CBSE Class 11

Here we are providing Class 11 Geography Important Extra Questions and Answers Chapter 3 Interior of the Earth. Important Questions for Class 11 Geography are the best resource for students which helps in class 11 board exams.

Important Questions for Class 11 Geography Chapter 3 Interior of the Earth

Interior of the Earth Important Extra Questions Very Short Answer Type

Question 1.
What are Body waves?
Answer:
The earthquake waves which travel through the solid body of the earth are called Body waves.

Question 2.
Name two types of Body waves.
Answer:
‘P’ (primary) and ‘S’ (secondary) waves.

Question 3.
Where does the asthenosphere lie?
Answer:
Asthenosphere lies in the upper mantle, or below the earth’s crust.

Question 4.
What is Gutenberg discontinuity?
Answer:
A plane of the discontinuous surface between the core and the mantle is known as Gutenberg discontinuity.

Question 5.
What is the effect on ‘P’ waves at the mantle-core boundary?
Answer:
The ‘P’ waves make an abrupt drop in velocity at the mantle- core boundary.

Question 6.
What does ‘M’ discontinuity stand for?
Answer:
It stands for Mohorovicic discontinuity.

Question 7.
Which region in the earth’s interior is referred to as the low-velocity zone?
Answer:
Asthenosphere in the upper part of the mantle is referred to as the low-velocity zone.

Question 8.
Which layer in the interior of the earth consists of ‘shadow zone’?
Answer:
Shadow zone lies within the earth’s core.

Question 9.
What is Love wave?
Answer:
It is an earthquake wave that travels along the surface of the ‘ earth with a motion entirely horizontal.

Question 10.
Name the three layers of the earth.
Answer:
They are core (barysphere), mantle (mesosphere) and crust (lithosphere).

Question 11.
What is a seismograph?
Answer:
It is a sensitive instrument that records the intensity of vibrations of earthquake waves and helps in earthquake prediction.

Question 12.
Name two types of surface waves.
Answer:

1. Rayleigh waves
2. Love waves

Question 13.
What is the temperature of the core?
Answer:
The temperature of the core is about 2000°C.

Question 14.
What are the various sources of heat in the earth?
Answer:

1. Radioactivity
2. The heat of aggradation
3. The temperature of materials of which the earth is made

Question 15.
What is the depth of the earth’s crust?
Answer:
0-100 km. from the surface of the earth.

Question 16.
What is the radius of the earth’s core?
Answer:
3470 km. approximately.

Question 17.
What do you mean by Sial and Sima?
Answer:
It is the uppermost layer of the earth. It consists of silica and magnesium. Its average depth is 2800 km. It has a density of 4.75.

Question 18.
Define the term Nife.
Answer:
The core of the earth is called Nife. It consists of Nickel and ferrous. It has an average depth of 3500 km. and a density of 13 g/cm3.

Question 19.
What is a caldera?
Answer:
Caldera complexes are the most explosive of earth’s volcanoes.

Question 20.
Name the basic parts of a volcano.
Answer:
Crater, caldera, vent, fumaroles are the basic parts of a volcano.

Question 21.
Name the various intrusive forms.
Answer:
Batholiths, Lacoliths, Lapoliths, Phacoliths, Sills and Dykes.

Question 22.
Define ‘Pacific ring’.
Answer:
It is the region around the Pacific ocean. There are active volcanoes all around the Pacific OceAnswer:

Question 23.
What is lithosphere?
Answer:
The crust and the uppermost part of the mantle together are called the lithosphere.

Question 24.
Name the different types of earthquakes.
Answer:
Tectonic/Volcanic, Collapse, Explosion and Reservoir induced earthquake.

Question 25.
How explosion earthquakes occurs?
Answer:
Explosion earthquakes occur due to the explosion of chemical or nuclear devices. .

Question 26.
Name the direct sources which provide information about the earth’s interior.
Answer:
Volcanic eruptions, Deep Ocean Drilling Project and mining.

Interior of the Earth Important Extra Questions Short Answer Type

Question 1.
How do the rocks of the earth’s mantle behave when subjected to the earthquake waves?
Answer:
The earth’s mantle behaves as an elastic solid when subjected to the earthquake waves. It changes the shape of the landscape when stresses are applied, but returns exactly to its original shape when these stresses are removed.

Question 2.
What is asthenosphere?
Answer:
The asthenosphere is the zone of hot rocks, believed to be in a plastic condition, underlying the solid lithosphere or the earth’s crust. It is sometimes termed as the soft layer of mantle or the low-velocity zone because the earthquake waves travel in it at reduced velocities.

Question 3.
Distinguish between Body waves and surface waves.
Answer:
The earthquake waves which travel longitudinally through the solid body of the earth are called Body waves. They move-faster. Those waves which move transversally along the surface are known as Surface waves. They move slowly and cause more disaster.

Question 4.
Define surface waves along with their sub-types.
Answer:
Hie earthquake waves which move along the free upper crust of the earth are called surface waves. Surface waves are of two types, viz, Rayleigh waves and Love waves. Rayleigh waves can be visualised as water waves travelling across the surface of a still pond after a pebble has been tossed into the water. But the motion in the Love waves is entirely horizontal, at right, angles to the direction of the wave motion. The Rayleigh and Love waves travel more or less the same length, but with different speeds.

