9th Std Social Science Term 2 Solution | Lesson.6 Biosphere

Lesson.6 Biosphere

9th Standard Social Science Book Term 2 - Biosphere

Lesson.6 Biosphere

I. Fill In The Blanks

1. An area where animals, plants and micro organisms live and interact with one another is known as. ………..

Ans : Eco system

2. ……….. are also called Heterotrophs.

Ans : Consumbers

3. ……….. is a system of interlocking and independent food chains.

Ans : Food web

4. ……….. is an extensive large ecosystem.

Ans : Biome

5. The vegetative type commonly found in desert biomes is called ………..

Ans : Xerophytes

6. ……….. is an aquatic biome that is found where fresh water and salt water mix.

Ans : Estuary

II. Choose the correct answer

1. The coldest biome on Earth is

  1. Tundra
  2. Taiga
  3. Desert
  4. Oceans

Ans : a) Tundra

2. This is the smallest unit of biosphere.

  1. Ecosystems
  2. Biome
  3. Environment
  4. None of the above

Ans: a) Ecosystems

3. Nutrients are recycled in the atmosphere with the help of certain micro organisms, referred to as ……………

  1. Producers
  2. Decomposers
  3. Consumers
  4. None of the above

Ans : a) Producers

4. To which climatic conditions are Xerophytic plants specifically adapted to?

  1. Saline and sandy
  2. Limited moisture availability
  3. Cold temperature
  4. Humid

Ans : b) Limited moisture availability

5. Why is the usage of rainforest biomes for large scale agriculture unsustainable?

  1. Because it is too wet
  2. Because the temperature is too warm.
  3. Because the soil is too thin
  4. Because the soil is poor

Ans : a) Because it is too wet

Questions 6 – 8 are assertion type questions.


  1. Both assertion (A) and reason(R) are true; R explains A
  2. Both assertion(A) and reason(R) are true; R does not explain A
  3. A is true; R is false
  4. Both A and R are false

6. A: Heterotrophs do not produce their own food.

R: Tey depend on autotrophs for their nourishment.

Ans : a) Both assertion (A) and reason(R) are true; R explains A

7. A: Hotspots are the regions characterised by numerous endemic plants and animal species living in  a vulnerable environment.

R: To manage and focus on conservation work more effectively, researchers identifed hotspots.

Ans : a) Both assertion (A) and reason(R) are true; R explains A

8. A: The number of gorillas in Africa has plummeted by 60% in the past twenty years.

R: Non intervention of human beings in the forest areas.

Ans : c) A is true; R is false

III. Answer the following in brief: 

1. What is Biosphere?

  • Biosphere, the fourth sphere of the Earth is a life supporting layer that exists on the Earth’s surface.
  • This layer on Earth encompasses the Lithosphere, Hydrosphere and Atmosphere.
  • It includes flora and fauna that thrive on or near the Earth’s surface.

2. What is an ecosystem?

  • Ecosystem is a community where all living organisms live and interact with one another.
  • It also interacts with their non-living environment such as land, soil, air, water, etc.

3. What does the term ‘biodiversity’ mean?

  • Biodiversity or biological diversity refers to a wide variety of living organisms which live in a habitat
  • It is highly influenced by topography, climate as well as human activities.
  • It maintains the ecological balance and facilitates social benefits such as tourism, education, research etc., over an area.

4. What is meant by loss of biodiversity?

  • The extinction of species (flora and fauna) due to human and natural influences is called Loss of biodiversity.
  • The biodiversity loss has a great impact on mankind and also affects land, water, air, etc.

5. Mention the various terrestrial biomes.

Terrestrial biomes is a group of living organisms that live and interact with one another on land. They are mainly determined by temperature and rainfall.

Some of the major territorial biomes of the world are-

  • Tropical forest biomes
  • Tropical Savanna Biomes
  • Desert Biomes
  • Temperature Grassland Biomes
  • Tundra Biomes

IV. Distinguish the following:

1. Producers and Decomposers.

1. These are self nourishing components of the ecosystem.These organisms are incapable of preparing its own food.
2. The Producers are also known as Autotrophs.The Decomposers are known as Saprotrophs.
3. Plants, Algae, Bacteria, etc are examples of ProducersFungus, Mushrooms, etc are examples of Decomposers.

