How did the presence of life on Earth has bring about environmental change?

Question 1

Oxygen production

Answer 1

Oxygen was first produced by photosynthetic bacteria, then by algae and plants.

Question 2

Ozone layer

Answer 2

Ozone was produced by chemical reactions involving oxygen and ultraviolet light in the stratosphere.

Question 3

Carbon sequestration

Answer 3

Atmospheric carbon dioxide concentrations were reduced by photoautotrophs.

Question 4

Biogeochemical cycles

Answer 4

The processes of biogeochemical cycles are linked by living organisms, preventing the build-up of waste products or shortages of resources.