5 Some laundry detergents used to wash clothes contain enzymes. These enzymes break down the molecules that cause stains. (a) Suggest enzymes that may be components of a laundry detergent that will break down stains made of: starch … fat. … [2] (b) Savinase is a protease enzyme produced by genetically engineered bacteria. The enzyme is a component of laundry detergents. The graphs show the results of an investigation into the effects of temperature and pH on the rate of Savinase activity. 0 0 rate of Savinase activity 10 20 30 40 50 temperature / °C 60 70 80 90 4 0 rate of Savinase activity 5 6 7 8 9 pH effect of temperature effect of pH 10 11 12 (i) Describe how the effect of temperature on Savinase activity differs from the effect of temperature on a protease that functions in the human stomach. … … … … … … … … [3] (ii) Suggest why laundry detergents that contain Savinase also contain chemicals that dissolve to form an alkaline solution. … … … … [2] (iii) After washing clothes using laundry detergents, the waste water is sometimes released into the environment. This waste water contains inorganic phosphate ions that are also found in fertilisers. Explain the harmful effect on aquatic life of releasing this waste water into the environment. … … … … … … … … [4] [Total: 11]

5(a) (starch) amylase ; (fat) lipase ; 2 5(b)(i) optimum AW + 60oC ; (optimum) not 37oC ; correct ref. temperature + denaturation for either enzyme ; 3 5(b)(ii) savinase / enzyme + increased rate / works faster / optimum ; prevents denaturation ; detergent more effective / clothes cleaner ; 2 5(b)(iii) pollution ; eutrophication ; two correct details of the eutrophication process for two marks ;; less oxygen available / kills + fish / consumers / animals AW ; 4

6 (a) Yoghurt is a milk product. Outline the role of microorganisms in the process of yoghurt production. … … … … … … … [5] (b) The diagram shows a food label from a pot of yoghurt. contents nutritional values in 100 g of yoghurt energy 344 kJ fat 4.5 g total carbohydrates 5.5 g sugar 5.5 g fibre 0.0 g protein 4.2 g salt 0.1 g calcium 0.125 g water 81% Yoghurt can contribute to a balanced diet but adult humans cannot survive by eating only yoghurt. Explain this statement using the information on the label. … … … … … … … [5] [Total: 10]

6(a) any five from: heating / pasteurisation at start of process or after fermentation ; denaturation of milk protein / kill unwanted bacteria ; starter culture / bacteria ; Lactobacillus (bulgaricus) / Streptococcus (thermophiles) ; fermentation / anaerobic respiration ; warm temperature ; lactose / milk sugar ; lactic acid produced ; decreases pH ; coagulation / thickening ; 5 6(b) any five from: (yoghurt contributes to a balanced diet) carbohydrates for energy ; proteins for growth / repair ; water for chemical reactions / cytoplasm / transport ; fats for energy / insulation ; calcium for bones / prevent rickets ; (yoghurt is not suitable on its own) no + fibre + so poor bowel health / constipation ; no + iron ; no + vitamin C or other named vitamin ; 5

9 Describe the large-scale production of a named antibiotic and explain the importance of each stage of the process. … … … … … … … … … … … … … … … … … … … … [Total: 10]

9 1 named antibiotic ; 1 if marking point 1 awarded, marking point 2 must be correctly linked any nine from … 2 fungus / bacterium / correct named ; 3 fermenter ; 4 sterilised / steam + to prevent contamination AW ; 5 carbohydrate (or named) + respiration / energy ; 6 protein / amino acids + growth ; 7 paddles / impeller / stirring + reason for stirring ; 8 oxygen / air + aerobic ; 9 sparger / bubbles + increased surface area ; 10 control temperature / reference to temp. between 25–45 °C ; 11 removal of CO2 / pH control / ref. a pH between 5–8 ; 12 temperature / pH + enzymes ; 13 maximum / increased + growth ; 14 extraction / filtration / purification / crystallisation ; 9

3 The flow chart shows steps taken in the production of yoghurt from milk. a starter culture containing two species of bacteria is added fruit may be added and the yoghurt is refrigerated the mixture is kept at 43 °C for several hours milk is cooled to 43 °C milk is heated to 90 °C for 15 minutes (a) Heating the milk to 90 °C for 15 minutes sterilises the milk. Suggest the importance of sterilising the milk. … … … … [2] (b) Explain why the milk must be cooled to 43 °C before the starter culture of bacteria is added. … … … … … … [3] (c) The two species of bacteria added to the milk are not mobile and are not pathogens. (i) State the external structure used for movement by some species of bacteria. … [1] (ii) Explain why it is important that the bacteria added to milk are not pathogens. … … [1] (d) Describe, with reference to named chemicals, the role of the bacteria during the time for which the mixture is kept at 43 °C. … … … … … … … … [4] (e) Suggest and explain one benefit to human health of eating yoghurt to which fruit has been added rather than eating yoghurt to which no fruit has been added. … … … … [2] [Total: 13]

3(a) kill + bacteria / fungi / microorganisms ; removal of pathogens ; removal of competition (with starter culture bacteria) ; no products that might change taste of yoghurt AW ; 2 3(b) prevent denaturation ; of enzymes ; reference to optimum temperature ; reference to (starter culture) bacteria not killed ; increase / maximum + yield of product ; 3 3(c)(i) flagella / flagellum / cilia ; 1 3(c)(ii) do not cause disease ; 1 3(d) enzymes (in bacteria) ; digest ; proteins (in milk) ; (convert) lactose ; to lactic acid ; milk thickens ; 4 3(e) vitamin C ; prevention of scurvy / aids gum health AW ; fibre ; prevention of constipation / aids peristalsis AW ; 2 To earn marks, you must state that sterilising kills unwanted microorganisms (bacteria/fungi), removes pathogens, eliminates competition for the starter culture, or prevents products that could alter the yoghurt's taste. To earn marks, you must explain that cooling prevents denaturation of enzymes, ensures the temperature is optimal for the starter culture bacteria, and prevents the bacteria from being killed, leading to maximum product yield. To earn the mark, you must name 'flagella' or 'cilia'. To earn the mark, you must state that the bacteria do not cause disease. To earn marks, you must explain that bacterial enzymes digest milk proteins, convert lactose to lactic acid, and this process causes the milk to thicken. To earn marks, you must name vitamin C and its function (e.g., preventing scurvy), and fibre and its function (e.g., preventing constipation).

Cambridge O Level Biology · 5090

O-Level Biology (5090) Biotechnology and genetic modification past paper questions

Revise O-Level Biology (5090) — Biotechnology and genetic modification with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

36 free questions from 2017–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Biotechnology and genetic modification in O-Level Biology 5090 exams, 2020–2025

Across 2020–2025, Biotechnology and genetic modification accounted for 36 questions worth 155 marks in Cambridge O Level Biology (5090) papers.

By year
Year	Questions	Marks
2020	7	29
2021	7	35
2022	9	18
2023	4	21
2024	5	32
2025	4	20

Most-tested subtopics

18.1 Biotechnology109 marks
18.2 Genetic modification22 marks

Appears in

Paper 1 · 24 qs
Paper 2 · 12 qs

All most-tested Biology topics

2021 Oct/Nov · Paper 2 · Q5 · 11 marks
Marking scheme
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2021 May/Jun · Paper 2 · Q6 · 10 marks
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2021 May/Jun · Paper 2 · Q9 · 10 marks
Marking scheme
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2020 May/Jun · Paper 2 · Q3 · 13 marks
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2021 May/Jun · Paper 1 · Q27 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q27
Answer: C
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