O Level / IGCSE Biology MCQs with answers
Practise O Level / IGCSE Biology (5090 / 0610) with 560 exam-style MCQs, each with the answer and a short explanation. Every test is marked the moment you finish and shows your score chapter by chapter, so you know what to revise next. It is free and needs no sign-up.
560 questions · 19 chapters · 14 Cambridge past papers · 5 mock exams
What each chapter covers 19 chapters
The questions follow the syllabus chapter by chapter. You can test the whole subject or one chapter at a time.
- Cells 20 questionsCell structure and function, Specialised cells, tissues and organs
- Classification 20 questionsConcept and use of a classification system, Features of organisms
- Movement into and out of cells 21 questionsDiffusion and osmosis, Active transport
- Biological molecules 11 questions
- Enzymes 19 questionsEnzyme action, Effects of temperature and pH
- Plant nutrition 33 questionsPhotosynthesis, Leaf structure, Mineral nutrition
- Transport in flowering plants 21 questionsUptake and transport of water and ions, Transpiration and translocation
- Human nutrition 34 questionsDiet, Human digestive system, Absorption and assimilation
- Human gas exchange 12 questions
- Respiration 26 questionsRespiration, Aerobic respiration, Anaerobic respiration
- Transport in humans 43 questionsCirculatory system, Heart, Blood vessels, Blood
- Disease and immunity 36 questionsDisease, Antibiotics, Immunity
- Excretion 20 questionsExcretion, Urinary system
- Coordination and control 60 questionsMammalian nervous system, Mammalian sense organs, Mammalian hormones, Homeostasis, Temperature control, Blood glucose control
- Coordination and response in plants 11 questions
- Development of organisms and continuity of life 57 questionsNuclear division, Asexual and sexual reproduction, Sexual reproduction in plants, Sexual reproduction in humans
- Inheritance 45 questionsVariation, DNA, Inheritance, Selection
- Biotechnology and genetic modification 19 questionsBiotechnology, Genetic modification
- Relationships of organisms with one another and with the environment 52 questionsEnergy flow, Nutrient cycles, Ecosystems and biodiversity, Effects of humans on ecosystems, Conservation
Sample O Level / IGCSE Biology MCQs with answers 12 questions
12 questions from the test, one or two from each chapter. Try each one, then open the answer.
1. A mitochondrion is 3 µm long. A student draws it at a magnification of ×20 000. How long is the drawing, in mm?
- A
600 mm
- B
6 mm
- C
0.06 mm
- D
60 mm
Show answer
Answer: D. Drawing length = actual length × magnification = 3 µm × 20 000 = 60 000 µm, and 60 000 µm ÷ 1000 = 60 mm.
2. A horse and a donkey can mate to produce a mule, but mules are infertile. What does this show?
- A
they belong to different genera, because they look different from each other
- B
they are the same species, because they are able to mate with each other
- C
they are different species, because the mule is infertile
- D
the mule is a new species, because it is a mixture of both parents
Show answer
Answer: C. Members of one species can reproduce to produce fertile offspring. A mule is infertile, so a horse and a donkey are different species even though they can mate.
3. What is needed for active transport but not for diffusion?
- A
energy from respiration
- B
a concentration gradient
- C
a partially permeable membrane
- D
a high temperature
Show answer
Answer: A. Active transport uses energy released by respiration. Diffusion relies only on the random movement of particles.
4. A food is shaken with ethanol and the liquid is then poured into water. A cloudy white emulsion forms. Which nutrient is present?
- A
lipid
- B
protein
- C
starch
- D
glucose
Show answer
Answer: A. Lipids dissolve in ethanol; when mixed with water they form tiny droplets that make a milky emulsion.
5. A student adds protease to a solution of amylase. The amylase then stops digesting starch. What is the best explanation?
- A
the protease changes the pH so the amylase is denatured
- B
the protease uses up the starch that amylase needs
- C
the protease digests the amylase, because amylase is a protein
- D
the protease raises the temperature of the mixture
Show answer
Answer: C. Enzymes are proteins, so a protease digests amylase into amino acids and it can no longer work. The protease does not act on starch.
