Answer:
It enters the citric acid cycle and associates with a 4-carbon molecule, forming citric acid, and then through redox reactions regenerates the 4-carbon molecule.
Explanation:
Acetyl-CoA(2C) associates with oxalacetate(4C) to form citric acid(6C). Then through redox reactions, CO2 molecules result from decarboxylation (COOH becomes R-(R1)CH-R2). And through dehydrogenation H2 molecules are incorporated in NADH+ in FADH2, resulting in the 4-carbon molecule at the beginning (oxalacetate). That's why it's called a cycle(Kreb's cycle or citric acid cycle)
Photosynthesis makes the glucose that is used in cellular respiration to make Atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while the water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.