(A-D) - $RuBP$ Carboxylase: It is involved in the dark reaction (Calvin cycle) for the fixation of $CO_2$ in the $C_3$ pathway.
- $PEPcase$: It is involved in the fixation of $CO_2$ in photosynthesis,specifically in the $C_4$ pathway,where it forms $4C$ oxaloacetate.
- Pyruvate dehydrogenase: It is involved in aerobic respiration,catalyzing the conversion of pyruvic acid into Acetyl $CoA$.
- $ATPase$: It is involved in both respiration and photosynthesis. In both processes,it is associated with the proton pump in the electron transport system,where it synthesizes $ATP$ using the proton gradient.
- Cytochrome oxidase: It is involved in both respiration and photosynthesis as an electron carrier substance in the electron transport chain.
- Hexokinase: It is involved in glycolysis (respiration),where it converts glucose to glucose-$6$-phosphate,consuming one $ATP$.
- Lactate dehydrogenase: It is involved in anaerobic respiration (e.g.,in Lactobacillus),converting pyruvic acid to lactic acid.