Question 5.
Describe Mohorovicic Discontinuity.
Answer:
The surface of a sudden increase in wave velocity, which separates the crust above from the mantle below is Mohorovic or ‘Moho’ or ‘M’ discontinuity. It is named after the Yugoslavian seismologist Mohorovicic, who first detected it in 1909.

Question 6.
How is the crust distinguished from the mantle?
Answer:
The crust is distinguished from the mantle by the presence of an abrupt change in the velocity of seismic waves. This corresponds to the abrupt change in the rigidity of the rock from crust to mantle. This change in rigidity is due to the change in the mineral composition or in the physical state of rocks.

Question 7.
Write a short note on the earth’s core.
Answer:
‘Core’ means the innermost part. Earth’s core is the innermost or central part of the earth’s interior. It has a radius of approximately 3470 km (2160 miles). On the basis of the behaviour of the seismic waves, it has been proved that the earth’s outer core is in a liquid state. Earth’s magnetic field is generated here. Between the outer core and the mantle that envelops it is the Gutenberg discontinuity.

Question 8.
Describe the earth’s crust.
Answer:
Earth’s crust is the topmost layer of the earth’s interior. It is also called the lithosphere. It has an average density of 3.0 g/cm. Its thickness varies from about 7 km. beneath the oceans to 70 km. under some parts of the continents. It is separated from the mantle below by Mohorovicic Discontinuity.

Question 9.
Discuss the properties of the upper mantle.
Answer:
Based on the behaviour of seismic waves, the mantle is subdivided into two major parts – the upper mantle and the lower mantle. The upper mantle extends from the crust to a depth of about 650 km. including the asthenosphere, which occupies the upper 300 to 400 km. The upper boundary of the upper mantle is forward by Mohorovicic Discontinuity, which separates it from the overlying crust.

Question 10.
How do the rocks of the earth’s mantle behave when subjected to the earthquake waves?
Answer:
The P’ waves move faster and make an abrupt drop in velocity of the mantle-core boundary, whereas ‘S’ waves move slowly and terminate at the mantle-core boundary. Through earth’s mantle (nearly ’ 2900 km) the speed of the earthquake waves is so high that only a very rigid and dense rock will satisfy the observed condition; the rocks behave as an elastic solid so that the mantle changes its shape when shear stresses are applied and returns exactly to its former shape when stresses are removed.

Question 11.
What is the main evidence in favour of the layered structure of the earth?
Answer:
The scientists accept that the earth has a layered structure. The earth has three layers or shells :

1. crust
2. mantle
3. core.

These layers are distinguished on the basis of their physical and chemical properties, i.e.,

1. thickness,
2. density,
3. temperature,
4. metallic contents and
5. rocks.

Question 12.
What do you mean by the term ‘Barysphere’?
Answer:
The Barysphere is the central core of the earth. It has a depth of 4980 km to 6400 km. It has a density of 17 g/cm3. It consists of heavy minerals and it is also called ‘core’. The core of the earth is metallic in > nature.

Question 13.
Describe the three types of earthquake waves.
Answer:
These waves are :

1. ‘P’waves or longitudinal waves-These are also known as primary waves. These travel in the direction of their movement. They can travel through solids as well as liquid and gaseous matter.
2. ‘S’ waves or transverse waves – These are also known
   as secondary waves. These travel at a right angle to the direction of their oscillation. They can travel in solid ‘? medium only.
3. ‘L’ waves – These are known as surface waves. These waves do hot go deep into the earth.

Question 14.
What do you understand by the structure of the earth?
Answer:
The earth is made up of many layers of different materials. The density and temperature of each layer vary according to the depth. The study of the layered composition of the earth is known as the structure of the earth.

Interior of the Earth Important Extra Questions Long Answer Type

Question 1.
Write short notes on :
1. Shadow zone
2. The earth’s crust
Answer:
1. Shadow zone – It lies beneath the surface of the earth, i.e., in its interior. The seismic waves bend as they travel through the core and, therefore, ‘P’ waves are not directly received in a zone known as the shadow zone. Also, ‘S’ waves are not received there because they do not travel through the liquid outer core. Only surface waves are received in the shadow zone.

2. The earth’s crust – This is also known as the lithosphere. The crust is the outermost shell 1 of the earth. It consists of the surface granite SIAL and the intermediate basic SIMA layers. It is separated from the under layer MANTLE by the Mohorovicic Discontinuity. There are two kinds of crust – continental and oceanic. Continental crust has an average density of 3 g/cnt3, the average thickness of 35 to 40 km. (22 to 25 miles) with large areas older than 1500 million years. Continental crust is a complicated structure and has a variable composition. Oceanic crust is thinner than continental crust. Its average density is 2.7 g/cm3 and average thickness of only 6 km. (3.7 miles), with the simple layered structure of the uniform composition.

Question 2.
Discuss how do seismic waves suggest layering of the earth’s interior.
Answer:
Seismic waves are the earthquake waves. The movement of seismic waves tells us a great deal about the earth’s internal structure. The shock waves arising from earthquakes pass through the interior of the earth in different ways and provide evidence about the inaccessible interior region of the earth. Seismic waves are of two types -: body waves and surface waves. Body waves travel through the solid body of the earth, whereas surface waves move along the free upper crust of the earth. Surface waves, in turn, are of two types, viz, Rayleigh waves and Love waves.

