Gas Exchange Systems

Question 1

What is pO₂?

Where is it high/low?

Answer 1

Partial pressure of oxygen

High in the lungs

Low at respiring cells/tissues

Question 2

How do the following affect the oxygen dissociation curve (O.D.C.)?

1. Increased carbon dioxide levels
2. Increased affinity for oxygen
3. Environment with a lower pO₂
4. Organism with higher activity levels

Answer 2

1. Displaces curve to the right
2. Displaces curve to the left
3. Displaces curve to the left
4. Displaces curve to the right

Question 3

What happens to carbon dioxide in the bood?

Answer 3

Dissolves in the plasma to form carbonic acid

Question 4

State the quarternary structure of haemoglobin.

Answer 4

Four polypeptide chains each containing a haem group

Question 5

How does pH affect haemoglobin?

Answer 5

Lowering the pH changes haemoglobin’s conformation lowering its affinity for oxygen (releases oxygen more readily)

Question 6

What are spiarcles?

Answer 6

Air pores on the surface of insects

Question 7

What are the components of the gas exchange network in insects?

Answer 7

Trachea - ringed tubes strengthened with chitin

Tracheoles - smaller, thinner tubes leading directly to individual cells

Question 8

How can some insects ventilate air?

Answer 8

Contract abdominal mucles

Question 9

Give on drawback of the tracheal system

Answer 9

Limits size (relies on diffusion)

Question 10

What is the structure of a gill?

Answer 10

• Gill bar
• Feathery gill filaments attached to the bar
• Secondary lamellae attached to the filaments

Question 11

How is a concentration gradient maintained along the whole length of the gills?

Answer 11

Counter-current flow