Moderate

Where does oxygen come from in photosynthesis?

Correct answer: C. Water

  • A. Hydrogen sulphide
  • B. Carbon dioide
  • C. Water
  • D. Hydrogen peroxide

Explanation

In photosynthesis, photosystem II loses its electrons when excited by photons. To fill the electron 'gaps', water is split into oxygen, hydrogen ions and electrons by photons via a process called photolysis. The oxygen is released as a by-product.

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About Bioenergetics

Cellular respiration explains how cells release energy from glucose through glycolysis, the link reaction, Krebs cycle and electron transport chain. It includes ATP production, substrate-level and oxidative phosphorylation, aerobic versus anaerobic respiration, and the roles of mitochondria, oxygen and fermentation in energy transfer.

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