Solved.
Multiple choice questions.
Question 1(i).
Which one of the following is included in biosphere?
(a) Only plants
(b) All living and non-living organisms
(c) Only animals
(d) All living organisms
Answer:
(b) All living and non-living
Question 1(ii).
Tropical grasslands are also known as:
(a) The prairies
(b) The savannas
(c) The steppes
(d) None of the above.
Answer:
(b) The savannas
Question 1(iii).
Oxygen combines with iron found in the rocks to form:
(a) Iron carbonate
(b) Iron nitrites
(c) Iron oxides
(d) Iron sulphate.
Answer:
(e) Iron oxides
Question 1(iv).
During photosynthesis, carbon dioxide combines with water in the presence of sunlight to form:
(a) Proteins
(b) Amino acids
(c) Carbohydrates
(d) Vitamins.
Answer:
(c) Carbohydrates.
2. Answer the following questions in about 30 words.
Question 2(i).
What do you understand by the term ‘ecology’?
Answer:
It is a scientific study of the interactions of organisms with their physical environment and with each other.
Question 2(ii).
What is an ecological system? Identify the major types of ecos_ stems in the world.
Answer:
The diversity of life-forms is maintained to bring a kind of balance. This balance is maintained in a particular proportion so that a healthy interaction between the biotic and the abiotic components goes on. The interactions of a particular group of organisms with abiotic factors within a particular habitat resulting in clearly defined energy flows and material cycles on land, water and air, are called ecological systems.
Ecosystems are of two major types: terrestrial and aquatic. Terrestrial ecosystem can be further be classified into ‘biomes’. Aquatic ecosystems can be classed as marine and freshwater ecosystems.
Question 2(iii).
What is food-chain? Give one example of a grazing food-chain identifying the various levels.
Answer:
The sequence of eating and being eaten and the resultant transfer of energy from one level to another is known as the food chain. There are two types of food chain, grazing food chain and detritus food chain.
1. In a grazing food chain, the first level starts with plants as producers and ends with carnivores as consumers at last level, with the herbivores being at the intermediate level. A capture initiated by grazing detritus food chain is based on autographs energy capture initiated by grazing animals and involves the decomposition or breaking down of organic wastes and death matter derived from the grazing food chain. For example plant- beetle- paddy stalk-frog-snake-hawk
2. A detritus food-chain is based on autotrophs energy capture initiated by grazing animals and involves the decomposition or breaking down of organic wastes and dead matter derived from the grazing food-chain.
Question 2(iv).
What do you understand by the term ‘food web’? Give examples.
Answer:
The interconnecting network of species is known as food web. A mouse feeding on grain may be eaten by different secondary consumers (carnivores) and these carnivores may be eaten by other different tertiary consumers (top carnivores). In such situations, each of the carnivores may consume more than one type of prey. As a result, the food- chains get interlocked with one another.
Question 2(v).
What is a biome?
Answer:
A biome is a plant and animal community that covers a large geographical area. The boundaries of different biomes on land are determined mainly by climate. Therefore, a biome can be defined as the total assemblage of plant and animal species interacting within specific conditions. These include rainfall, temperature, humidity and soil conditions. Some of the major biomes of the world are: forest, grassland, desert and tundra biomes.
3. Answer the following questions in about 150 words.
Question 3(i).
What are bio-geochemical cycles? Explain how nitrogen is fixed in the atmosphere.
Answer:
The sun is the source of all energy on earth. This energy initiates life processes in the biosphere through photosynthesis, the main source of food and energy for green plants. A very small fraction of about 0.1 percent of solar energy reaching earth is fixed in photosynthesis. More than half is used for plant respiration and the remaining part is temporarily stored or is shifted to other portions of the plant. During photosynthesis carbon dioxide is converted into organic compounds and oxygen.
The balance of the chemical elements is maintained by a cyclic passage through the tissues of plants and animals. The cycle starts by absorbing the chemical elements by the organism and is returned to the air, water and soil through decomposition. These cyclic movement of chemical elements of the biosphere between the organism and the environment are referred to as bio-geochemical cycles.
Fixing of nitrogen in the atmosphere Action of soil micro-organisms and associated plant roots on atmospheric nitrogen found in pore spaces of the soil comprise the principal source of free nitrogen. Lighting and cosmic radiation can also fix nitrogen in the atmosphere.
Question 3(ii).
What is an ecological balance? Discuss the important measures needed to prevent ecological imbalances.
