Question

(i) What is nutrient cycle?
(ii) Explain the carbon cycle on earth with the help of linear diagram.

Answer 1

(i) The term biogeochemical or nutrient cycle is used to describe the circulation of nutrients between living and non-living components of biosphere. The nutrient cycle can be gaseous cycle in which the materials involved in circulation between living and nonliving components are gasses or vapours.

(ii) The carbon cycle is the pathway through which the cycling of the carbon molecules occurs from the atmosphere to biosphere to geosphere and again back in the same process. The plants can fix carbon dioxide from the atmosphere which is taken in through stomata. The carbon dioxide is converted in the presence of light and chlorophyll pigments to synthesize carbon-containing organic compounds such as sugar, fats and proteins. This creates the plant biomass which when eaten by other organisms recycles the carbon from on level to other. Finally the carbon enters the geosphere and then the atmosphere. The oxygen which is formed during photosynthesis is liberated in the atmosphere and used for cellular respiration. The oxygen is used to break down the molecules and release the carbon dioxide. The carbon gets recycled in the environment from plants to animals and then again enters the environment.