Long Questions: Major Domains of the Earth | NCERT Summary: UPSC PDF Download

Q1: Describe four major oceans of the world.
Ans: Four major oceans of the world are: The Pacific Ocean, The Atlantic Ocean, The Indian Ocean and The Arctic Ocean.

The Pacific Ocean is the largest ocean:

• It is spread on 33.3% area of the earth.
• Mariana Trench, the deepest part of the earth lies under the Pacific Ocean.
• The Pacific Ocean is circular in shape.
• It is bounded by Asia and Australia on one side and North and South Americas on the other.

The Atlantic Ocean is the second largest ocean of the world.

• It is ‘S’ shaped.
• It is flanked by the North and the South America on the Western side and Europe and Africa on the eastern side.
• Its coastline is highly indented. This irregular and indented coastline facilitates development of natural harbours.
• The Atlantic ocean is the busiest ocean from the point of view of commerce.

The Indian Ocean is the only ocean which has been named after India.

• The shape of this ocean is almost triangular.
• In the North, it is bounded by Asia, by Africa in the west and by Australia in the east. Indian Peninsula divides it into two parts.
• The Arabian Sea and the Bay of Bengal.

The Arctic Ocean is located within the Arctic circle and surrounds the North Pole.

• It is actually a northward extension of Atlantic Ocean.
• A narrow water body named the Berring Strait connects it with Pacific Ocean.
• It is bounded by the northern coasts of North America and Eurasia in the north.

Q2: Why is the earth called the blue planet?
Ans:

• The earth is called the blue planet because 71% of the earth is covered with water and 29% with land.
• Hydrosphere consists of water in all its forms in the oceans, lakes, ponds, rivers, streams, ice caps and ice sheets. On the surface as surface water and below the surface of the earth, in the form of under-ground water.
• Water is also present in the atmosphere in the form of water vapour.
• In other words running water in rivers and oceans, in lakes, glaciers, underground water and the water vapour in the atmosphere all make the hydrosphere.
• The oceans form the major part of the hydrosphere.
• They are all connected with one another.

Q3: Write a short note on atmosphere?
Ans: The earth is surrounded by a layer of gas called the atmosphere. This thin blanket of air is an integral and important aspect of the planet. It provides us with the air we breathe and protects us from the harmful effects of sun's rays. The atmosphere extends upto a height of about 1600 km. The atmosphere is divided into five layers based on composition, temperature and other properties. These layers starting from earth's surface are called the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.

Q4: Differentiate between isthmus and strait with example.
Ans: The difference between isthmus and strait is as follows:

• Isthmus: It is a narrow strip of land that joins two landmasses. North America is linked with South America with a narrow strip of land called Isthmus of Panama.
• Strait: It is a narrow stretch of shallow water, which connects two large water bodies like seas and oceans. The Palk strait divides India and Sri Lanka.

Q5: The earth is called a blue planet due to large availability of water, but still we face shortage of water. Explain it.
Ans: The majority of the water is found on Earth in salt form. The large per cent of fresh water is present in the form of icesheets and underground water, only 0.03 per cent is available as fresh water for our use. It is the reason why there is a lack of water on the earth.

Q6: Define pressure, temperature and density of atmosphere.
Ans: The density of atmosphere varies with height. It is maximum at the sea level and decreasing while going up. The temperature also decreases when we go up.
The atmosphere exerts pressure on the earth.The atmospheric pressure changes from place to place. Some places may have high pressure while some have low pressure.

Q7: Where do the Equator, tropic of cancer and the tropic of capricorn pass in Africa?
Ans: The Equator passes on by the countries- Republic of Congo, Uganda and Kenya. The tropic of cancer passes on through the countries-Morocco, Libya, Algeria and Egypt. The tropic of capricorn passes on through the country South Africa.

Q8: Which are the Seven Continents of the world? Give a brief description of each of them.
Ans: There are seven major continents, namely: Asia, Europe, Africa, North America, South America, Australia and Antarctica.
1. Asia

• Asia is the largest continent.
• It covers about 1/3 of the total land area of the earth.
• Asia lies in the eastern hemisphere.
• Alt is separated from Europe by Ural mountain on the west’
• The combined landmass of Asia and Europe is called Eurasia.

2. Europe

• Europe is the second smallest continent.
• Water bodies bound it on three sides.
• The Atlantic Ocean lies on the western side, the Arctic Ocean on the Northern side and the Mediterranean sea on the southern side.

3. Africa

• Africa is the second largest continent after Asia. Equator runs almost through the middle of this continent.
• The wider part of Africa lies in the Northern hemisphere.
• It is the only continent which both the Tropic of Cancer and the Tropic of Capricorn pass through.
• The continent is bounded on all sides by oceans and seas.
• The largest hot desert of the world, the Sahara desert is situated in Africa.
• The world’s longest river, Nile, flows through Africa.

4. North America

• North America is the third largest continent of the world.
• It is linked with South America by the Panama Isthmus.
• It lies completely in the Northern and Western Hemisphere.
• Three oceans surround it. They are the Pacific Ocean in the West, The Atlantic Ocean in the East and the Arctic Ocean in the North.

5. South America

• South America lies mostly in the Southern Hemisphere.
• It is bounded by the Pacific Ocean in the west, by Atlantic Ocean in the East and by Antarctic Ocean in the South.
• The world’s longest mountain range, the Andes runs through its full length.
• World’s largest river, Amazon flows through this continent.

6. Australia

• Australia is the smallest continent of the world.
• It lies entirely in the Southern hemisphere.
• It is surrounded on all sides by oceans and seas so it is called an island continent.

7. Antarctica

• Antarctica is completely in the Southern Hemisphere.
• It is a continent larger than Europe and Australia put together.
• The South Pole lies almost at the centre of this continent. Hence the continent is permanently covered with thick ice’sheets.
• It has no permanent human settlements.
• Numerous countries have set up their research stations op. this continent, India has set up Maitri, Dakshin Gangotri as its research centres here.

Q9: What are the two main divisions of the earth’s surface?
Ans: Divisions of the Earth’s Surface:

• The two main divisions of the earth’s surface are:
• The large landmasses are known as the continents.
• The ocean basins, contain large water bodies.
• Continents and Oceans differ from each other in their relative levels.
• All the Oceans of the world are connected with one another.
• Level of seawater remains the same everywhere. It is called sea level. The continents have an average depth of 3800 metres in Oceans.
• The highest point on Continents is 8848 metres in the form of Mount Everest in Nepal while the deepest depth is 11022 metres in the form of Mariana Deep (Mariana Trench) in the Pacific Ocean.

Q10: Explain the layers of the Atmosphere.
Ans:

• The atmosphere extends upto a height of about 1,600 kilometres.
• The atmosphere is divided into five layers based on composition, temperature and other properties.
• They are in ascending order from the earth’s surface:
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere, and
• Exosphere
• The ozone layer crucial to life on the earth is located in the stratosphere.

Q11: Discuss the organisms found in the Biosphere.
Ans:

• The organisms found in the biosphere are broadly divided into plant kingdom and animal kingdom.
• The four realms of the earth interact with one another and affect one another in some way or the other.

The growth of human population is a major cause of change in the biosphere. The growing population requires space for living. This leads to increase of silt in rivers that results ultimately into floods.

• Floods provide new soil or alluvial (sand and earth).
• But simultaneously floods destroy human habitation and cause complete disruption in smooth living of people.