Gas exchange practise questions

Question 1

Suggest and explain how a reduced tidal volume affects the exchange of
carbon dioxide between the blood and the alveoli.

Answer 1

• less carbon dioxide removed from lung ( alveoli)
• so reduced concentration gradient between blood and alveoli
• so less movement of CO2 out of blood into alveoli

Question 2

(c) Figure 2 shows changes in concentration of oxygen in two gas exchange
systems.

A student studied Figure 2 and concluded that the fish gas exchange
system is more efficient than the human gas exchange system.
Use Figure 2 to justify this conclusion.

Answer 2

In fish, blood leaving GE system (V) has more oxygen than water leaving (E);

(But) in humans, blood leaving (V) has less oxygen than air leaving

( 2 marks)

this shows that in fish more oxygen is obtained during gas exchange, higher rate of diffusion

Question 3

A high concentration of particulate matter results in the death of some
alveolar epithelium cells. If alveolar epithelium cells die inside the human
body they are replaced by non-specialised, thickened tissue.
Explain why death of alveolar epithelium cells reduces gas exchange in
human lungs.

Answer 3

• reduced surface area ( less alveoli)
• greater diffusion distance due to thickened walls
• both of these elements decrease rate of gas exchange

Question 4

Describe and explain one feature of the alveolar epithelium that makes the
epithelium well adapted as a surface for gas exchange. Do not refer to
surface area or moisture in your answer.

Answer 4

• single layer of cells
• reduces diffusion distance

Or

• permeable
  -to allow diffusion of oxygen and carbon dioxide