Paraquat is an herbicide that blocks the transfer of electrons from photosystem I to NADPH. Mechanistically, paraquat is effective because it:
A)prevents the reduction of NADPH.
B)prevents the formation of reactive oxygen species.
C)increases the formation of reactive oxygen species.
D)absorbs light energy that cannot then be used for photosynthesis.
E)increases cyclic electron transport, which does not produce NADPH.

Question

Quizplus · Accepted Answer

Paraquat increases the formation of reactive oxygen species (ROS) by blocking the transfer of electrons from photosystem I to NADPH. This results in the accumulation of electrons, which can be transferred to molecular oxygen to form highly reactive superoxide anions and ultimately other ROS. High levels of ROS can damage various cellular components, leading to cell death.

Paraquat Is an Herbicide That Blocks the Transfer of Electrons