Question

What is the reservoir in the phosphorus cycle? a. oceans b. marine sediments c. plants d. animals

Short answer

The main reservoir in the phosphorus cycle is (b) marine sediments.

Step-by-step solution

Understand the Phosphorus Cycle

The phosphorus cycle is a biogeochemical process involving the movement of phosphorus through the environment, including the lithosphere, hydrosphere, and biosphere. Phosphorus is a crucial element for living organisms as it is a part of DNA, RNA, and ATP molecules. To answer this question, we need to know the primary reservoir that stores the most phosphorus in this cycle.

Evaluate Option (a) Oceans

Oceans contain phosphorus in the form of dissolved phosphates or organic matter. However, compared to other reservoirs, the phosphorus concentration in the oceans is relatively low. Thus, oceans are not the primary reservoir of the phosphorus cycle.

Evaluate Option (b) Marine Sediments

Marine sediments, including underwater continental shelves, consist of large amounts of phosphorus in the form of phosphorite minerals. As weathering and erosion processes occur, phosphorus from rocks is transported and deposited in marine sediments. Over time, these sediments accumulate and form significant phosphorus reservoirs. This option suggests a more significant storage capacity and is likely the primary reservoir for the phosphorus cycle.

Evaluate Option (c) Plants

Plants require phosphorus for growth and cellular functions. They absorb phosphorus from soil or water in the form of inorganic phosphate. However, the storage capacity in plants is limited due to their relatively small biomass compared to other reservoirs. Therefore, plants are not the main reservoir in the phosphorus cycle.

Evaluate Option (d) Animals

Animals also require phosphorus for growth and cellular functions, obtaining it from their diet (by consuming plants or other animals). Like plants, animals' phosphorus storage capacity is limited compared to other reservoirs due to their smaller biomass. Thus, animals are not the primary reservoir in the phosphorus cycle.

Conclude

After evaluating all options, we can conclude that the main reservoir in the phosphorus cycle is (b) marine sediments. Marine sediments contain large amounts of phosphorus in the form of phosphorite minerals, making them the primary storage location for the phosphorus cycle.