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← Theoretical A

Q39 — Snow Leopard Hemoglobin at High Altitude

Theoretical A Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Respiratory Physiology

Snow leopards (Panthera uncia) inhabit high-altitude areas in East and South Kazakhstan and are known to hyperventilate. To examine possible differences in the oxygenation properties of big cats’ hemoglobins (Hbs), O2-equilibrium curves were measured for purified HbA and HbB isoforms of African lion and snow leopard hemoglobin under standardized conditions of pH and anion concentrations. Furthermore, the effects of KCl and DPG were also analyzed. KCl and DPG (2,3-diphosphoglycerate) are allosteric cofactors of hemoglobin.

O2-equilibrium curves for African lion and snow leopard HbA/HbB isoforms compared to human hemoglobin, with and without the allosteric cofactor DPG, plus a bar chart of P50 changes upon KCl or DPG addition. Figure 1. Hb-O2 equilibrium curves of African lion (A) and snow leopard (B) compared with those of human adult Hb. Triangles – DPG-added, circles – DPG-free; Black-filled shapes – HbA, gray-filled shapes – HbB, white-filled shapes – human adult Hb, FS - fractional saturation (ratio of Hb-O2 to total Hb). C shows the changes in P50 values from DPG-free Hb with the addition of KCl or DPG (P50 is the oxygen partial pressure when hemoglobin is 50% saturated with oxygen). 1 – African Lion and 2 – Snow Leopard.

On your answer sheet, indicate “T” for true statements and “F” for false ones.

A. DPG has a stronger allosteric effect on hemoglobin in snow leopards than in humans.
B. Renal compensation stimulates snow leopards inhabiting high-altitude areas to excrete more bicarbonate (HCO3-) than those inhabiting lowland areas.
C. The hemoglobin of snow leopards is specifically adapted to low oxygen partial pressure.
D. KCl causes a stronger increase in affinity to oxygen in African lion's HbA than in snow leopard's HbB.
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Question reproduced from IBO 2024, Theoretical Exam Part A, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)