Cycles Within Ecosystems

Why is carbon essential to living organisms?

It is an essential part of the biological molecules from which cells are built — carbohydrates, proteins and fats.

How is carbon taken out of the atmosphere?

By plants during photosynthesis, which takes in carbon dioxide and uses the carbon to make glucose.

What happens to the carbon a plant takes in?

It is used to make glucose, which can be turned into carbohydrates, fats and proteins within the plant's biomass.

How is carbon transferred between living organisms?

By feeding — from plants to animals when herbivores feed, and between animals when carnivores feed.

How does respiration return carbon to the atmosphere?

Respiration in plants and animals releases carbon as carbon dioxide.

How does decomposition return carbon to the atmosphere?

Microorganisms such as bacteria and fungi use dead and waste material to fuel their respiration, releasing carbon dioxide.

How are fossil fuels formed?

When animals and plants die in conditions where decomposers are not present, the carbon in their bodies is converted into fossil fuels.

How does combustion return carbon to the atmosphere?

Burning fossil fuels releases the carbon stored in them as carbon dioxide.

Name the four processes of the carbon cycle.

• Photosynthesis

• Respiration

• Decomposition

• Combustion

Carbon is removed from the atmosphere by plants during ＿＿＿＿＿＿＿＿.

Carbon is removed from the atmosphere by plants during photosynthesis.

Burning fossil fuels releases carbon dioxide into the atmosphere by ＿＿＿＿＿＿＿＿.

Burning fossil fuels releases carbon dioxide into the atmosphere by combustion.

True or False?

Only animals return carbon dioxide to the atmosphere by respiration.

False.

Respiration occurs in plants as well as animals, and in the microorganisms that decompose dead material.

True or False?

Fossil fuels form when dead matter is decomposed by bacteria.

False.

Fossil fuels form when organisms die where decomposers are not present, so the carbon is not released.