Question

If the amount of nitrogen and phosphorous cycling through an ecosystem is greatly affected by local environmental conditions, such as heavy rainfall or the removal of large numbers of plants. Select the correct statement that signifies, the amount of carbon in an ecosystem is affected by such factors.

• A. Plants make their own carbon compounds through photosynthesis
• B. Plants absorb large amounts of carbon from the soil
• C. Bacteria in the soil absorb large amounts of carbon
• D. The primary source of carbon is the atmosphere, whereas much nitrogen and phosphorous come from the soil
• E. Organisms need only minute levels of carbon

Answer 1

The correct option is D The primary source of carbon is the atmosphere, whereas much nitrogen and phosphorous come from the soil

The primary source of carbon is the atmosphere, whereas much nitrogen and phosphorous come from the soil.

Carbon is found as graphite and diamond in nature. It also occurs as carbon dioxide in the atmosphere. Due to the position of its electrons, an atom of carbon can form covalent bonds with hydrogen, oxygen, nitrogen, phosphorus and other carbon atoms. Because of this versatility, the carbon atom is the principal building block of many kinds of molecules, which make up the living organisms. A carbon cycle is a perfect cycle in the sense that carbon is returned to the atmosphere as soon as it is removed.

Sources of Carbon:

1) The major source of carbon for the living world is carbon dioxide. The atmosphere contains about 700 x 109 metric tonnes of carbon dioxide while ocean water contains about 35,000 x 109 metric tonnes of carbon dioxide.

2) Carbonates of earth's crust derived from rocks, which by chemical reactions give rise to carbon dioxide.

3) Fossil fuels like peat, coal and petroleum products found in the lithosphere contain about 2.81 x 1021 kg of carbon

4) Oceans, where carbon remains stored as carbonates in the form of limestone and marble rocks.