Question

question 1 of 10
a green plant absorbs a toxic substance, which inhibits the calvin cycle. how would this most likely affect the light reactions?
a. the light reactions would continue to produce oxygen.
b. the light reactions would produce more carbon dioxide.
c. the light reactions would slow down.
d. the light reactions would start to produce glucose.

Explanation:

The Calvin cycle uses ATP and NADPH from the light reactions. If it's inhibited, the light reactions' products (ATP and NADPH) build up. This causes feedback inhibition, slowing down the light reactions. Oxygen is produced in light reactions (not affected here as per the question's focus on Calvin cycle - light reaction link). Carbon dioxide is used in Calvin cycle (not produced by light reactions). Glucose is made in Calvin cycle (not light reactions). So, the light reactions slow down due to product accumulation from Calvin cycle inhibition.

Answer:

C. The light reactions would slow down.