During digestion, large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes
Your body breaks large food molecules into small pieces using digestion. Only these small pieces are tiny enough to pass through cell membranes and enter the bloodstream.
Formula
Hydrolysis: Large molecule + H₂O → smaller molecules (bond broken)
Real World
Lactase tablets taken by people who are lactose intolerant supply the enzyme that hydrolyses lactose into glucose and galactose — small enough to be absorbed across the gut epithelium.
Exam Focus
Use the word 'hydrolysis' explicitly and state that water is added across the bond — describing digestion as simply 'breaking down' will not score the mechanism mark.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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