IGCSE Biology Practice Test 18 – 60 Questions with Answers (Cambridge 0610)
Use this test to practise applying syllabus ideas to new contexts, checking each answer before moving to the next question.
Characteristics and classification of living organisms
Q1. Which characteristic of living organisms involves making more organisms of the same kind?
- (A) Movement
- (B) Excretion
- (C) Sensitivity in this context, when the other conditions are taken into account
- (D) Reproduction
Show Answer
Answer: D – Reproduction produces new organisms, ensuring the continuation of the species.
Q2. Which group contains organisms with jointed legs and a hard exoskeleton?
- (A) Molluscs
- (B) Annelids
- (C) Arthropods
- (D) Cnidarians in this context, when the other conditions are taken into account
Show Answer
Answer: C – Arthropods, including insects and crustaceans, have jointed legs and an exoskeleton.
Q3. Which feature identifies an organism as a mammal?
- (A) Hair and mammary glands
- (B) Feathers and a beak
- (C) Scales and gills
- (D) A moist skin and no legs
Show Answer
Answer: A – Mammals have hair or fur and females produce milk from mammary glands.
Organisation of the organism
Q4. Which specialised cell carries oxygen in human blood?
- (A) Ciliated cell
- (B) Red blood cell
- (C) Root hair cell in this context, when the other conditions are taken into account
- (D) Palisade cell
Show Answer
Answer: B – Red blood cells are adapted with haemoglobin and no nucleus to carry oxygen efficiently.
Q5. Which example shows an organ system?
- (A) Digestive system
- (B) Muscle tissue
- (C) A single liver cell
- (D) A chloroplast
Show Answer
Answer: A – The digestive system is a group of organs working together to digest and absorb food.
Q6. Which cell is adapted for absorbing water in a plant root?
- (A) Guard cell
- (B) Root hair cell
- (C) Xylem vessel cell
- (D) Epidermal cell of a leaf
Show Answer
Answer: B – Root hair cells have a large surface area and thin walls for efficient water absorption.
Movement into and out of cells
Q7. Which statement about active transport is correct?
- (A) It needs no energy
- (B) It only moves water
- (C) It moves particles down a gradient in this context, when the other conditions are taken into account
- (D) It uses energy to move particles against a gradient
Show Answer
Answer: D – Active transport uses energy from respiration to move substances against their concentration gradient.
Q8. Which term describes a solution with the same solute concentration as cell cytoplasm?
- (A) Dilute solution
- (B) Concentrated solution
- (C) Isotonic solution
- (D) Saturated solution
Show Answer
Answer: C – An isotonic solution has the same water potential as the cell, so there is no net water movement.
Q9. A plant cell in a concentrated sugar solution becomes plasmolysed. What has happened?
- (A) The vacuole has burst
- (B) The cell wall has dissolved
- (C) Water has left the cell and the membrane has pulled away from the wall
- (D) Water has entered and the cell is turgid in this context, when the other conditions are taken into account
Show Answer
Answer: C – Water leaves by osmosis, the cytoplasm shrinks, and the membrane pulls away from the cell wall.
Biological molecules
Q10. Which molecule is formed when two glucose molecules join together?
- (A) Maltose
- (B) Starch, a large polysaccharide stored in plant cells for later use as an energy reserve
- (C) Sucrose
- (D) Cellulose
Show Answer
Answer: A – Two glucose molecules joined by condensation form maltose, a disaccharide.
Q11. Which test identifies the presence of lipids in a food sample?
- (A) Iodine test
- (B) Emulsion test with ethanol
- (C) Benedict’s test in this context, when the other conditions are taken into account
- (D) Biuret test
Show Answer
Answer: B – Mixing the sample with ethanol and adding water gives a milky emulsion if lipids are present.
Q12. Which sugar is a disaccharide made from glucose and fructose?
