B4.1.7 - The carbon cycle

Question 1

What is the carbon cycle?

Answer 1

The process by which carbon is cycled through the atmosphere, the Earth, and plants and animals

Question 2

How is carbon removed from the environment?

Answer 2

• By photosynthesis. This occurs in green plants, algae, etc…
• When animals eat plants, carbon in the plant is transferred to the animal. Some of this is used to produce fats and proteins in the animal’s body

Question 3

How is carbon released back into the atmosphere?

Answer 3

• Respiration is used by living organism to transfer energy from chemical stores in food resulting in CO2 being produced and released
• When plants, algae and animals die, decomposers break down their remain, releases CO2 as they respire
• Fossil fuels are a store of carbon as they are burned this trapped carbon is released

Question 4

Why does the CO2 level vary throughout the day?

Answer 4

• Photosynthesis only takes place in the light so CO2 is only removed from the atmosphere in the daytime
• Respiration is carried out throughout the day and night releasing CO2 at a relatively consistent rate

Question 5

Why have the CO2 levels increased significantly over the past 200 years?

Answer 5

Due to human activities such as the combustion of fossil fuels and deforestation