AP BIOLOGY

Detailed explanation-1: -It shows nitrogen changing from organic matter in the soil, to bacteria, to plants and back to organic matter. Plant and animal wastes decompose, adding nitrogen to the soil. Bacteria in the soil convert those forms of nitrogen into forms plants can use. Plants use the nitrogen in the soil to grow.

Detailed explanation-2: -Decomposition. Plants take up nitrogen compounds through their roots. Animals obtain these compounds when they eat the plants. When plants and animals die or when animals excrete wastes, the nitrogen compounds in the organic matter re-enter the soil where they are broken down by microorganisms, known as decomposers.

Detailed explanation-3: -When plants and animals die, they become food for decomposers like bacteria, fungi and earthworms. Decomposers or saprotrophs recycle dead plants and animals into chemical nutrients like carbon and nitrogen that are released back into the soil, air and water.

Detailed explanation-4: -The correct answer is A. returned to the soil by decomposition. When an animal dies, most of the nitrogen in the animal’s tissues are returned to the soil by decomposition. The nitrogen in the dead animals’ tissues is in the form of organic nitrogen (for example, in proteins and nucleic acids).

Detailed explanation-5: -Explanation: When nitrogen is returned to the soil when dead plants decompose, the interaction is between geosphere and biosphere.