F211 - Water Transport

Question 1

Describe features of a xerophytic and how this reduces loss of water vapour.

Answer 1

• Thick waxy layer makes it waterproof which then reduces the loss of water (decreases the rate of transpiration).
• The leaf is curled which reduces the amount of exposed surface area so less water is lost.
• The leaf contains hair which traps moisture (water vapour) so there’s a high water potential outside of the stomata, meaning less water is lost.
• There’s a reduced number of stomata so there are fewer places where transpiration can happen.

Question 2

What’s a source?

Answer 2

It’s where assimilates such as sucrose are loaded into the phloem.

Question 3

What’s a sink?

Answer 3

It’s where assimilates such as sucrose are unloaded from the phloem.

Question 4

State some adaptions of sieve tubes that enable mass flow to occur.

Answer 4

There are pores in the end walls (sieve tube plates). There’s no nucleus and few organelles.