Download Geography Answer Key

Answer Key (Geo)
Term I (class XI)
1. Immanual Kant and revised by Laplace.
½ + ½ =1
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2. The percentage of moisture present in the atmosphere as compared to its full capacity at a given
temperature is called Relative Humidity.
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3. The insolation received by the earth from which 35 units are reflected back to the space and this is
called Albedo.
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4. When sinkholes and dolines join together because of slumping of material along their margin a long
narrow to wide trenches are formed called Uvalas.
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5. Mineral is a naturally occurring organic and inorganic substance, having a definite chemical and
physical property.
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6. The upper portion of the mantle is called asthenosphere.
7. Sir George Darwin.
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8. Any three types of rapid mass movements are:
a. Earth flow- These movements are mostly prevalent in humid climatic region and occur over
gentle to steep slopes. Movement of water saturated clayey or silty earth materials down low
angle terraces or hill sides is known as earth flow.
b. Mud flow- In absence of vegetation cover and with heavy rainfall, thick layer of weathered
materials get saturated with water and either slowly or rapidly flow down along definite
channels. It looks like stream of mud.
c. Avalanche- Which is more characteristics of humid region with or without vegetation cover and
occurs in narrow tracks on steep slopes. This debris avalanche can be much faster than the mud
flow.
(3)
9.
The earthquake waves get recorded in seismograph located at far off location. However there exists
some specific area where waves are not reported, this zone is called Shadow Zone.
It is observed that seismograph located at any distance within 105 degree from the epicenter recorded
the arrival of both P and S wave. However Seismograph located beyond 145 degree from the
epicenter only record the arrival of P wave but not the S wave. Thus zone between 105 degree to 145
degree from the epicenter is the shadow zone for both P and S wave. The entire zone beyond 105
degree does not receive S wave. The shadow zone of S wave is larger than the P waves.
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10. The facts that helped Hess to propose his hypothesis are:
a. It was realized that all along the mid oceanic ridges volcanic eruptions are common and they
bring huge amount of lava to the surface of this region.
b. The rocks equidistant on either sides of mid oceanic ridges show remarkable similarities in terms
of period of formation, chemical compositions and magnetic properties.
c. The ocean crust rocks are much younger than the continental rocks. The age of the rocks in the
oceanic crust is nowhere more than 200 million years old and the rocks of the continental rocks
are as old as 3200 million years.
d. The sediments on the ocean floor are unexpectedly thin than the continental crust.
(Any three points to be explained)
1+1+1=3
11. Igneous rocks are formed through solidification of Lava. Igneous rocks are also called primary rocks.
When magma in its upward movement cools and turns in to solid form igneous rocks. The process of
cooling and solidification can happen in the crust or on the surface of the earth.
1+2 =3
12. Tropical cyclones are violent storms that originate over the ocean in tropical areas and move over the
coastal areas bringing about large scale destructions caused by violent winds. Very heavy rainfall
and storm surges. This is one of the most devastating natural calamities. They are known as cyclones
in Indian Ocean, Hurricane in the Atlantic, Typhoons in the western Pacific and South China Sea.
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Tropical cyclone Originate and intensify over the warm tropical ocean. The energy that intensifies
the storm that comes from condensation process. Eye is a region of calm with subsiding air. (3)
13. The three stages involved in the evolution of the atmosphere are:
a. 1st stage – this stage is marked by loss of primordial atmosphere
b. The hot interior of the earth contributed to the evolution of the atmosphere.
c. 3rd stage- the composition of the atmosphere was modified by living world through the process of
photosynthesis.
(3)
14. The atmosphere consists of different layers with varying density and temperature. The important
layers of the atmosphere are: Troposphere, Stratosphere, mesosphere, Thermosphere, and exosphere.
Troposphere – It is the lowest layer of the atmosphere its average height is 13 km, roughly 8 km at
the pole and 18 km at the equator.
This layer dust particles all changes in weather and climate takes place in this layer.
Stratosphere- It is found above the tropopause and extends up to the height of 50 km.
One important features of this layer is it contains ozone layer. This layer absorbs harmful ultra violet
rays.