Body waves also have two sub-types, viz, ‘P’ waves and ‘S’ waves. ‘P’ (primary waves) pass through all the medium solid, liquid and gaseous, whereas ‘S’ or secondary waves do not pass through liquids.

Based on the above observation related to seismic waves, the interior has been divided into three layers – core, mantle and crust.

The core is the innermost or central layer, the crust is the outermost layer, whereas mantle lies in the middle. Since ‘S’ waves cannot pass through the central part of the earth or core, it suggests that this part is made up of a medium which is not solid. This proves that the earth’s outer core is in a liquid state in contrast to the surrounding mantle which is solid.

The ‘P’ waves make an abrupt drop in velocity at the mantle-core _ boundary, whereas ‘S’ waves terminate here. Based on the behaviour of seismic waves, the mantle is sub-divided into two major parts – the upper mantle and the lower mantle.

The crust is distinguished from the mantle by the presence of an abrupt change in velocity of seismic waves. The change in rigidity, in turn, is due to change in the universal composition or in the physical state of the rocks.

Question 3.
Describe the earth’s mantle.
Answer:
The mantle is that part of the earth’s interior which lies between the core and the crust. It consists of solid ultrabasic rocks. The mantle is about 2900 km thick with a density of about (3.0 to 3.4) g/cm3. The lower surface of the mantle forces Gutenberg Discontinuity, the uppermost layer forces the Asthenosphere.

The ‘P’ or primary earthquake waves make an abrupt drop in velocity at the mantle-core boundary, whereas ‘S’ or secondary waves terminate at this boundary. . It is because of the presence of a plane of the discontinuous surface between the core and the mantle known as Gutenberg Discontinuity.

Based on the behaviour of seismic waves, the mantle is sub-divided into two major parts – the upper mantle and the lower mantle. The upper mantle extends from the crust to a depth of about 650 km. and includes 300 to 400 km wide Asthenosphere, the uppermost part of the mantle. Rocks in Asthenosphere behave as an elastic solid. This region is referred to as the low-velocity zone.

Question 4. How do the waves of different types tell us about the changes in the nature of different layers of the earth’s interior?
Answer:
Seismic waves are the earthquake waves. The movement of seismic waves tells us a great deal about the earth’s internal structure. The shock waves arising from earthquakes pass through the interior of the earth in different ways and provide evidence about the inaccessible interior region of the earth. Seismic waves are of two types -: body waves and surface waves. Body waves travel through the solid body of the earth, whereas surface waves move along the free upper crust of the earth. Surface waves, in turn, are of two types, viz, Rayleigh waves and Love waves.

Body waves also have two sub-types, viz, ‘P’ waves and ‘S’ waves. ‘P’ (primary waves) pass through all the medium – solid, liquid and gaseous, whereas ‘S’ or secondary waves do not pass through liquids.

Based on the above observation related to seismic waves, the interior has been divided into three layers – core, mantle and crust.

The core is the innermost or central layer, the crust is the outermost layer, whereas mantle lies in the middle. Since ‘S’ waves cannot pass through the central part of the earth or core, it suggests that this part is made up of a medium which is not solid. This proves that the earth’s outer core is in a liquid state in contrast to the surrounding mantle which is solid.

The ‘P’ waves make the abrupt drop in velocity at the mantle-core boundary, whereas ‘S’ waves terminate here. Based on the behaviour of seismic waves, the mantle is sub-divided into two major parts – the upper mantle and the lower mantle.

The crust is distinguished from the mantle by the presence of an abrupt change in velocity of seismic waves. The change in rigidity, in turn, is due to change in the universal composition or in the physical state of the rocks.

The mantle is that part of the earth’s interior which lies between the core and the crust. It consists of solid ultrabasic rocks. The mantle is about 2900 km thick with a density of about (3.0 to 3.4) g/cm3. The lower surface of the mantle forces Gutenberg Discontinuity, the uppermost layer forces the Asthenosphere.

The ‘P’ or primary earthquake waves make an abrupt drop in velocity at the mantle-core boundary, whereas ‘S’ or secondary waves terminate at this boundary. . It is because of the presence of a plane of the discontinuous surface between the core and the mantle known as Gutenberg Discontinuity.

Based on the behaviour of seismic waves, the mantle is sub-divided into two major parts – the upper mantle and the lower mantle. The upper mantle extends from the crust to a depth of about 650 km. and includes 300 to 400 km wide Asthenosphere, the uppermost part of the mantle. Rocks in Asthenosphere behave as elastic solid. Th,is region is referred to as the low-velocity zone.

Question 5.
Distinguish between :
1. Body Waves and Surface Waves
2. The crust of the earth and Core of the earth
3. Gutenberg Discontinuity and Mohorovicic Discontinuity
Answer:
1. Body waves and Surface Waves :
Seismic waves are the earthquake waves. The movement of seismic waves tells us a great deal about the earth’s internal structure. The shock waves arising from earthquakes pass through the interior of the earth in different ways and provide evidence about the inaccessible interior region of the earth. Seismic waves are of two types -: body waves and surface waves. Body waves travel through the solid body of the earth, whereas surface waves move along the free upper crust of the earth. Surface waves, in turn, are of two types, viz, Rayleigh waves and Love waves.

