Download Leaves and Photosynthesis

Leaves and Photosynthesis
• What adaptations do leaves
have for photosynthesis?
Plant cell
cell wall
cell membrane
cytoplasm
nucleus
vacuole
chloroplast
Name the structure…
Function
Structure
Controls what goes in and out of the
cell.
Contains the genetic material.
cell membrane
Surrounds the cell and gives support.
cell wall
Contains chlorophyll and absorbs
sunlight.
Contains cell sap and gives support.
Where all the chemical reactions
happen.
nucleus
chloroplasts
vacuole
cytoplasm
Chloroplasts absorb sunlight
External: How leaves are adapted for efficient
photosynthesis
Side vein
Apex
Mid-rib vein
Leaf stalk
(petiole)
Leaf blade
(lamina)
Draw this table in your books
Feature of leaves
Broad, flat leaves
Stomata
Veins
Chloroplasts
Waxy layer
Thin
How it aids photosynthesis
How leaves are suited to photosynthesis
• Leaves are broad and flat, giving
large surface area to absorb as much
light as possible.
They have ‘holes’ in the leaves to allow
carbon dioxide in and oxygen out. These
are STOMATA.
Stoma
Guard cells
There are veins in the leaves to transport
water and sugar around.
Many of the cells are packed with
chloroplasts which contain a light trapping
pigment- chlorophyll.
There is a waxy layer on top to stop water
being lost from the leaf.
Thin leaves provide a short diffusion
distance for carbon dioxide to reach the
palisade and mesophyll cells
HT: How structure of the leaf is adapted for
efficient photosynthesis
• Epidermis is transparent;
• Palisade layer at the top
containing most of the
chloroplasts;
• Air spaces in the spongy
mesophyll allow diffusion
between stomata and
photosynthesising cells;
• Internal surface area / volume
ratio very large.
Leaf cross section
• In pairs examine a slide of
FT: Plenary
• Use what you now know about leaves and
photosynthesis to design an ‘ideal leaf’ that will
maximise photosynthesis
• Draw and label your leaf to explain how it is
adapted to be more efficient
(You may want to include the external environment
it would be found in e.g. A desert or rainforest)
HT: Plenary Questions
• Draw this diagram of a Marram grass leaf.
Marram grass is found on sand dunes.
1) What does the waxy cuticle do?
2) How does the position of the stomata help this
plant?
3) Why are there no stomata on the outer surface of
the leaf?
4) Explain the function of the hairs on the inner
surface of the leaves?
5) Explain how having sunken stomata will affect
gaseous exchange in the plant, and why this would
be an advantage to the plant.