Gaseous exchange in humans — KCSE Biology

KCSE Biology · 74 practice questions · 3 syllabus objectives

31 easy31 medium12 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Draw and label the human respiratory system

Describe the mechanism of breathing (inspiration and expiration)

Gaseous exchange in humans

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easySHORT ANSWER3 marks

State three changes that occur in the thoracic cavity during expiration. (3 marks)

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Part (a) — 3 marks

Decreased thoracic volume as the diaphragm relaxes (1 mk)

Increased air pressure in the thoracic cavity (1 mk)

Intercostal muscles relax, causing rib cage to move downwards (1 mk)

easySHORT ANSWER2 marks

State two roles of the diaphragm in the process of breathing in humans. (2 marks)

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Part (a) — 2 marks

Contracts to increase thoracic volume during inspiration (1 mk)

Relaxes to decrease thoracic volume during expiration (1 mk)

easySHORT ANSWER3 marks

State three functions of the human respiratory system. (3 marks)

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Part (a) — 3 marks

Facilitates gas exchange (O₂ and CO₂) (1 mk)

Regulates blood pH through CO₂ removal (1 mk)

Provides voice production through vocal cords (1 mk)

State three components of the human respiratory system. (3 marks)

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