IGCSE Biology Topic 21: Biotechnology and genetic modification MCQs – 30 Practice Questions with Answers (Cambridge 0610)
Free practice for Cambridge IGCSE Biology 0610 on biotechnology and genetic modification, covering useful microbes, enzymes, fermenters and the genetic modification of bacteria and crops, with every question followed by a worked explanation.
Why Bacteria Are Useful in Biotechnology
Q1. Why is the rapid reproduction rate of bacteria an advantage in biotechnology?
- (A) Large numbers of bacteria can be grown quickly for production
- (B) Individual bacteria grow to a very large size before they divide in two
- (C) Bacteria need no nutrients in order to grow
- (D) Bacteria never change during growth
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Answer: A – Fast division means a small starter culture can soon provide the huge numbers needed for large-scale production.
Q2. What useful ability makes bacteria valuable for making human proteins?
- (A) They can make only simple sugars and no other useful molecules at all for industry
- (B) They can make complex molecules, including proteins from an inserted gene
- (C) They can make only waste products
- (D) They can make no useful products at all
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Answer: B – Bacteria carry out protein synthesis, so a bacterium given a human gene can produce the human protein it codes for.
Q3. Why are there fewer ethical concerns about manipulating bacteria than about manipulating animals?
- (A) No safety rules apply to growing bacteria
- (B) Bacteria experience pain in the same way as animals and other living things
- (C) There are few ethical concerns over the manipulation and growth of bacteria
- (D) Bacteria are not living organisms
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Answer: C – Bacteria are single-celled microbes without sentience, so growing and altering them raises far fewer ethical objections than work with animals.
Q4. What is a plasmid, and why is it useful in genetic modification?
- (A) An energy-releasing structure inside the cell that powers all of the cell’s activities and growth
- (B) A rigid layer forming the cell wall
- (C) The central nucleus of the bacterial cell
- (D) A small, separate piece of DNA that can carry an inserted gene into a bacterium
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Answer: D – Plasmids are small circular DNA molecules separate from the main chromosome, and they can be cut open to receive a new gene.
Q5. What does biotechnology mean?
- (A) Using living organisms or their products, such as enzymes, to make useful things
- (B) Breeding from chosen parents within one species only
- (C) The use of farm machinery to harvest crops
- (D) The purely chemical synthesis of medicines in factories, without any living organisms
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Answer: A – Biotechnology covers processes from bread-making to fermenter production, all based on living organisms or what they produce.
Yeast, Enzymes and Everyday Biotechnology
Q6. During the production of ethanol for biofuels, what does anaerobic respiration in yeast produce?
- (A) Oxygen gas released from the yeast cells
- (B) Ethanol and carbon dioxide
- (C) Lactic acid only
- (D) Methane gas
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Answer: B – Without oxygen, yeast respire glucose anaerobically, giving ethanol as the useful product for fuel.
Q7. In bread-making, why is anaerobic respiration by yeast useful?
- (A) The ethanol produced makes the dough rise as it evaporates during baking
- (B) The oxygen produced makes the dough rise
- (C) The carbon dioxide produced forms bubbles that expand the dough
- (D) The lactic acid produced makes the dough rise
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Answer: C – Carbon dioxide gas is trapped in the sticky dough, making it rise, while the small amount of ethanol is driven off during baking.
Q8. Biofuel production and bread-making both use yeast. What is the same, and what differs?
- (A) Different organisms are used in each process
- (B) Bread-making uses aerobic respiration while biofuel production uses anaerobic respiration only
- (C) Biofuel production uses bacteria instead of yeast
- (D) Both use anaerobic respiration in yeast; biofuel values ethanol, bread values carbon dioxide
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Answer: D – The yeast process is the same in both cases; only the product that matters most is different.
Q9. Why is the enzyme pectinase used in fruit juice production?
- (A) It breaks down pectin in fruit pulp, giving clearer juice and a higher yield
- (B) It sweetens the juice by adding sugar during the pressing of the fresh fruit pulp
- (C) It kills bacteria in the juice
- (D) It adds colour to the juice
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Answer: A – Pectin makes pulp thick and cloudy, so digesting it releases more juice and leaves it clear.
Q10. How do biological washing powders containing enzymes remove stains?
