Question

Which of the following statements are correct?
(a) Energy flow from producers to consumers is unidirectional
(b) Energy pyramid can never be inverted
(c) Transfer of energy follows the 1% law
Choose the correct answer from the options given below :

• A. (b) and (c) only
• B. (a), (b) and (c)
• C. (a) and (b) only
• D. (a) and (c) only

Hint:

Pyramids of biomass and numbers can occasionally be inverted (e.g., in deep marine ecosystems or a single-tree ecosystem). However, the pyramid of energy is strictly upright in all ecosystems due to the laws of thermodynamics.

Answer 1

The Correct Option is C

Concept:

• Unidirectional Energy Flow: Energy captured from the sun by producers travels linearly through successive trophic levels. It cannot travel back to previous levels.

• Pyramid of Energy: It is universally upright because energy is lost as heat at each trophic level. It can never be inverted.

• 10% Law of Energy (Lindeman): Only about \(10\%\) of the organic energy from one trophic level is stored and passed on to the next.

Step 1: Examine the validity of each statement
Statement (a) is correct: Energy flows in a single direction, from autotrophs to herbivores and then to carnivores.
Statement (b) is correct: The pyramid of energy is always upright because metabolic heat loss at each transfer prevents higher levels from containing more energy.
Statement (c) is incorrect: Energy transfer between successive trophic levels follows the

10% law, not the 1% law. (The 1% value is the efficiency with which plants convert solar energy into chemical energy during photosynthesis).

Step 2: Identify the correct option
Since only (a) and (b) are correct, option (3) is the correct choice.