1. The amount of carbon and oxygen (as O2 and CO2) in the Earth's atmosphere is closely linked to the number of living plants and animals. Photosynthesis and plant growth extract CO2 from and release O2 into the atmosphere. In contrast, animal respiration extracts O2 from and releases CO2 into the atmosphere. If for some reason the number of plants on Earth were to increase, predict the impact on O2 and CO2 composition of the atmosphere.