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Composition and Structure of Atmosphere Class 11 Important Extra Questions Geography Chapter 8

 


Composition and Structure of Atmosphere Class 11 Important Extra Questions Geography Chapter 8



Composition and Structure of Atmosphere Important Extra Questions Very Short Answer Type


Question 1.

How is the atmosphere held to the earth?

Answer:

The atmosphere is held to the earth by the force of gravity.

Question 2.

What is heterosphere?

Answer:

The layer of the atmosphere 90 km above the surface of the earth where the composition begins to change with a progressive increase in the lighter gases, is called heterosphere.

Question 3.

Which are the major constituents of clean dry air of atmosphere?

Answer:

Oxygen and nitrogen are the major constituents of clean dry air of the atmosphere.

Question 4.

Which gas of the atmosphere does not take part in a chemical reaction?

Answer:

‘Argon’ does not take part in a chemical reaction.

Question 5.

What are aerosols?

Answer:

Aerosols are huge amounts of s0lid and liquid particles present in the atmosphere.

Question 6.

Which gas despite its small percentage is crucial in atmospheric processes?

Answer:

Carbon dioxide is an important gas in the atmospheric processes.

Question 7.

What is the atmosphere?

Answer:

The atmosphere is a gaseous envelope extending thousands of kilometres above the earth’s surface.

Question 8.

What energises the atmosphere?

Answer:

The atmosphere is energised by the sun.

Question 9.

Where does much of life exist on the earth?

Answer:

Much of life exists at the bottom of the atmosphere where it meets the lithosphere and the hydrosphere.

Question 10.

Name two broad layers of the atmosphere.

Answer:

Homosphere and heterosphere are two broad layers of the atmosphere.

Question 11.

Name the three thermal layers of the homosphere.

Answer:

Troposphere, stratosphere and mesosphere.

Question 12.

What is wind?

Answer:

The horizontal motion of the air is known as wind.

Question 13.

Mention some forms of precipitation.

Answer:

Rain, hail, sleet or snow are some forms of precipitation.

Question 14.

Which gas acts as a filter and protects us from ultraviolet rays?

Answer:

Ozone gas protects us from the ultraviolet rays and acts as a filter.

Question 15.

Which layer transmits the radio waves?

Answer:

Ionosphere.

Question 16.

Name the gas which is found in the upper part of the atmosphere.

Answer:

Hydrogen.

Question 17.

What are the two causes of depletion of the ozone layer?

Answer:

Use of carbons and deforestation are the two causes of depletion of the ozone layer.

Question 18.

Name the gas which is most essential for life.

Answer:

Oxygen.

Question 19.

What are the principal elements of weather and climate?

Answer:

Temperature, pressure, wind, moisture and precipitation are the principal elements of weather and climate.

Question 20.

Why do the jet aircraft fly through the lower stratosphere?

Answer:

Because it provides the easiest flying conditions. It is the layer of calm and clean air. There is no water vapour and clouds are present.

Question 21.

What are the constituents of dust particles?

Answer:

Smoke-soot, ash, pollen are the main constituents of dust particles.

Question 22.

What is the weather?

Answer:

The cumulative effect of wind, temperature, pressure, clouds, humidity and precipitation is called weather.

Question 23.

What is the role of elements of weather?

Answer:

They influence temperature and precipitation.


Composition and Structure of Atmosphere Important Extra Questions Short Answer Type


Question 1.

Why are the vapour and dust particles important variables of weather and climate?

Answer:

The water vapour and dust particles are important variables of weather and climate because they are the source of all forms of condensation and principal absorbers of heat received from the sun or radiated from the earth. Besides, they affect the stability of the atmosphere.

Question 2.

What is meant by a normal lapse rate?

Answer:

The temperature decreases with altitude because the atmosphere is heated more by the heat radiated from the earth’s surface. Wanner air lying under the cooler air goes up or turns downward. In this layer, the temperature decreases vertically at a rate of 0.65°C per 100 metres. It is called the normal lapse rate.

Question 3.

What is homosphere?

Answer:

The atmospheric layer up to an altitude of 90 km. above the surface of the earth is generally called homosphere. It is uniform in term of these major gases – nitrogen, oxygen and argon. In addition, it also contains some rare gases like neon, krypton and xenon.

Question 4.

Name the gases and other materials which compose the atmosphere.

Answer:

Nitrogen, oxygen and argon are the most important gases of the atmosphere. In addition, it contains gases like carbon dioxide, neon, helium, ozone, hydrogen, methane, krypton and xenon. Besides, there are also present huge amounts of solid and liquid particles collectively called aerosols.

Question 5.

Discuss the properties of nitrogen gas.

Answer:

Nitrogen is the most abundant gas of the atmosphere. By volume, it constitutes 78.8% of the total gases present in the atmosphere. Nitrogen does not easily enter into chemical union with other substances but gets fixed into the soil. It serves mainly as diluent or dissolver. It regulates combustion.

Question 6.

What is the importance of carbon dioxide on the earth?

Answer:

By volume carbon dioxide constitutes 0.03% of the total gases of the earth’s atmosphere. Although it forms a small portion, it is an important gas in the atmospheric processes. It can absorb the heat and thus allows the lower atmosphere to be warmed up by heat radiation coming from the sun and from the earth’s surface. Green plants in the process of photosynthesis utilise carbon dioxide from the atmosphere.