2. Terrestrial biomes and Aquatic biomes.

Terrestrial biomesAquatic biomes
1. Terrestrial biomes is a group of living organisms that live and interact with one another on landAquatic biome is a group of living organisms that live and interact with one another in aquatic environment.
2. They are mainly determined by temperature and rainfallAquatic biomes are influenced by a series of abiotic factors.
3. Terrestrial biomes are broadly classified into five biomesAquatic biomes are classified into two biomes

3. Tropical vegetation and Desert vegetation

Tropical vegetationDesert vegetation
1. Tropical vegetation found between 10° N and 20°S of the Equator.Deserts usually between 20° and 30° N and S latitudes.
2. The climate shows little seasonal variation with high annual rainfall and constant & high temperature.Here, the annual rainfall is less than 25cm and temperature is maximum thought out the year.
3. The chief trees found here are rubber, bamboo, ebony, etc.Drought resistant thorny scrubs, bushes, palms, etc., are found here

4. Savannas and Tundra

1. Savannas (grassland) are generally found between tropical forests and deserts.Tundra regions are found where the ground remains frozen.
2. The chief occupation of the people is herdingHunting and fishing are the major occupation of the people
3. Lion, leopard, tiger, deer, zebra, giraffe, etc. are the animals found in this biome.Polar bear, wolverine, reindeer, snowy owl, etc., are the animals found here.

V. Give reasons for the following:

1. Producers are also called autotrophs.

  • The organism that can produce its own food using light, water, carbon dioxide or other chemicals present in the environment is known as producers.
  • Producers are self nourishing components of the ecosystem.
  • Hence, they are called as autorophs.

2. Biosphere provides a stable ecosystem.

  • Ecosystems range in size from the smallest units that can sustain life to the global ecosystem or ecosphere.
  • Biosphere harbours all ecosystems on the Earth and sustains life forms including mankind.
  • Therefore, Biosphere provides a stable ecosystem.

VI. Answer in a paragraph 

1. Explain the various components of ecosystem.

Ecosystem is a community where all living organisms live and interact with one another and also with their non-living environment.

The three basic components of eco system are :

  1. Abiotic components
  2. Biotic components and
  3. Energy component

Abiotic Components

Abiotic components include the non-living, inorganic, physical and chemical factors in the

Eg. Land, Air ,Water, Calcium, Iron etc.

Biotic Components

Biotic components include plants, animals and micro organisms. Biotic components can be classified into three categories.

They are-

  • Autotrophs are self nourishing components of the ecosystem. Hence, they are called as Producers. They are found both on land and water.
  • Heterotrophs are those that depend on producers, directly or indirectly. Hence they are called as Consumbers
  • Decomposers are some organisms that are incapable of preparing their own food. They live on dead and decaying plants and animals. Hence they are called Saprotrophs.

Energy Components

  • All organisms in the biosphere use energy to work and convert one form of energy into another.
  • The Sun is the ultimate source of energy for the biosphere as a whole.
  • The solar energy gets transformed into other forms of energy through the various components in the ecosystem.
  • The producers, consumers and the decomposers contribute a lot to the energy flow in an ecosystem

2. Write a paragraph on the functions of an ecosystem.

The functions of an ecosystem are as follows-

  • The living organisms form an interacting set of flora and fauna which are organized into trophic levels, food chains and food webs.
  • The functioning of an ecosystem depends on the pattern of the energy flow, as it helps in the distribution and circulation of the organic and inorganic matter within an ecosystem.
  • Energy flow generally takes place in a hierarchical order in an ecosystem through various levels. These levels are called trophic levels.
  • The chain of transformation of energy from one group of organisms to another, through various trophic levels is called a food chain.
  • A system of interlocking and interdependent food chains is called a food web.

3. Explain about the aquatic biomes on Earth.

  • Aquatic biome is a group of living organisms that live and interact with one another and its aquatic environment for nutrients and shelter.
  • Like terrestrial biomes, aquatic biomes are influenced by a series of abiotic factors. It is broadly classified as Fresh water biomes and Marine biomes.

Fresh water Biomes:

  • Fresh water biome comprises lakes, ponds, rivers, streams, wetlands etc.
  • It is influenced by various abiotic components such as the volume of water, water flow, composition of oxygen, temperature, etc.
  • Humans rely on freshwater biomes for drinking water, crop irrigation, sanitation and industry. Water lily, lotus, duck weeds etc. are the common plants found here.
  • Trout, salmon, turtles, crocodiles etc. are the animals found here.

Marine Biomes:

  • Marine biomes are the largest aquatic biomes on earth.
  • It provides a wide range of habitats for marine plants and animals.
  • Coral reefs are a second kind of marine biomes within the ocean.
  • Estuaries, coastal areas where salt water and fresh water mix, form a third unique marine biome.
  • Apart from animals, plants such as kelp, algae, phytoplankton etc. also grow in water.
  • Aquatic biomes are not only important for plants and animals, but also for humans.
  • Humans use aquatic biomes for water, food and leisure activities.
  • Some of the threats and issues to aquatic biomes are overfishing, pollution and rise in sea level.

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