What is one of the main differences between the phosphorus and sulfur cycles? a) plants absorb phosphorus mainly from the air and sulfur mainly from the soil. b) animals get phosphorus by eating plants and sulfur from the air they breathe. c) human activities contribute only to the amount of sulfur in the atmosphere but not to that of phosphorus. d) the atmosphere has no significant role in the phosphorus cycle, but is an essential part of the sulfur cycle.

The right answer is D.

The phosphorus cycle is unique among the major biogeochemical cycles because it does not have a gaseous component; it hardly affects the atmosphere.

The sulfur cycle is the biogeochemical cycle of the different forms of sulfur. Sulfur is an essential element of life that, like carbon, phosphorus, oxygen, nitrogen or even water, has its own life cycle. Indeed, sulfur is present everywhere on Earth, atmosphere, oceans, continents, but also in all living beings in the form of organic molecules: sulfur-containing amino acids constituting proteins (methionine and cysteine).

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.