Video Transcript
A product of the light-dependent reactions is oxygen. What specific process produces oxygen? (A) The photolysis of water. (B) The phosphorylation of ADP. (C) The movement of electrons through the electron transport chain. Or (D) the active transport of hydrogen ions.
The light-dependent reactions are a series of reactions in the first stage of photosynthesis, which take place in the thylakoid membranes of the chloroplast. Within the thylakoid membranes, there are a series of photosystems, electron carrier proteins, proton pumps, and enzymes that make up what is collectively known as the electron transport chain.
The photosystems in the electron transport chain absorb light energy. This excites the electrons within the photosystems. As these electrons move to a higher energy level and leave photosystem I, they need to be replaced. To replace the electrons lost, a molecule of water is split into hydrogen and oxygen using light energy. The splitting of water using light energy is called photolysis. We can remember this by knowing that the word part photo- means light and -lysis means to break down. So the splitting of water provides electrons to photosystem I, but it also produces oxygen in the process.
We now have enough information to answer the question. The correct answer choice is (A). The specific process in the light-dependent reactions that produces oxygen is the photolysis of water.
