Which of the following statements is incorrect about the flow of energy between the various components of the environment?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Trophic levels are always more than five.
Energy enters an ecosystem through the green plants and passes from one trophic level (feeding level) to the next, with a large part lost at every step.
Option (1) Terrestrial ecosystems capture about 1% of the energy of sunlight. Correct statement. The green plants of a terrestrial ecosystem change only about 1% of the sunlight falling on their leaves into food energy.
Option (2) Only 10% of energy reaches the next level of consumers. Correct statement. By the 10 per cent law, each level passes on only about a tenth of its energy; the rest is used in its own life processes and lost as heat.
Option (3) Energy transfer between trophic levels is unidirectional. Correct statement. Energy flows one way, from the Sun to the producers to the consumers; the energy lost as heat does not come back to the plants.
Option (4) Trophic levels are always more than five. Incorrect statement. Because so little energy is passed on, food chains usually have only three or four trophic levels; too little energy is left to support a fifth or sixth.