Major Domains of the Earth
Q43. What is the composition of the Atmosphere?
The atmosphere is composed mainly of nitrogen and oxygen, which make up about
99 per cent of clean, dry air. Nitrogen 78 per cent, oxygen 21 per cent and other
gases like carbon dioxide, argon and others comprise 1 per cent by volume.
Q44. Explain the following terms:
strip of land joining two landmasses is called Isthmus.
air is known as wind.
is a narrow of water connecting two large water bodies like seas and oceans.
The biosphere is the narrow zone of
contact between the land, water and air. It is the zone where life exists.
The solid portion of the earth is called the
Water covers a very big area of the earth’s
surface and this area is called the Hydrosphere.
Q45. Distinguish between the lithosphere
and the hydrosphere.
The solid portion of the earth on which we live is called the Lithosphere.
covers a very big area of the earth’s surface and this area is called the
It comprises the rocks of the earth’s crust and the thin layers of soil that
contain nutrient elements which sustain organisms.
in oceans and rivers and in lakes, ice in glaciers, underground water and the
water vapor in atmosphere, all comprise the hydrosphere.
Q46. Why air temperature decreases with
increase in height?
Ans. Air temperature decreases with increase in height
because Earth's atmosphere is heated upward from the lowest level. Though
sunlight passes through the higher altitudes before reaching the earth’s surface
but the earth surface is much better at absorbing the solar heat.
Q47. Give reason why biosphere is
important for living organisms?
The biosphere is the narrow zone of contact between the land, water and air. It
is this zone where life exists. There are several species of organisms that
vary in size from microbes and bacteria to huge mammals. All the living organisms
including humans are linked to each other and to the biosphere for survival.
Q48. Write a short note on continent Asia.
Important fact about Asia
Asia is the largest continent.
It covers about one third of the total land
area of the earth.
The continent lies in the Eastern
The Tropic of Cancer passes through this
Asia is separated from Europe by the Ural
mountains on the west
The combined landmass of Europe and Asia is
called the Eurasia (Europe + Asia).
Q49. Write some characteristics of the continent - Africa.
Following are the characteristics of the continent - Africa.
Africa is the second largest continent
The Equator runs almost through the middle
of the continent. A large part of Africa lies in the Northern Hemisphere.
It is the only continent through which the
Tropic of Cancer, the Equator and the Tropic of Capricorn pass.
The Sahara Desert, the world’s largest hot
desert, is located in Africa.
The continent is bound on all sides by
oceans and seas.
The world’s longest river the Nile flows
Q50. List some features of the Europe continent.
Here are some features of the Europe continent:
1. Europe is
much smaller than Asia.
continent lies to the west of Asia.
Arctic Circle passes through it.
4. It is bound by water bodies on three sides.
Q51. How is the continent of North America different from that
of South America?
North America is the third largest
continent of the world.
It is linked to South America by a very
narrow strip of land called the Isthmus of Panama.
The continent lies completely in the
Northern and Western Hemisphere.
Three oceans surround this continent are
Pacific Ocean, Atlantic ocean and arctic Ocean.
South America lies mostly in the Southern
The Andes, world’s longest mountain range,
runs through its length from north to south.
South America has the world’s largest river,
Q52. Write short note on
Atlantic Ocean, Artic Ocean and Indian Ocean
Atlantic Ocean is the second largest Ocean in the world. It is ‘S’ shaped. It
is flanked by the North and South Americas on the western side, and Europe and
Africa on the eastern side. The coastline of Atlantic Ocean is highly indented
which provides ideal location for natural harbors and ports.
Arctic Ocean is located within the Arctic Circle and surrounds the North Pole.
It is connected with the Pacific Ocean by a narrow stretch of shallow water known
as Berring strait. It is bound by northern coasts of North America and Eurasia.
Indian Ocean is the only ocean named after a country, that is, India. The shape
of ocean is almost triangular. In the north, it is bound by Asia, in the west
by Africa and in the east by Australia.