A Changing Atmosphere

Question 1

Explain how the growth of primitive plants used carbon dioxide and released oxygen by photosynthesis and consequently the oxygen in the atmosphere increased.

Answer 1

Over time, more photosynthesising organisms and plants evolved. Increasing levels of photosynthesis sped up the rate of which carbon dioxide was removed from the atmosphere and the rate which oxygen was added.

Question 2

How was the amount of carbon dioxide in the atmosphere reduced?

Answer 2

• The dissolution of carbon dioxide into the oceans (carbon dioxide dissolved in the water- how half of it was lost)
• the later incorporation of this dissolved carbon dioxide into marine organisms which eventually formed carbonate rocks (coral/molluscs/star fish use dissolved carbon dioxide to make shells of Calcium carbonate- as they died shells fell and became sediment)