6. On a bright winter day the temperature in a greenhouse is 5 °C and the carbon dioxide concentration is high. Which change would most increase the rate of photosynthesis?
- A
adding extra lamps to raise the light intensity above that of the Sun
- B
increasing the humidity so that the stomata stay open for longer
- C
shading the plants to reduce water loss on the bright day
- D
raising the temperature with heaters
Show answer
Answer: D. Light and carbon dioxide are already plentiful, but 5 °C is too cold for the enzymes to work quickly, so temperature is the limiting factor. Raising it increases the rate.
7. What is transpiration?
- A
the uptake of water by roots
- B
the loss of water vapour from leaves
- C
the transport of sucrose in the phloem
- D
the movement of water in the xylem only
Show answer
Answer: B. Transpiration is the loss of water vapour from the leaves, mainly through the stomata.
8. In which region of the gut are most digested nutrients absorbed?
- A
the stomach
- B
the small intestine
- C
the large intestine
- D
the oesophagus
Show answer
Answer: B. Most digested nutrients are absorbed in the small intestine, where the ileum is folded into villi to give a large surface area.
9. How do goblet cells and ciliated cells protect the gas exchange system?
- A
goblet cells make enzymes that digest bacteria; cilia beat to push air into the lungs
- B
goblet cells make mucus to trap dust and pathogens; cilia move the mucus to the throat
- C
ciliated cells make mucus that traps dust; goblet cells sweep the mucus to the throat
- D
goblet cells absorb oxygen from the air; cilia beat to pump air down to the alveoli
Show answer
Answer: B. Goblet cells produce mucus that traps dust and pathogens, and the ciliated cells beat to move the mucus towards the throat, where it is swallowed or coughed out.
10. Hydrogencarbonate indicator is red; it turns yellow when carbon dioxide increases and purple when it decreases. Maggots are kept above red indicator in a sealed tube in the dark for one hour. What colour does the indicator become?
- A
colourless, because the maggots use up all of the indicator
- B
yellow, because the maggots respire and release carbon dioxide
- C
red, because the maggots do not respire when there is no light
- D
purple, because the maggots absorb carbon dioxide in the dark
Show answer
Answer: B. Maggots respire, releasing carbon dioxide into the tube, so the indicator turns yellow. Animals respire in the dark and in the light.
11. Which blood vessel carries oxygenated blood from the lungs to the heart?
- A
pulmonary vein
- B
pulmonary artery
- C
aorta
- D
vena cava
Show answer
Answer: A. The pulmonary vein is the only vein carrying oxygenated blood. The pulmonary artery carries deoxygenated blood to the lungs.
12. Which is an example of passive immunity?
- A
a baby receives antibodies from its mother across the placenta
- B
a child produces its own antibodies after having chickenpox
- C
a teenager is given a measles vaccine containing weakened virus
- D
an adult makes memory cells after being infected with flu
Show answer
Answer: A. Passive immunity comes from antibodies made by another individual, such as via the placenta or breast milk.
Try 548 more questions
Ways to practise 7 ways
- Quick check. 10 questions drawn fresh each time, about 10 minutes.
- By chapter. 10 questions from one chapter, for the topic you are revising now.
- Full paper. A full-length timed paper across the whole syllabus.
- Past papers. 14 Cambridge multiple-choice papers, answered on screen and marked for you.
- Mock exams. 5 full papers of our own questions in the style of the real paper.
- Practice mode. See the right answer and an explanation after every question, with no clock.
- Exam mode. Timed like the real paper, with no going back.
When you get a question wrong, a short note called "The idea behind this" explains the topic it belongs to, with the rules to remember and a worked example.
Common questions
Is this O Level / IGCSE Biology test free?
Yes. Every test and every explanation is free, and you do not need an account. If you sign in, your results are kept across your devices.
Are these past paper questions?
The 560 MCQs are our own, written to the syllabus in the style of the exam. The 14 Cambridge past papers are listed separately inside the test.
How is the test marked?
Instantly. You get your score, the right answer and an explanation for every question, and a list of the topics to work on.
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