Question

Describe the biogeochemical cycle of carbon as it moves into and through organisms and back to the environment. Do the same for phosphorus, nitrogen, and sulfur.

Short answer

Biogeochemical cycles describe how elements move through ecosystems, and include the carbon cycle (where carbon moves from atmosphere to plants and animals and back), the phosphorus cycle (from soil to plants and animals and back), the nitrogen cycle (from atmosphere through soil bacteria and plants to animals and back), and the sulfur cycle (from atmosphere to plants and animals and back through decay).

Step-by-step solution

Carbon Cycle

The carbon cycle starts when plants use carbon dioxide from the air for photosynthesis. The plants are then consumed by animals, and through digestion, the carbon is transferred to them. When the animals breathe out, carbon dioxide is released back into the air. Furthermore, when the plants or animals die and decay, carbon is returned to the soil, from where it can be used by plants again. Carbon can also be released back to the atmosphere through combustion of organic material and fossil fuels.

Phosphorus Cycle

Phosphorus cycle begins as phosphate salts are released from rocks through weathering. These salts are then absorbed by plants and are transferred to animals when they eat the plants. When plants and animals decay, phosphates return to the soil and gradually back to the rock and the water bodies.

Nitrogen Cycle

Nitrogen can be found in the atmosphere and is not usable in this form by most living organisms. The nitrogen cycle commences when nitrogen-fixing bacteria in the soil and in the roots of some plants convert nitrogen gas from the atmosphere into ammonia, which can be used by plants. Animals then get their nitrogen by consuming these plants or other animals that have consumed the plants. When animals excrete waste or die, decomposing bacteria convert the nitrogen compounds back to nitrogen gas, which goes back to the atmosphere.

Sulfur Cycle

In the sulfur cycle, sulfur is released into the atmosphere by volcanic activity and decay of living organisms. Once in the atmosphere, it can return to the earth in rain, where it is taken up by plants. Animals then consume these plants, receiving the sulfur. When the animal dies and decays, the sulfur is returned to the soil and can be taken up by plants again.