Answer:
Ecological balance is a state of dynamic equilibrium within a community of organisms in a habitat or ecosystem. It can happen when the diversity of the living organisms remains relatively stable. Gradual changes do take place but that happens only through natural succession. It can also be explained as a stable balance in the numbers of each species in an ecosystem. This occurs through competition and cooperation between different organisms where population remains stable.
This balance is brought about by the fact that certain species compete with one another determined by the environment in which they grow. This balance is also attained by the fact that some species depend on others for their food and sustenance. Such accounts are encountered in vast grasslands where the herbivorous animals (deer, zebras, buffaloes, etc.) are found in plenty.
Ecological balance may be disturbed due to the introduction of new species, natural hazards or human causes. Human interference has affected the balance of plant communities leading to disturbances in the ecosystems. Such disturbances bring about numerous . secondary successions. Human pressure on the earth’s resources has put a heavy toll on the ecosystem. This has destroyed its originality and has caused adverse effects to the general environment. Ecological imbalances have brought many natural calamities like floods, landslides, diseases, erratic climatic occurrences, etc. There is a very close relationship between the plant and animal communities within particular habitats. Diversity of life in a particular area can be employed as an indicator of the habitat factor. Proper knowledge and understanding of such factors provide a strong base for protecting and conserving the ecosystems.
Class 11 Geography Chapter 15 NCERT Extra Questions
Class 11 Geography Chapter 15 Multiple Choice Questions
Question 1.
Which of the following is not a type of biome?
(a) Forest biome
(b) Desert biome
(c) Aquatic biome
(d) Sundri biome.
Answer:
(d) Sundri Biome
Question 2.
Very less rainfall and high rate of evaporation is a feature of which type of biome?
(a) Forest biome
(b) Desert biome
(c) Aquatic biome
(d) Sundri biome.
Answer:
(b) Desert biome
Question 3.
Which of the following is related to ecology?
(a) Birth of living organism
(b) Growth
(c) Development
(d) All of the above.
Answer:
(d) All of the above
Question 4.
All organisms become so much interlinked and interdependent on each other that the life of one cannot be imagined without the other. It is called:
(a) Biome
(b) Ecology
(c) Food chain
(d) Food web.
Answer:
(b) Ecology
Question 5.
Which of the following is included in biotic factors?
(a) Producers
(b) Consumers
(c) Decomposers
(d) All of the above.
Answer:
(d) All of the above
Question 6.
Ecosystems are of two types. These are:
(a) Terrestrial and aquatic ecosystem
(b) Biotic and abiotic ecosystem
(c) Regional and world ecosystem
(d) All of the above.
Answer:
(a) Terrestrial and aquatic ecosystem
Question 7.
Biome is a group of:
(a) Plants and animals
(b) Abiotic elements
(c) Aquatic elements
(d) None of the above.
Answer:
(a) Plants and animals
Question 8.
Which of the following is included in primary consumers?
(a) Carnivores
(b) Herbivores
(c) Decomposers
(d) All of the above.
Answer:
(a) Carnivores
Question 9.
Which of the following is included in secondary consumers?
(a) Carnivores
(b) Herbivores
(c) Decomposers
(d) All of the above.
Answer:
(b) Herbivores
Question 10.
A very small portion of the sunlight received on the earth is used in photosynthesis. What percent is it?
(a) Only 0.50 percent
(b) Only 1 percent
(c) Only 0.1 percent
(d) Only 0.2 percent.
Answer:
(c) Only 0.1 percent.
Class 11 Geography Chapter 15 Very Short Answer Type Questions
Question 1.
Name important biomes of the world.
Answer:
A biome is a plant and animal community that covers at large geographical area. Abiome can be defined as the total assemblage of plant and animal species interacting within specific conditions. These include rainfall, temperature, humidity and soil conditions. Some of the major biomes of the world are forest, grassland, desert and tundra biomes.
Question 2.
Who are primary and secondary consumers?
Answer:
The primary consumers include herbivorous animals like deer, goats,
mice and all plant-eating animals. The carnivores include all the flesh-eating animals like snakes, tigers and lions. Certain carnivores that feed also on carnivores are known as top carnivores like hawks and mongooses.
Question 3.
On whom do primary, secondary and tertiary producers depend?
Answer:
Primary consumers depend on producers who make the food themselves. Secondary consumers depend on primary consumers and tertiary consumers in turn depend on secondary consumers.
Question 4.
Give meaning of food chain with examples.
Answer:
The sequence of eating and being eaten and the resultant transfer of energy from one level to another is known as food chain. There are two types of food chain: grazing food chain and detritus food chain. For example plant- beetle- paddy stalk-frog-snake-hawk.