Question 7.

Explain the difference between weather and climate.

Answer:

The weather of any place is the sum total of its temperature, pressure, winds, moisture and precipitation conditions for a short period of time. Climate, on the other hand, is the composite weather conditions over a considerable period of time.

Question 8.

Identify the climatic controls.

Answer:

The various climatic controls are given below :


Latitude or sun.


Distribution of land and water


The great semi-permanent high and low-pressure belts


Winds


Altitude


Mountain barriers


Ocean currents


Storms of various kinds


Question 9.

What is the importance of the atmosphere for the earth?

Answer:

The earth is the only known planet to have life. The atmosphere, which is unlike that of any other planet, encircles and protects the earth. Changes in the composition of the atmosphere are closely associated with the evolution of the earth. One of the most important transition was the increase in oxygen when photosynthetic plants evolved.

The atmosphere is a mixture of gases, the largest proportion of which is nitrogen. However, the most important is oxygen, without which life could not be sustained. The very survival of life processes is associated with the atmosphere.

The influence of the atmosphere on humans particularly is not only direct but also indirect through natural vegetation, soil and topography.

Question 10.

What is tropopause?

Answer:

The tropopause is the plane which separates the troposphere and stratosphere. It is the boundary between these two layers. It is a thin transitional zone between two layers.

Question 11.

Explain three major features of the troposphere.

Answer:

Three major features are :


It is 16 km thick at the equator and 10 km thick at the poles.


The temperature decreases with the altitude at the rate of l°C per 165 metres.


Biological activities take place in this layer.


Question 12.

What are the main characteristics of the lowermost layer of the atmosphere?

Answer:

The lowermost layer is the troposphere.


Its average height is 16-18 km.


All biological activities occur in this layer.


All the atmospheric processes take place in this layer.


It is 16 km thick at the equator and 10 km thick at the poles.


Composition and Structure of Atmosphere Important Extra Questions Long Answer Type


Question 1.

Distinguish between troposphere and stratosphere.

Answer:

TroposphereStratosphere(1) It is the lowermost layer of the atmosphere.(1) It is the second layer of the atmosphere above the earth.(2) Its height varies from 10-18 km. at the equator.(2) Its height is up to 50 km.(3) Temperature decreases at the rate of 1 °C per 165 metres in this layer.(3) In this layer temperature is very low and fairly constant.(4) It is the zone of convection currents of the atmosphere.(4) It is a zone of non-convection currents of the atmosphere.(5) Water vapour, dust particles, clouds are found in this layer.(5) There is no water vapour but dust particles and clouds are found.(6) Atmospheric processes occur in this layer.(6) This zone is free from atmospheric disturbances.

Question 2.

What is the difference between condensation and precipitation?

Answer:

Condensation is the physical process of the transition of a substance from the vapour to the liquid state, e.g., as a result of cooling or increase of pressure. It occurs in the atmosphere when the air is saturated or when it is cool. Thus, the change of state of the moisture from invisible water vapour to visible liquid (water) or solid (ice or snow ) state is known n as condensation. It is opposite of evaporation.

Precipitation, on the other hand, means ‘throwing down of moisture’. Continuous condensation in the body of the air helps the water droplets to grow in size so that the resistance of the air fails to keep them suspended. In such cases, only an ascending air current can keep them floating in the air. In the absence of such a current, the products of condensation begin to fall on the earth’s surface. The process whereby the water vapour first condenses in the air and then falls on to the earth is called precipitation.

Question 3.

Discuss the principal elements of weather and climate and the major climatic controls.

Answer:

The principal elements of weather and climate are temperature precipitation, moisture, pressure and winds. These are called elements because they are the ingredients out of which various weather and climate types are compounded. The temperature and precipitation are the main basic elements to which pressure, winds and other elements are related.

Temperature expresses the intensity of heat. Practically all the heat energy on the earth is the result of insulation or the increasing solar radiation. Unequal distribution of temperature over the earth’s surface causes differences in atmospheric pressure, which causes winds.

Higher the temperature, the greater is the capacity’ of air to hold moisture on cooling. The air is not able to retain all the moisture it gathers while warm. This leads to condensation and precipitation.

Thus, the temperature is the basic element on which other elements of climate depend.

The climatic controls are :

Latitude (or sun), distribution of land and water, the great semi¬permanent high and low-pressure belts, winds, altitude, mountain barriers, ocean currents and storms of various kinds.

Question 4.

Define the atmosphere. Explain its importance to human life.

Answer:

The atmosphere is a mixture of air and various gases which envelopes the earth all around. It represents the gaseous realm of the earth. It is held to the earth by the force of gravity.

Importance of atmosphere:


It contains gases like oxygen (essential for breathing) for man and animals and carbon dioxide for plants.


By trapping the heat, it acts as a greenhouse. It keeps the earth

warm.


One of its layer, the ionosphere, reflects radio waves back to the earth and makes radio communication possible.


It protects us from the deadly cosmic rays and meteors which are continuously showered on the earth from outer space.


All the weather phenomenon take place in the atmosphere. Presence of water vapour in the atmosphere brings many changes such as condensation and precipitation. These processes influence the human life, plants and animals.


