Of the incident solar radiation, what is the percentage of photosynthetically active radiation (PAR)?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Less than 50%
Photosynthetically active radiation (PAR) is the part of sunlight that plants can use for photosynthesis. Out of all the sunlight falling on the earth, less than half is PAR. Plants then capture only a small part of this PAR.
Option (1) 100% — Incorrect. Sunlight also has wavelengths such as infrared and ultraviolet that cannot drive photosynthesis.
Option (2) Less than 50% — Correct. Less than 50 per cent of the incident solar radiation is PAR.
Option (3) 1-5% — Incorrect. The share of sunlight that is PAR is far more than 1-5 per cent; it is close to half.
Option (4) 2-10% — Incorrect. 2-10 per cent is the part of PAR that plants capture, not the part of sunlight that is PAR.
NCERT Extract:
Energy Flow –
