Which of the following statements are correct regarding the food chain?
A. Detritus food chain begins with dead organic matter.
B. Grazing food chain begins with dead organic matter.
C. In aquatic ecosystem, grazing food chain is the major conduit for energy flow.
D. Detritus food chain may be connected with the grazing food chain at some levels.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A, C and D only
Energy flows through an ecosystem along food chains. The grazing food chain (GFC) begins with producers, the green plants, which capture solar energy. The detritus food chain (DFC) begins with dead organic matter and is made up of decomposers, mainly fungi and bacteria.
(A) Detritus food chain begins with dead organic matter. — Correct. Decomposers get their energy by breaking down dead matter, or detritus.
(B) Grazing food chain begins with dead organic matter. — Incorrect. The grazing food chain begins with living producers, the green plants. It is the detritus food chain that begins with dead matter.
(C) In aquatic ecosystem, grazing food chain is the major conduit for energy flow. — Correct. In a land ecosystem more energy flows through the detritus food chain than through the grazing food chain. In water it is the other way round.
(D) Detritus food chain may be connected with the grazing food chain at some levels. — Correct. Some animals of the detritus chain are eaten by animals of the grazing chain. Some animals, such as crows and cockroaches, are omnivores. These links make a food web.
NCERT Extract:
Energy Flow – “… The detritus food chain (DFC) begins with dead organic matter. It is made up of decomposers which are heterotrophic organisms, mainly fungi and bacteria.”
Energy Flow – “… In an aquatic ecosystem, GFC is the major conduit for energy flow. As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the GFC. Detritus food chain may be connected with the grazing food chain at some levels: some of the organisms of DFC are prey to the GFC animals, and in a natural ecosystem, some animals like cockroaches, crows, etc., are omnivores.”