6.4,6.5: Gas exchange in leaves & limiting water loss

Question 1

Features of the diffusion pathway

2

Answer 1

short and fast

Question 2

Process by which gases move in leaves

Answer 2

diffusion

Question 3

Stomata

Answer 3

Minute pores that occur mainly on the underside of leaves. Each stoma is surrounded by a pair of guard cells.

Question 4

Guard cells

Answer 4

Surround the stoma and control their opening and closing and therefore the rate of gaseous exchange.

Question 5

Terrestrial

Answer 5

live on land

Question 6

Insects’ adaptations for reducing water loss

3

Answer 6

small SA:V ratio
waterproof coverings
spiracles

Question 7

Insect’s waterproof covering

Answer 7

Rigid outer skeleton of chitin which is covered with a waterproof cuticle

Question 8

Spiracles in insects

Answer 8

Openings of the trachea at the body surface which can be closed to reduce water loss.

Question 9

Xerophytes

Answer 9

Plants adapted in living in areas where water is in short supply

Question 10

Limiting water loss in plants
(non-xerophytes)
2

Answer 10

waterproof coverings

and ability to close stomata

Question 11

Adaptations to limit water loss in xerophytes

5

Answer 11

A thick cuticle
Rolling up of leaves
Hairy leaves
Stomata in pits or grooves
A reduced SA:V ratio of the leaves

Question 12

Thick cuticle in xerophytes function

Answer 12

Reduces water loss

Question 13

Rolling up of leaves

Answer 13

traps a region of air within the rolled leaf which becomes saturated with water vapour and has very high water potential. Therefore there is no water potential gradient between the inside and outside of the leaf.