Question

What is a biogeochemical cycle?

Answer 1

Hint: The four main nutrients present in nature are carbon, hydrogen, oxygen and nitrogen, which constitute about 95% mass of living organisms. There occurs the cyclic flow of these nutrients in the living and non-living organisms. The cyclic flow involves the transfer of matter and energy between the different components of the biosphere.

Complete answer:
Biogeochemical cycles are the cyclic flow of nutrients between non-living environments (soil, rock, air and water) and living organisms, which makes it a dynamic but stable system.

The four biogeochemical cycles are-
Water cycle – There is a constant exchange of water between the air, land, sea and living organisms. The whole process in which water evaporates and falls on the land as rain and later flows back into sea via rivers is called the water cycle.

Nitrogen cycle – The cyclic process in which nitrogen passes from its elemental form in the atmosphere into simple molecules in the soil and water, that get converted to more complex molecules in living beings and back again to the simple molecules in the atmosphere is called the nitrogen cycle.

Carbon cycle – Carbon that is present in the atmosphere travels into organisms and the Earth and is released back into the atmosphere. Plants use carbon dioxide to prepare their food and then this food is eaten by animals and stored in their bodies for energy and released through respiration is called the carbon cycle.

Oxygen cycle – The sequence in which organisms use up the oxygen which is present in the atmosphere and released back into the atmosphere with the help of photosynthesis is called the oxygen cycle.

Note:
- Decomposers play an important role in the biogeochemical cycles. They decompose the dead plants and excreta of animals.
- During this process, complex organic compounds are broken down into simple forms. These compounds are released into the nutrient pool and are reutilized by the plants from the soil.