- (A) Starch
- (B) Cellulose
- (C) Glycogen
- (D) Sucrose
Show Answer
Answer: D – Sucrose is formed when a glucose molecule joins with a fructose molecule.
Enzymes
Q13. Which factor affects enzyme activity by changing the shape of the active site?
- (A) Substrate concentration only
- (B) Temperature and pH
- (C) Product colour
- (D) Light intensity
Show Answer
Answer: B – Both extreme temperature and pH can alter the active site shape and reduce enzyme activity.
Q14. Which statement is true of enzymes in a reaction?
- (A) They remain unchanged at the end of the reaction
- (B) They are converted into products
- (C) They increase the energy of products in this context, when the other conditions are taken into account
- (D) They work on any substrate
Show Answer
Answer: A – Enzymes are biological catalysts and are not used up, so they can act repeatedly.
Q15. At low substrate concentration, why does increasing substrate concentration increase the reaction rate?
- (A) Enzymes denature more slowly
- (B) More enzyme molecules are made in this context, when the other conditions are taken into account
- (C) The pH becomes optimal
- (D) More active sites become occupied
Show Answer
Answer: D – With more substrate particles available, collisions with active sites happen more often, so the rate rises.
Plant nutrition
Q16. Which ion is needed for healthy plant growth and protein synthesis, and is often added as fertiliser?
- (A) Magnesium ion
- (B) Calcium ion
- (C) Nitrate ion
- (D) Chloride ion
Show Answer
Answer: C – Nitrate provides nitrogen for amino acids and proteins, so deficiency stunts growth and yellows older leaves.
Q17. At which part of a leaf does most photosynthesis take place?
- (A) Upper epidermis, the transparent layer that protects the leaf surface from damage
- (B) Lower epidermis
- (C) Spongy mesophyll
- (D) Palisade mesophyll
Show Answer
Answer: D – Palisade cells are packed with chloroplasts and sit just below the upper surface, where light is strongest.
Q18. Which structure in a leaf controls gas exchange and water loss?
- (A) Midrib
- (B) Cuticle alone in this context, when the other conditions are taken into account
- (C) Stoma with guard cells
- (D) Vein network
Show Answer
Answer: C – Each stoma is a pore flanked by guard cells that open and close to regulate gas exchange.
Human nutrition
Q19. Which nutrient provides the most energy per gram?
- (A) Protein
- (B) Fat
- (C) Carbohydrate
- (D) Fibre
Show Answer
Answer: B – Fat releases about twice as much energy per gram as carbohydrate or protein.
Q20. Which food group is needed for growth and repair of body tissues?
- (A) Protein
- (B) Fat
- (C) Vitamin D
- (D) Water
Show Answer
Answer: A – Proteins provide amino acids used to build new cells and repair damaged tissues.
Q21. Which organ stores bile and releases it into the duodenum?
- (A) Liver
- (B) Gall bladder
- (C) Pancreas in this context, when the other conditions are taken into account
- (D) Appendix
Show Answer
Answer: B – Bile made in the liver is stored and concentrated in the gall bladder until needed for fat digestion.
Transport in plants
Q22. Which process moves water up a plant stem in the xylem?
- (A) Translocation
- (B) Active transport only
- (C) Diffusion of sugars
- (D) Transpiration pull
Show Answer
Answer: D – Water evaporating from leaves pulls more water up through the xylem in a continuous column.
Q23. A leafy shoot in a potometer shows faster water uptake on a windy day. Why?
- (A) Wind increases transpiration, raising water uptake
- (B) Wind closes the stomata
- (C) Wind cools the roots
- (D) Wind increases photosynthesis only in this context, when the other conditions are taken into account
Show Answer
Answer: A – Wind removes humid air around leaves, increasing transpiration and therefore water uptake.
Q24. Which statement about phloem is correct?
