Multiple choice

Which of the following gases is used up in respiration and released during photosynthesis?

  1. Nitrogen

  2. Carbon dioxide

  3. Oxygen

  4. Hydrogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxygen is consumed during cellular respiration as the final electron acceptor in the electron transport chain, producing water and ATP. During photosynthesis, oxygen is released as a byproduct when water molecules are split to provide electrons for the light-dependent reactions. This reciprocal relationship sustains atmospheric oxygen levels.

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