Waec Model Questions Vol1 2021 Biology Question 4

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

Waec Model Questions Vol1 2021 Biology Essay / Theory
Topic: respiration
Question 4 WAEC_MODEL_QUESTIONS_VOL1 • 2021 • BIOLOGY • essay
Waec 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 inhaled air follows from the external environment to the site where gas exchange occurs, naming each structure in the order shown in the diagram.
( b )
Explain how contraction of the diaphragm and the external intercostal muscles produces ventilation. Indicate the changes in thoracic cavity volume during inhalation and exhalation.
( c )
Given that the partial pressure of oxygen (PO₂) in alveolar air is 100 mmHg and in the pulmonary capillary blood is 40 mmHg, discuss why oxygen diffuses from alveoli into blood using the concept of concentration gradient. State what would happen to the rate of diffusion if the alveolar wall became abnormally thick, as in emphysema.
( d )
A resting adult has a tidal volume of 500 mL and a respiratory rate of 12 breaths per minute. Calculate the minute ventilation. Then discuss two physiological factors that would increase minute ventilation during vigorous exercise.

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About This Question

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

The question covers respiration .

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