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.

[UPSC Civil Services Exam – 2014 Prelims]

(a) 1 and 3 only

(b) 2 only

(c) 1, 2 and 4 only

(d) 1, 2, 3 and 4

Answer: (c)        

Explanation:

• The Process of photosynthesis takes up Carbon dioxide and release oxygen. Hence photosynthesis does not add carbon dioxide to the carbon cycle. Hence, Statement 3 is NOT correct.
• Volcanic activity contributes to the release of carbon dioxide into the atmosphere.
• Respiration is the process of taking in oxygen from the external environment and releasing carbon dioxide, which is the opposite of photosynthesis.
• Decomposition, which is the breakdown of organic matter, also releases carbon dioxide into the atmosphere.