Mesosphere- Lies above the stratosphere and extend up to the height of 80 km In this layer again the
temp. Starts decreasing. And reaches up to minus 100 degree up to the height of 80 km
Ionosphere – Located between 80 to 400 km above the mesopause.
It contains electrically charged particle known as ions. Radio waves transmitted from the earth is
reflected back by this layer.
Exosphere- The upper most layer above the thermosphere is called Exosphere.
This layer gradually merges with the space.
1+1+1+1+1=5
15. The incoming solar radiation is called insolation.
The temperature of air at any place by the following factors:
a. The latitude
b. Altitude
c. Distance from the Sea
d. Air mass and Ocean current. 1+1+1+1+1+1=5
16. I do Agree Which can be justified by following points:
a. Land forms provide the base for human activities and the plains are utilized for agriculture.
b. Plateaus provide forests and minerals, mountain provide pasture forests tourists spots and are the
sources of rivers providing water for low lands.
c. Climate influences our house types clothing and food habits. The climate has a profound effect
on vegetation, cropping pattern, livestock farming etc.
d. Temperature and precipitation ensures density of forest and quality of grass lands. Precipitation
recharges the ground water aquifers which later provides water for agriculture and domestic use.
e. The Ocean is the store house of resources. Besides fish and other sea foods and ocean are also
store house of minerals.
1+1+1+1+1=5
17. The earth is a play field of two opposing geomorphic processes. The earth is dynamic and ever
changing. All these changes take place under the influence of certain forces working continuously
within the earth as well as over the surface of the earth. The forces working on the surface of the
earth is known as external or exogenic forces while those working within the earth are called internal
Or endogenic forces. The exogenic forces cause wearing down degradation of relief of elevations and
filling up or aggradations’ of basin or depression on the earth surface. The phenomenon of wearing
down by the exogenic forces is called degradation. The variation on the earth is brought by endogenic
forces working inside the earth.
1+1+1+1+1=5
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18.
Continental drift theory
1. Continental drift theory assumes that
continents have arisen by breaking and
then drifting of the component of super
continent pangea.
2. This theory is based on the evidences of
Jig-saw-fit fossils placers deposits etc.
3. This theory considers the horizontal
movement of the continents.
4. Continental drift theory is validated by the
concept of plate tectonics
5. This theory was propound by Alfred
Wegener –A German meteorologist in
1912
Plate tectonic theory
The theory proposes that the earth’s lithosphere
is divided into seven major and some minor
plates they are constantly moving.
This theory is based on scientific analysis of the
processes inside the earth’s surface.
Plate tectonic considers the subduction of plates
also.
This theory validates the drift theory and is not
to be validated by the same.
The concept of plate tectonics was proposed in
1967 by Mckenzie and Parker and also Morgan.
(5)
19. . Explanation on development of these land forms:
a. Valleys.
b. Gorge and canyons.
c. Potholes and Plunge pool.
d. Incised meanders.
e. River terraces.
(Explanation on each one of them)
1+1+1+1+1 = 5
20. Convectional Rain- When the air becomes heated, it becomes light and rises up in convection current
As it rises it expands and loses heat and consequently .Condensation takes place and cumulous
clouds are formed. With thunder and lightning heavy rainfall takes place, but this rainfall does not
last for long. Such a rain common in summer or hotter part of the day and is very common in
equatorial region.
Orographic rainfall – When the saturated air mass come across a mountain and it is forced to ascend
and as it rises it expands and the temperature falls and condensation takes place. In this type of
rainfall the windward side of the mountain receive rainfall and when the wind reach other slope they
descend and their temperature rises. Then the capacity of air to hold moisture increases and so the
leeward side of the mountain remain dry and rain less
1 ½ + 1 ½ =3 + 2 diagram
21. i. The Ocean currents are to be identified.
a. Brazilian current ( Warm current)
b. Kurishio current warm current.
c. West Australian current.
d. Labrador Current.
e. Humboldt Current.
ii) Locating the following on the Physical map of the world.
a. N. America.
b. Pacific.
c. Asia.
d. Indian Ocean.
e. Australia.
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