- (A) It carries water upwards only
- (B) It is made of dead hollow tubes
- (C) It carries sugars both up and down the plant
- (D) It is found only in roots
Show Answer
Answer: C – Phloem transports sucrose from sources such as leaves to sinks in either direction as needed.
Transport in animals
Q25. Which blood component helps blood to clot at a wound?
- (A) Red blood cells
- (B) Lymphocytes
- (C) Platelets
- (D) Plasma proteins only
Show Answer
Answer: C – Platelets gather at a wound and trigger clotting, sealing the damage and reducing blood loss.
Q26. Which vessel returns blood from the body to the right atrium?
- (A) Vena cava
- (B) Pulmonary vein
- (C) Coronary artery
- (D) Hepatic vein only
Show Answer
Answer: A – The vena cava collects deoxygenated blood from the body and delivers it to the right atrium.
Q27. What is the function of the bicuspid valve in the heart?
- (A) It stops blood entering the aorta
- (B) It separates the two ventricles
- (C) It pumps blood to the lungs
- (D) It prevents backflow from ventricle to atrium on the left side
Show Answer
Answer: D – The bicuspid valve between the left atrium and left ventricle prevents blood flowing backwards.
Diseases and immunity
Q28. Which pathogen causes malaria?
- (A) A bacterium
- (B) A protoctist
- (C) A virus
- (D) A fungus
Show Answer
Answer: B – Malaria is caused by Plasmodium, a protoctist carried by female Anopheles mosquitoes.
Q29. How does passive immunity differ from active immunity?
- (A) It lasts longer
- (B) It requires memory cells
- (C) It involves vaccination
- (D) Ready-made antibodies are given and protection is short-lived
Show Answer
Answer: D – In passive immunity, antibodies are supplied directly, giving immediate but temporary protection.
Gas exchange in humans
Q30. Which muscle relaxes during exhalation to reduce chest volume?
- (A) External intercostal muscle
- (B) Diaphragm
- (C) Abdominal muscle only
- (D) Internal intercostal muscle
Show Answer
Answer: B – The diaphragm relaxes and domes upwards during exhalation, reducing the volume of the chest cavity.
Q31. Which gas is at the highest concentration in inhaled air compared with exhaled air?
- (A) Carbon dioxide
- (B) Water vapour
- (C) Oxygen
- (D) Nitrogen
Show Answer
Answer: C – Inhaled air contains about 21 percent oxygen, while exhaled air contains about 16 percent after uptake.
Respiration
Q32. Which statement about anaerobic respiration in humans is correct?
- (A) Glucose is broken down without oxygen to lactic acid
- (B) Glucose is fully broken down to water
- (C) Much more energy is released than aerobically
- (D) Oxygen is produced as a product
Show Answer
Answer: A – Without oxygen, glucose is only partly broken down, yielding lactic acid and much less energy.
Q33. Which organ system increases its activity most during prolonged exercise?
- (A) Circulatory and respiratory systems working together
- (B) Digestive system alone
- (C) Excretory system alone
- (D) Reproductive system
Show Answer
Answer: A – The heart and lungs work harder to deliver oxygen and remove carbon dioxide during exercise.
Excretion in humans
Q34. Which waste product is excreted by the lungs?
- (A) Urea
- (B) Excess salts
- (C) Carbon dioxide
- (D) Bile pigments
Show Answer
Answer: C – Carbon dioxide produced in respiration diffuses into the alveoli and is breathed out.
Q35. Which part of the nephron is a tangled knot of capillaries?
- (A) Collecting duct
- (B) Glomerulus
- (C) Loop of Henle
- (D) Ureter
Show Answer
Answer: B – The glomerulus is a knot of capillaries where ultrafiltration takes place under high pressure.
Q36. A person drinks very little water on a hot day. What urine is expected?
- (A) Large volume, dilute
- (B) Large volume, concentrated in this context, when the other conditions are taken into account
- (C) No urine at all
- (D) Small volume, concentrated
Show Answer
Answer: D – ADH release increases water reabsorption, conserving water and producing concentrated urine in small volume.