It absorbs ultraviolet rays.


It acts as an air conditioner by moderating the extremes of heat ‘ and cold.


It is a storehouse of water vapour.


Question 5.

Discuss the proportion of the constituent gases of the atmosphere.

Answer:

The atmosphere is a mixture of various gases. It includes :

Nitrogen (N,), Oxygen (O,), Argon (Ar), Carbon dioxide (CO,), Neon (Ne), Helium (He), Ozone (O,), Hydrogen (H), Methane (CH4), Krypton (Kr) and Xenon (Xe).

Nitrogen (N2): It is a colourless, odourless gas, the main constituent (i.e. 78.8% by volume) of the atmosphere. It is an essential constituent of living organisms. It is an important element for plants.

Oxygen (O,): Constitutes 20.94% of the total volume of the atmosphere. It is the second most abundant gas. It is essential to plant and animal life.

Argon (Ar): It constitutes one per cent volume of the total atmosphere. It is an inert gas, does not take part in any chemical reaction.

Carbon dioxide: It constitutes a very small amount (0.03%). It is an important gas in the atmospheric process. It can absorb heat and thus allows the lower atmosphere to be warmed up by heat radiation from the sun and from the earth’s surface. Green plants in the process of photosynthesis utilise carbon dioxide from the atmosphere.

Neon (Ne): Neon is an inert gaseous element occurring in’ trivial quantities (0.0018%) in the atmosphere.

Helium (He): It exists primarily in the sun’s atmosphere. It is an inert element of the atmosphere.

Ozone (03): It is an allotropic form of oxygen (02). Its main concentration lies between 20 to 25 km. from the earth’s surface.

Hydrogen (H): It is the lightest element. It is gaseous and inflammable. It is used in many chemical processes.

Water in the Atmosphere Class 11 Important Extra Questions Geography Chapter 11


 

Water in the Atmosphere Class 11 Important Extra Questions Geography Chapter 11


Water in the Atmosphere Important Extra Questions Very Short Answer Type


Question 1.

What is the greatest source of atmospheric moisture?

Answer:

The surface of the ocean is the greatest source of atmospheric moisture.

Question 2.

What is meant by humidity?

Answer:

The state of the atmosphere with respect to its content of moisture or water vapour is called humidity.

Question 3.

What is meant by sensible temperature?

Answer:

It is the cold or heat felt by the human body, depending not only on actual temperature but also on relative humidity and wind.

Question 4.

Name three states in which water exists.

Answer:

Water exists in three states or forms:


Solid (ice),


Liquid (water),


Gas (water vapour).


Question 5.

What is the measure of absolute humidity?

Answer:

Absolute humidity is measured in grams per cubic metre (g/m3).

Question 6.

What is the dew point?

Answer:

It is the temperature at which air, on cooling, becomes saturated with water vapour, and below which condensation begins and dew forms.

Question 7.

Why dew and frost form on grass quite readily?

Answer:

Because grass is a good radiator and, therefore, cools quickly.

Question 8.

Identify various forms of precipitation.

Answer:

Various forms of precipitation include rainfall, snowfall, hail, sleet and drizzle.

Question 9.

Name three types of precipitation.

Answer:

The three types of precipitation are convectional, orographic and cyclonic precipitation.

Question 10.

How does precipitation take place?

Answer:

Precipitation takes place as a result of the continued condensation and growth of the moisture particles until they become too large to remain suspended in the air.

Question 11.

What is the source of atmospheric moisture?

Answer:

The oceanic surface is the main source of atmospheric moisture.

Question 12.

Which factors control evaporation?

Answer:

There are three main factors which control evaporation:


aridity,


temperature,


movement of air.


Question 13.

Name the various types of clouds.

Answer:

Cirrus clouds, stratus clouds, stratocumulus and cumulus clouds.

Question 14.

What are the different types of fog?

Answer:

Fogs are of three types: radiating, advection and frontal fog.

Question 15.

What is condensation?

Answer:

Cooling of saturated air is called condensation.

Question 16.

What are the different types of rainfall?

Answer:

Rainfall is of three types: convectional, orographic and cyclonic rainfall.

Question 17.

What is sublimation?

Answer:

The process of conversion of ice into liquid or vapour is known as sublimation.

Question 18.

Name the temperature at which a given sample of air becomes saturated.

Answer:

Dew point.

Question 19.

What do you mean by saturated air?

Answer:

The air that contains moisture to full capacity.

Question 20.

What is relative humidity?

Answer:

The ratio of the amount of water vapour actually presents in the air at a particular temperature to the amount of water vapour required to saturate the same air at the same temperature.

Question 21.

What is sleet?

Answer:

The falling of frozen raindrops and frozen melted snow on the earth’s surface is known as sleet.

Question 22.

Name the various types of humidity.

Answer:

Absolute humidity, specific humidity and relative humidity.


Water in the Atmosphere Important Extra Questions Short Answer Type


Question 1.

Describe various processes involved in the change of state (form) of water.

Answer:

Water exists in three forms, solid (ice), liquid (water) and gas-(vapour). All three states are interchangeable. The change of solid to ‘ liquid is called melting; from liquid to solid is freezing; from liquid to gas is evaporation and from gas to liquid is condensation. But sometimes ice directly converts into vapour or vice-versa. This is called sublimation.



