Biology Class 12 NCERT Solutions: Chapter 14 Ecosystem Part 2

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Q.4 Secondary producers are

(a) Herbivores

(b) Producers

(c) Carnivores

(d) None of the above

Answer:

(d) None of the above

  • Plants are the only producers. Thus, they are called primary producers. There are no other producers in a food chain.

Q.5 What is the percentage of photo synthetically active radiation (PAR), in the incident solar radiation.

(a) 100%

(b) 50 %

(c) 1-5%

(d) 2-10%

Answer:

(b) 50%

  • Out of total incident solar radiation, about fifty percent of it forms photo synthetically active radiation or PAR.

Q.6 Distinguish between

(a) Grazing food chain and detritus food chain

(b) Production and decomposition

(c) Upright and inverted pyramid

(d) Food chain and Food web

(e) Litter and detritus

(f) Primary and secondary productivity

Answer:

  1. Grazing food chain and detritus food chain

Table of Grazing Food Chain V/S Detritus Food Chain
Table of Grazing Food Chain V/S Detritus Food Chain

Grazing food chain

Detritus food chain

1.

In this food chain, energy is derived from the Sun.

1.

In this food chain, energy comes from organic matter (or detritus) generated in trophic levels of the grazing food chain.

2.

It begins with producers, present at the first trophic level. The plant biomass is then eaten by herbivores, which in turn are consumed by a variety of carnivores.

2.

It begins with detritus such as dead bodies of animals or fallen leaves, which are then eaten by decomposers or detritivores. These detritivores are in turn consumed by their predators.

3.

This food chain is usually large.

3.

It is usually smaller as compared to the grazing food chain.

  1. Production and decomposition

Table of Production V/S Decomposition
Table of Production V/S Decomposition

Production

Decomposition

1.

It is the rate of producing organic Matter (food) by producers.

1.

It is the process of breaking own of complex organic matter or biomass from the body of dead plants and animals with the help of decomposers into organic raw material such as, and other nutrients.

2.

It depends on the photosynthetic capacity of the producers.

2.

It occurs with the help of decomposers.

3.

Sunlight is required by plants for primary production.

3.

Sunlight is not required for decomposition by decomposers

  1. Upright and inverted pyramid

Table of Upright V/S Inverted Pyramid
Table of Upright V/S Inverted Pyramid

Upright pyramid

Inverted pyramid

1.

The pyramid of energy is always upright.

1.

The pyramid of biomass and the pyramid of numbers can be inverted.

2.

In the upright pyramid, the number and biomass of organisms in the producer level of an ecosystem is the highest, which keeps on decreasing at each trophic level in a food chain.

2.

In an inverted pyramid, the number and biomass of organisms in the producer level of an ecosystem is the lowest, which keeps on increasing at each ropic level.

  1. Food chain and Food web

Table of Food Chain V/S Food Web
Table of Food Chain V/S Food Web

Food chain

Food web

1.

It is a single linear sequence of organisms.

1.

It contains a number of interconnected food chains.

2.

Members present at higher trophic levels feed on single types of organisms.

2.

One organism has alternate food sources.

  1. Litter and detritus

Table ofLitter V/S Detritus
Table ofLitter V/S Detritus

Litter

Detritus

1.

Litter contains all kinds of wastes generated above the ground.

1.

Detritus is composed of the remains of dead plants and animal.

2.

Litter contains both biodegradable and non-biodegradable matter.

2.

Detritus contains only biodegradable matter.

  1. Primary and secondary productivity

Primary and Sec Productivity
Primary and sec productivity

Primary productivity

Secondary productivity

1.

It is defined as the amount of organic matter produced by producers per unit area over a period of time.

1.

It is defined as the rate of production of organic matter by consumers over a period of time.

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