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CAIE IGCSE Biology 21.2 Biotechnology Questions

Practise biotechnology questions by applying yeast respiration, enzyme uses and fermenter conditions to bread, biofuel, fruit juice, milk and medicines.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • distinguish yeast anaerobic products: ethanol for biofuel versus carbon dioxide that makes dough rise
  • compare warm proving for yeast enzyme activity with high-temperature baking that kills yeast
  • identify pectinase in fruit-juice production and link treatment to increased juice yield
  • compare pectinase-treated fruit with a water control using filtrate volume
  • identify protease as the enzyme used in biological washing powder
  • explain how lactase hydrolyses lactose to produce lactose-free milk
  • explain how immobilised lactase can be reused without leaving enzyme in the milk
  • match bacteria or fungi with fermenter products such as insulin, penicillin and mycoprotein
  • outline inoculation, growth, sampling, removal and purification in large-scale production
  • explain how water jackets, pH monitoring, aeration and stirring maintain fermenter conditions
  • interpret nutrient or product graphs to identify depletion, waste build-up or the best harvest point

Covered syllabus points

21.2.1—Role of anaerobic respiration in yeast21.2.2—Role of anaerobic respiration in yeast21.2.3—Use of pectinase in fruit juice21.2.4—Use of biological washing powders that21.2.5—Use of lactase to produce lactose-21.2.6—Fermenters can be used21.2.7—Conditions that need to be controlled

Question 1

[Maximum number: 2]

Some countries have invested in biofuels such as ethanol, biomass and biodiesel.

Describe how ethanol can be made by microorganisms.

Question 2

[Maximum number: 1]

State one food product that is made using anaerobic respiration in yeast.

Question 3

[Maximum number: 1]

Apples are used to make apple juice.

State one enzyme used in fruit juice production.

Question 4

[Maximum number: 1]

Which enzyme would be used in a biological washing powder?

A

DNA ligase

B

lactase

C

pectinase

D

protease

Question 5

[Maximum number: 1]

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

Figure for Question 5 — 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

Question 6

[Maximum number: 1]

Bacteria are useful in biotechnology and genetic engineering.

Fig. 6.1 shows a photomicrograph of a bacterium.

Fig. 6.1

Fig. 6.1

Genetically modified bacteria are often grown in fermenters.

State the name of one commercial product, other than insulin, that is made in fermenters.

Question 7

[Maximum number: 5]

Bacteria are useful in biotechnology and genetic engineering.

Fig. 6.1 shows a photomicrograph of a bacterium.

Fig. 6.1

Fig. 6.1

Question (a)

(a)

Genetically modified bacteria are often grown in fermenters.

[ 5 ]

Question (i)

(i)

Suggest why steam is used to clean fermenters.

[ 2 ]

Question (ii)

(ii)

State three conditions inside a fermenter that are measured and controlled.

1

2

3

[ 3 ]
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