Body waves also have two sub-types, viz, ‘P’ waves and ‘S’ waves. ‘P’ (primary waves) pass through all the medium – solid, liquid and gaseous, whereas ‘S’ or secondary waves do not pass through liquids.

Based on the above observation related to seismic waves, the interior has been divided into three layers – core, mantle and crust.

The core is the innermost or central layer, the crust is the outermost layer, whereas mantle lies in the middle. Since ‘S’ waves cannot pass through the central part of the earth or core, it suggests that this part is made up of a medium which is not solid. This proves that the earth’s outer core is in a liquid state in contrast to the surrounding mantle which is solid.

The ‘P’ waves make an abrupt drop in velocity at the mantle-core boundary, whereas ‘S’ waves terminate here. Based on the behaviour of seismic waves, the mantle is sub-divided into two major parts – the upper mantle and the lower mantle.

The crust is distinguished from the mantle by the presence of an abrupt change in velocity of seismic waves. The change in rigidity, in turn, is due to change in the universal composition or in the physical state of the rocks.

2. Crust of the earth and Core of the earth:

3. Gutenberg Discontinuity and Mohorovicic Discontinuity:

Here we are providing Class 11 Geography Important Extra Questions and Answers Chapter 2 The Origin and Evolution of the Earth. Important Questions for Class 11 Geography are the best resource for students which helps in class 11 board exams.

Important Questions for Class 11 Geography Chapter 2 The Origin and Evolution of the Earth

The Origin and Evolution of the Earth Important Extra Questions Very Short Answer Type

Type

Question 1.
What is Nebula?
Answer:
The nebula is the name given to the slowly rotating cloud of gas, which later condensed and solidified to give birth to different planets.

Question 2.
Name our galaxy.
Answer:
Milky way.

Question 3.
Who first proposed the Nebular hypothesis?
Answer:
The German philosopher, Immanuel Kant, proposed the Nebular hypothesis in 1755.

Question 4.
How is it known that the moon was born along with the earth?
Answer:
Radiometric dating of the rocks from the moon shows that it was born along with the earth.

Question 5.
Name all the nine planets in their order from the sun.
Answer:
They are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

Question 6.
Name the largest and the smallest planet of our solar system.
Answer:
Jupiter is the largest and Mercury is the smallest planet of our solar system.

Question 7.
Name two scholars who had identical views on the origin of planets.
Answer:
Immanuel Kant, a German scholar and Laplace, a French mathematician, expressed identical views on Nebular hypothesis.

Question 8.
Name two English scientists who put forward the Collision hypothesis of the origin of planets.
Answer:
They were Sir James Jeans and Sir Harold Jeffreys.

Question 9.
Name the planet with a maximum number of satellites in our solar system.
Answer:
Saturn has the maximum number of satellites (20) in our solar system.

Question 10.
Which planets in our solar system have no satellite at all?
Answer:
Mercury and Venus have no satellites so far.

Question 11.
What are the various stages the sun has passed through during its formation?
Answer:
They are Nebula → Supernova → Protostar → Infant Sun → Sun.

Question 12.
Which other planet is known to have just one satellite-like our earth?
Answer:
Pluto.

Question 13.
What is a meteorite?
Answer:
A meteorite is a piece of rock or metal from outer space that hits the earth’s surface.

Question 14.
A piece of rock or metal from outer space falling on the earth?
Answer:
Meteorite.

Question 15.
The only planet with conditions favourable for the sustenance of life?
Answer:
The earth.

Question 16.
The second-largest planet of our solar system?
Answer:
Saturn.

Question 17.
What is a protostar?
Answer:
The infant son was the protostar.

Question 18.
Name two great ice areas of the present age.
Answer:
Antarctica and Greenland.

Question 19.
When did drifting start in Pangea?
Answer:
In the upper carboniferous age about 300 million years ago.

Question 20.
When was the earth formed?
Answer:
The earth came into existence about 4600 million years ago.

Question 21.
How does earth’s surface appear from the space?
Answer:
It appears blue from the space.

Question 22.
Why does earth appear as a round ball that shines bright and blue when viewed from space?
Answer:
Because a large part of the earth’s surface is covered with water, which is blue in colour.

Question 23.
Why is the study of the origin of earth essential?
Answer:
The study of the origin of the earth is essential because we are living on earth.

Question 24.
Why do planets differ in size, constituent matter and temperature?
Answer:
They differ in size, matter and temperature because of their varying distances from the sun.

Question 25.
What are planetesimals?
Answer:
Giant tongues of matter broke into small chunks or planetesimals, which went flying as cold bodies into orbits around the sun.

The Origin and Evolution of the Earth Important Extra Questions Short Answer Type

Question 1.
What is a protostar?
Answer:
Protostar means original star. It is believed that the gaseous cloud exploded to form a supernova. The explosion caused shock waves that caused the denser portion of the cloud to collapse under their own ‘ gravity. The dense core grew larger and hotter and its gravity attracted more material. In this process, the hot core developed into a protostar. ‘ Finally, it became the infant sun.

