Igcse Model Questions Vol1 2017 Biology Question 40

Practice objective / multiple choice question 40 from the 2017 Igcse Model Questions Vol1 Biology examination.

Igcse Model Questions Vol1 2017 Biology Objective / Multiple Choice Medium Difficulty
Question 40 IGCSE_MODEL_QUESTIONS_VOL1 • 2017 • BIOLOGY • objective

At sea level atmospheric pressure is 760 mmHg; water vapour pressure in the airways is 47 mmHg; the fraction of inspired oxygen is 0.21; arterial \(P_{CO_2}\) is 40 mmHg and the respiratory quotient \(R\) is 0.8. (a) Using the alveolar gas equation, calculate the alveolar partial pressure of oxygen \(P_{AO_2}\) at sea level. (b) At an altitude where atmospheric pressure falls to 560 mmHg, assuming the other variables remain unchanged, calculate the new \(P_{AO_2}\) and the percentage decrease relative to sea level.

Answer Options

A. Sea‑level \(P_{AO_2}\) ≈ 95 mmHg; at 560 mmHg altitude ≈ 55 mmHg; ≈45 % decrease
B. Sea‑level \(P_{AO_2}\) ≈ 110 mmHg; at 560 mmHg altitude ≈ 65 mmHg; ≈41 % decrease
Correct Answer C. Sea‑level \(P_{AO_2}\) ≈ 100 mmHg; at 560 mmHg altitude ≈ 58 mmHg; ≈42 % decrease
D. Sea‑level \(P_{AO_2}\) ≈ 90 mmHg; at 560 mmHg altitude ≈ 50 mmHg; ≈44 % decrease
Correct Answer
C
Correct Option:
Sea‑level \(P_{AO_2}\) ≈ 100 mmHg; at 560 mmHg altitude ≈ 58 mmHg; ≈42 % decrease

About This Question

This is Igcse Model Questions Vol1 2017 Biology Question 40. It is one of the objective questions from the 2017 Igcse Model Questions Vol1 Biology examination.

Difficulty level: Medium .

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