1.4 - THE CARBON CYCLE

Question 1

Which of the following represents a negative feedback loop affecting climate change?

a) Carbon dioxide levels increase >>> greenhouse effect intensifies >>> global average temperature increases >>> rates of decomposition increase >>> carbon dioxide levels increase
b) Carbon dioxide levels increase >>> greenhouse effect intensifies >>> global average temperature increass >>> humans continue releasing carbon dioxide
c) Carbon dioxide levels increase >>> photosynthesis rates in plants are stimulated and increase >>> carbon dioxide is consumed
d) Carbon dioxide levels increase >>> humans stop burning fossil fuels >>> carbon dioxide levels decrease

Answer 1

Choice C is correct.

Increasing carbon dioxide levels directly cause increased rates of photosnthesis in plants, which in turns lowers carbon dioxide levels.

Question 2

Which of the following BEST represents the gaseous phase of the carbon cycle in nature?

a) CO₂ and CH₄
b) CO₂ and H₂CO₃
c) CO₂ and C₂H₁₂O₆

d CO₂ and CO₃^2-

Answer 2

Choice A is correct because both carbon dioxide, CO₂, and methane, CH₄, are gases in nature and at room temperature.

Question 3

Where is the majority of carbon stored on Earth?

a) In plants.
b) in coal deposits.
c) In ocean sediments.
d) In the atmosphere.

Answer 3

Choice C is correct. Calcium ions combine with bicarbonate ions in the ocean to form calcium carbonate. This material is used by shell-building organisms, like coral and plankton. When these organisms die, they sink to the seafloor.

Over time, layers of shells and sediment become rock and the carbon they contain remains stored for millions of years. This makes ocean sediments the largest carbon storage areas on Earth.