Question 2.
Explain Heterogenous Accretion Hypothesis.
Answer:
According to Heterogeneous Accretion Hypothesis, the composition of the material from which the earth accreted changed r with time giving rise to the layered structure of the earth. According to this model, the earth formed ‘ inside out’ with an, oxidised and volatile-rich nucleus and a more metal-rich and depolarised outer rings.

Question 3.
Differentiate between supernova and protostar.
Answer:

Question 4.
What do you mean by plate tectonics?
Answer:
Plate tectonics is a theory. According to it, the crust and mantle (lithosphere) are divided into plates and blocks. Different tectonic movements take place along their edges. These plates drift due to convection currents. Continents also drift along with these plates, known as tectonic plates.

Question 5.
The moon was born along with the earth. How?
Answer:
Regarding the birth of the moon, there are many hypotheses. Radiometric dating of the rocks from the moon shows that it was born along with the earth. It either came out of the sun in a gaseous form but being too small was attracted by the earth, or it flew out of the earth due to a huge meteorite falling on the earth.

Question 6.
Why are inner planets heavier than the outer ones?
Answer:
Initially, the nebula was revolving in the form of a flat disc. Due to high temperature, the heavy materials of the flat disc condensed in the inner part of the disc. These include iron and aluminium. Thus, inner planets Mercury, Venus, Earth and Mars were formed.

Question 7.
What is Collision hypothesis?
Answer:
This hypothesis was proposed by Sir James Jeans and Sir Harold Jeffreys, a mathematician in England. According to this hypothesis, gaseous material was pulled away from the pre-existing sun by the gravitational force of a passing star.

Question 8.
Name the three layers of the earth’s interior.
Answer:

1. The Earth’s crust (lithosphere)
2. The intermediate layer (mantle)
3. The inner core (metallic core)

Question 9.
Why does the inner core of the earth behave like a solid?
Answer:
The inner core of the earth should have been molten owing to high temperature in such a great depth, but it is not molten; it behaves like a solid because of the great pressure of the outer shells.

Question 10.
What do you understand by a light-year?
Answer:
A light-year is a measure of distance and not of time. Light travels at a speed of 300,000 km/second. The distance that the light travels in one year is taken to be one light year. This is equal to 9.461 xlO12 km. The mean distance between the sun and the earth is Y‘ 149,598,000 km. In terms of light-years, it is 8,3 31 minutes.

Question 11.
How was the solid crust formed?
Answer:
The solid crust was formed by the cooling and condensation of the gaseous material on the surface of the earth.

Question 12.
What do you understand by the birth of the solar system?
Answer:
The entire solar system forms a very small part of the galaxy that consists of many stars. Our galaxy is called the Milky Way. The gaseous cloud exploded to form a supernova. The explosion caused shock waves that caused the denser portion to collapse under its own gravity. In the process, the hot core developed into a protostar. Finally, the protostar became the infant sun.

Question 13.
What are the outer and inner planets?
Answer:
The four planets Mercury, Venus, Earth and Mars are called inner planets. They lie between the sun and the belt of asteroids.

The five planets Jupiter, Saturn, Uranus, Neptune and Pluto are called outer planets. These are also known as Jovian or Gas Giant planets.

Question 14.
Write a note on Heterogenous Accretion Hypothesis.
Answer:
This hypothesis explains the layered structure of the earth. According to this theory, the earth is formed by the accretion of different ‘ types of materials. The materials changed with time. The earth formed from inside out due to the change of materials. It had an oxidised and hot, nucleus and more metal-rich rings.

The Origin and Evolution of the Earth Important Extra Questions Long Answer Type

Question 1.
Write short notes on :
1. Collision Hypothesis
2. Homogeneous Accretion Hypothesis
3. Origin of the Moon
Answer:
1. Collision Hypothesis – Sir James Jeans and Sir Harold Jeffreys gave this hypothesis. According to this hypothesis, gaseous material was pulled away from the pre-existing sun by the gravitational force of a passing star. By collision and gravitational attraction, the larger planetesimals swept up the smaller pieces and thus were formed the planets.

2. Homogenous Accretion Hypothesis – This hypothesis maintains that the earth accreted from an intermate mixture of silicate particles and metal particles. The material was assumed to have been formed in the solar nebula by a complex series of chemical and physical processes, which had occurred prior to the accretion of planets. According to a hypothesis, accretion of the earth occurred over a sufficiently long period (10—10s years) so that its gravitational potential energy was efficiently radiated away and it formed in an initially ‘cool’ and unmelted condition.

3. Origin of the moon – Radiometric dating of the rocks from the moon shows that it was born along with the earth. Apparently, there are two possibilities. It either came out of the sun in a gaseous form but being too small was attracted by the earth, or it flew out of the earth due to a huge meteorite falling on the earth. The area where the meteorite fell, a huge hollow was created, which is now filled up by an ocean and the landmass plunged to outer space to create the moon.

Question 2.
Discuss the various hypotheses for the evolution of the planets.
Answer:
There are two hypotheses :

1. Nebula hypothesis
2. Collision hypothesis

1. Nebula hypothesis – In 1755, German philosopher Immanuel Kant, hypothesised that slowly rotating cloud of gas, called Nebula, in some unspecified manner, condensed into a number of discrete and globular bodies. The great French mathematician Laplace also proposed, more or less, the same theory in 1796.

