Q. Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth?

1. Volcanic action
2. Respiration
3. Photosynthesis
4. Decay of organic matter

Select the correct answer using the code given below.

• 1 and 3 only
• 2 only
• 1, 2 and 4 only
• 1, 2, 3 and 4

Answer: (c) 1, 2 and 4 only

Notes:

• The Process of photosynthesis takes up Carbon dioxide and release oxygen. Hence photosynthesis does not add carbon dioxide to the carbon cycle.
• Volcanic action leads to the release of Carbon dioxide.
• Respiration is the movement of oxygen from the outside environment to the cells within tissues and the release of carbon dioxide in the opposite direction. 
• The process of decomposition releases Carbon dioxide.