Exchange and Transport

Question 1

What two factors change the rate of transpiration

Answer 1

Humidity and openness of stomatal pores

Question 2

What two factors move water up the xylem

Answer 2

cohesion tension and root pressure

Question 3

Explain cohesion tension theory

Answer 3

water evaporates from leaf
water molecules form hydrogen bonds between one another and stick together (cohesion)
the water forms a continuous pathway
as water evaporates through transpiration more water is pulled up known as transpirational pull

Question 4

What is the evidence for this theory

Answer 4

change in diameter of tree trunks
if the xylem is broken and air enters it can no longer bring water up
when the xylem is broken water does not fall out but air get dragged in due to tension