Question

after light excites electrons and they leave photosystem ii to travel down the first electron transport chain. how are these electrons replaced to photosystem ii? a. oxygen is reduced and the electrons are given to the chlorophyll molecules of photosystem ii. b. carbon dioxide is split, and the electrons are given to the chlorophyll molecules of photosystem ii. c. hydrogen undergoes fusion, and the electrons are given to the chlorophyll molecules of photosystem ii. d. water is split, and the electrons are given to the chlorophyll molecules of photosystem ii.

Explanation:

In photosynthesis, when light - excited electrons leave Photosystem II and travel down the electron transport chain, water is split (photolysis of water). The electrons from the split water are given to the chlorophyll molecules of Photosystem II. Oxygen is a by - product of water splitting, carbon dioxide is used in the Calvin cycle and not split to provide electrons to Photosystem II, and hydrogen fusion is a process in stars, not in photosynthesis.

Answer:

D. Water is split, and the electrons are given to the chlorophyll molecules of photosystem II.