Plant Cells
Applied Science: BTEC Level 3 National Extended Diploma, topic 1.4.3
Plants
Dicotyledonous plants are multicellular organisms that use gas exchange surfaces in their leaves. Gas exchange surfaces are parts of the body that are specialised for gas exchange.
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Mesophyll cells
- Gas exchange takes place in the mesophyll cells.
- Mesophyll cells are the site of photosynthesis and are located in the middle layer of plant leaves.
- Mesophyll cells have a large surface area to allow rapid exchange of carbon dioxide and oxygen with the environment.
Stomata
- Carbon dioxide diffuses into plant leaves through pores on the underside of the leaf called stomata (singular = stoma).
- The underside of the leaf is called the epidermis.
Guard cells
- Stomata also play a role in controlling water.
- There is a guard cell on either side of a stoma that can open and close the stomata to control water loss.
- When the guard cells swell, the stomata open.
Root Hair Cell
Root hair cells are specialised (to perform a specific function). Their structure allows the plant to absorb more water. They also allow a plant to take in the minerals it needs to survive.
No chloroplasts
- These cells are located underground.
- This means that they do not contain chloroplasts (there is no light for photosynthesis).
Long projections
- Root hair cells have long projections that increase the surface area that the plant can use to absorb water and minerals.
Test yourself on Plant Cells
Which of the following statements about plant gas exchange are true?
Which of these is NOT a role of stomata?
Why do root hair cells have long projections (also known as 'hairs')?