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. Surrounds the cell and gives support. Contains chlorophyll and absorbs sunlight. Contains cell sap and gives support. Where all the chemical reactions happen. cell membrane nucleus cell wall 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 How it aids photosynthesis Broad, flat leaves Stomata Veins Chloroplasts Waxy layer Thin

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. 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. What does the waxy cuticle do? How does the position of the stomata help this plant? Why are there no stomata on the outer surface of the leaf? Explain the function of the hairs on the inner surface of the leaves? Explain how having sunken stomata will affect gaseous exchange in the plant, and why this would be an advantage to the plant.