Question

Which of the following statements about the global phosphorus cycle is true?

a) Phosphorus enters the atmosphere through volcanic eruptions.
b) It primarily cycles through the lithosphere.
c) It is not essential for plant and animal life.
d) Human activities have no impact on the phosphorus cycle.

Answer 1

The global phosphorus cycle primarily cycles through the lithosphere, with phosphate entering the environment through rock weathering and volcanic activity. Human activities can also impact the cycle.

Step-by-step explanation:

The correct statement about the global phosphorus cycle is b) It primarily cycles through the lithosphere.

Phosphorus enters the environment through rock weathering and volcanic activity, which releases phosphate into the soil, water, and air. The phosphate then becomes available to terrestrial food webs and enters the oceans through surface runoff, groundwater flow, and river flow. It cycles back to the land over geologic time by the uplifting of Earth's surface.

Human activities, such as the use of fertilizers and the runoff from agricultural practices, can also impact the phosphorus cycle by increasing the input of phosphates into the environment.