IGCSE Biology Practice Test 2 – 60 Questions with Answers (Cambridge 0610)
Work through this test under timed conditions, then check each answer and note the topics where you lost marks.
Characteristics and classification of living organisms
Q1. A student observes an organism that feeds, grows and responds to light. Which conclusion is justified?
- (A) It must be a plant
- (B) It must be a fungus
- (C) It must be an animal
- (D) It shows characteristics of living organisms
Show Answer
Answer: D – Feeding, growth and sensitivity are life processes, but they do not identify a kingdom alone.
Q2. Which pair of features identifies an organism as an arthropod?
- (A) Jointed legs and an exoskeleton
- (B) Soft body and a shell
- (C) Four limbs and fur
- (D) Fins and gills
Show Answer
Answer: A – Arthropods are defined by jointed limbs and a hard outer skeleton.
Q3. Why are viruses not placed in any of the five kingdoms?
- (A) They are too small to see
- (B) They cause disease in humans
- (C) They are not made of cells and cannot reproduce alone
- (D) They contain only protein
Show Answer
Answer: C – Viruses lack cellular structure and need a host cell to replicate.
Organisation of the organism
Q4. A leaf, a root and a stem work together in a plant. What level of organisation is the whole plant?
- (A) Tissue made of similar cells
- (B) Organism
- (C) Cell
- (D) Organ
Show Answer
Answer: B – The whole plant is an organism made of cooperating organ systems.
Q5. Which organelle releases energy from glucose in both plant and animal cells?
- (A) Vacuole
- (B) Chloroplast in plant cells only
- (C) Mitochondrion
- (D) Cell wall
Show Answer
Answer: C – Mitochondria carry out aerobic respiration in both cell types.
Q6. A microscope slide shows cells with a large permanent vacuole and a cell wall. What type of cell is it?
- (A) Bacterial cell
- (B) Plant cell
- (C) Animal muscle cell
- (D) Red blood cell
Show Answer
Answer: B – A large vacuole and a cellulose wall are plant cell features.
Movement into and out of cells
Q7. Root hair cells absorb mineral ions from very dilute soil water. Which process must be involved?
- (A) Osmosis only
- (B) Diffusion only down a gradient
- (C) Transpiration
- (D) Active transport
Show Answer
Answer: D – Ions move against their gradient, which requires energy from respiration.
Q8. Why does a red blood cell burst in pure water?
- (A) Water enters by osmosis and the cell has no wall
- (B) Salts diffuse into the cell rapidly
- (C) The cell membrane dissolves in water
- (D) Active transport pumps water inward
Show Answer
Answer: A – Without a rigid wall, the swelling cell cannot resist the incoming water.
Q9. Which factor increases the rate of diffusion of a gas into a cell?
- (A) A steeper concentration gradient
- (B) A smaller surface area
- (C) A lower temperature
- (D) A thicker cell membrane with fewer pores
Show Answer
Answer: A – A larger difference in concentration drives faster net diffusion.
Biological molecules
Q10. A food sample turns blue-black with iodine solution. What does this show?
- (A) Protein is present
- (B) Fat is present
- (C) Reducing sugar is present
- (D) Starch is present
Show Answer
Answer: D – Iodine solution is the test for starch, turning blue-black in its presence.
Q11. Which food test uses ethanol to show a cloudy white emulsion?
- (A) Test for starch
- (B) Test for fat
- (C) Test for reducing sugar
- (D) Test for protein
Show Answer
Answer: B – Fat forms a white emulsion when ethanol and water are mixed with the sample.
Enzymes
Q12. A student adds protease to a protein solution at 20 degrees Celsius and at 40 degrees Celsius. The reaction is faster at 40 degrees. Why?
- (A) More enzyme molecules are produced
- (B) The substrate changes shape
- (C) Molecules collide more often and with more energy
- (D) The enzyme becomes a substrate
Show Answer
Answer: C – Higher temperature raises collision frequency until denaturation begins.
Q13. Which graph shape shows the effect of pH on a single enzyme?
- (A) A peak at the optimum pH with lower rates either side
- (B) A flat line at all pH values from very acidic to very alkaline
- (C) A steady rise that never falls
- (D) A sharp fall that never recovers at low pH only
Show Answer
Answer: A – Enzyme activity is highest at the optimum pH and falls away on either side.
Plant nutrition
Q14. A plant kept in darkness for two days is tested with iodine and shows no blue-black colour. What does this suggest?
- (A) The plant made starch from stored fat
- (B) The plant absorbed starch from soil
- (C) No photosynthesis occurred, so no new starch was made
- (D) Chlorophyll was destroyed by light
Show Answer
Answer: C – Without light, photosynthesis stops and starch reserves are used up.
Q15. Which mineral deficiency causes yellow leaves with dead spots?
- (A) Magnesium deficiency
- (B) Nitrate deficiency
- (C) Phosphate deficiency
- (D) Potassium deficiency
Show Answer
Answer: B – Nitrate shortage limits protein and chlorophyll production, yellowing leaves.
Human nutrition
Q16. A person lacks vitamin D over a long period. Which condition is most likely?
- (A) Scurvy
- (B) Anaemia
- (C) Night blindness
- (D) Rickets
Show Answer
Answer: D – Vitamin D is needed for calcium absorption and healthy bone growth.
Q17. Why is fibre important in the diet even though it is not digested?
