During oxygenic photosynthesis, which molecule is released as a byproduct?

During oxygenic photosynthesis, which molecule is released as a byproduct?

• A. Oxygen
• B. Carbon dioxide
• C. Hydrogen
• D. Methane

Answer: (B)

The key idea is that oxygen gas is released as a byproduct when water is split during the light-dependent reactions of oxygenic photosynthesis. In the photosystem II stage, photons drive the splitting of water, providing electrons to the photosynthetic electron transport chain and releasing O2 as a gas. Carbon dioxide, on the other hand, is taken up later in the Calvin cycle to build sugars, so it’s a reactant rather than a byproduct. Hydrogen is used in forming energy carriers and organic molecules, not released as a separate gaseous byproduct here. Overall, the process converts CO2 and H2O into sugars and O2, with oxygen being released.

The key idea is that oxygen gas is released as a byproduct when water is split during the light-dependent reactions of oxygenic photosynthesis. In the photosystem II stage, photons drive the splitting of water, providing electrons to the photosynthetic electron transport chain and releasing O2 as a gas. Carbon dioxide, on the other hand, is taken up later in the Calvin cycle to build sugars, so it’s a reactant rather than a byproduct. Hydrogen is used in forming energy carriers and organic molecules, not released as a separate gaseous byproduct here. Overall, the process converts CO2 and H2O into sugars and O2, with oxygen being released.