DP Biology (last assessment 2024)

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Question 23M.2.SL.TZ2.a

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Date May 2023 Marks available [Maximum mark: 4] Reference code 23M.2.SL.TZ2.a
Level SL Paper 2 Time zone TZ2
Command term Explain Question number a Adapted from N/A
a.
[Maximum mark: 4]
23M.2.SL.TZ2.a

Explain how temperature affects enzymes.

[4]

Markscheme
  1. speed of reaction/catalysis increases as temperature rises;
  2. faster molecular motion so more collisions between substrate and active site;
  3. denaturation at higher temperatures;
  4. (denaturation causes) shape/conformation/structure of enzyme/active site altered/damaged;
  5. an enzyme works fastest at its optimum temperature;
  6. inactivation at lower temperatures (due to very few collisions);
  7. sketch graph to model the effect of temperature on enzyme activity;

Graphs would need to be well annotated.

Must not be bell shaped.

Examiners report

Most candidates gained some marks for explaining the effect of temperature on enzyme activity. One common error was to state that denaturation happens at too high and too low temperatures. Many candidates also explained the effect of changing pH which was outside the question and risked losing the quality mark for superfluous material.

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