1. Leaves How is a leaf adapted for photosynthesis?
What is the cohesion-tension theory?

2. Leaf Structure Blade – leaf surface
Petiole – stalk connecting blade to stem

3. Leaf Structure Most are covered with cuticle for protection
Parencyhma tissue present for photosynthesis
Guard cells are present on underside of leaf

4. Function of Guard Cells
Guard cells surround stoma
Stoma allow gas exchange
Open and close depending on environmental conditions
At night and during dry conditions they are closed

5. Cohesion-Tension Theory
Stoma also allow water to leave - Transpiration
Water molecules bind to each other (cohesion) and to walls of xylem (adhesion)
As one water molecule leaves, another is pulled up behind it
This enables water to move to the top of the plant