Coordination and response
Q37. Which structure in the eye detects light and produces impulses?
- (A) Lens, which changes shape to focus light onto the back of the eye
- (B) Cornea
- (C) Retina
- (D) Iris
Show Answer
Answer: C – Light-sensitive cells in the retina convert light into nerve impulses sent to the brain.
Q38. Which part of the brain coordinates balance and fine movement?
- (A) Cerebrum
- (B) Cerebellum
- (C) Medulla
- (D) Hypothalamus
Show Answer
Answer: B – The cerebellum coordinates posture, balance and precise movements.
Q39. In bright light, what happens to the pupil of the eye?
- (A) It constricts to reduce light entering
- (B) It dilates to admit more light
- (C) It changes colour
- (D) It moves to the side
Show Answer
Answer: A – Circular iris muscles contract in bright light, making the pupil smaller to protect the retina.
Drugs
Q40. Which chemical in cigarette smoke reduces oxygen transport in blood?
- (A) Nicotine
- (B) Tar
- (C) Oxygen
- (D) Carbon monoxide
Show Answer
Answer: D – Carbon monoxide binds to haemoglobin more readily than oxygen, reducing oxygen delivery to tissues.
Q41. Which effect is associated with excessive alcohol consumption over many years?
- (A) Improved liver function
- (B) Stronger reaction times
- (C) Better social judgement
- (D) Liver damage
Show Answer
Answer: D – Long-term heavy drinking can cause liver cirrhosis and other serious health damage.
Q42. Why should a full course of antibiotics be completed even if symptoms improve?
- (A) To kill all bacteria and reduce resistant strains surviving
- (B) To build immunity to viruses
- (C) To replace damaged antibodies
- (D) To increase the dose gradually
Show Answer
Answer: A – Stopping early can leave resistant bacteria alive, which may multiply and cause a harder-to-treat infection.
Reproduction
Q43. Which process in plants involves transfer of pollen from anther to stigma?
- (A) Fertilisation
- (B) Pollination
- (C) Germination
- (D) Photosynthesis
Show Answer
Answer: B – Pollination is the transfer of pollen, while fertilisation is the later fusion of gamete nuclei.
Q44. Which hormone triggers the development of secondary sexual characteristics in males at puberty?
- (A) Oestrogen
- (B) Insulin
- (C) Testosterone
- (D) Progesterone in this context, when the other conditions are taken into account
Show Answer
Answer: C – Testosterone from the testes drives male secondary sexual characteristics at puberty.
Q45. Where does implantation of an embryo normally occur?
- (A) In the ovary
- (B) In the lining of the uterus
- (C) In the oviduct wall
- (D) In the cervix
Show Answer
Answer: B – After fertilisation in the oviduct, the embryo travels to the uterus and implants in its lining.
Inheritance
Q46. Which term describes different versions of the same gene?
- (A) Alleles
- (B) Chromosomes
- (C) Genotypes
- (D) Phenotypes
Show Answer
Answer: A – Alleles are alternative forms of a gene occupying the same position on homologous chromosomes.
Q47. Which condition is caused by an extra chromosome 21 in humans?
- (A) Sickle cell anaemia
- (B) Cystic fibrosis
- (C) Down syndrome
- (D) Haemophilia
Show Answer
Answer: C – Down syndrome results from trisomy 21, where a person has three copies of chromosome 21.
Q48. A pure-breeding tall plant (TT) is crossed with a short plant (tt). What proportion of offspring is expected to be tall?
- (A) None, because the recessive allele always prevents the tall allele from being expressed
- (B) One quarter
- (C) Three quarters
- (D) All of them
Show Answer
Answer: D – All offspring are Tt, and the dominant tall allele is expressed in every one of them.
Variation and selection
Q49. Which statement about mutations is correct?
