Question

Natural reservoir of phosphorus is
A. Sea water
B. Animal bones
C. Rock
D. Fossils

Answer 1

Hint: All living organisms require as nutrients eight elements in relatively large amounts. The movement of nutrient elements through the living and nonliving components of the biosphere, or of any particular ecosystem, is called the biogeochemical cycle or cycle of matter.

Complete answer: Elements such as phosphorus, sulphur, potassium, and calcium, have sedimentary cycles. Phosphorus is very important for all organisms. It is a component of the cell membrane, membranes of cell organelles, nucleic acids, and adenosine triphosphate (ATP), the major "energy molecule". In animals, it is also the constituents of bones and teeth. Phosphorus also participates in respiration, photosynthesis, and other metabolic reactions. The major reservoir of phosphorus is in the phosphate rocks and fossil bone laid down in the past geological ages. There is no atmospheric phase in the phosphorus cycle. Phosphorus becomes available in the soil for plant use by the natural erosion of rocks and by human efforts. As rocks are eroded, small amounts of phosphorus dissolve, usually as phosphates that seep into the soil.
So, the correct answer is option C-Rock

Note: The biogeochemical cycle is of two types: gaseous and sedimentary cycle. Gaseous cycle, the reservoir for the nutrient elements is in the atmosphere (air) or hydrosphere (water). In a sedimentary cycle, the reservoir for the nutrient elements is in the sediments of the earth. The sedimentary cycles are very slow and less perfect systems in that the elements may get locked in the reservoir pool and go out of circulation for long periods.