Question

which photosynthetic process can occur at night?
a. the reaction at photosystem ii
b. the calvin cycle
c. the reaction at photosystem i
d. the formation of nadph

Explanation:

Photosynthesis has light - dependent and light - independent reactions. The Calvin cycle is the light - independent reaction. It does not directly require light. It uses the ATP and NADPH (produced in light - dependent reactions during the day) to fix carbon dioxide. Photosystem I and II reactions (options A and C) and NADPH formation (option D) are part of light - dependent reactions which need light. So, the Calvin cycle (option B) can occur at night.

Answer:

B. The Calvin cycle