Question

Of the incident solar radiation, what is the percentage of photosynthetically active radiation (PAR)?

• A. 100%
• B. Less than 50%
• C. 1-5%
• D. 2-10%

Hint:

Only a small fraction (2-10%) of incident solar radiation is used in photosynthesis as PAR.

Answer 1

The Correct Option is D

Photosynthetically active radiation (PAR) refers to the portion of solar radiation that plants use for photosynthesis. It primarily consists of light in the visible spectrum (400–700 nm).
Step 1: Analyzing the options.
- 100% (Option 1): This is incorrect. Not all solar radiation is used in photosynthesis; only a small fraction is active for photosynthesis.
- Less than 50% (Option 2): This is also incorrect. The actual percentage is much smaller than 50%.
- 1-5% (Option 3): This is closer to the actual range but slightly lower than the true percentage.
- 2-10% (Option 4): This is the correct range. Around 2-10% of the incident solar radiation is converted into PAR, which plants use for photosynthesis.
Step 2: Conclusion.
The correct percentage of solar radiation that is photosynthetically active is 2-10%.
Final Answer: \[ \boxed{\text{The correct answer is (4) 2-10%.}} \]