Question 2.

Describe various sources of atmospheric moisture on the earth.

Answer:

The surface of the ocean is the greatest source of atmospheric moisture. Besides, smaller water bodies, vegetation and damp surfaces also contribute significant amounts of moisture.

Question 3.

What is relative humidity and how is it measured?

Answer:

The amount of water vapour in the air compared with the amount that would be present if the air was saturated at that temperature. It is expressed in percentage determined by dividing the absolute humidity by water holding capacity of air. If the air is saturated, its relative humidity is 100%; if only half saturated, the relative humidity. is 50%. Since the capacity of air for absorbing and retaining moisture varies with temperature, the relative humidity of air mass can be altered by merely lowering its temperature without changing the actual amount of moisture present in it.

Question 4.

Discuss the reasons which impede the formation of dew or frost.

Answer:

On cool nights in early winter, when Radiation from the ground is relatively rapid, the air in contact with the ground may be chilled to the dew point and moisture condenses on the leaves and grass in the form of dew. If the dew point is below the freezing point, the condensation takes place in the form of ice crystals or frost. The formation of dew or frost is impeded by


Dry air,


Wind mixes the air and prevents its lower portion from reaching the dew point, and


Clouds which slow down terrestrial radiation.


Question 5.

What are the middle clouds?

Answer:

The clouds which form at height of2000-7000 km. above the ground are called middle clouds. Altostratus and altocumulus are examples.

Altostratus – It is a uniform sheet of cloud, grey or bluish in colour and usually has a fibrous structure.

Altocumulus – These are flattened globular masses of clouds arranged in lines or waves. They have large globules with shadows.

Question 6.

Why does the amount of water vapour decrease rapidly with altitude?

Answer:

Water vapour in the atmosphere is the result of the evaporation of water from the earth’s surface, a continual process dependent on air. Since the air becomes thinner with the altitude, so also does the water vapour.

Question 7.

What is condensation and how does it take place?

Answer:

Condensation is the process of water vapour changing to a liquid state. If the air is cooled below its dew point, some of the air’s water vapour becomes liquid. Thus, any amount of cooling of saturated air starts the process of condensation. Condensation may start with the addition of any further water vapour to the saturated air, or with the reduction of its temperature.

Question 8.

What is precipitation? What are the conditions to determine the form of precipitation?

Answer:

Precipitation is a process of condensation of water vapour in ‘ the atmosphere which falls to the earth in the form of rain, snow, hail or sleet. These are the various forms of precipitation.

Conditions for precipitation.


There should be evaporation so that the relative humidity is „ high in the air.


There should be adiabatic cooling of the moist air.


There should be dust particles in the air.


Question 9.

What are the effects of humidity?

Answer:

The main effects of humidity are:


The skin of the human body starts to crack due to low relative humidity.


It causes joint pain in the human body.


The high relative humidity is harmful to the human body.


The joints of furniture get loosened.


Question 10.

Why does the amount of water vapour decrease rapidly with altitude?

Answer:

The amount of water in the atmosphere is variable from place to place and from time to time. It decreases rapidly with altitude. The temperature decreases as the altitude increases.

Question 11.

How is rainfall caused?

Answer:

The moist air is cooled, saturated and condensation takes place. Water vapour condenses on a large number of dust particles to form clouds.

The cloud droplets merge to form raindrops. When these raindrops become so heavy that air cannot hold them, these fall on the earth in the form of rainfall. The release of moisture in the form of drops of water is called rainfall.

Question 12.

Describe the conditions for the formation of dew.

Answer:

Following are the favourable conditions for the formation of dew:


Clear sky


Calmness, i.e., the wind should not blow


High relative humidity


Rich vegetation cover


Long nights


Water in the Atmosphere Important Extra Questions Long Answer Type


Question 1.

Distinguish between:

1. Relative humidity and Absolute humidity.

2. Evaporation and Condensation.

3. Dew and Frost.

Answer:

1. Relative humidity and Absolute humidity:

Relative humidity:

The amount of water vapour in the air compared with the amount that would be present if the air was saturated at that temperature. It is expressed in percentage determined by dividing the absolute humidity by water holding capacity of air. If the air is saturated, its relative humidity is 100%; if only half saturated, the relative humidity. is 50%. Since the capacity of air for absorbing and retaining moisture varies with temperature, the relative humidity of air mass can be altered by merely lowering its temperature without changing the actual amount of moisture present in it.

Absolute humidity:

It is the actual amount of water vapour present per unit volume of air and it is measured in grams per cubic meter.

2. Evaporation and Condensation

Evaporation is the process by which a solid or liquid is converted to a gaseous state or vapour. It occurs whenever energy is transported to an evaporated surface and temperature rises. The molecules become more mobile and overcome the forces binding them to the water surface and break away resulting in evaporation.

Condensation:

Condensation is the process of water vapour changing to a liquid state. If the air is cooled below its dew point, some of the air’s water vapour becomes liquid. Thus, any amount of cooling of saturated air starts the process of condensation. Condensation may start with the addition of any further water vapour to the saturated air, or with the reduction of its temperature.

