Question

Natural reservoir of phosphorus is:

• A. Ocean
• B. River
• C. Rock
• D. Lake

Hint:

The phosphorus cycle is a sedimentary cycle. Its major reservoir is phosphate-containing rocks, not the atmosphere.

Answer 1

The Correct Option is C

Concept: Phosphorus is an essential element required for the formation of nucleic acids, ATP, phospholipids and several biological molecules. Unlike carbon and nitrogen cycles, the phosphorus cycle does not involve a significant gaseous phase. The major reservoir of phosphorus is found in rocks.

Step 1: Understand the phosphorus cycle. Phosphorus exists mainly in the form of phosphate minerals in sedimentary rocks. Weathering of rocks gradually releases phosphate ions into the soil.

Step 2: Movement through ecosystem. Plants absorb phosphate ions from soil. Animals obtain phosphorus through food chains. After death and decomposition, phosphorus returns to soil and sediments.

Step 3: Identify the major reservoir. Although oceans, rivers and lakes contain dissolved phosphates, they are not considered the principal natural reservoir. The largest long-term storage of phosphorus occurs in phosphate-bearing rocks.

Step 4: Final conclusion. \[ \boxed{\text{Rock}} \] is the natural reservoir of phosphorus. Hence option (C) is correct.