O Level / IGCSE Biology chapter 18: Biotechnology and genetic modification MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
19 exam-style questions on Biotechnology and genetic modification, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Ten Biotechnology and genetic modification questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. Why is sterile air bubbled through a fermenter used to grow a fungus that makes penicillin?
A
to cool the fermenter as the fungus grows
B
to stir up the waste products so they are removed
C
to provide oxygen for aerobic respiration
D
to add carbon dioxide for the fungus to photosynthesise
Show answer
Answer: C. The fungus respires aerobically, so it needs oxygen. The air is sterile so no other microorganisms get in.
2. What is genetic modification?
A
mixing genes from two parents by sexual reproduction
B
producing identical offspring from a single parent
C
breeding the best animals together over many generations
D
altering an organism's genes by inserting or removing DNA
Show answer
Answer: D. Genetic modification directly alters specific genes. Selective breeding works over generations with whole organisms.
3. Why is the pH inside a fermenter monitored and controlled?
A
a low pH increases the temperature of the culture
B
enzymes work best at a particular pH
C
a constant pH makes sure the culture stays sterile
D
pH changes the amount of oxygen that dissolves
Show answer
Answer: B. Waste products can change the pH of the culture; enzymes are less active, or denatured, away from their optimum pH.
4. Some people worry that crops modified to produce an insecticide may harm the environment. Which concern is most valid?
A
people who eat the crop will become resistant to insecticides
B
the plants will no longer be able to photosynthesise
C
the crops will need much more water than normal plants do
D
it could harm insects that are not pests, such as bees
Show answer
Answer: D. Non-target insects feeding on the plant or its pollen could be harmed, reducing biodiversity.
5. How is human insulin produced commercially?
A
bacteria are selectively bred until they produce insulin
B
yeast is used to make insulin by anaerobic respiration
C
the human gene is put into bacteria, which then make insulin
D
insulin is extracted from the pancreases of donated human bodies
Show answer
Answer: C. Bacteria given the human insulin gene make human insulin, which is collected from large fermenters.
6. Why are bacteria suitable for producing human insulin after genetic modification?
A
they already make small amounts of insulin of their own
B
they reproduce sexually, so the insulin gene is passed on easily
C
they reproduce rapidly, so many copies of the gene are made
D
they have a nucleus like human cells and so can read the gene
Show answer
Answer: C. Each bacterium copies the inserted gene when it divides, so a huge population producing insulin grows quickly.
7. Why are plasmids useful in genetic modification of bacteria?
A
they contain the whole genome of the bacterium
B
they are enzymes that cut DNA at particular places
C
they make the bacteria reproduce faster than normal
D
they are small rings of DNA that can carry a new gene
Show answer
Answer: D. Plasmids are small circles of DNA. They can be cut open, have a new gene inserted and be taken up by bacteria, which then make the gene's product.
8. What is a possible risk of growing herbicide-resistant GM crops?
A
the resistance gene could spread to wild plants
B
the crop will not produce any seeds for the farmer
C
the crop will contain fewer vitamins than normal plants
D
the crop will be killed by the herbicide it was designed for
Show answer
Answer: A. Pollen from a GM crop could spread the resistance gene to related wild plants, creating weeds that herbicides cannot kill.
9. How does pectinase help in fruit juice production?
A
it adds sugar so that the juice tastes sweeter
B
it kills bacteria in the fruit before it is pressed
C
it breaks down pectin, releasing more juice
D
it breaks down starch in the fruit into glucose
Show answer
Answer: C. Pectin holds plant cells together; pectinase breaks it down, so more juice is released and the juice is clearer.
10. Why must a fermenter be cooled with a water jacket?
A
to keep the pH of the culture from changing
B
to stop the culture being contaminated by other microbes
C
the microorganisms need cold conditions in order to grow
D
respiration releases heat that could denature enzymes
Show answer
Answer: D. The microorganisms release heat as they respire; cooling keeps the temperature near the optimum for their enzymes so that they are not denatured.
Biotechnology and genetic modification: questions students ask
How many Biotechnology and genetic modification MCQs are there?
19, each with the answer and a short explanation, across 2 topics: Biotechnology, Genetic modification. Every chapter test draws ten of them, so you can take it many times.
Is the O Level / IGCSE Biology chapter 18 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
