Biology Class 12 NCERT Solutions: Chapter 14 Ecosystem Part 1 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q. 1 Fill in the blanks.

(a) Plants are called as________ because they fix carbon dioxide.

(b) In an ecosystem dominated by trees, the pyramid (of numbers) is ________ type.

(c) In aquatic ecosystems, the limiting factor for the productivity is ________.

(d) Common detritivores in our ecosystem are________.

(e) The major reservoir of carbon on earth is________.

Answer:

(a) Plants are called as autotrophs because they fix carbon dioxide.

(b) In an ecosystem dominated by trees, the pyramid (of numbers) is of inverted type.

(c) In aquatic ecosystems, the limiting factor for productivity is light.

(d) Common detritivores in our ecosystem are earthworms.

(e) A major reservoir of carbon on Earth is oceans.

Q. 2 Which one of the following has the largest population in a food chain?

(a) Producers

(b) Primary consumers

(c) Secondary consumers

(d) Decomposers

Answer:

(d) Decomposers

  • Decomposers include micro-organisms such as bacteria and fungi. They form the largest population in a food chain and obtain nutrients by breaking down the remains of dead plants and animals.
Food Chain

Q. 3 The second trophic level in a lake is

(a) Phytoplankton

(b) Zooplankton

(c) Benthos

(d) Fishes

Answer:

(b) Zooplankton

  • Zooplankton are primary consumers in aquatic food chains that feed upon phytoplankton. Therefore, they are present at the second trophic level in a lake.
Zooplankton

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