IGCSE Biology: Biotechnology and Genetic Modification Practice Questions
Biotechnology uses microorganisms to make useful products. Bacteria are ideal because they reproduce very rapidly, contain plasmids that can carry inserted genes, and raise fewer ethical concerns than using animals.
Topic 21 of Cambridge IGCSE Biology 0610 is the final topic and often the least revised, which makes it an easy source of marks. The insulin production sequence and the list of reasons bacteria are useful are both standard questions with fixed mark points. The questions below cover both, plus fermenters and GM crops.
What you need to know for Biotechnology and Genetic Modification
- Why bacteria are usefulThey reproduce very rapidly in favourable conditions, they contain plasmids that can be cut and used to carry genes from other species, they can make complex molecules, they have few ethical concerns compared with animals, and they can be grown on a wide range of inexpensive nutrients.
- Restriction enzymes and ligaseRestriction enzymes cut DNA at specific sequences, leaving sticky ends. DNA ligase joins the cut ends of the required gene and the plasmid together.
- Fermenter conditionsTemperature is controlled by a water jacket to keep enzymes at their optimum without denaturing them, pH is monitored and adjusted, oxygen is supplied for aerobic respiration, nutrients are added, and the mixture is stirred to keep the organisms and nutrients evenly distributed.
- Yeast in industryAnaerobic respiration by yeast produces ethanol for biofuel and alcoholic drinks, and carbon dioxide that makes bread dough rise.
- Enzymes in industryPectinase increases fruit juice yield, biological washing powders contain protease and lipase to remove stains, and lactase is used to produce lactose free milk.
- GM cropsAdvantages include higher yield, improved nutritional value such as extra vitamins, and resistance to pests, disease or herbicides. Concerns include effects on non-target species, transfer of genes to wild plants, and control of seed supply by a small number of companies.
IGCSE Biology Biotechnology and Genetic Modification questions and answers
4 exam-style questions written to the 0610 syllabus. Try each one on paper first, then open the worked answer to check your method against the marks.
Explain why bacteria are particularly useful for producing human proteins such as insulin.
Show the worked answer
- Bacteria reproduce very rapidly in favourable conditions, so a large population producing the protein can be built up quickly.
- They contain plasmids, small circular pieces of DNA that can be removed, cut open and used as vectors to carry a human gene into the bacterium.
- The genetic code is universal, so a human gene inserted into a bacterium is transcribed and translated to make the correct human protein.
- Bacteria can be grown on inexpensive nutrient media, and their use raises far fewer ethical objections than extracting insulin from animals.
Describe how genetic modification is used to produce human insulin from bacteria.
Show the worked answer
- Identify the human insulin gene and cut it out of the human DNA using a restriction enzyme, which leaves sticky ends.
- Cut open a bacterial plasmid using the same restriction enzyme, so it has complementary sticky ends.
- Join the insulin gene into the plasmid using DNA ligase, forming a recombinant plasmid.
- Insert the recombinant plasmid into a bacterium, which now carries the human insulin gene.
- Culture the modified bacteria in a fermenter under controlled conditions. They reproduce rapidly and express the gene, producing insulin, which is then extracted and purified.
State three conditions that must be controlled inside an industrial fermenter and explain why each matters.
Show the worked answer
- Temperature is controlled using a water jacket. It must be high enough for a fast reaction rate but not so high that the enzymes of the microorganism denature.
- pH is monitored by probes and adjusted. Enzymes have an optimum pH, and a change reduces the rate or denatures them.
- Oxygen is supplied by sterile air bubbled through the mixture, because the microorganisms respire aerobically to release the energy needed for growth and product formation.
- Nutrients are added and the mixture is stirred by paddles to keep the microorganisms and nutrients evenly distributed and to prevent settling.
Give one advantage and one concern associated with growing genetically modified crops.
Show the worked answer
- Advantage: crops can be modified to resist pests, disease or herbicides, or to tolerate drought, so yields are higher and less pesticide is needed. Crops can also be given improved nutritional value, such as extra vitamin A.
- This can help address food shortages and specific dietary deficiencies in some regions.
- Concern: the inserted gene may transfer by pollen to wild relatives, for example spreading herbicide resistance to weeds.
- Other concerns include effects on non-target insect species, reduced biodiversity from large scale monoculture, and dependence of farmers on a small number of seed companies.
Common mistakes in this topic
- Forgetting to say the same restriction enzyme is used on both the gene and the plasmid. That is why the sticky ends match.
- Confusing restriction enzyme with ligase. Restriction enzymes cut, ligase joins.
- Describing selective breeding as genetic modification.
- Saying yeast produces carbon dioxide in bread by aerobic respiration. Dough rising relies on anaerobic respiration.
- Listing fermenter conditions without explaining why each is needed.
Exam tips
- Learn the five step insulin sequence in order. Cambridge marks each step separately.
- Use the phrase the genetic code is universal. It explains why a human gene works in a bacterium and often earns a mark.
- For fermenter questions, name the physical feature as well as the condition: water jacket, pH probe, sterile air inlet, paddles.
- Balance GM answers. If asked to discuss, give both benefits and concerns even if the question seems one sided.
- Link biological washing powders back to enzyme optimum temperatures. The two topics are often combined.
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Biotechnology and Genetic Modification FAQs
Why are bacteria used in genetic modification?
Bacteria reproduce very rapidly, so large populations can be grown quickly. They contain plasmids that can be cut open and used to carry a gene from another organism. The genetic code is universal, so a human gene inserted into a bacterium produces the correct human protein. They also grow on cheap nutrients and raise fewer ethical concerns than animals.
How is human insulin produced using bacteria?
A restriction enzyme cuts the human insulin gene out of human DNA, and the same enzyme cuts open a bacterial plasmid so the sticky ends match. DNA ligase joins the gene into the plasmid, the recombinant plasmid is inserted into a bacterium, and the modified bacteria are cultured in a fermenter where they produce insulin, which is then extracted and purified.
What conditions are controlled in a fermenter?
Temperature, using a water jacket to stay at the optimum without denaturing enzymes. pH, monitored by probes and adjusted as needed. Oxygen, supplied as sterile air for aerobic respiration. Nutrients are added, the contents are stirred by paddles to keep everything evenly distributed, and the vessel is kept sterile to exclude competing microorganisms.
What are the arguments against genetically modified crops?
Inserted genes may transfer by pollen to wild relatives, potentially spreading herbicide resistance to weeds. There may be effects on non-target insect species and reduced biodiversity from large scale monoculture. There are also economic concerns about farmers depending on a small number of companies that control the seed supply.
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Written to the published Cambridge IGCSE Biology (0610) syllabus. Check your school entry code and syllabus year, because Core and Extended candidates are assessed on different content. Last reviewed 2026-08-12.