Gas Exchange in Plants
Plants need carbon dioxide and water for photosynthesis to take place. In I/GCSE Biology, they get carbon dioxide by diffusion through their leaves. Most plants have thin, flat leaves which increase the surface area and keep a short distance for the CO2 to diffuse.
In I/GCSE Biology, leaf cells constantly lose water by evaporation. When it is dark, leaves do not photosynthesize and so do not need CO2. Leaf Cells are adapted to allow carbon Dioxide in only when it is needed:
- They are covered with a waxy cuticle, which I waterproof and gas proof
- There are small openings all over the leaf surface called Stomata
- Stomata can open and close to allow air (CO2) into the cells but can close to stop water loss
Intake of Mineral Ions and Water in Plants 💦
Plant roots have cells on the outside called Root Hair Cells.
They have tiny projections on them which increase the surface area and allow mineral ions and water to easily diffuse or complete osmosis. The water only has a short distance to get to the Xylem, where it can move around the plant.
That's the end of the topic!
Drafted by Joey (Biology)