Answer:
Biogeochemical cycles can be described as the movement of substances in different compartments of the Earth. The substances which are part of the geosphere might be a part of the atmosphere after a certain time. The substances are rearranged to form new substances to maintain a stable environment on the Earth.
For example, the carbon dioxide and sun light taken by plants from the atmosphere and the water taken from hydrosphere are converted into glucose and oxygen by the plant. The oxygen is released into the atmosphere which is taken by other organisms from the atmosphere and converted into carbon dioxide and water.