3. Dew and Frost:

Dew: When the moisture is deposited in the form of water droplets on cooler surfaces of solid objects, such as stones, grass blades and plant leaves, it is known as dew. Clear sky, calm air, high relative humidity, cold and long nights are the ideal conditions for the formation of dew.

Frost: Frost forms on cold surfaces at a dew point which is at or below the freezing point when an excess of moisture is deposited in the form of minute ice crystals instead of droplets of water.

Question 2.

Write short notes on:

(a) Convectional precipitation

(b) Cyclonic precipitation

(c) Orographic precipitation

Answer:

(a) Convectional precipitation:

It occurs when moist air over the heated ground becomes warmer than the surrounding air and is forced to rise, expand, cool and yield some of its moisture.

Convectional rain is common in low latitudes and usually comes in the form of short heavy showers, often during the hottest part of the day. Thunder and lightning generally accompany the showers. If the convection currents are especially strong and turbulent, hail is formed.



(b) Cyclonic precipitation:

It occurs in low-pressure areas, where cyclonic winds coming from various directions converge and force the large volumes of light air to rise and cause rain.

Cyclonic precipitation is generally associated with the passage of depression in middle or high latitudes, as the warm moist air mass of the depression rises and over-rides colder, heavier air.



(c) Orographic precipitation:

It is caused due to relief. It occurs when the moist wind is forced to rise over a mountain or any other height. Precipitation occurs due to cooling of moisture-laden air as it rises over a high relief barrier. It happens, particularly on the windward slopes! On the other side of the barrier or on the leeward side of the slopes, there develops rain shadow area with no or very little rainfall because as the moisture-laden wind descends down the slope, after precipitating on the windward side, it becomes warmer and drier. Such a situation occurs along the western coasts of Qudra, North America and South America. The moist air from the Arabian Sea is forced by Sahyadri hills of the Western Ghats to rise up resulting in expansion, cooling and rainfall.

Amount of precipitation depends on slope, the height of the hills, temperature and moisture content of the air mass. On the other side of the mountain, the descending wind is devoid of moisture and, hence, does not give rain. The eastern slope of Sahyadri mountains in India falls in the rain shadow area.



Question 3.

Describe the factors controlling the rate of evaporation and evapotranspiration.

Answer:

vaporation is the process by which liquid water or ice changes into water vapour. It occurs whenever energy is transported to an evaporated surface and temperature rises. The molecules become more mobile and overcome the forces binding them to the water surface and break away resulting in evaporation.

Evapotranspiration, on the other hand, is the amount of moisture transferred to the atmosphere by evaporation of liquid and solid water plus transpiration from living tissues principally from the plants.

Factors like the temperature of the air, source of moisture, vegetation cover, latitude, permeability and water retention effect evaporation and evapotranspiration.

Evaporation depends upon air temperature. Greater the temperature, higher is the rate of evaporation and so on. Therefore, the highest rate of evaporation occurs in deserts in conditions Of great heat and lack of surface cone.

The surface of oceans is the greatest source of atmospheric moisture.

Vegetation is an important factor, particularly in evapotranspiration. Because, under transpiration, the loss of water takes place from the green plants resulting in a stream of water with dissolved mineral salts surfing up through the plants.

Question 4.

Describe the various forms of precipitation and the major precipitation regimes of the world.

Answer:

Precipitation results from the continued condensation and growth of the moisture particles until they become too large to remain suspended in the air.

If condensation takes place at a temperature above 0°C, the resulting precipitation is in the form of rain.

If the process through a layer of colder air on the way down, it may freeze and fall as sleet.

In a strong turbulent current of a thunderstorm, water drops may be carried upward into freezing temperatures and eventually fall as hail. In fact, violent air currents may keep hailstones shuttling up and down until they grow to enormous sizes.

When the more. moisture crystallises into ice particles from vapour at a temperature below freezing point, it called snow. If snowflakes grow without interference, they form beautiful symmetrical, six-sided Crystals.

Ice-storms result when rain, already near the freezing point, falls on colder ground and vegetation and freezes upon contact.

Major precipitation regimes:

(a) Convectional precipitation:

It occurs when moist air over the heated ground becomes warmer than the surrounding air and is forced to rise, expand, cool and yield some of its moisture.

Convectional rain is common in low latitudes and usually comes in the form of short heavy showers, often during the hottest part of the day. Thunder and lightning generally accompany the showers. If the convection currents are especially strong and turbulent, hail is formed.



(b) Cyclonic precipitation:

It occurs in low-pressure areas, where cyclonic winds coming from various directions converge and force the large volumes of light air to rise and cause rain.

Cyclonic precipitation is generally associated with the passage of depression in middle or high latitudes, as the warm moist air mass of the depression rises and over-rides colder, heavier air.



(c) Orographic precipitation:

It is caused due to relief. It occurs when the moist wind is forced to rise over a mountain or any other height. Precipitation occurs due to cooling of moisture-laden air as it rises over a high relief barrier. It happens, particularly on the windward slopes! On the other side of the barrier or on the leeward side of the slopes, there develops rain shadow area with no or very little rainfall because as the moisture-laden wind descends down the slope, after precipitating on the windward side, it becomes warmer and drier. Such a situation occurs along the western coasts of Qudra, North America and South America. The moist air from the Arabian Sea is forced by Sahyadri hills of the Western Ghats to rise up resulting in expansion, cooling and rainfall.

