Question

Make a sketch that shows a carbon atom and the molecule it is a part of before soil is wet. A second sketch should show the same carbon atom now as a part of CO₂ in the atmosphere. Describe what happened to cause the carbon atom to become a part of a different molecule.

Answer 1

Carbon is an essential element of all living organisms about 18% of body is made up of carbon. Carbon dioxide from the atmosphere is taken by photosynthetic organisms and is used to make organic molecules, they travel via food chains to the environment and the carbon atoms are released to the atmosphere via respiration in the form of CO2.

Slow geological processes, helps in the formation of sedimentary rocks and fossil fules also contribute to the carbon cycle over a long time period. Human activities like burning of fossil fuels for industrial and domestic use also increases atmospheric CO2.

Carbon remains in air mostly as carbon dioxide gas, it gets dissolved in water and reacts with water molecules to produce bicarbonate HCO_{3 .} Photosynthesis by land plants, bacteria, and algae also converts carbon dioxide or bicarbonate into organic molecules. Organic molecules made by photosynthesis is passed through food chains. Cellular respiration converts the organic carbon back to carbon dioxide gas and returns to atmosphere.

When matter of living organisms is buried deep underground or sinks to the bottom of the ocean and forms sedimentary rocks, long term storage of carbon occurs. By volcanic activity as well as human burning of fossil fuels this stored carbon comes back to the carbon cycle.

Carbon cycle :- Carbon cycle is a biogeochemical cycle in which carbon is exchanged in between the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. It is an important cycles of the earth and it helps the carbon to be recycled and reused in biosphere and by all organisms.

During photosynthesis plants take CO2 to produce food, the food produced is taken by heterotrophs like animals and humans, food contains carbon, when taken by animals it enters body of the organism, when organism respires it again goes back to atmosphere, also after death of the animal the carbon molecule found in its body goes to soil. Microorganisms degrade the body, some enters the atmosphere in the form of CO2 and some other carbon again enters soil.

When rain water or some other form of water falls on soil, soil gets wet and carbon mixed with water, it is taken by plants as food material it enters plant and the carbon cycle proceedes, some carbon flows down to water bodies their they are used by phytoplanktons and consmed by water living organisms they again enter the food chain , when these animals respire Co2 released and goes back to the atmosphere.

When water gets evaporated due to sunlight, evaporated water gets condensed and falls on ground, while falling rain water mixes with atmopsheric CO2 and CO2 comes back to ground, during photosynthesis also CO2 is used by plants bringing them back to food chain. in this way carbon cycle goes on .

Sketch -1 Carbon cycle- carbon atom and the molecule, it is a part of cycle before soil is wet. Sketch -2 In carbon cycle carbon atom now as a part of CO2 in the atmosphere.

In the oceans, dissolved carbonate combines with dissolved calcium to form solid calcium carbonate, CaCO3. When the microscopic organisms organisms die, their shells sink and accumulate on the ocean floor, Gradually with passing time these carbonate sediments form limestone,it is the largest reservoir of carbon in the carbon cycle.

The level of carbon dioxide in the atmosphere is influenced by the reservoir of carbon in the oceans and vice versa. Carbon dioxide from the atmosphere dissolves in water and reacts with water molecules.

On land, carbon is stored in soil as organic carbon by the decomposition of living organisms or as inorganic carbon by weathering of terrestrial rock and minerals.