The phosphorous cycle is a biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.

The phosphorus cycle article on Khan Academy explains the process of phosphorus cycling through ecosystems, including its sources, sinks, and environmental impact.

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Khan Academy offers free AP US History courses with videos, articles, and practice exercises to help students prepare for exams.

Learn about Bohr's model of the atom and its significance in understanding atomic structure.

Aprende sobre las fases de la mitosis en biología con Khan Academy.

El ciclo del carbono describe el flujo continuo de carbono entre los reservorios de carbono en la Tierra.

Feb 16, 2021 · New usernames have two basic requirements: They must be at least five characters long and start with a letter Only letters and numbers can be used; no special characters, spaces nor symbols All u...