According to Kant and Laplace, the original mass of gas-cooled and began to contract. The rotational speed increased as a consequence of the law of conservation of angular momentum. Then, successive rings of gaseous material were spun off from the central mass by centrifugal force. In the final stage, the rings condensed into planets.

2. Collision hypothesis – Sir James Jeans and Sir Harold Jeffreys gave this hypothesis. According to this hypothesis, gaseous material was pulled away from the pre-existing sun by the gravitational force of a passing star. By collision and gravitational attraction, the larger planetesimals swept up the smaller pieces and thus were formed the planets.

Question 3.
Describe the evolution of the Solar system,
Answer:
The entire solar system consists of the sun, the nine planets and their various satellites. The sun is a large brilliant star in the centre of the solar system. It is thought to be about 5 billion years old. The pressure and temperature at the centre of the Nebula (cloud of gas) that produced the solar system became so great that it triggered a nuclear reaction. Some of the hydrogen in the cloud fused into helium, releasing a great amount of energy.

The gaseous cloud exploded to form a supernova. The explosion caused shock waves that pushed the denser portion of the cloud to collapse under its own gravity. The dense core grew larger and hotter as its gravity attracted more material. In the process, the hot core developed into a protostar, that finally became the sun.

Question 4.
Describe the origin of life and die cause for its origin,
Answer:
Modern scientists refer to the origin of life as a kind of chemical reaction, which first generated complex organic molecules and then 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 blue algae have been found in geological formations that are much older than some 3000 million years. It can be assumed that simpler forms precede these. Scientists consider that life began to evolve sometime 3800 million years ago.

The last phase in the evolution of the earth relates to the origin and evolution of life. The initial or even the early atmosphere of the earth was not conducive for the development of life.

Question 5.
Describe in short the evolution of atmosphere and hydrosphere (oceans).
Answer:
There are three stages in the evolution of the present atmosphere. The first stage is the loss of the primordial atmosphere. In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere. The third stage in the composition of the atmosphere was modified by the living world through the process of photosynthesis.

The early atmosphere, with hydrogen and helium, has been stripped off as a result of the solar winds. All the terrestrial planets are supposed to have lost their primordial atmosphere through the impact of solar winds. During the differentiation and cooling of the earth, gases and water vapour were released from the interior solid earth. This started the evolution of the present atmosphere. 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. Continuous volcanic eruptions contributed water vapour and gases to the atmosphere. As the earth cooled, the water vapour released started getting condensed. The carbon dioxide in the atmosphere got dissolved in rainwater and the temperature further decreased causing more condensation and more rains, The rainwater falling on 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. Oceans began to have the contribution of oxygen through the process of photosynthesis.

Here we are providing Class 11 Geography Important Extra Questions and Answers Chapter 1 Geography as a Discipline. Important Questions for Class 11 Geography are the best resource for students which helps in class 11 board exams.

Important Questions for Class 11 Geography Chapter 1 Geography as a Discipline

Geography as a Discipline Important Extra Questions Very Short Answer Type

Question 1.
Who first used the term ‘geography’?
Answer:
The term ‘geography’ was first used by Eratosthenes, a Greek scholar, who lived in Alexandria, Egypt during 276-192 BC.

Question 2.
What do you mean by process?
Answer:
A process is a sequence of changes systematically related through a chain of causes and effects.

Question 3.
Name the area that still remains largely inaccessible even today.
Answer:
Antarctica still remains largely inaccessible and unexplored even today.

Question 4.
What is meant by ‘culture’?
Answer:
‘Culture’ is the cumulative product of experiences. It consists of values, processes, beliefs, thoughts, ethical standards, and styles of life and living.

Question 5.
Name the oldest school of geographical thought.
An’s,
The Greek school is the oldest school of geographical thought.

Question 6.
Name two leading ‘possibilists’.
Answer:
They were Vidal dela Blache and Lucien Febvre.

Question 7.
Who were the leaders of ‘Deterministic’ philosophy?
Answer:
Fredrich Ratzel and Ellsworth Huntington were the leaders of ‘Deterministic’ philosophy.

Question 8.
Who were the discoverers of the unknown lands?
Answer:
Egyptians, Mesopotamians, Greeks, and Arabs were the first discoverers of the unknown lands.

Question 9.
The Greek scholar w housed the term ‘Geography’ for the first time.
Answer:
Eratosthenes.

Question 10.
The viewpoint about the universe stating that all planets revolve around the sun and the sun is stationary.
Answer:
Heliocentric.

Question 11.
The ancient Indian scholar who first propounded the theory of a heliocentric universe.
Answer:
Aryabhatta.

Question 12.
The technique of aerial photo interpretation.
Answer:
Photogrammetry.

Question 13.
The genetic study of landforms.
Answer:
Geomorphology.

Question 14.
The branch of biogeography that studies the man-nature relationship.
Answer:
Human ecology.

Question 15.
The doctrine believes that the environment controls human activities.
Answer:
Determinism.

Question 16.
What is cartography?
Answer:
It is the technique of drawing maps and diagrams.

Question 17.
What do you mean by geomorphology?
Answer:
It is the science that studies landforms.

Question 18.
What is cultural geography?
Answer:
It includes the cultural aspects of human groups such as ornaments, food, cloth, etc.

