IB Biology HL 8.1.5 Induced-fit model Question Bank
Practise IB Biology HL 8.1.5 by comparing lock-and-key and induced-fit models and explaining how conformational change enables catalysis.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- Compare lock-and-key and induced-fit models as explanations for substrate binding.
- Explain how conformational change positions catalytic groups and supports reaction specificity.
C1.1.5—Induced-fit binding question 1
[Maximum number: 6]
Describe the lock and key model of enzyme activity and how the induced fit model extends it.
enzymes are (globular) proteins that are catalysts/lower activation energy of chemical reactions;
lock and key model: explains specificity of enzyme-substrate; the substrate (key) fits into/has complementary shape to the active site (lock) of the enzyme;
the active site can be changed by different chemicals/temperatures/ pH so substrate cannot bind;
induced-fit model:
changes in the active site/conformational changes to allow substrate to bind; the substrate induces the active site to change; bonds weakened in the substrate (so easier to break); explain reduction of activation energy/wider substrate specificity;
Marking guidance:
Accept the above points in the form of a clearly drawn annotated diagram.
Award [3 max] if only one model addressed.
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