Chapter - Review:

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• The solid section of the earth made up of rocks and soil is known as the lithosphere, and it is made up of rocks from the crust and layers of soil containing nutritional elements.
• The earth's surface is divided into vast landmasses known as continents and huge water bodies known as oceans, and these nutritional componen5ts sustain organisms on the planet. All of the world's oceans are linked.
• in all regions, the ocean level is the same. The elevation of the sea level is assumed to be zero, and elevations are calculated accorsingly. From here, a variety of differenty places are measured.
• Mount Everest is the world's highest mountain peak with an elevation of 8,848 meters above sea level.
• Because water covers more than 71% of the earth, it is commonly referred to as the "Blue Plant". The hydrosphere is made up of water in all of its forms, including flowing water in rivers, oceaus, and lakes, ice in glaciers water vapor in the atmosphere and subsurface water.
• The Oceans make up 97% of the hydrosphere. This water is excessively salty for human consumption.
• A large portion of freshwater is found in ice sheets and glaciers, asa well as subsurface water.
• The earth's oceans make up the majority of the hydrosphere. They're all linked together.
• The ocean currents are always moving, waves, tides and ocean currewnts all - cause movement in the ocean.
• The pacific ocean, the Atlantic ocean, the Indian ocean, the Southern oceans and the Arctic ocean are the world's oceans.
• The pacific ocean is the world's largest, covering one - third of its surface.
• Mariana Trench is located in pacific oceans and is the deepest portion of the earth. It encircles North and south America, Asia, and Australia and is typically round.
• The Atlantic oceans, the world's second - biggest oceans, is formed like an 's' and is bordered on the east by Europe and Africa and on the west by North and south America.
• The atmosphere is a blanket of air that surrounds the planet like a blanket and protects the biosphere from the destructive effects of sun rays.

 

Exercise - Question:

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Q1. Answer the following questions briefly.

(a) What are the four major domains of the earth ?

Ans. The four realms of the earth are :

(i) Lithosphere,   (ii) Hydrosphere,   (iii) Atmosphere,   (iv) Biosphere.

(b) Name the major continents of the earth.

Ans. The major continents of the earth are :

Asia, Europe, North America, South America, Australia and Antarctica.

(c) Name the two continents that lie entirely in the Southern Hemisphere are :

Ans. 1. Australia, 2. Antarctica

(d) Name the different layers of the atmosphere.

Ans. The different layers of the atmosphere are :

Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.

(e) Why is the earth called the 'blue planet' ?

Ans. More the 71 percent of earth is covered with water. Therefore, from outer space it appears blue. That is why, it is called a blue planet.

(f) Why is Northern Hemisphere called land Hemisphere ?

Ans. The greater part of the land masses lie in the Northern Hemisphere.

(g) Why is the Biosphere Important for the living organisms ?                Ans. The Biosphere is the narrow zone of contact between land, water and air. It is in this zone that life that is unique to the planet exists. The growth and survival of the biosphere is made possible by the transfer of energy and matter between elements of the environment.

Q2. Tick the correct answers.

(a) The mountain range that separates Europe from Asia is

(i) the Andes

(ii) the Himalayas

(iii) the Ural

(b) The continent of North America is linked to south America by

(i) Isthmus

(Ii) Strait

(iii) Suez canal

(c) The major continent of atmosphere by per cent is

(i) Nitrogen

(ii) Oxygen

(iii) Carbon dioxide

(d) The domain of the earth consisting of solid rocks is

(i) the Atmosphere

(ii) the Hydrosphere

(iii) the Lithosphere

(e) Which is the largest continent ?

(i) Africa

(ii) Asia

(iii) Australia

Ans. a. (iii), b. (i), c. (i), d. (iii), e. (ii)

Q3. Fill in the blanks.

(a) The deepest point on earth is ......... in the pacific Ocean.

(b) The ......... Ocean is named after a country.

(c) The ........ is the narrow contact zone of land, water and air that supports life.

(d) The continents of Europe and Asia together are known as ........ .

(e) The highest mountain peak on the earth is .........

Ans. (a) Mariana Trench, (b) Indian, (c) Biosphere, (d) Eurasia, (e) Mt. Everest.

 

Additional Question:

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Que: Which is larger - Europe or Australia?

Ans: Europe is larger than Australia.

Que: How is nitrogen a significant gas?

Ans: Nitrogen helps in the growth of living organisms.

Que: What is the Junction of carbon dioxide?