Question 19.
What is called economic geography?
Answer:
The discipline dealing with the distribution of economic activities of man which relate to the production of a commodity, its marketing, and distribution is called economic geography.

Question 20.
What do you understand by Hydrology?
Answer:
It is the science which deals with oceans, rivers, glaciers, etc.

Question 21.
What do you understand by Regionalism?
Answer:
The process of identifying various regions is known as v regionalism.

Geography as a Discipline Important Extra Questions Short Answer Type

Question 1.
What is geography?
Answer:
The word geography is a combination of two Greek words. ‘Geo’ meaning the earth and “Graphy’ meaning description. Thus, the meaning of geography could be to write about the earth including all that is upon it. Geography is the science dealing with the spatial distribution of various phenomena (physical & human & biotic) on the surface of the earth.

Question 2.
What is the relation of geography with other sciences?
Answer:
Geography draws its contents from both natural science and social science (sociology, economics, political science). It has also. contributed to them. Hence there are several interdisciplinary’ areas in; geography. For example. Geomorphology is closely linked with. Geology, Economic Geography with Economics, and Bio-geography with life sciences (Botany and Zoology).

Question 3.
What are the three features of systematic geography?
Answer:

1. It studies geographical facts in an individual manner.
2. It implies the detailed study of a single specific geographical factor.
3. It is explanatory and is largely interpretative.
4. A detailed study of agriculture is done by marking the agricultural regions of India.

Question 4.
Why did geography become a popular subject in school by the end of the eighteenth century?
Answer:
It was because it gave knowledge about the land to prospective migrants, administrators and traders. Gradually, along with the description of places and peoples, explanation for varying responses of people to the natural environment was also presented. Thus, geography emerged as the study of the dynamics of the man-environment relationship and its imprints on the earth’s surface.

Question 5.
What are the two ways of studying geographic problems?
Answer:
The two ways of studying geographic problems are systematic and regional. A study of a specific natural or social phenomenon that gives rise to certain spatial patterns and structures on the earth’s surface is called systematic geography. Unlike systematic geography, regional geography starts with the spatial imprints of one or all the systematic geographic processes discernible as regions of different sizes.

Question 6.
Distinguish between physical geography and biogeography.
Answer:
Geography is a spatial science dealing with the distribution of various elements and phenomena over the earth’s surface. When these elements are natural and no one is living they are called physical, e.g. land-form, climate, water, and soil. Accordingly, physical geography has branches like geomorphology, climatology, hydrology, soil geography. On the other hand, the life-form or living elements constitute the part of bio-geography. Therefore, the main branches of bio-geography are plant geography, zoo-geography, and human ecology.

Question 7.
Write in brief on the geographic methods and techniques.
Answer:
Geographers use various types of methods and techniques in order to collect and analyze information related to the surface of the earth. They include the following :

1. Field studies (physical as well as socio-economic surveys).
2. Cartography (the science of drawing maps and diagrams).
3. Quantitative geography (covers a number of mathematical and statistical techniques).
4. Spatial information system, e.g., GIS, LIS, GPS.

Question 8.
What are the natural and cultural features on the surface of the earth?
Answer:
The physical elements which are the outcome of natural processes in action are natural features, such as continents, mountains, rivers, plains, oceans, atmosphere, etc., whereas the elements which are products of human activities are cultural features, e.g., countries, villages, towns, cities, agriculture, industry, means of transport and communication, etc.

Question 9.
Name the branches of geography on the basis of the regional approach.
Answer:

1. Regional studies/Area studies comprising Macro, Meso, and Micro regional studies.
2. Regional planning comprising country/rural planning and town and urban planning.
3. Regional development.
4. Regional Analysis.

Question 10.
What is Political geography?
Answer:
Political geography looks at the space from the angle of political events and studies boundaries, space relations between neighboring political units, delimitations of constituents, and election scenario, and develops a theoretical frame to understand the political behavior of the population.

Question 11.
Name the various branches of bio-geography. What led to the development of bio-geography?
Answer:
The interface between Physical geography and Human geography has led to the development of Bio-geography. It includes:

1. Plant geography – Study of the spatial. the pattern of natural vegetation in their habitats.
2. Zoo-geography – Study of spatial patterns and geographic characteristics of animals and their habitats.
3. Ecology/Ecosystem – Study of the habitats characteristic of species.
4. Environmental geography – The environmental concern world over leading to the realization of environmental problems, such as land degradation, pollution, and concerns for conservation, led to the introduction of this new branch of geography.

Question 12.
What do you mean by Systematic geography?
Answer:
A study of a specific natural or cultural phenomenon that gives rise to certain spatial patterns on the earth’s surface is called Systematic geography. There are four branches of systematic geography :

1. Physiography
2. Biogeography
3. Human ecology
4. Geographic methods and techniques.

Geography as a Discipline Important Extra Questions Long Answer Type

Question 1.
Write a short note on Spatial Information Technology (SIT).
Answer:
The last quarter of the 20th century has put geography on a new trajectory of development with SIT as the main source of information and information processing. SIT is concerned with data collection and analysis related to physical space or the surface of the earth with the help of advanced means of information technology, such as remote sensing, aerial photographs, and satellite imageries.

