Question

In photosynthesis, the net uptake of CO by a plant is greatest

A) when PAR equals zero.
B) at the light compensation point.
C) during photoinhibition.
D) at the light saturation point.

Answer 1

The greatest net uptake of CO2 during photosynthesis in plants occurs at the light saturation point, where photosynthesis rate is maximal.

Step-by-step explanation:

In photosynthesis, the net uptake of CO2 by a plant is greatest at the light saturation point. This point is where the rate of photosynthesis remains constant, and maximum, even if the light intensity increases. Before reaching this point, the rate of photosynthesis increases with light intensity.

However, at the light compensation point, the rate of photosynthesis equals the rate of respiration, resulting in no net exchange of CO2. Photoinhibition occurs when excess light damages the photosynthetic apparatus, reducing photosynthesis efficiency. When PAR, or Photosynthetically Active Radiation, equals zero, no photosynthesis occurs because light is a key component of the process.