Question 5.
What kind of changes take place during photosynthesis?
Answer:
During photosynthesis, carbon dioxide is converted into organic compounds and oxygen. Out of the total solar insolation that reaches the earth’s surface, only a very small fraction (0.1 percent) is fixed in photosynthesis. More than half is used for plant respiration and the remaining part is temporarily stored or is shifted to other portions of the plant.
Question 6.
What is water cycle?
Answer:
All living organisms, the atmosphere and the lithosphere maintain between them a circulation of water in solid, liquid or gaseous form referred to as the water or hydrologic cycle.
Question 7.
What is carbon cycle?
Answer:
The carbon cycle is mainly the conversion of carbon dioxide. This conversion is initiated by the fixation of carbon- dioxide from the atmosphere through photosynthesis. Such conversion result in the production of carbohydrates, glucoses that may be converted to other organic compounds such as sucrose, starch, cellulose, etc. Here, some of the carbohydrates are utilised directly by the plant itself. During this process, more carbon dioxide is generated and is released through its leaves or roots during the day. The remaining carbohydrates not being utilised by the plant become part of the plant tissue. Plant tissues are either being eaten by the herbivorous animals or get decomposed by the micro¬organisms. The herbivores convert some of the consumed carbohydrates into carbon dioxide for release into the air through respiration. The microorganisms decompose the remaining carbohydrates after the animal dies.
Question 8.
How many types of biogeochemical cycles are there?
Answer:
There are two types of biogeochemical cycles: the gaseous and the sedimentary cycle. In the gaseous cycle, the main reservoir of nutrients is the atmosphere and the ocean. In the sedimentary cycle, the main reservoir is the soil and the sedimentary and other rocks of the earth’s crust.
Question 9.
How many types of decomposers are there?
Answer:
There are two types of decomposers Scavengers and micro-organisms. Scavengers feed on dead organisms, like vultures and crows. Further breaking down of the dead matter is done by other decomposing agents like bacteria and various micro-organisms.
Question 10.
How does biosphere get formed?
Answer:
The biosphere includes all the living components of the earth. It consists of all plants and animals, including all the micro-organisms that live on the planet earth and their interaction with the surrounding environment. The biosphere and its components are very significant elements of the environment. These elements interact with other components of the natural landscape such as land, water and soil.
Question 11.
What is ecological adaptation?
Answer:
Different types of ecosystems exist with varying ranges of environmental conditions where various plants and animals species have got adapted through evolution. This phenomenon is known as ecological adaption.
Class 11 Geography Chapter 15 Short Answer Type Questions
Question 1.
Write a short note on biosphere.
Answer:
Life on the earth is found almost everywhere. Living organisms are found from the poles to the equator, from the
bottom of the sea to several kilometres in the air, from freezing waters to dry valleys, from under the sea to underground water lying below the earth’s surface. The biosphere includes all the living components of the earth. It consists of all plants and animals, including all the micro-organisms that live on the planet earth and their interactions with the surrounding environment.
The biosphere and its components are very significant elements of the environment. These elements interact with other components of the natural landscape such as land, water and soil. They are also influenced by the atmospheric elements such as the temperature, rainfall, moisture and sunlight. The interactions of biosphere with land, air and water are important to the growth, development and evolution of the organism.
Question 2.
Write and explain about oxygen cycle.
Answer:
Oxygen is the main by-product of photosynthesis. It is involved in the oxidation of carbohydrates with the release of energy, carbon dioxide and water. The cycling of oxygen is a highly complex process. Oxygen occurs in a number of chemical forms and combinations. It combines with nitrogen to form nitrates and with many other minerals and elements to form various oxides such as the iron oxide, aluminium oxide and others. Much of oxygen is produced from the decomposition of water molecules by sunlight during photosynthesis and is released in the atmosphere through transpiration and respiration processes of plants.
Question 3.
Explain the difference between terrestrial eco system and aquatic ecosystem.
Answer:
Difference between terrestrial and aquatic eco system is summarized below:
| Terrestrial Ecosystem | Aquatic Ecosystem |
| Terrestrial ecosystem can be further be classified into ‘biomes’. A biome is a plant and animal community that covers a large geographical area. The boundaries of different biomes on land are determined mainly by climate. Therefore, a biome can be defined as the total assemblage of plant and animal species interacting within specific conditions. Some of the major biomes of the world are: forest, grassland, desert and tundra biomes. | Aquatic ecosystems can be classed as marine and freshwater ecosystems. Marine ecosystem includes the oceans, estuaries and coral reefs. Freshwater ecosystem includes lakes, ponds, streams, marshes and bogs. |
| Rainfall, temperature, soil type, latitude, height, etc determines the boundaries of terrestrial ecosystem. | Water bodies determine the boundaries of aquatic ecosystem. |
Question 4.
