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CAIE IGCSE Biology 21.2.5 Using Lactase for Lactose-free Milk

Practise explaining how lactase breaks down lactose in milk and how immobilised enzyme beads improve the process.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • identify lactase as the enzyme that breaks down lactose when making lactose-free milk
  • distinguish enzyme hydrolysis from filtering, heating or using lipase to remove lactose
  • explain that immobilised lactase can be reused and kept out of the final milk

21.2.5—Use of lactase to produce lactose- question 1

[Maximum number: 1]

The diagram shows some apparatus that was used to produce lactose-free milk.

Figure for Question 21.2.5—Use of lactase to produce lactose- question 1 — CAIE IGCSE Biology

The alginate beads do not react with any of the substances. X is an enzyme that catalyses a reaction involving one of the substances found in milk.

What are X and Y ?

X

Y

amylase

glucose

amylase

starch

lactase

glucose

lactase

starch

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