Plants
Structure –
Leaves
stem
roots
Leaves
Function of leaves
 Trap light energy for photosynthesis
Producing sugar from photosynthesis
 Exchange of gases –
oxygen and carbon dioxide
Structure
Wide
Helps to catch more light
energy
Thin
Help get carbon dioxide
from bottom to top of
leaf for photosynthesis
Leaf structure
Greener on top
CO2 gets in
here
Leaf diagram – palisade layer
Most
chlorophyll
CO2
Leaf cell palisade
Position?
Upper surface of
leaf
Features?
Box shape
Chloroplasts
Function?
Photosynthesis
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
Leaf diagram –
stoma and guard cells
Stoma position
Stoma is a small hole
Its size is controlled by 2 guard cells
closed
open
Stoma function is for gas
exchange in the leaf
Guard
cell
oxygen
Provided plant is
photosynthesising
Carbon
dioxide
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
Gas exchange
Roots – function and
structure
 Hold plant in position
 Absorb water and minerals
from the soil
 Specialised cells to increase
surface area for water intake
Wheat
seed
Root hairs
Fragile parts of
cells that grow
from the main root
They massively
increase the
surface area for
absorption
Root hair cells
(x150)
Root ‘B’ has had
the hairs damaged -
Toughened root cap