IB Biology HL B3.1.3 Maintaining Concentration Gradients Questions

Explore how oxygen partial pressure and ventilation or circulation determine the steep gradients that drive gas exchange in IB Biology HL B3.1.3.

Exam points

Explain how lower oxygen partial pressure at high altitude reduces the diffusion gradient and gas exchange efficiency.

[Maximum number: 3]

The graph shows the relationship between partial pressure of oxygen in air and altitude.

Figure for Question IB Biology HL B3.1.3 Maintaining Concentration Gradients Questions question 1 — IB Biology HL

Explain the consequence of high altitude for gas exchange in humans.

a. lower oxygen partial pressure reduces oxygen availability (for the blood);

b. less oxygen diffuses/is exchanged with the blood OR less oxygen diffuses across the alveolar membrane/alveoli;

c. less saturation of hemoglobin with oxygen;

d. more $\mathrm{CO}_{2}$ remains in the blood OR less $\mathrm{CO}_{2}$ is exhaled;

e. breathing rate/depth is increased (in the short term);

f. (to compensate for the lack of oxygen) the body will produce more erythrocytes/RBCs/hemoglobin;

Mp a: Do not accept lower oxygen concentration at high altitude. Partial pressure must be mentioned.

Mp c: Do not accept increased hemoglobin affinity for oxygen instead of saturation.

Mp d: Allow higher $\mathrm{CO}_{2}$ decreasing hemoglobin affinity for oxygen.

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IB Biology HL B3.1.3 Maintaining Concentration Gradients Questions question 1