With reference to 'Ecosystem', which of the following statements is/are correct ?
1. Green plants in terrestrial ecosystem capture about 1% of energy of the sunlight that falls on their leaves.
2. Aro

Question

With reference to 'Ecosystem', which of the following statements is/are correct ?
1. Green plants in terrestrial ecosystem capture about 1% of energy of the sunlight that falls on their leaves.
2. Around 10% of organic matter reaches to the next higher level of consumers.
Select the correct answer from the code given below :
Code :

UnlockIAS · Accepted Answer

Correct — B, Both 1 and 2. Both statements are lifted almost word for word from the standard school treatment of energy flow. Statement 1 is the NCERT formulation: of all the sunlight that falls on the leaves of green plants in a terrestrial ecosystem, only about one per cent is captured and converted into food energy — the rest is reflected, passes through, warms the leaf, or falls outside the wavelengths photosynthesis can use. Statement 2 is Lindeman's ten per cent law: of the organic matter and energy available at one trophic level, only about ten per cent is built into the body of the next level and so becomes available to the consumers above; the other ninety per cent is burnt off in respiration, lost as heat, or never assimilated. Since both propositions are correct as stated, the answer is (b).

Why the other options are wrong — (a) This rejects the one per cent figure, usually because the candidate remembers a higher number such as 'two to ten per cent'. That higher figure is measured against photosynthetically active radiation only — a much smaller denominator. Against total incident sunlight the capture is about one per cent, which is precisely what statement 1 says.  (c) Both statements are standard, correct textbook propositions about energy flow. Rejecting both would mean rejecting the ten per cent law itself, which is one of the most settled generalisations in ecology.  (d) This accepts the one per cent capture but rejects the ten per cent transfer, and the ten per cent transfer is the better-established of the two. Raymond Lindeman set it out in 1942, and it is why food chains rarely run beyond four or five links and why the pyramid of energy is always upright.

Concept: Energy enters an ecosystem in one place only — sunlight fixed by producers — and then moves in one direction, from producers to herbivores to carnivores and finally to decomposers, leaking away as heat at every step. Two numbers describe the whole system. At the entry point, green plants convert only about one per cent of the sunlight falling on their leaves into chemical energy. At every step after that, roughly ten per cent of the energy in one trophic level is passed up to the next. Nutrients, unlike energy, are recycled; energy is not, which is why an ecosystem needs a continuous solar input to keep running.

State PCS 2025 Q89 — Environment & Ecology PYQ with Answer

State PCS 2025 Q89 — Environment & Ecology PYQ with Answer