BIOLOGY 9 Lecture Notes - Lecture 13: East Los Angeles College, Phosphorus Cycle, Carbon Cycle
Document Summary
The carbon cycle: starts with the reservoir of carbon dioxide in the air. Becomes organic molecules in organisms by photosynthesis. Carbon is respired by plants and animals into the air or is deposited in soil. Photosynthesis in oceans moves co2 from seawater into organisms. Fossilization of dead plants and animals into fossil fuel. Combustion of fossil fuels releases co2 to the air. Mineral elements originate in rock and soil minerals. A shortage of phosphorus is a limiting factor. As rock breaks down, phosphate is released. Replenishes phosphate lost through leaching or runoff. Organic phosphate: incorporated into organic compounds by plants from soil or. Broken down in cell respiration or by decomposers water. Enters into chemical reactions with other substances. The most serious intrusion comes from fertilizers. Phosphorus is mined and made into fertilizers, animal feeds, detergents, etc. When added to soil, it can stimulate production. Human applications have tripled the amount reaching the oceans, accelerating the cycle.