Ans: Carbon dioxide absords the heat rediated by the earth and thus keeps the planet warm.

Que: What is the height of the mt. Everest.

Ans: The height of the mt. Everest is 8,848 meters.

Que: In which Hemisphere does asoia life?

Ans: Asia lies in the Eastern Hemisphere.

Que: Name the world's largest hot desert. Where is the locted.

Ans: The sahara desert. It is located in Africa.

Que: How is North America linked to south America? 

Ans: North America is linked to south America by a narrow strip of land called the Isthmus of panama.

Que: Name of Oceans that surround the continent - North America.

Ans: The Pacific Ocean, the Atlantic ocean and the Artic Ocean.

Que: Which two oceans surround South America on the east and the west.

Ans: On the east - the Atlantic ocean On the west - the pacific Ocean.

Que: Name the research stations of India in Antaractica.

Ans: Maitri and Dakshin Gangotri.

Que: What percent of the earth is covered with water?

Ans: More than 71 percent of the earth is covered with water.

Que: What percent of earth is covered with land.

Ans: 29 percent of earth is covrered with land.

Que: How much of the earth's water is found in the oceans?

Ans: More than 97 percent of the earth's water is found in the ocean.

Que: Why is the ocean water not fit for human use?

Ans: It is becuse the ocean water is very salty.

Que: Why do the mountaineers carry with the oxygen cylinders?

Ans: The mountaineers carry with them oxygen cylinders so that they can easily breathe at high altitudes.

Que: What is the nature of the temperature?

Ans: The temperature decreases as we go upwards.

Que: Name the continents that surround the pacific oceans.

Ans: Asia, Australia, North America and South America.

Que: Which is the busiet oceans from the point of view of commerce?

Ans: The Atlantic ocean is the busiest ocean from the point of view of commerce.

Que: mention two reasons of fast removal of soil from stops.

Ans: (i) Cutting of forests for wood.

(ii) Clearing land for agriculture.

Que: What happened to Andman and Nicobar island durig Tsunami?

Ans: Parts of these island were submerged under water during Tsunami.

Que: What makes the mater of lakes and rivers unsuitable for human use.

Ans: Discharge of waste material into lakes and rivers makes the water unsuitable for human use.

Que: Mention any two reasons of air pollution.

Ans: (i) Emission from industries.

(ii) Emission from vehicles.

Que: Mention  the three main components of the environment. 

Ans: the three main components of the environment are - the lithosphere, the atmosphere and the hydrosphere. The lithosphere is the solid portion of the earth. The gaseous layers that surround the earth is the atmosphere. The atmosphere is made up of oxygen, nitrogen, carbondioxide and other gases. The hydroshere refers to the big area of the water that cover the earth's surface. This water is in the fors of ice, water and water vapour.

Que: Write a short note on the 'hydrosphere'.

Ans: The hydrosphere refers to the water bodies that are found on the earth's surface. More than 71% of the earth is covered with water. This water is found in all its forms - ice, water and water vapour. Running water in oceans and rivers and in lakes, ice in glaciers, underground water and the water vapour in atmosphere. More thanj 97% of the earth's water is found in oceans. the ocean water is very salty, herce not to human utility. A large proportion of the rest of water is in the from of the icesheets and glaciers of under the ground. A very small percentage (0.03%) is available as frash water. It is this water that we use.

Que: Explain biophere - the domain of life.

Ans: The biosphere is a narrow zone of the earth where land, water and air interact with each other to support life. it is in the this zone that life exists. There are several species of organisms that very in size from microbers and bacteria to large mammals. All living organisms including human are linked to each other and to the biophere for survival.

Que: Give an account of the composition of the atmosphere. Also, discuss the importance of the components.

Ans: The atmosphere is composed mainly of nitrogen and oxygen. Together they make up about 90% of clean, dry air. Nitrogen 78% and oxygen 21%. A part from these two major gases, there are other gases too in the atmosphere. These gases include carbon dioxide, argon and other comprise 1% by volums.

Oxygen is the breath of life while nitrogen helps in the growth of living organisms. Carbon dioxide absords heat radiated by the earth. In this way, it keeps the planet warm. It is also essential for the growth of plants.

Que: What is atmosphere? Write about its different layers.

Ans: The atmosphere is a thin blanket of air that surrounds the earth. It provides us with the air we breathe and protects us from the harmful effects of sun's rays. the atmosphere extends up to a height of about 1,600km. The atmosphere is divided into five layers based on composition, temperature and other properties. These layers are - the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.