UPSC CSE Prelims
Question 15
In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?
View correct answer and explanation
Correct answer: C
Correct Option: C (Phosphorus cycle)
Explanation: The phosphorus cycle is largely sedimentary: phosphate enters soils and waters when phosphate-bearing rocks weather, with no significant atmospheric reservoir.
Option-wise Analysis:
A. Incorrect-The carbon cycle centres on atmospheric CO2, photosynthesis and respiration.
B. Incorrect-Nitrogen enters ecosystems largely by fixation of atmospheric N2.
C. Correct-rock weathering releases phosphate into ecosystems.
D. Incorrect-Sulphur also comes from volcanic and atmospheric sources; rock weathering is not as uniquely defining.