UPSC CSE Prelims
Question 58
Consider the following :
- Photosynthesis
- Respiration
- Decay of organic matter
- Volcanic action
Which of the above add carbon dioxide to the carbon cycle on Earth ?
View correct answer and explanation
Correct answer: C
Correct Option: C
Explanation: Respiration, microbial decomposition and volcanic degassing add CO₂ to the atmosphere or carbon cycle; photosynthesis takes up rather than releases net CO₂.
Statement / Item-wise Analysis:
1: Incorrect - Incorrect for CO₂ addition: photosynthesis fixes carbon dioxide into organic compounds.
2: Correct - Correct: respiration oxidises organic carbon and releases CO₂.
3: Correct - Correct: decomposition releases CO₂ (and sometimes methane) from dead matter.
4: Correct - Correct: volcanic activity emits geologic CO₂.
Option-wise Analysis:
A: Incorrect - includes unsupported item 1; omits supported items 2, 3.
B: Incorrect - omits supported item 4.
C: Correct - includes the supported statements and excludes the unsupported ones.
D: Incorrect - includes unsupported item 1.