Multiple choice

Which of the following gases is used 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 the gas used in respiration by most organisms and released during photosynthesis by plants. This is a fundamental biological process - animals breathe in oxygen and exhale carbon dioxide, while plants do the opposite during photosynthesis. Nitrogen makes up most of the atmosphere but is not used in respiration.

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