Question

Oxidative phosphorylation and photophosphorylation both require the electron carrier

• A. Cytochrome
• B. Oxygen
• C. Carbon dioxide
• D. Water

Answer 1

The correct option is A Cytochrome

Oxygen is a byproduct of photosynthesis formed by sunlight-driven splitting of water at PSII during light reactions of photosynthesis. The final electron acceptor is oxygen in mitochondrial electron transport chain and is reduced into water. Carbon dioxide is fixed into carbohydrates during the dark phase of photosynthesis using the energy of ATP and NADPH. The cytochromes are proteins with heme prosthetic groups and characteristic strong absorption of visible light. Mitochondria contain cytochrome a, b, and c as a component of complex III and complex IV. Cytochromes receive electron from ubiquinone and pass to oxygen. The cytochrome $b_6$f complex is present throughout the thylakoid membrane and photolysis of water at PSII excites its reaction center and pass the electron to cytochrome $b_6$f complex. Thus, the correct answer is option A.