The removal of undigested food substances from the body is called

Analyze the question: The question asks for the term for removing undigested food (faeces) from the body. The key words are "undigested food substances."

Explain the concept: Nutrition involves several stages, and each has its own term:

• Ingestion: taking food into the body through the mouth.
• Digestion: breaking food down into simple, soluble molecules.
• Absorption: taking digested food into the blood.
• Assimilation: using the absorbed food to build tissues or release energy.
• Egestion: removing undigested, unabsorbed food (faeces) from the body through the anus.

Excretion is different. It is the removal of metabolic waste products made inside body cells, such as urea, carbon dioxide and excess water. These substances come from chemical reactions in the cells, not directly from undigested food.

Solution:

1. The material being removed is undigested food, so it was never absorbed into the body cells.
2. Material that was never absorbed is passed out as faeces, and this process is called egestion.
3. Checking the other options: • A. Assimilation is the use of absorbed food, so it is wrong. • C. Excretion removes metabolic wastes, so it is wrong. • D. Elimination is a general word and not the specific biological term, so it is wrong. • E. Ingestion is taking food in, the opposite of what is asked, so it is wrong.

Answer: B. egestion.

Exam tip: Remember Egestion = Exit of Excess food (undigested). Excretion is for waste made by the cells (metabolic waste). Egestion is for food that was never absorbed. NECO and JAMB like to test this pair.