Gas Exchange

Question 1

Describe how the structure of the insect gas exchange system:
Provides cells with sufficient oxygen
Limits water loss

Answer 1

1 spiracles, trachea, tracheoles
2 spiracles allow diffusion of oxygen
3 tracheoles are highly branched so large surface area for exchange
4 tracheoles walls thin so short diffusion distance
5 tracheole walls are permeable to oxygen

Question 2

Describe how humans breath in and out

Answer 2

Breathing in
1 diaphragm muscles contract and diaphragm flattens
2 external intercostal muscles contract and ribcage pulled out
3 causes volume increase and pressure decrease in thoracic cavity
Breathing out
4 diaphragm muscles relax and diaphragm moves up
5 external intercostal muscles relax and ribcage moves down

Question 3

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 3

1 single layer of cells
2 reduces diffusion distance

Question 4

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

Answer 4

1 less carbon dioxide exhaled
2 so reduced concentration gradient between blood and alveoli
3 less movement of carbon dioxide out of blood

Question 5

Describe and explain the advantage of the counter-current principle in gas exchange across a fish gill

Answer 5

1 water and blood flow in opposite directions
2 maintains concentration gradient of oxygen
3 diffusion along length of lamellae