Which one of the following nutrient cycle involves sedimentary rocks?

The correct answer is Option (2) → Phosphorus

Option (2) Phosphorus — Correct. Nutrient cycles are gaseous or sedimentary. The reservoir of phosphorus is the earth’s crust: phosphates in sedimentary rocks. So the phosphorus cycle is a sedimentary cycle.

Note: This question is from the topic “Phosphorus Cycle” in Chapter 14, Ecosystem, of the pre-rationalised NCERT book. This portion is not in the present NCERT book, where the chapter is now Chapter 12, Ecosystem. The extract below is from the pre-rationalised edition.

NCERT Extract (Pre-rationalised edition, Chapter 14, Ecosystem):
Ecosystem – Phosphorus Cycle – “… Phosphorus is a major constituent of biological membranes, nucleic acids and cellular energy transfer systems. Many animals also need large quantities of this element to make shells, bones and teeth. The natural reservoir of phosphorus is rock, which contains phosphorus in the form of phosphates. When rocks are weathered, minute amounts of these phosphates dissolve in soil solution and are absorbed by the roots of the plants (Figure 14.7).”