1.4 Enzymes and Digestion
Enzyme specificity and rate, temperature effects, inhibitors, digestion, ileum absorption, villi and enzyme applications.
How to study for CCEA GCSE Biology
Learn each process as a structure-and-mechanism chain, use data with units, and prepare every prescribed practical from planning through conclusion and evaluation.
Core concepts
Concept 1
An enzyme's active site is complementary to its substrate, allowing a specific reaction without the enzyme being used up.
Exam cue: Distinguish a slow enzyme reaction at low temperature from irreversible denaturation above the optimum.
Concept 2
Temperature changes collision rate up to an optimum, while higher temperatures increasingly denature the active site and reduce activity.
Exam cue: When comparing rates, identify the dependent measurement and keep substrate amount, pH and timing controlled.
Concept 3
Digestion produces small soluble molecules for absorption; folds, villi, thin surfaces and a good transport supply make the ileum effective.
Exam cue: Trace food from large insoluble molecules to soluble products, then across the villus into transport systems.
Risk pitfalls and guardrails
Saying enzymes are killed by heat rather than describing denaturation of protein shape.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a biological mechanism with a vague purpose statement.
Assuming every enzyme has the same optimum temperature or substrate.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a biological mechanism with a vague purpose statement.
Confusing digestion in the gut with absorption through the ileum wall.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a biological mechanism with a vague purpose statement.
Memory anchors
Enzyme
A biological catalyst that speeds a reaction without being used up.
Active site
The specifically shaped region where a complementary substrate binds.
Optimum
The condition at which the measured enzyme reaction rate is greatest.
Denaturation
An irreversible shape change that prevents the substrate fitting the active site.
Digestion
Breakdown of large insoluble food molecules into small soluble molecules.
Villus
A thin, well-supplied projection that increases the ileum's absorptive surface.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Why can one enzyme usually catalyse only a particular reaction?
What happens to enzyme activity as temperature rises from a low value toward its optimum?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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