How does nitrogen get fixed?
Answer:
Nitrogen is a major constituent of the atmosphere comprising about seventy- nine percent of the atmospheric gases. It is also an essential constituent of different organic compounds such as the amino acids, nucleic acids, proteins, vitamins and pigments. Only a few types of organisms like certain species of soil bacteria and blue green algae are capable of utilising it directly in its gaseous form. Generally, nitrogen is usable only after it is fixed. Ninety percent of fixed nitrogen is biological. The principal source of free nitrogen is the action of soil micro-organisms and associated plant roots on atmospheric nitrogen found in pore spaces of the soil. Nitrogen can also be fixed in the atmosphere by lightning and cosmic radiation.
Class 11 Geography Chapter 15 Long Answer Type Questions
Question 1.
Explain in detail about carbon cycle.
Answer:
The Carbon Cycle: Carbon is one of the basic elements of all living organisms. It forms the basic constituent of all the organic compounds. The biosphere contains over half a million carbon compounds in them. The carbon cycle is mainly the conversion of carbon dioxide. This conversion is initiated by the fixation of carbon dioxide from the atmosphere through photosynthesis. Such conversion results in the production of carbohydrate, glucose that may be converted to other organic compounds such as sucrose, starch, cellulose, etc. Here, some of the carbohydrates are utilised directly by the plant itself. During this process, more carbon dioxide is generated and is released through its leaves or roots during the day.
The remaining carbohydrates not being utilised by the plant become part of the plant tissue. Plant tissues are either being eaten by the herbivorous animals or get decomposed by the micro- organisms. The herbivores convert some of the consumed carbohydrates into carbon dioxide for release into the air through respiration. The micro-organisms decompose the remaining carbohydrates after the animal dies. The carbohydrates that are decomposed by the micro-organisms then get oxidised into carbon dioxide and are returned to the atmosphere.
Question 2.
Explain in detail about food chain.
Answer:
Food Chain: This sequence of eating and being eaten and the resultant transfer of energy from one level to another is known as the food-chain. Transfer of energy that occurs during the process of a food chain from one level to another is known as flow of energy. The food- chains get interlocked with one another. This inter- connecting network of species is known as food web. For example, a plant eating beetle feeding on a paddy stalk is eaten by a frog, which is, in turn, eaten by a snake, which is then consumed by a hawk. This sequence of eating and being eaten and the resultant transfer of energy from one level to another is known as the food-chain.
- Producers: The producers include all the green plants, which manufacture their own food through photosynthesis.
- Primary consumers: The primary consumers include herbivorous animals like deer, goats, mice and all plant-eating animals.
- Carnivores: The carnivores include all the flesh-eating animals like snakes, tigers and lions. Certain carnivores that feed also on carnivores are known as top carnivores like hawks and mongooses.
- Decomposers: Decomposers are those that feed on dead organisms (for example, scavengers like vultures and crows), and further breaking down of the dead matter by other decomposing agents like bacteria and various micro-organisms.
Generally, two types of food-chains are recognised: grazing food-chain and detritus food-chain.
- Grazing food chain: In a grazing food- chain, the first level starts with plants as producers and ends with carnivores as consumers at the last level, with the herbivores being at the intermediate level. There is a loss of energy at each level which may be through respiration, excretion or decomposition. The levels involved in a food- chain range between three to five and energy is lost at each level.
- A detritus food-chain: A detritus food chain is based on autotrophs energy capture initiated by grazing animals and involves the decomposition or breaking down of organic wastes and dead matter derived from the grazing food-chain.
Question 3.
Explain about the working and structure of ecosystem.
Answer:
The structure of an ecosystem involves a description of the available plant and animal species. From a structural point of view, all ecosystems consist of abiotic and biotic factors. Abiotic factors include rainfall, temperature, sunlight, atmospheric humidity, soil conditions, inorganic substances (carbon dioxide, water, nitrogen, calcium, phosphorus, potassium, etc.). Biotic factors include the producers, the consumers (primary, secondary, tertiary) and the decomposers. The producers include all the green plants, which manufacture their own food through photosynthesis.
