4.9

4.9 Describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion

1)    Photosynthesis

Carbon dioxide (0.03% of atmosphere) combined with water using chlorophyll traps light energy. This forms organic molecules such as glucose. This is responsible for reducing atmospheric carbon dioxide.

2)    Feeding

Carbon molecules are passed along various trophic levels. When primary consumers eat producers, carbon is passed along and as a result the consumers grow. Since each organism carries out respiration, they all send out carbon dioxide into the air.

3)    Respiration:

Oxygen is broken down by enzymes through aerobic respiration. This releases energy and produces carbon dioxide. This adds carbon dioxide to the atmosphere.

4)    Decomposition

Producers and consumers all die in the end. Then, organic molecules that remain are broken down by decomposer organisms, such as, bacteria and fungi. This releases carbon dioxide back into the air.

5)    Combustion:

Fossil fuels are formed over millions of years as animal and plant materials are compressed. This forms oil and coal, which are combusted to release carbon dioxide. The best known examples are industrial factories and motor vehicles like cars and airplanes. However, this can also occur naturally. If a lightning strikes the vegetation, it can cause forest or grassland fires.