Which one of the following gases is given out during photosynthesis?

Question

Which one of the following gases is given out during photosynthesis?

1. A. Carbon dioxide
2. B. Nitrogen
3. C. Hydrogen
4. D. Oxygen (Correct answer)

Correct Answer

Option D — Oxygen

Detailed Solution & Explanation

The correct answer is Oxygen.

Key Points

• Photosynthesis releases oxygen. Green plants take in carbon dioxide and water and, using sunlight captured by chlorophyll, produce glucose and give out O₂.
• The overall equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, in the presence of sunlight and chlorophyll.
• The oxygen released comes from the splitting of water (photolysis), not from carbon dioxide.

Additional Information

• Respiration is the reverse process — it consumes oxygen and releases carbon dioxide — and the two together maintain atmospheric balance.
• Photosynthesis takes place in the chloroplasts; the light reactions occur in the thylakoid membranes and the dark (Calvin) cycle in the stroma.
• Gas exchange happens through the stomata on leaves, guarded by guard cells that open and close the pores.