The primary consumers include herbivorous animals like deer, goat, mice and all plant-eating animals. The carnivores include all the flesh-eating animals like snakes, tigers and lions. Certain carnivores that feed also on carnivores are known as top carnivores like hawks and mongooses. Decomposers are those that feed on dead organisms (for example, scavengers like vultures and crows), and further breaking down of the dead matter by other decomposing agents like bacteria and various micro- organisms.
Question 4.
Explain in detail about nitrogen cycle.
Answer:
Nitrogen is a major constituent of the atmosphere comprising about seventy- nine per cent of the atmospheric gases. It is also an essential constituent of different organic compounds such as the amino acids, nucleic acids, proteins, vitamins and pigments. Only a few types of organisms like certain species of soil bacteria and blue green algae are capable of utilising it directly in its gaseous form. Generally, nitrogen is usable only . after it is fixed. Ninety percent of fixed nitrogen is biological. The principal source of free nitrogen is the action of soil micro-organisms and associated plant roots on atmospheric nitrogen found in pore spaces of the soil.
Nitrogen can also be fixed in the atmosphere by lightning and cosmic radiation. In the oceans, some marine animals can fix it. After atmospheric nitrogen has been fixed into an available form, green plants can assimilate it. Herbivorous animals feeding on plants, in turn, consume some of it. Dead plants and animals, excretion of nitrogenous wastes are converted into nitrites by the action of bacteria present in the soil. Some bacteria can even convert nitrites into nitrates that can be used again by green plants. There are still other types of bacteria capable of converting nitrates into free nitrogen, a process known as denitrification.
Question 5.
Explain the features of different forest biomes of the world.
Answer:
Forest biomes are of following types:
1. Tropical Equatorial Forest: Found in 10° N-S
Temp. 20-25°C, evenly distributed Acidic, poor in nutrients Rich in nutrients
2. Tropical Deciduous Forest: Found in 10°-25° N-S
Temp. 25-30°C, Rainfall, ave. ann. 1,000 mm, seasonal
3. Temperate: Found in Eastern North America, N.E. Asia, Western and Central Europe
Temp. 20-30° C, Rainfall evenly distributed 750- 1,500 mm, Well- defined seasons and distinct winter. Fertile, en-riched with decaying litter
4. Boreal: Found in Broad belt of Eurasia and North America (parts of Siberia, Alaska, Canada and Scandinavia).
Short moist moderately warm summers and long cold dry winter; very low temperatures. Precipitation mostly snowfall 400 -1,000 mm.
Acidic and poor in nutrients, thin soil cover.
Rich in nutrients with little or no organic matter.
Class 11 Geography Chapter 15 HOTS Questions
Question 1.
Differentiate between Grazing Food Chain and detritus food chain.
Answer:
Question 2.
How does an ecosystem work?
Use a diagram to clear the concept of food chain.
Answer:
An ecosystem works with the help of producers and consumers. The producers include all the green plants, which manufacture their own food through photosynthesis. The primary consumers include herbivorous animals like deer, goats, mice and all plant-eating animals. The carnivores include all the flesh eating animals like snakes, tigers and lions. Certain carnivores that feed also on carnivores are known as top carnivores like hawks and mongooses. Decomposers are those that feed on dead organisms (for example, scavengers like vultures and crows), and further breaking down of the dead matter by other decomposing agents like bacteria and various micro¬organisms.
Question 3.
Use a diagram to clear the concept of food chain.
Answer:
Question 4.
Differentiate between food chain and food web.
Answer:
Food chains follow a single path as animals eat each other.
Example:
- The sun provides food for grass.
- The grass is eaten by a grasshopper.
- The grasshopper is eaten by a frog.
- The frog is eaten by a snake.
- The snake is eaten by a hawk.
Food webs show how plants and animals are interconnected by different paths.
Example:
- Trees produce acorns which act as food for many mice and insects.
- Because there are many mice, weasels and snakes have food.
- The insects and the acorns also attract birds, skunks, and opossums.
- With the skunks, opposums, weasels and mice around, hawks, foxes, and owls can find food.
- They are all connected. Like a spiders web, if one part is removed, it can affect the vchole web.
Map Skills
Question 1.
Show diagram for carbon cycle
Answer:
Question 2.
Show a diagram explaining nitrogen cycle.
Answer:
Question 3.
Show oxygen cycle and its reservoirs with the help of a diagram.
Answer:
Question 4.
Show with the help of a diagram, the water or hydrological cycle.
Answer:
Class 11 Geography
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