Plants fix Sun’s radiant energy to make food from simple inorganic materials. The amount of energy fixed by plants is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2-10% of photosynthetically active radiation
Photosynthetically active radiation (PAR) is the part of sunlight that plants can use for photosynthesis. Less than half of the incident solar radiation is PAR. Of this PAR, plants capture only 2-10 per cent, and this small amount feeds the whole living world.
(1) 50% of incident solar radiation — Incorrect. Less than 50 per cent of the incident radiation is PAR, and plants fix only a small part of even that.
(2) 50% of photosynthetically active radiation — Incorrect. This is far above the 2-10 per cent that plants capture.
(3) 2-10% of photosynthetically active radiation — Correct. The share is counted out of PAR.
(4) 2-10% of incident solar radiation — Incorrect. The 2-10 per cent is taken out of PAR, not out of all the incident radiation.
NCERT Extract:
Energy Flow –
