Limiting Water Loss

Question 1

Why is water loss an issue at gas exchange surfaces?

Answer 1

the features of an efficient gas exchange system are the same as those that increase water loss

Question 2

Explain why an insect has a small surface area to volume ratio

Answer 2

minimise the area over which water is lost

Question 3

Describe the waterproof covering on an insect

Answer 3

rigid outer skeleton of chitin with a waterproof cuticle

Question 4

Explain why an insects spiracles are closed mainly at rest

Answer 4

Closed spiracles means less oxygen which is required more during movement

Question 5

Why can a plant not have a small surface area?

Answer 5

it requires a large surface area to absorb light and exchange gases for photosynthesis

Question 6

What do we call plants that are adapted to limit water loss through transpiration

Answer 6

xerophytes

Question 7

Describe the purpose of the cuticle on a leaf

Answer 7

reduce water loss from the upper surface of the leaf

Question 8

Explain how rolling leaves reduces water loss

Answer 8

“A region of still air is trapped just outside the leaf
This becomes saturated with water (high water vapour potential)
Lower water vapour potential gradient between inside and outside of leaf
Less water loss”

Question 9

Explain how hairy leaves reduce water loss

Answer 9

“Layer of still, moist air trapped in the hairs
Reduces the water vapour potential gradient
Less water loss”

Question 10

Explain how stomata in pits reduce water loss

Answer 10

“Layer of still, moist air trapped in the pit
Reduces the water vapour potential gradient
Less water loss”

Question 11

Explain how stomata in pits reduce water loss

Answer 11

“Layer of still, moist air trapped in the pit
Reduces the water vapour potential gradient
Less water loss”