Neco Model Questions Vol1 2021 Biology Question 49

Practice objective / multiple choice question 49 from the 2021 Neco Model Questions Vol1 Biology examination.

Neco Model Questions Vol1 2021 Biology Objective / Multiple Choice Medium Difficulty
Question 49 NECO_MODEL_QUESTIONS_VOL1 • 2021 • BIOLOGY • objective

At sea level atmospheric pressure is 760\,mmHg. The water vapour pressure in the alveoli is 47\,mmHg, the arterial CO\(_2\) partial pressure (PaCO\(_2\)) is 40\,mmHg, the respiratory quotient (R) is 0.8 and the fraction of inspired oxygen (F\(_{i}O_{2}\)) is 0.21. Using the alveolar gas equation \(PAO_{2}=F_{i}O_{2}(P_{atm}-P_{H_{2}O})-\frac{PaCO_{2}}{R}\), calculate the alveolar O\(_2\) partial pressure (PAO\(_2\)) at sea level. Then, repeat the calculation for a patient at altitude where the atmospheric pressure is 630\,mmHg, keeping all other variables unchanged. State the decrease in PAO\(_2\) caused by the altitude change.

Answer Options

A. Sea‑level PAO_{2} \approx 105\,mmHg; Altitude PAO_{2} \approx 78\,mmHg; Decrease = 27\,mmHg
B. Sea‑level PAO_{2} \approx 95\,mmHg; Altitude PAO_{2} \approx 68\,mmHg; Decrease = 27\,mmHg
Correct Answer C. Sea‑level PAO_{2} \approx 100\,mmHg; Altitude PAO_{2} \approx 72\,mmHg; Decrease = 28\,mmHg
D. Sea‑level PAO_{2} \approx 110\,mmHg; Altitude PAO_{2} \approx 80\,mmHg; Decrease = 30\,mmHg
Correct Answer
C
Correct Option:
Sea‑level PAO_{2} \approx 100\,mmHg; Altitude PAO_{2} \approx 72\,mmHg; Decrease = 28\,mmHg

About This Question

This is Neco Model Questions Vol1 2021 Biology Question 49. It is one of the objective questions from the 2021 Neco Model Questions Vol1 Biology examination.

Difficulty level: Medium .

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