Carbon Cycle Pack A

Question 1

What characteristics do systems?

Answer 1

• Inputs
• Outputs
• Stores
• Processes
• Equilibrium
• Feedback
• Tipping points

Question 2

What are the stores in the carbon cycle?

Answer 2

• Lithosphere and sedimentary rocks 99.9% (fossil fuels = 0.007%) with a residence time of 150 million years
• Oceans 0.064% with a residence time of 25-1000 years
• Biosphere 0.03% with a residence time of 18 years
• Atmosphere 0.01% with a residence time of 6 years

Question 3

How do feedback cycles happen in the carbon cycle?

Answer 3

• Negative feedback maintain a stable state by preventing the system moving beyond thresholds (cancelling change)
  e.g. Rising temperatures and photosynthesis
• Positive feedbacks shifts the system away from its previous state to a new one
  e.g. Permafrost

Question 4

What are the three main ways humans are adding carbon to the atmosphere?

Answer 4

• Burning fossil fuels
• Making cement
• Deforestation

Question 5

What is the photosynthesis flow of carbon between vegetation and the atmosphere?

Answer 5

• Terrestrial and marine vegetation photosynthesises
• Energy from the sun is used to turn CO2 into carbohydrates
• Form of carbon sequestration
• More photosynthesis in summer and during the day

Question 6

What is the respiration flow of carbon between vegetation and the atmosphere?

Answer 6

• Oxygen is combined with carbohydrates to release energy
• CO2 and water is released
• Happens at day and night

Question 7

What is the decomposition flow of carbon between vegetation and the atmosphere?

Answer 7

• Decomposers break down cells and tissues in dead organisms
• Fungi, worm and bacteria respire and release CO2
• More decomposition when it is warm and wet (autumn especially)
• Some plants become part of the sedimentary rock and fossil fuel pools if not decomposed
• Some plants become peat due to slow decomposition