9.3 Transpiration

Question 1

Waxy cuticle

Answer 1

Waterproof covering found on leaves

Question 2

Stomata

Answer 2

Microscopic pores in the leaf allowing C0² into the leaf and oxygen out of the leaf by diffusion down concentration gradients

Question 3

Guard cells

Answer 3

Cells with the ability to close and open stomata.

Question 4

Transpiration

Answer 4

Loss of water vapour from leaves as stomata open allowing exchange of C0² and oxygen from air inside the leaf and outside.

Question 5

Transpiration stream

Answer 5

Water is turned into vapour from surface of mesophyll cells into internal air. Move out of stomata into surrounding air. Lowers water potential of cell so water moves back in by osmosis

Question 6

Transpiration pull

Answer 6

Water is drawn up the xylem in a continuous stream replacing water lost by evaporation

Question 7

Cohesion-tension theory

Answer 7

When water is lost through transpiration, more can be drawn up through the roots. This is due to cohesion and surface tension of the water

Question 8

Cellulose hoop (guard cell)

Answer 8

Prevents cell from swelling in width, so they extend lengthways

Question 9

Soil-water availability

Answer 9

Amount of water in the soil. Affects transpiration rate