Photosynthesis - how plants affect the atmosphere
During the day a plant is both respiring and photosynthesising. So there is a two-way traffic of oxygen and carbon dioxide both into and out of the plant. During the night when the plant is respiring but not photosynthesising, oxygen is being taken in but not given out - and carbon dioxide is being given out but not taken in.
Photosynthesis - Takes CO2 from the air and puts oxygen into the air, it is active in the day but not at night.
Respiration - Takes Oxygen from the air and puts CO2 in the air, it is active in the day AND the night.
Plants use up more carbon dioxide in photosynthesis than they produce in respiration. And they produce more oxygen by photosynthesis than they use in respiration. This means the overall result is that plants put oxygen into the atmosphere. This makes it possible for animals to breathe.
Photosynthesis- how plants affect the atmosphere 2