- (A) By bleaching the fabric white and removing colour from the stain molecules entirely
- (B) By breaking down stain molecules, such as proteins and fats, into soluble pieces
- (C) By softening the water only
- (D) By adding fragrance to the clothes
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Answer: B – Proteases, amylases and lipases digest the large molecules in stains, so they dissolve and wash away, even at lower temperatures.
Q11. How does lactase produce lactose-free milk?
- (A) By removing all sugar from the milk so that it tastes completely unsweetened
- (B) By adding extra lactose to the milk
- (C) By breaking down lactose into smaller sugars that can be digested
- (D) By fermenting the milk into yoghurt
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Answer: C – Lactase splits lactose into glucose and galactose, which people who lack lactase can digest.
Fermenters and Large-Scale Production
Q12. Which products can be made on a large scale by bacteria and fungi in fermenters?
- (A) Bread and wine only, made in small batches at home
- (B) Chemical fertilisers
- (C) Plastics for packaging
- (D) Insulin, penicillin and mycoprotein
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Answer: D – Fermenters grow genetically modified bacteria for insulin, fungi for penicillin and fungi for the protein-rich food mycoprotein.
Q13. Why must temperature be carefully controlled in a fermenter?
- (A) Microbes and enzymes work best near an optimum, and high heat denatures enzymes
- (B) Hotter conditions always give faster production and higher yields in every fermenter process
- (C) Temperature has no effect on microbial growth
- (D) Cold conditions always increase the yield
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Answer: A – Growth and enzyme action rise with temperature only up to an optimum, beyond which enzymes denature and cells die.
Q14. Why must pH be controlled in a fermenter?
- (A) pH affects only the colour of the product and never the microbes growing inside it
- (B) Enzymes work best at an optimum pH, so drifting pH slows or stops production
- (C) pH has no effect on microbes
- (D) Acidic conditions are always best for every product
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Answer: B – Enzyme shape and activity depend on pH, so the fermenter is kept near the optimum for the organism and its enzymes.
Q15. How is the oxygen supply managed in a fermenter?
- (A) Oxygen is always pumped in at maximum rate throughout the whole process without exception
- (B) Oxygen is always completely excluded
- (C) It is controlled to suit the organism, supplied where aerobic and limited otherwise
- (D) Oxygen is used only to stir the mixture
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Answer: C – Some fermenter processes need oxygen for aerobic growth, while others, such as ethanol production by yeast, must limit it.
Q16. Why must nutrient supply and waste products be managed in a fermenter?
- (A) Waste products are left to build up without harm to the growing microbes inside
- (B) Nutrients are added only once at the start
- (C) Waste products steadily increase the yield
- (D) Nutrients are topped up, and waste is removed before it harms the microbes
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Answer: D – Microbes consume nutrients as they grow, and their waste can poison them, so both must be managed to keep production going.
Q17. What is mycoprotein?
- (A) A protein-rich food produced by growing fungi in a fermenter
- (B) An antibiotic made by bacteria growing in large industrial fermenter vessels
- (C) A protein extracted from crop plants
- (D) Ethanol produced by yeast
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Answer: A – Mycoprotein is made from filamentous fungi grown in fermenters and is used as a meat alternative.
Q18. Which type of organism produces penicillin in a fermenter?
- (A) A bacterium of the kind used to make insulin
- (B) A fungus of the Penicillium group
- (C) A green plant
- (D) An animal cell culture
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Answer: B – Penicillin is an antibiotic made naturally by Penicillium fungi, which are grown on a large scale in fermenters.
Genetic Modification: Process, Crops and Debate
Q19. What does genetic modification mean?
- (A) Crossing two parents of the same species
- (B) Selecting parents with wanted features over generations within one species only
- (C) Changing an organism’s genetic material by removing or inserting single genes
- (D) Cloning a whole organism without changing its genes
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Answer: C – Genetic modification works directly on genes, rather than by choosing which individuals breed.
Q20. How does genetic modification differ from selective breeding?
- (A) The two processes are identical
- (B) Genetic modification works only within a single species and never transfers genes between species
- (C) Selective breeding inserts genes from another species
- (D) Genetic modification moves genes between species; selective breeding stays in one species
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Answer: D – This is the key distinction: a human gene can be placed in a bacterium, but selective breeding cannot cross a human with a bacterium.
