Which of the following statements are correct about energy flow?
(A) Net primary productivity is available to consumers.
(B) Secondary productivity increases with each trophic level.
(C) The growth of the food chain is limited by the inefficiency of energy transfer.
(D) About 90% energy at one trophic level does not appear at the next level.
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (C) and (D) only
(A) Net primary productivity is available to consumers. — Correct. NPP is what is left of gross productivity after the plants’ own respiration. It is the biomass available to heterotrophs (herbivores and decomposers).
(B) Secondary productivity increases with each trophic level. — Incorrect. Only about 10 per cent of the energy passes from one level to the next, so the amount of new biomass falls at each higher level.
(C) The growth of the food chain is limited by the inefficiency of energy transfer. — Correct. With 90 per cent lost at each step, too little energy is left to support many levels, so food chains are short.
(D) About 90% energy at one trophic level does not appear at the next level. — Correct. This is the 10 per cent law: only about 10 per cent is transferred; the rest is used in respiration or lost as heat.