Plants exchange gases through their leaves which are flat and thin and have a lot of internal air spaces.
They take up water through their roots which have root hairs to increase surface area.
Water evaporates through leaves.
They respire all the time:
- during the day oxygen is produced by photosynthesis, so diffusion into leaves is mainly CO2.
- at night oxygen diffuses through leaves, as only respiration can take place.
Gases diffuse though tiny holes in leaves called stomata:
- O2 is needed for respiration and is a waste product of photosynthesis.
- CO2 is needed for photsynthesisancd is a waste product of respiration.
The movement of thses gases depend on which process is taking place most quickly.
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