The point at which the rate of photosynthesis is equal to the rate of respiration is called the:

Correct answer: (d) Compensation point

Explanation

The compensation point is the light intensity (or CO₂ concentration) at which the rate of photosynthesis equals the rate of respiration. The CO₂ used in photosynthesis then equals the CO₂ given out in respiration, so there is no net exchange of gases, as happens around dawn and dusk.

• The respiratory quotient is the CO₂ given out ÷ the O₂ taken in during respiration.
• The photosynthetic quotient is the O₂ given out ÷ the CO₂ taken in during photosynthesis.