Biology: Concepts and Investigations 2nd Edition by Mariëlle Hoefnagels

Exercise 22

The light reactions described in this chapter are sometimes called "noncyclic photophosphorylation" because the electron transport chain that generates ATP does not return the electrons to chlorophyll. Some photosynthetic bacteria, however, generate ATP by cyclic phosphorylation. In these cells, light energy boosts chlorophyll's electrons, which pass through an electron transport chain and then return to the chlorophyll molecule. Would the light reactions of cyclic photophosphorylation produce ATP? NADPH? O₂ ? Explain your answers.