DP Biology (last assessment 2024)
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2.5 Enzymes

Description

Nature of science:
Experimental design—accurate, quantitative measurements in enzyme experiments require replicates to ensure reliability. (3.2)
Understandings:
  • Enzymes have an active site to which specific substrates bind.
  • Enzyme catalysis involves molecular motion and the collision of substrates with the active site.
  • Temperature, pH and substrate concentration affect the rate of activity of enzymes.
  • Enzymes can be denatured.
  • Immobilized enzymes are widely used in industry.
Applications and skills:
  • Application: Methods of production of lactose-free milk and its advantages.
  • Skill: Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes.
  • Skill: Experimental investigation of a factor affecting enzyme activity. (Practical 3)
Guidance:
  • Lactase can be immobilized in alginate beads and experiments can then be carried out in which the lactose in milk is hydrolysed.
  • Students should be able to sketch graphs to show the expected effects of temperature, pH and substrate concentration on the activity of enzymes. They should be able to explain the patterns or trends apparent in these graphs.
 Theory of knowledge:
  • Development of some techniques benefits particular human populations more than others. For example, the development of lactose-free milk available in Europe and North America would have greater benefit in Africa/Asia where lactose intolerance is more prevalent. The development of techniques requires financial investment. Should knowledge be shared when techniques developed in one part of the world are more applicable in another?
Utilization:
  • Enzymes are extensively used in industry for the production of items from fruit juice to washing powder.
Syllabus and cross-curricular links:
  • Biology
  • Topic 8 AHL Metabolism, cell respiration and photosynthesis

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