They have enabled geographers to develop geographic information systems (GIS), land information systems (LIS), and global positioning systems (GPS) as location decision administration and managerial tools. Geography in the 21 st century has entered a new era of spatial information technology (SIT). They are going to be used not only in answering the question of what is where and why but also in what should be where and why. They will not only be generating information for decision-making but also will be actively participating in decision-making.

Question 2.
Describe the various branches of geography.
Answer:
Today geography is the only discipline that brings all-natural and human sciences on a common platform. It is an interdisciplinary and integrative science having numerous branches :
A. Systematic geography :

1. Physiography: Studies the physical aspects of the earth’s surface, as landforms, climate, water, and soil.
2. Plant Geography: Studies the distribution of various kinds r- of forests and grasslands. Zoo-geography studies the
   distribution of animals and micro-organisms. Human ecology studies the changing human-nature relationship and its consequences on human life and living. Environmental y geography studies the quality of the living environment and
   its implications for human welfare.
3. Human Geography: Human beings interact with nature and create a great variety of cultural phenomena like villages, Ji towns, cities, countries, factories, roads, houses, etc. The study of location and distribution of all such phenomena falls under the purview of human geography.
4. Geographic methods and techniques: Field studies, cartography, quantitation geography, and spatial information system (GIS, LIS, GPS).

B. Regional Geography :

1. Regional Studies
2. Regional Planning
3. Regional Development
4. Regional Approach

Question 3.
Discuss two perspectives of study that characterized geography in the twentieth century.
Answer:
Geography in the twentieth century became a discipline that studied the earth’s surface from two perspectives systematic and regional. The former produced sub-disciplines like physiography, climate, biography, political geography, economic geography, health geography, etc., while the latter gave rise to regional geography, regional science, regional development, regional planning, area planning, etc.

The first started with systematic knowledge to arrive at regional patterns, while the second started with a region to arrive at systematic details. In both cases, humans remained a central theme i.e., the emphasis of the study being on the impact of systematic processes and regional patterns on humans and their activities.

Question 4.
How did the Indian scholars contribute to geography in the ancient period?
Answer:
Indian scholars were among those who laid the foundation of geography in the ancient period. Atharva Veda, written around the 10th century B.C., gives the details of the then known earth, its physical features, bio-geography, and human settlements. Indians went to different parts of the world to carry the message of Indian culture, particularly of Hinduism and Buddhism. The contribution of Indian astronomers and geographers was highly advanced for their times. Aryabhatta propounded the theory of heliocentric universe a century before Copernicus, and Bhaskaracharya mentioned the gravity of the earth 1200 years before Newton. Kalidas’s description of the geography of Central India in ‘Meghaduta’ is highly professional,

Question 5.
What is the importance of Physical geography?
Answer:
Physical geography includes the study of the lithosphere, atmosphere, hydrosphere, and biosphere.

• Soils are formed through the process of pedogenesis and depend. upon the parent rocks, climate, biological activity, and time. Time provides maturity to soils and helps in the development of soil profiles. Each element is important for human beings.
• Landforms provide the base on which human activities are located.
• The plains are utilized for agriculture. Plateaus provide forests and minerals. Mountains provide pastures, forests, tourist spots and are sources of rivers providing water to lowlands.
• Climate influences our house types, clothing, and food habits.
• Climate has a profound effect on vegetation, cropping pattern, livestock farming, and some industries, etc.
• Temperature and precipitation ensure the density of forests and the quality of grassland.
• Oceans are the storehouse of resources and are rich in mineral resources, fish, and other seafood.

Soils are renewable resources, which influence a number of economic activities such as agriculture.

Physical geography is fast emerging as a discipline for evaluating and managing natural resources.

NCERT Exemplar Class 11 Biology Solutions

• Chapter 1 The Living World
• Chapter 2 Biological Classification
• Chapter 3 Plant Kingdom
• Chapter 4 Animal Kingdom
• Chapter 5 Morphology of Flowering Plants
• Chapter 6 Anatomy of Flowering Plants
• Chapter 7 Structural Organisation in Animals
• Chapter 8 Cell: The Unit of Life
• Chapter 9 Biomolecules
• Chapter 10 Cell Cycle and Cell Division
• Chapter 11 Transport in Plants
• Chapter 12 Mineral Nutrition
• Chapter 13 Photosynthesis in Higher Plants
• Chapter 14 Respiration in Plants
• Chapter 15 Plant Growth and Development
• Chapter 16 Digestion and Absorption
• Chapter 17 Breathing and Exchange of Gases
• Chapter 18 Body Fluids and Circulation
• Chapter 19 Excretory Products and Their Elimination
• Chapter 20 Locomotion and Movement
• Chapter 21 Neural Control and Coordination
• Chapter 22 Chemical Coordination and Integration

NCERT CBSE Extra Questions for Class 11 English: Here we are providing NCERT Extra Questions for Class 11 English Hornbill and Snapshots. Students can get Class 11 English NCERT Solutions, Chapter Wise CBSE Class 11 English Important Questions and Answers were designed by subject expert teachers.

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Extra Questions for Class 11 English Hornbill and Snapshots Important Questions

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Extra Questions for Class 11 English Hornbill Prose

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Extra Questions for Class 11 English Hornbill Poem

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Extra Questions for Class 11 English Snapshots

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