Case study·Hard exam skill (4/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
A protein sample is active at room temperature. After heating, it coagulates and no longer catalyses its biological reaction. Acid hydrolysis of a separate portion gives amino acids.
Total: 4 marks
(a) What change occurred on heating? (1 mark)
(b) Did heating necessarily break all peptide bonds? (1 mark)
(c) What does acid hydrolysis prove about the sample? (1 mark)
(d) Which level of structure is represented by the amino-acid sequence? (1 mark)
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