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A-LevelBiologyImmunityOct/Nov 2014Paper 1 Q71 Mark

Proteases are a group of enzymes that digest proteins. Which statement about proteases is correct?

Abacterial protease that is secreted from a disease-causing bacterium could act as an antigen and cause the production of an antibody.
BBacterial proteases are important in the nitrogen cycle as they are able to catalyse the breakdown of the organic nitrogen molecules nucleotides and urea.
CNon-competitive inhibition of a protease that has an optimum pH of pH2 can be overcome by increasing the substrate concentration and increasing the pH.
DWater molecules are required when peptide bonds that link the monomers together are broken by the action of proteases in condensation reactions.

✓ Correct Answer

The correct answer is A: bacterial protease that is secreted from a disease-causing bacterium could act as an antigen and cause the production of an antibody.

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Biology Question

Topic

This multiple-choice question tests Immunity in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Biology Oct/Nov 2014 examination, Paper 1 Variant 2.

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