Chapter 2, Problem 33A

Summary Introduction

Introduction :

Phosphorus is an essential element of the cell membrane. It is present in a long molecule of DNA and the bone as calcium phosphate. The phosphorus cycle is involved in two ways for living organisms.

1. Long term
2. Short term

Answer to Problem 33A

Correct answer :

The correct answer is option (A) organic materials buried at the bottom of oceans.

Explanation of Solution

Explanation for the correct answer :

Option (A) organic materials buried at the bottom of the oceans. The aquatic plants absorb phosphorus in the ocean. Animals use these phosphates to form shells and bones. When organisms die, remaining deposits are found on the surface of the ocean and covered with sediment. The deposit becomes rock gradually, but phosphorous is remains present. That is the way phosphorus continues the cycle for the long term.

Explanation for incorrect answer :

Option (B) phosphate is released into the soil not directly. Soil phosphorus is present in two forms, organic and inorganic. Phosphorus is present high concentrations, and 80 percent of phosphorus is immobile. Inorganic phosphorus is chemically bound to soil particles, and it is not available to plants. It does not lock phosphorus for long term process. So, this is an incorrect option.

Option (C) Animal and plant eliminating wastes from living things. Detritivores use phosphate from Plants and animals excrete waste. Bacteria make phosphate available by mineralization, and this is not a long process of phosphate recycling. So, this is an incorrect option.

Option (D) Rain eroding mountain. Phosphorus is found millions of years onto mountain rock. Rain erosion runoff this phosphorus from the mountain. So, this is an incorrect option.