Amount of precipitation depends on slope, the height of the hills, temperature and moisture content of the air mass. On the other side of the mountain, the descending wind is devoid of moisture and, hence, does not give rain. The eastern slope of Sahyadri mountains in India falls in the rain shadow area.



Question 5.

Why dew is not formed on cloudy, windy nights and in shady places?

Answer:

Dew is formed when objects radiate heat thoroughly so that the moist air coming into contact with them may be sufficiently cooled down and the water vapour condenses into water droplets. The clouds act as a blanket for the earth’s surface. They check the radiation of heat so it does not radiate heat thoroughly. Hence, dew is not formed on cloudy nights and in shady places.

Similarly, dew is not formed on windy nights, because the winds blow fast and the moist air does not come long enough into contact with cold objects to get cooled. Hence, condensation does not take place and no dew can be formed.

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


 

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


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:


Rayleigh waves


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:


Radioactivity


The heat of aggradation


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 :


crust


mantle


core.


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


thickness,


density,


temperature,


metallic contents and


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 :


‘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.


‘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.


‘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:

The crust of the EarthThe core of the Earthl. This is the outermost layer of the earth.1. This is the innermost layer of

of the earth.

2. The average density is 2.73g/cm3.2. The average density is I7.2g/cm3.3. It covers about 0.5% part of the earth.3. It covers about 83% part of the

the earth.

4. It is made up of silica and

aluminium.

4. It is made up of nickel and ferrous.

3. Gutenberg Discontinuity and Mohorovicic Discontinuity:

Gutenberg DiscontinuityMohorovicic Discontinuity1. It is the boundary between the mantle and the core.1. It is the boundary between the crust arid the mantle.2. It was observed by Beno Gutenberg in 1926.2. It was observed by a Yugoslavian seismologist Mohorovicic in 1909.3. The ‘P’ waves make an abrupt drop in the velocity at the mantle-core boundary, while S-waves disappear here.3. The surface of a sudden increase in wave velocity, which separates crust above from the mantle below is Mohorovicic discontinuity.4. This making a place at the dis-continuous surface between the core and mantle is known as Gutenberg discontinuity.

Distribution of Oceans and Continents Class 11 Important Extra Questions Geography Chapter 4



 Distribution of Oceans and Continents Class 11 Important Extra Questions Geography Chapter 4



Distribution of Oceans and Continents Important Extra Questions Very Short Answer Type


Question 1.

What is Pangaea?

Answer:

All landmasses of the world have been formed from one super¬continent called Pangaea.

Question 2.

Who first propounded the theory of continental drift?

Answer:

Alfred Wegner propounded the theory of continental drift in 1912.

Question 3.

Which plate is composed of mainly oceanic crust?

Answer:

The Pacific plate is composed of mainly oceanic crust.

Question 4.

How did the Himalayas rise?

Answer:

The collision between the Indian Plate and the Eurasian plate took place north of the Indian plate giving rise to the Himalayas.

Question 5.

What is the evidence in support of continental drift theory?

Answer:


Geological matching


Palaeoclimatic unity, and


Palaeornagnetism.


Question 6.

Name the continents into which the supercontinent, Pangaea, got split.

Answer:

They are Laurasia and Gondwanaland.

Question 7.

How many years ago Pangaea, the supercontinent has evolved?

Answer:

Pangaea, the supercontinent, had evolved some 280, million years ago.

Question 8.

What are hot spots?

Answer:

The centers of volcanic activity are called hot spots.

Question 9.

Name the three kinds of boundaries based on their Relative motion.

Answer:


Zones or margins of divergence or spreading,


Margins of convergence, and


Fracture zones or transform faults.


Question 10.

How many plates the lithosphere is divided into?

Answer:

Seven plates.

Question 11.

The collision between which two plates gave rise to the Himalayas?

Answer:

The collision between Indian and Eurasian plates gave rise to the Himalayas.

Question 12.

Name two fossils that tell us that continents were once united.

Answer:

The fossils of the plant Glossopteris and animals Mesosaurus and Lystosaurus, suggests that these continents were once joined.

Question 13.

What is Palaeornagnetism?

Answer:

It is the fossil magnetism evident today in igneous rocks such as magnetite, hematite, pyrrhotite, etc.

Question 14.

What is the Pacific plate?

Answer:

The latest plate in terms of its formation or origin.

Question 15.

What do you understand by the spreading of crust from the ridge and the widening of the ocean basin?

Answer:

It is the seafloor spreading.

Question 16.

Name the northern and southern parts of Pangaea.

Answer:

Laurasia and Gondwanaland.

Question 17.

Name the sea separating Laurasia and Gondwanaland.

Answer:

The Tethys sea.

Question 18.

In which parts Pangaea was split?

Answer:

Pangaea was split into northern continent Laurasia and Southern continent, Gondwanaland.

Question 19.

Name the original supercontinent. When was it formed?

Answer:

Pangaea. It was formed about 280 million years ago.

Question 20.

State three causes of plate movements.

Answer:


Thermal convection,


Hot spots of volcanic activity,


Movement of currents.


Question 21.

What is meant by sea-floor spreading?

Answer:

The crust spreads away from the ridge and the ocean basin widens. This phenomenon is known as sea-floor spreading.

