Question

Which of the following is false about the food chain?
A. Grazing food chain is a major conduit of energy for the aquatic ecosystem.
B. In the terrestrial ecosystem, a large fraction of energy flows through the detritus food chain.
C. Primary consumers belong to the first trophic level.
D. Detritus food chain begins with dead organic matter.
E. Cockroaches and crows are omnivores.

Answer 1

Hint: Food chain is a sequence of transfer of energy and matter in form of food from one trophic level to another. Primary consumers are herbivores. Producers belong to the first trophic level.

Complete Answer:
The food chains are mainly of two types: grazing food chain and detritus food chain.
1. The grazing food chain starts with a producer and is followed by herbivores, primary carnivore and secondary carnivore. It reaches up to decomposers. The grazing food chain is thought to be the major conduit of energy for the aquatic ecosystem. Here, the producers are found to occupy the first trophic level. The primary consumers are herbivores occupy the second trophic level while the secondary consumers are found to occupy the third trophic level.

2. A detritus food chain always starts with dead organic matter which goes to detritivores. In a terrestrial ecosystem, there is a large fraction of energy flowing through the detritus food chain. Omnivores are those organisms that feed on plants as well as animals. Examples include cockroaches, crows, humans.

Thus, the correct answer is option (C) Primary consumers belong to the first trophic level.

Note: The first trophic level in the detritus food chain is a detrivore which feeds on dead decaying matter. However, the first trophic level of a grazing food chain is found to be the producers which fix radiant energy into chemical energy.