Plants

1
Plants

• Structure
• Leaves
• stem
• roots

2
Leaves
3
Function of leaves

• Trap light energy for photosynthesis
• Producing sugar from photosynthesis
• Exchange of gases
  oxygen and carbon dioxide

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5
Structure
Wide Helps to catch more light energy Thin Help
get carbon dioxide from bottom to top of leaf for
photosynthesis
6
Leaf structure
Greener on top
CO2 gets in here
7
Leaf diagram palisade layer
Most chlorophyll
CO2
8
Leaf cell - palisade

• Position?
• Upper surface of leaf
• Features?
• Box shape
• Chloroplasts
• Function?
• Photosynthesis

9
Gas exchange

• Leaves are designed to allow carbon dioxide to
  get to the main chlorophyll layer at the top of
  the leaf
• They have small holes called stomata on the under
  surface
• Each hole is open closed by 2 guard cells

10
Leaf diagram stoma and guard cells
11
Stoma position
12
Stoma is a small hole
Its size is controlled by 2 guard cells
closed
open
13
Stoma function is for gas exchange in the leaf
oxygen
Guard cell
Provided plant is photosynthesising
Carbon dioxide
14
Stomata open and close at different times of the
day When it is light the plant needs CO2 for
photosynthesis so the stoma open At night
(darkness) they close
15
Gas exchange
16
Roots function and structure

• Hold plant in position
• Absorb water and minerals from the soil
• Specialised cells to increase surface area for
  water intake

17
Wheat seed
Root hairs Fragile parts of cells that grow from
the main root They massively increase the
surface area for absorption
18
Root hair cells (x150)
19
Root B has had the hairs damaged -
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