Neco Model Questions Vol1 2021 Biology Question 4

Practice essay / theory question 4 from the 2021 Neco Model Questions Vol1 Biology examination. This question covers respiration .

Neco Model Questions Vol1 2021 Biology Essay / Theory
Topic: respiration
Question 4 NECO_MODEL_QUESTIONS_VOL1 • 2021 • BIOLOGY • essay
Neco Model Questions Vol1 2021 Biology Question 4 diagram

The diagram shows the major structures of the human respiratory system.

Question Parts

( a )
Describe the complete pathway that air follows from the external environment to the alveoli, naming each structure shown in the diagram and stating its principal function in the process of respiration.
( b )
The partial pressure of oxygen in alveolar air (PAO₂) is 100 mmHg while that in the pulmonary capillary blood (PvO₂) is 40 mmHg. Using Fick’s law of diffusion, discuss the factors that determine the rate of diffusion of O₂ across the alveolar–capillary membrane.
( c )
In emphysema the effective alveolar surface area is reduced by 30 % and the thickness of the alveolar membrane is increased by 20 %. Assuming all other variables in Fick’s law remain unchanged, calculate the percentage change in the rate of O₂ diffusion compared with a healthy lung.
( d )
Answer the following:
( ) Define ventilation, perfusion and the V/Q ratio.
( ) Explain the physiological consequences when ventilation is 80 % of normal but perfusion is only 50 % of normal.

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About This Question

This is Neco Model Questions Vol1 2021 Biology Question 4. It is one of the essay questions from the 2021 Neco Model Questions Vol1 Biology examination.

The question covers respiration .

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