Q21. Why are human genes inserted into bacteria?
- (A) So that the bacteria produce a human protein, such as insulin
- (B) So that the bacteria become human cells with a human nucleus and organelles
- (C) So that the bacteria produce antibiotics only
- (D) So that the bacteria can photosynthesise
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Answer: A – Bacteria carrying the human insulin gene synthesise human insulin, which can then be collected and purified.
Q22. In the production of a human protein by bacteria, what do restriction enzymes do?
- (A) They join pieces of DNA together to form a recombinant plasmid molecule
- (B) They cut DNA at specific sequences, leaving sticky ends
- (C) They copy plasmids inside the cell
- (D) They insert plasmids into bacterial cells
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Answer: B – The same restriction enzyme cuts both the human DNA and the plasmid DNA, so the sticky ends match.
Q23. What is the role of DNA ligase in forming a recombinant plasmid?
- (A) It cuts the plasmid DNA open at specific sequences to receive the human gene
- (B) It copies the human gene many times
- (C) It seals the human DNA into the plasmid DNA, joining the fragments
- (D) It multiplies the bacteria carrying the plasmid
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Answer: C – Ligase joins the complementary sticky ends, producing a single recombinant plasmid carrying the human gene.
Q24. After recombinant plasmids are formed, what happens next?
- (A) They are injected directly into patients to treat the disease at once and for all
- (B) They are planted in soil to grow
- (C) They are fed to farm animals
- (D) They are inserted into bacteria, which multiply and express the gene
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Answer: D – Bacteria that take up the recombinant plasmid are grown in a fermenter, where they produce the human protein.
Q25. What is the purpose of inserting a herbicide-resistance gene into a crop plant?
- (A) Farmers can spray to kill weeds without killing the crop
- (B) The crop no longer needs any water to grow in dry conditions
- (C) The crop kills all insect pests itself
- (D) The crop grows without sunlight
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Answer: A – A herbicide-resistant crop survives spraying that kills competing weeds, keeping yields up.
Q26. What is the purpose of inserting an insect-resistance gene into a crop plant?
- (A) The crop repels every animal that approaches it, including birds and mammals
- (B) The crop suffers less insect damage, so more of it survives to harvest
- (C) The crop no longer needs soil to grow
- (D) The crop grows much taller than usual
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Answer: B – Insect resistance reduces losses to pests, which can also cut the need for insecticide spraying.
Q27. What is meant by improving the nutritional qualities of a crop by genetic modification?
- (A) The crop never spoils after harvest, however long it is stored before sale
- (B) The crop tastes exactly like meat
- (C) The crop is given genes that raise the level of a nutrient it contains
- (D) The crop needs no harvesting at all
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Answer: C – A crop can be modified to produce more of a vitamin or other nutrient, improving its value as food.
Q28. Which is a possible advantage of genetically modifying crops?
- (A) There is guaranteed to be no effect on the environment or on wild relatives nearby
- (B) Farmers never need to buy seed again
- (C) The crop will succeed in every climate
- (D) Yields may rise because losses to pests, weeds or poor nutrition are reduced
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Answer: D – Resistance traits and improved nutrition can protect yields, though the size of the gain depends on local conditions.
Q29. Which is a possible disadvantage or concern about genetically modified crops?
- (A) Modified genes may spread to wild relatives, and farmers may rely on seed suppliers
- (B) Modified crops always fail completely in every field where they are grown each year without exception
- (C) Modified crops contain no genes at all
- (D) Farmers need no knowledge to grow them
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Answer: A – Gene flow to wild plants and dependence on companies that supply seed are both recognised concerns raised about GM crops.
Q30. A student is asked to discuss genetically modified crops. What makes a good exam answer?
- (A) Considering only the yield, and nothing else about risks, ethics or the environment
- (B) Weighing benefits against risks and ethical questions, not one-sided claims
- (C) Stating that genetic modification is always unethical
- (D) Stating that genetic modification carries no risks
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Answer: B – A balanced discussion covers advantages, disadvantages and ethical issues, since the topic involves science and values together.
Revisit any questions you missed, especially the order of steps in bacterial production of a human protein and the balanced case for and against GM crops, then test yourself again without looking at the answers.