AP BIOLOGY

Detailed explanation-1: -Phosphorus enters the atmosphere from volcanic aerosols. As this aerosol precipitates to earth, it enters terrestrial food webs. Some of the phosphorus from terrestrial food webs dissolves in streams and lakes, and the remainder enters the soil. Another source of phosphorus is fertilizers.

Detailed explanation-2: -Phosphorus is found in the Earth’s crust, primarily in sedimentary rocks that contain phosphate (PO43-) minerals. As these rocks weather and erode, dissolved phosphates enter the soil and travel via rivers to the ocean.

Detailed explanation-3: -Weathering of rocks and minerals release phosphorus in a soluble form where it is taken up by plants, and it is transformed into organic compounds.

Detailed explanation-4: -Phosphorus moves in a cycle through rocks, water, soil and sediments and organisms. Over time, rain and weathering cause rocks to release phosphate ions and other minerals. This inorganic phosphate is then distributed in soils and water. Plants take up inorganic phosphate from the soil.

Detailed explanation-5: -So, the correct answer is ‘Weathering’.