PRELIMS 2017 REVISION TEST 28

Solution: a)

NCERT Class XI Fundamental of Physical Geography, Page 26-27

As most volcanoes are made up of basalt, these volcanoes are not steep as basalt is very fluidic in nature.

Solution: a)

NCERT Class XI Fundamental of Physical Geography, Page 27 – 28

Yardangs (dessert feature) are the result of sand grains pushed by persistent winds to form low ridges of sand carved in soft rock. This is commonly found in flat deserts where steady winds blow away dust and silt. Higher front faces of Yardangs are undercut as erosion is concentrated in the lower areas because wind driven sand stays near the ground. These are an example of erosional landforms.

Solution: a)

NCERT Class XI Fundamental of Physical Geography, Page 31

believed that Pangaea originated near the south pole and that the centrifugal force of the planet caused the protocontinent to break apart and the resultant continents to drift towards the equator.  He called this the “pole-fleeing force”.  This idea was quickly rejected by the scientific community primarily because the actual forces generated by the rotation of the earth were calculated to be insufficient to move continents.  Wegener also tried to explain the westward drift of the Americas by invoking the gravitational forces of the sun and the moon, this idea was also quickly rejected.  Wegener’s inability to provide an adequate explanation of the forces responsible for continental drift and the prevailing belief that the earth was solid and immovable resulted in the scientific dismissal of his theories.

Solution: b)

NCERT Class XI Fundamental of Physical Geography, Page 35

The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru–Chile Trench, of the Nazca Plate under the South American Plate is largely responsible for the Andean orogeny. The Nazca Plate is bounded on the west by the Pacific Plate and to the south by the Antarctic Plate through the East Pacific Rise and the Chile Rise respectively.

Solution: a)

NCERT Class XI Fundamental of Physical Geography, Page 36

Transform boundaries are places where plates slide sideways past each other. At transform boundaries lithosphere is neither created nor destroyed. Many transform boundaries are found on the sea floor, where they connect segments of diverging mid-ocean ridges. California’s San Andreas fault is a transform boundary.

AT transform boundaries, lava is not erupted all along the crest. (Source NCERT)

Solution: d)

NCERT Class XI Fundamental of Physical Geography, Page 42

All are sedimentary rocks.

Solution: d)

NCERT Class XI Fundamental of Physical Geography, Page 47

In geology, denudation is the processes that cause the wearing away of the Earth’s surface by moving water, ice, wind and waves, leading to a reduction in elevation and relief of landforms and landscapes. Endogenous processes such as volcanoes, earthquakes, and plate tectonics uplift and expose continental crust to the exogenous processes of weathering, erosion, and mass wasting.

Solution: d)

NCERT Class XI Fundamental of Physical Geography, Page 51

Biological weathering is the weakening and subsequent disintegration of rock by plants, animals and microbes.

Growing plant roots can exert stress or pressure on rock. Although the process is physical, the pressure is exerted by a biological process (i.e., growing roots). Biological processes can also produce chemical weathering, for example where plant roots or microorganisms produce organic acids which help to dissolve minerals.

Microbial activity breaks down rock minerals by altering the rock’s chemical composition, thus making it more susceptible to weathering. One example of microbial activity is lichen; lichen is fungi and algae, living together in a symbiotic relationship. Fungi release chemicals that break down rock minerals; the minerals thus released from rock are consumed by the algae. As this process continues, holes and gaps continue to develop on the rock, exposing the rock further to physical and chemical weathering.

Burrowing animals can move rock fragments to the surface, exposing the rock to more intense chemical, physical, and biological processes and so indirectly enhancing the process of rock weathering.

Solution: b)

NCERT Class XI Fundamental of Physical Geography, Page 60

• Youthful river: A river with a steep gradient that has very few tributaries and flows quickly. Its channels erode deeper rather than wider. Examples are the Brazos, Trinity and Ebro
• Mature river: A river with a gradient that is less steep than those of youthful rivers and flows more slowly. A mature river is fed by many tributaries and has more discharge than a youthful river. Its channels erode wider rather than deeper. Examples are the Mississippi, Saint Lawrence, Danube, Ohio, Thames and Paraná
• Old river: A river with a low gradient and low erosive energy. Old rivers are characterized by flood plains. Examples are the Yellow, lower Ganges, Tigris, Euphrates, Indus and lower Nile

Solution: b)

Please check diagram and explanation on page 63 of  NCERT Class XI Fundamental of Physical Geography

Solution: b)

For explanation, please refer to NCERT Class XI Fundamental of Physical Geography, Page 91

Solution: d)

NCERT Class XI Fundamental of Physical Geography, Page 82

Compared to land, sea gets heated slowly and gets cool slowly, hence there is less variation in temperature.

With increasing altitude, generally temperature decreases.

Solution: a)

NCERT Class XI Fundamental of Physical Geography, Page 77

Radio waves transmitted from earth are reflected back to the earth by ionosphere

Solution: b)

NCERT Class XI Fundamental of Physical Geography, Page 76-77

Its volume in air decreases as we move towards poles due to less evaporation away from equators.

Solution: a)

NCERT Class XI Fundamental of Physical Geography, Page 67

The highest peak in Alps, Matterhorn and highest peak in Himalayas, Mt Everest are Horns formed through headward erosion of radiating cirques.