Question

Read the following statement.
I. In a food chain, there is a multidirectional flow of energy from the sun to producers, consumer and decomposer.
II. Shorter food chains provide more energy as compared to longer food chains.
III. In an ecosystem, no food chain is independent.
IV. If 100 joules of energy is available at the producer level, then the amount of energy present at the level of the secondary consumer is 10 joules.
Which of these statements are correct?
A. I and II
B. II and III
C. III and IV
D. I and IV

Answer 1

Hint: Food chain is defined as the series or sequence of flow of energy in terms of food from the producers to the decomposers. It describes the succession of eating and being eaten by other organisms.

Complete Answer:
To solve this question, we must know about the properties of the food chain.
- In a food chain, the flow of energy takes places from producers to decomposers. The producers (plants) produce food by utilising the sunlight.
- The plants are eaten up by the primary consumers or the herbivores which are further eaten by the carnivores or the secondary consumers. The flow of energy is unidirectional from the producer to the secondary consumer. (Statement I is incorrect).
- In a food chain the net 10% of the energy is transferred from one trophic level to another.
- The producers transfer 10% of the energy to the primary consumers and the primary consumers transfer 10% of the energy they received to the secondary consumers and so on.
- This shorter the food chain more the energy. (Statement IV is incorrect and II is correct)
- The food chain is dependent on each other and forms a food web. (Statement III is correct)

The correct answer is (B).

Note: A food web is an interconnected food chain. It represents how all the organism is dependent on each other either directly or indirectly for food. Food chain is a linear representation whereas the food web is a graphical model.