Cambridge O Level Biology · Syllabus 5090 · Human Nutrition
Assimilation
What is Assimilation?
The uptake and use of absorbed nutrients by the cells of the body. Glucose is taken into cells and respired to release energy, or stored as glycogen in the liver and muscles; amino acids are used to build proteins including enzymes; and the products of lipid digestion are used to build cell membranes or stored as fat.
This definition is part of the Human Nutrition chapter in Cambridge O Level Biology.
Assimilation in context
Human nutrition is the study of how food is taken in, broken down and used. A balanced diet supplies every required nutrient, plus fibre, water and energy, in suitable proportions. Digestion converts large, usually insoluble food molecules into small soluble ones. Absorption moves those small molecules through the wall of the intestine into the blood or lymph. Assimilation is what the body's cells then do with them. Material that was never digested leaves the body unchanged as faeces — that is egestion, and it is not excretion.
Common mistakes with Assimilation
- “Absorption and assimilation are two words for the same thing.” Why it is wrong Absorption is entry into the blood or lymph across the gut wall. Assimilation is what a cell then does with the molecule. A glucose molecule in the plasma has been absorbed and not yet assimilated. Write instead "Absorption is movement into the blood; assimilation is uptake and use by cells."