Absorption, assimilation and egestion — KCSE Biology

KCSE Biology · 103 practice questions · 3 syllabus objectives

35 easy42 medium26 hard

What You'll Learn

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

Describe how digested food is absorbed in the small intestine

Distinguish between absorption, assimilation, and egestion

Absorption, assimilation and egestion

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easySHORT ANSWER6 marks

Identify and explain the key differences between absorption, assimilation, and egestion in the human digestive system. (6 marks)

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Part (a) — 2 marks

Absorption is the process where digested food molecules pass from the intestine into the bloodstream. (1 mk)

It is significant as it allows nutrients to enter the body for energy and growth. (1 mk)

Part (b) — 2 marks

Assimilation is the utilisation of absorbed nutrients by body cells. (1 mk)

It occurs when cells convert glucose into glycogen for storage or use amino acids to build proteins. (1 mk)

Part (c) — 2 marks

Egestion is the elimination of undigested food from the body. (1 mk)

Its role is to remove waste products, thus maintaining the health of the digestive system. (1 mk)

easySHORT ANSWER3 marks

Distinguish between absorption, assimilation, and egestion in humans.

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Part (a) — 3 marks

Absorption: uptake of digested food into blood/lymph (1 mk)

Assimilation: use of absorbed nutrients by body cells (1 mk)

Egestion: removal of undigested material as faeces (1 mk)

easySHORT ANSWER3 marks

Explain how egestion is important for maintaining homeostasis in humans. (3 marks)

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Part (a) — 3 marks

Egestion eliminates undigested food, preventing toxic buildup in the body. (1 mk)

It helps regulate the balance of water and electrolytes by removing excess material. (1 mk)

By disposing of waste, egestion supports overall metabolic functions and health. (1 mk)

State two roles of assimilation in the human body. (2 marks)

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