Question 22.

Name the process in which one plate overrides the other and the overriding plate slips down into the mantle and is submerged.

Answer:

Subduction.

Question 23.

What is thermal convection?

Answer:

It acts as a driving force for the movement of plates.

Question 24.

Name the four different types of plate interactions.

Answer:

Spreading, collision, subduction, and transform.

Question 25.

How was drifting of continents caused?

Answer:

It was caused by two forces :


pole fleeing force, and


tidal force.


Distribution of Oceans and Continents Important Extra Questions Short Answer Type


Question 1.

How do lithosphere plates behave along the transform fault?

Answer:

The lithospheric plates slide over each other, neither creating nor destructing any landmass. Instead, the. friction arising from the f* movement of the plates usually causes severe earthquakes and earth tremors.

Question 2.

Why do geographers focus their attention on plate boundaries?

Answer:

Geographers focus their attention on plate boundaries because each plate is a tectonic plate. It is rigid and moves as a single unit. Nearly all major tectonic activity occurs along the plate boundaries.

Question 3.

What does the term ‘supercontinent’ refer to?

Answer:

The term ’supercontinent’ refers to a single common geological landmass called Pangaea. It has been proposed that all landmasses of the world had formed from this ‘supercontinent’. Pangaea had evolved some 280 million years ago, at the end of the Carboniferous period and by mid-Jurassic age, 150 million years ago. Pangaea land split into Laurasia, the northern continent, and Gondwanaland, the southern continent. About 65 million years ago, i.e. at the end of the cretaceous, bound mainland were further broken up to give rise to several other continents such as South America, Africa, Australia, and Antarctica.

Question 4.

Discuss the causes of plate movement.

Answer:

Sub-crustal convection currents invoke the mechanism of thermal convection that acts as a driving force for the movement of plates. Hot currents rise, then cool as they reach the surface. At the same time, cool currents sink down. This convectional movement moves the crustal plates. .. Owing to current movements, the rigid plates of the lithosphere, which ‘float’ on more mobile asthenosphere, are in constant motion.

Question 5.

What is a geological time-scale?

Answer:

The chronology of the geological history’ of the earth is revealed by its rocks. Geological time scale indicates the hierarchy of time periods during which different rocks of the earth have formed.

Question 6.

What is subduction?

Answer:

The process in which the overridden plate slips down into the mantle and is submerged is known as subduction. Besides volcanism and shallow to deep-focus earthquakes, boundaries also formed deep trenches and folded mountains.

Question 7.

What is polar wandering?

Answer:

There has been a periodic change in the position of the magnetic pole. These changes are recorded in rocks by way of permanent magnetism. Unraveling of the signatures of such changes in the geologically old rocks by scientific methods provides the changing position of poles in geological time scale. It is known as ‘polar wandering’. It demonstrates that the continents have frequently moved and changed their direction of motion from time to time.

Question 8.

Account for the formation of the Himalayas according to the theory of plate tectonics in three points.

Answer:


South-east Indian ocean ridge collided between the Indian plate and European plate. The Indian plate gave rise to the Himalayas.


The suture between the Indian and Eurasian plates in the Himalayan region has been along the Indus and Brahmaputra.


The mid-Indian ocean ridge has been spreading faster.


Question 9.

What is ‘Zolrt of Convergence’?

Answer:

Zone of Convergence is the boundary along which the edge of ‘ one plate overrides the other. It produces deep trenches and folds mountains. Volcanoes and deep-focus earthquakes mark it.

Question 10.

Describe the driving force for the movement of plates.

Answer:

The sub-crustal convection currents invoke the mechanism of thermal convection that acts as a driving force for the movement of plates. As these currents reach the surface, the hot current rises, then cools. Sometimes, cooler currents sink down. This type of convectional movement causes the movement of crustal plates.

Question 11.

Name the major plates of the earth. Which plate is composed of the oceanic plate?

Answer:

Pacific plate, Eurasian plate, Indo-Australian plate, African plate, North American plate, South American plate, and Antarctica plate are the major plates of the earth.

The zone of divergence is the boundary along which the plate is composed of mainly oceanic crust. It is known as the Pacific plate.

Question 12.

What is palaeoclimatic unity?

Answer:

The uniformity in the nature of the sediment in the biological past indicates that these continents were together in the geological past and experienced similar climatic conditions. It is the native of glacial deposits of the separated continents indicating that these continents were together in the geological past and experienced similar climatic conditions.


Distribution of Oceans and Continents Important Extra Questions Long Answer Type


Question 1.

What do you mean by ‘jig-saw-fit’? Describe the similarities found on the east and west coasts of the Atlantic ocean. What do they suggest?

Answer:

The ‘jig-saw-fit’ means the landmasses on the east and west coast of the Atlantic ocean can be fitted together. There are many similarities found on the two coasts :


The Gulf of Guinea can be fitted into Cape San-Rogue of Brazil, the shoulder of Africa can be fitted into Gulf of Mexico, Western Europe and Eastern coast of North America along with Greenland can be fitted together.


Gold deposits of Ghana lands are found on the east and in Brazil on the west.


The glacial deposits are found in all landmasses of Gondwana land.


These similarities suggest that these continents were together in the geological past.

Question 2.

