First draw the diagram given on the study material.
Carbon is one of the essential elements of all organic substances and it enters the ecosystem through the process of photosynthesis.
1. Enters the food web through plants by the process of photosynthesis.
2. Some of the CO2 captured by plants are converted into organic molecules and is returned to the atmosphere by respiration.
3. Carbon inside the plant body is passed on to herbivores.
4. Animals and other living things release CO2 while breathing.
5. CO2 is released into the atmosphere by death and decay of dead bodies and excretas.
6. Formation of fossil fuels is a part of carbon cycle, where carbon is trapped for millions of years.
7. CO2 from air dissolves in upper layers of water forming carbonates
8. Plants in sea water use these carbonates as a source of CO2 during photosynthesis.
9. Food produced by water plants passes through the aquatic food chain. Eg: Plant - Fish - Bigger Fish.
10. Some of the CO2 produced by the breathing of marine plants and animals dissolved in sea water can be re-utilized by plants
11. Some of CO2 thus evolved escapes into the atmosphere.
12. Organisms like snails, oysters etc take CO2 in water and combine it with Calcium to form Calcium Carbonate which forms their shells. These shells become limestone once they die.