Gas exchange - Insects

Question 1

How does gas exchange occur in small molecules

Answer 1

Down a concentration gradient by diffusion

Question 2

How does gas exchange occur in fluids (gases and liquids)

Answer 2

Down a pressure gradient by mass flow

Question 3

Define mass flow

Answer 3

The movement of a fluid from an area of high pressure to low pressure

Question 4

Describe the gas exchange in an insect

Answer 4

Air enters through the spiracles, then through the tracheae, then the tracheoles and then is delivered to the respiring cells.

Question 5

Explain how insects reduce water loss

Answer 5

• The spiracles can close to reduce the surface area over which evaporation can take place
• The hairs in the spiracles trap water vapour, reducing the concentration gradient, decreasing the rate of evaporation
• The thick chitin exoskeleton decreases permeability to water and increases the diffusion distance, reducing the rate of evaporation