1What is the xylem?
tubes contained within a plant that transports water up from the roots to the leaf
2What are 4 specilisations of Xylem vessles?
-Xylem vessles are covered in liginin
-Individual cells are long and have no end walls
-There are pits/holes in the walls of the xylem vessel
-Xylem cells contain no organnels/ no cytoplasm
3What two reasons are xylem vessles covered in lignin?
This provides structural support and makes the xylem waterproof
4Why do xylem cells have no end walls?
It creates a hollow tube which allows a continous water colum to be formed as there is nothing blocking the flow of water
5Why do xylem cells have holes in the walls?
This allows the lateral movement of water to bypass blockages
6What 2 reasons are there for being xylem being vessles dead?
This prevents chemical reactions which would slow down the flow of water
This allows more space for water
7How is a transpiration pull created?
When water evaporated from the stomata it lowers the water potential of the mesophyll
8What causes cohsesive forces between water molecules?
Hydrogen bonds
9Why is there negative pressure in the xylem?
Transpiration pull puts the xylem under tension
10Why doesnt the xylem collapse when under pressure?
Because the xylem is strengthend by lignin
11Why does water move up the xylem?
There is adhesion between the water moleules and the xylem and also negative pressure in the xylem
12What happens to the diameter of the xylem when there is lots of transpiration?
It decreases due to negative pressure
13What does 'Many evenings left wondering how cats(when cold) try purring aloud' stand for?
Movement, evaporation, Lowers, Pulls, Hydrogen, Continous(Water column), Transpiration Pull, Adhesion