Lesson 2

Question 1

Name 3 gas exchange surfaces

Answer 1

• Gill lamellae in fish
• Alveoli in lungs
• Ends of tracheoles in insects

Question 2

Describe features which a gas exchange surface may have

Answer 2

• Thin diffusion pathway
• Moist to allow gases to dissolve
• Permeable
• Large SA:V

Question 3

What else may be needed for efficient gas exchange?

Answer 3

Extensive circulation of good blood supply to maintain conc. grad. and to transport gases in animals
• A respiratory pigment such as haemoglobin may increase O2 capacity in blood

Question 4

How does an insect meet oxygen demands when flying?

Answer 4

Movements of abdomen ventilate the tracheae

Question 5

What are spiracles?

Answer 5

Paired holes running along each side of the body

Question 6

What are tracheae?

Answer 6

System of branched chitin-lined air tubes

Question 7

Why can spiracles close?

Answer 7

To reduce water loss when oxygen demands are met

Question 8

Describe advantages of insect gas exchange system

Answer 8

• Ends of tracheoles are fluid-filled and close to muscle fibres so oxygen is directly supplied to muscles for respiration
• Chitin keeps airways open during movement and allows some flexibility
• Oxygen diffuses faster in air than blood
• Spiracles can close to reduce H2O loss