- (A) They are always harmful
- (B) They are caused only by humans
- (C) They are random changes in genes or chromosomes
- (D) They never affect offspring
Show Answer
Answer: C – Mutations are random changes that may be harmful, neutral or occasionally advantageous.
Q50. Which example best illustrates adaptation by natural selection?
- (A) A plant wilting in drought
- (B) A person learning a skill
- (C) A muscle growing with exercise
- (D) Antibiotic-resistant bacteria increasing after antibiotic use
Show Answer
Answer: D – Resistant bacteria survive antibiotic treatment and reproduce, so resistance spreads in the population.
Q51. Which type of selection occurs when humans breed cows for higher milk yield?
- (A) Natural selection
- (B) Artificial selection
- (C) Random selection
- (D) Environmental selection
Show Answer
Answer: B – Artificial selection is human-directed breeding for desired characteristics.
Organisms and their environment
Q52. Which organism occupies the second trophic level in a grass to rabbit to fox food chain?
- (A) Rabbit
- (B) Grass
- (C) Fox
- (D) Decomposer
Show Answer
Answer: A – Grass is the producer at level one, the rabbit is the primary consumer at level two, and the fox is level three.
Q53. Which process in the nitrogen cycle converts nitrogen gas into compounds plants can use?
- (A) Nitrogen fixation by bacteria
- (B) Denitrification
- (C) Photosynthesis
- (D) Decomposition alone
Show Answer
Answer: A – Nitrogen-fixing bacteria in soil and root nodules convert nitrogen gas into usable nitrogen compounds.
Q54. Which factor is a biotic factor in an ecosystem?
- (A) Soil pH
- (B) Rainfall
- (C) Temperature
- (D) Predation
Show Answer
Answer: D – Predation involves living organisms, while soil pH, rainfall and temperature are abiotic factors.
Human influences on ecosystems
Q55. Which human activity increases the risk of flooding in lowland areas?
- (A) Planting trees on slopes
- (B) Building flood defences
- (C) Deforestation on hillsides
- (D) Creating nature reserves
Show Answer
Answer: C – Removing trees reduces water absorption and increases run-off, raising flood risk downstream.
Q56. Which pollutant from untreated sewage can cause eutrophication in rivers?
- (A) Carbon monoxide
- (B) Nitrate
- (C) Sulfur dioxide
- (D) Methane gas
Show Answer
Answer: B – Nitrate enrichment encourages algal growth, which later decays and depletes oxygen in the water.
Q57. Which strategy supports sustainable use of a forest?
- (A) Clear-felling the whole forest at once
- (B) Replanting trees at least as fast as they are felled
- (C) Removing all dead wood permanently
- (D) Introducing invasive species
Show Answer
Answer: B – Replanting maintains forest cover and allows continued timber harvest without permanent loss.
Biotechnology and genetic modification
Q58. Which enzyme is used to cut DNA at specific sites in genetic engineering?
- (A) Lipase
- (B) Amylase
- (C) Restriction enzyme
- (D) Protease
Show Answer
Answer: C – Restriction enzymes cut DNA at specific base sequences, allowing genes to be removed and inserted.
Q59. Which use of biotechnology produces a food product by fermentation?
- (A) Making insulin in bacteria
- (B) Producing a herbicide-resistant crop
- (C) Sequencing a genome
- (D) Making yoghurt with bacteria
Show Answer
Answer: D – Yoghurt is made when bacteria ferment lactose in milk, producing lactic acid that thickens it.
Q60. Why are fermenters kept sterile in biotechnology?
- (A) To prevent contamination by unwanted microorganisms that would compete or spoil the product
- (B) To keep the temperature and pH constant so that the microorganisms inside grow at their fastest possible rate
- (C) They must be grown in soil
- (D) They produce animal insulin only
Show Answer
Answer: A – If other microorganisms entered, they could outgrow the cultured organism or produce unwanted substances.
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