B2(i) - Life Processes 2.

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Specialised Cells.

Most cells are specialised for a specific function within a tissue or organ in the body or plant.

1) Palisade Leaf Cells Are Adapted for Photosynthesis.

(http://www.science-resources.co.uk/KS3/Biology/Life_Processes_and_Cells/Cell_Functions/Leaf_Cell.jpg)

 1) Packed with chloroplasts for photosynthesis. More of them are crammed at the top of the cells - so they are nearer the light.

2) The tall shape means a lot of surface area exposed down the side for absorbing CO2 from the air into the leaf.

3) The thin shape means that you can pack loads of them in at the top of the leaf. Palisade leaf cells are grouped together to give the palisade layer of a leaf. This is where most of the photosynthesis happens. 

2) Guard Cells are Adapted to Open and Close Pores.

(http://www.science-resources.co.uk/KS3/Biology/Life_Processes_and_Cells/Cell_Functions/Guard_Cell.jpg)

1) Special kidney shape which opens and close the stomata (pores) of the leaf.

2) When the plant has lots of water the guard cells fill with it and gets plump and turgid. This makes the stomata open so gases can be exchanged for photosynthesis.

3) When the plant is short of water the guard cells lose water and become flaccid making the stomata close. This helps stop too much water vapour escaping.

4) Thin outer walls and thickened inner make the opening and closing work.

5) They're also sensitive to light and close at night to save water without losing out on

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