IB Biology HL B3.1.12 Hl Bohr Shift Questions

Explore how carbon dioxide from active tissues lowers pH, produces the Bohr shift and increases haemoglobin oxygen unloading during exercise in IB Biology HL B3.1.12.

Exam points

Explain how increased carbon dioxide from respiring tissues lowers blood pH and reduces haemoglobin affinity for oxygen.
Interpret an oxygen dissociation graph to identify the Bohr shift as a rightward curve displacement at higher carbon dioxide concentration.
Use the right-shifted curve to explain greater oxygen unloading at the same pO2 in actively respiring tissues, including during exercise.

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Study B3.1.12 (HL)—Bohr shift conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 3]

(a)

The graph shows the oxygen dissociation curve for adult hemoglobin.

[ 3 ]

(i)

Using the graph, draw a line to show how the oxygen dissociation curve changes with the Bohr shift.

[ 1 ]

(ii)

Explain the role of the Bohr shift during vigorous exercise.

[ 2 ]

a. more $\mathrm{CO}_{2}$ is produced which lowers the pH of the blood;
b. hemoglobin releases more oxygen (at lower pH ) for same partial pressure of oxygen;
c. more oxygen is available to respiring tissues;

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IB Biology HL B3.1.12 Hl Bohr Shift Questions question 1

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