Discuss the Continental Drift Theory.

Answer:

Continental Drift Theory was proposed by Alfred Wegner in 1912. He postulated that all landmasses of the world have been formed from one super-continent called Pangaea.

The supercontinent, Pangaea, had evolved some 280 million years ago, at the end of the Carboniferous period and by the mid-Jurrasic age, 150 million years ago. Pangaea had split into a northern continent, Laurasia, and a southern continent Gondwanaland. About 65 million years ago, i.e., at the end of the Cretaceous, Gondwanaland further broke up to give rise to several other continents, such as South America, Africa, Australia, and Antarctica. Thus, the present distribution of the continental masses and the oceans are the n .uit of fragmentation of one or more pre-existing masses. These landmasses have drifted apart the intervening hollows having been occupied by the oceans.



There are several pieces of evidence that suggest the existence of Pangaea. This evidence is available in the form of geological watching, palaeoclimatic units, and paleomagnetism.

Question 3.

Describe sea-floor spreading in brief.

Answer:

The present distribution of continents has taken place in the last 65 million years. The drift of continents still continues. The ridges down the middle of ocean floors have been emitting lava continuously. Those mid-oceanic ridges are cracks on the floor of the ocean where molten rocks push up to form a new crust. The crust spreads among the ridge and the ocean basin widens. This phenomenon is known as sea-floor spreading. The Atlantic ocean is getting smaller and the Red Sea is the part of a crack in the crust that will widen to produce new ocean millions of years ahead in the future. In the past, the widening of the South Atlantic ocean has separated Africa and South America.



Question 4.

Explain the plate tectonic theory and its mechanism.

Answer:

Plate tectonic theory proves that the earth’s crust consists of several plates that carry continents and the ocean floors and float on the asthenosphere, moving very slowly, the movement probably resulting from currents in the asthenosphere. As shown in fig., the lithosphere is broken into seven major plates. They include :


Pacific plate


Eurasian plate


Indo-Australian plate


African plate


North American plate


South American plate


Antarctic plate


The latest among these is the Pacific plate which is composed of oceanic crust almost entirely. The other plates have both continental and ocean crust. No plate consists of only continental crust. Plates range in thickness from about 70 km. beneath oceans to 150 km. under continents. Each tectonic plate is rigid and moves on a single unit. Nearly all major tectonic activities occur along the plate boundaries.

Based on the relative motion of plates, three kinds of plate boundaries have been recognized. They are :

1. Zones of divergence: These are boundaries along which plates separate and in the process of separation molten materials upwell. This is commonly observed along linear ocean edge where the new lithosphere is created in the form of new ocean floors. Active volcanism and shallow focus earthquakes make such boundaries,

2. Zones of convergence: There are the boundaries along which, the edge of one plate overrides the other. The overridden plate slips down into the mantle and is absorbed. This process is known as subduction.

3. Fracture zones or Transform faults: The plates slide past each other effect creating or destructing the boundaries. However, shallow focus earthquakes may result due to this friction.



Question 5.

Describe the main features of the Indian plate.

Answer:

Indian ocean floor presents striking topography consisting of a number of elevated ridges and plateaus. Two of the ocean ridges, namely, the Mascarene Plateau, Chagos-Maldweep-Lakshadweep island ridge are said to be the volcanic tracts of two hot spots. The Northward extension of Ninety-east Ridge indeed in the trench which consumed the seafloor to the north of the Indian continental mass. The Chagos- Lakshadweep ridge linked the ancient Carlsberg ridge with the Southeast Indian ridge during the Eocene period (50 million years ago).

Consequent to the Carlsberg-Southeast Indian ocean ridge, the collision between the Indian plate and the Eurasian plate took place north of the Indian plate giving rise to the Himalayas. The suture between Indian and Eurasian plates in the Himalayan region has been along the Indus and Brahmputra rivers.

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



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



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:

It formed when the nebula of hot gaseous cloud exploded.The denser part of the super¬nova collapsed under its own gravity and became larger and hotter. It came to be known as protostar and finally infant sun.

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:


The Earth’s crust (lithosphere)


The intermediate layer (mantle)


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 :


Nebula hypothesis


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.

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



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



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:


It studies geographical facts in an individual manner.


It implies the detailed study of a single specific geographical factor.


It is explanatory and is largely interpretative.


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 :


Field studies (physical as well as socio-economic surveys).


Cartography (the science of drawing maps and diagrams).


Quantitative geography (covers a number of mathematical and statistical techniques).


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:


Regional studies/Area studies comprising Macro, Meso, and Micro regional studies.


Regional planning comprising country/rural planning and town and urban planning.


Regional development.


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:


Plant geography – Study of the spatial. the pattern of natural vegetation in their habitats.


Zoo-geography – Study of spatial patterns and geographic characteristics of animals and their habitats.


Ecology/Ecosystem – Study of the habitats characteristic of species.


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 :


Physiography


Biogeography


Human ecology


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 :


Physiography: Studies the physical aspects of the earth’s surface, as landforms, climate, water, and soil.


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.


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.


Geographic methods and techniques: Field studies, cartography, quantitation geography, and spatial information system (GIS, LIS, GPS).


B. Regional Geography :


Regional Studies


Regional Planning


Regional Development


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.

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