During photosynthesis carbon dioxide oxidized
Global Redox Carbon Cycle and Photosynthesis …
Plant photosynthesis, both the Light Phase and Dark phasereactions, takes place in chloroplasts, which may be regarded asthe "power plants" of the green leaf cells. At night,when there is no sunlight energy, ATP continues to be generatedfor the plant's needs by respiration, i.e., oxidation of(photosynthetically produced) carbohydrate in mitochondria(similar to animals).
During photosynthesis carbon ..
The 2 pyruvate molecules arereduced by the 2 NADH produced in stage II to a variety of different endproducts, thus regenerating the 2 NAD+ needed to continue the oxidationreactions of stage II.
Likewise, oxygen produced during photosynthesis ..
The oxidative chemical reactions of respiration releaseenergy, some of which is heat and some of it is captured in theform of high energy compunds such as Adenosine triphosphate (ATP)and Nicotinamide adenide dinucleotide phosphate (NADPH). Thesecompounds have a high energy (unstable) terminal phosphate bondand that terminal phosphate is easily detached with the transferof the energy to drive chemical reactions in the synthesis ofother biomolecules. In this case, the ATP loses one phosphate tobecome the energy-depleted ADP (Adenosine diphosphate)and the NADPH loses one electron to become energy-depleted NADP+.
Chemistry for Biologists: Photosynthesis
In a broad chemical sense, the opposite of photosynthesis isrespiration. Most of life on this planet (all except in the deepsea vents) depends on the reciprocal photosynthesis-drivenproduction of carbon containing compounds by a series of reducing(adding electrons) chemical reactions carried out by plants andthen the opposite process of oxidative (removing electrons)chemical reactions by animals (and plants, which are capable ofboth photosynthesis and respiration) in which these carboncompounds are broken down to carbon dioxide and water.