- (A) It provides most of our energy for growth
- (B) It builds muscle protein
- (C) It carries vitamins in blood
- (D) It keeps food moving through the gut
Show Answer
Answer: D – Fibre adds bulk and aids peristalsis, preventing constipation.
Q18. Where does most chemical digestion of fat begin in effect, through emulsification?
- (A) Stomach
- (B) Small intestine
- (C) Mouth
- (D) Large intestine
Show Answer
Answer: B – Bile emulsifies fat in the small intestine, where lipase then acts.
Transport in plants
Q19. A potometer shows faster water uptake on a windy day. What explains this?
- (A) Wind increases transpiration, pulling more water up the xylem
- (B) Wind closes the stomata
- (C) Wind cools the roots directly
- (D) Wind forces water into the leaves
Show Answer
Answer: A – Faster water loss from leaves increases the pull on the water column.
Q20. Which part of a root is adapted for water uptake?
- (A) Root cap
- (B) Woody stem base
- (C) Root hair cell
- (D) Lateral root tip only
Show Answer
Answer: C – Root hairs give a large surface area and a thin wall for absorption.
Q21. Aphids feed from phloem. What does this tell us about phloem sap?
- (A) It is mostly water with no solutes
- (B) It contains dissolved sugars
- (C) It carries only mineral ions
- (D) It flows only downwards
Show Answer
Answer: B – Phloem transports sucrose solution from sources to sinks.
Transport in animals
Q22. Blood in the pulmonary vein is different from blood in the pulmonary artery because it is:
- (A) Oxygenated
- (B) Low in glucose
- (C) Carrying urea to the kidney
- (D) Under the lowest pressure
Show Answer
Answer: A – The pulmonary vein returns oxygenated blood from the lungs to the heart.
Q23. Why do capillaries have walls only one cell thick?
- (A) To resist high pressure
- (B) To store extra blood
- (C) To allow rapid exchange of materials
- (D) To prevent white cells escaping into tissues
Show Answer
Answer: C – A short diffusion distance speeds exchange between blood and tissues.
Q24. Which sequence shows the double circulation correctly?
- (A) Heart, lungs, heart, body, heart
- (B) Heart, body, lungs, body, heart
- (C) Lungs, heart, lungs, body
- (D) Heart, lungs, heart, body
Show Answer
Answer: D – Blood passes through the heart twice in one complete circuit.
Diseases and immunity
Q25. A child is given a vaccine containing a weakened pathogen. What happens next?
- (A) Antibodies are injected directly
- (B) The pathogen multiplies unchecked
- (C) Lymphocytes respond and memory cells are made
- (D) The immune system is switched off
Show Answer
Answer: C – The immune response to the harmless form creates lasting memory.
Q26. Which disease is spread through contaminated water?
- (A) HIV
- (B) Cholera
- (C) Influenza
- (D) Tuberculosis
Show Answer
Answer: B – Cholera bacteria spread in water contaminated with sewage.
Q27. Why do antibiotics not cure influenza?
- (A) They only work in the stomach
- (B) They kill human cells first
- (C) They are blocked by mucus
- (D) Influenza is caused by a virus, not a bacterium
Show Answer
Answer: D – Antibiotics target bacterial structures absent from viruses.
Gas exchange in humans
Q28. During exercise, breathing rate rises. What is the main reason?
- (A) More carbon dioxide must be removed and more oxygen supplied
- (B) The lungs need to rest between breaths
- (C) The diaphragm becomes tired
- (D) Blood volume falls sharply
Show Answer
Answer: A – Faster respiration in muscles raises both oxygen demand and carbon dioxide output.
Q29. Which structure prevents the trachea from collapsing?
- (A) Thin muscle fibres
- (B) Rings of cartilage
- (C) Mucus lining
- (D) Alveolar walls
Show Answer
Answer: B – C-shaped cartilage rings keep the airway open.
Q30. What happens to the ribs during exhalation?
- (A) They move down and inwards
- (B) They move up and outwards
- (C) They stay fixed in place
- (D) They rotate around the spine
Show Answer
Answer: A – Intercostal muscles relax, reducing chest volume and forcing air out.
Respiration
Q31. Yeast respiring anaerobically in a sealed tube produces bubbles of gas. Which gas is it?
- (A) Oxygen
- (B) Hydrogen gas from the yeast culture
- (C) Carbon dioxide
- (D) Nitrogen
Show Answer
Answer: C – Anaerobic respiration in yeast yields ethanol and carbon dioxide.
Q32. A muscle cell respires anaerobically during a sprint. Which substance builds up?
- (A) Glucose
- (B) Oxygen
- (C) Ethanol
- (D) Lactate
Show Answer
Answer: D – Human muscle produces lactate, not ethanol, without oxygen.
Q33. Why does aerobic respiration release more energy per glucose molecule than anaerobic respiration?
- (A) It uses no enzymes
- (B) It works only in plants
- (C) It needs no mitochondria
- (D) It breaks glucose down completely
Show Answer
Answer: D – Complete oxidation to carbon dioxide and water releases the full energy store.
Excretion in humans
Q34. Which substance is removed from the blood by the kidneys in addition to urea?
- (A) Glucose, which is filtered from the blood but normally reabsorbed completely
- (B) Protein
- (C) Excess salts
- (D) Red blood cells
Show Answer
Answer: C – The kidneys excrete excess salts as well as urea, helping to control the water and salt balance of the blood.
Q35. What happens to most of the water filtered in the kidney?
- (A) It is reabsorbed into the blood
- (B) It passes straight to the bladder
- (C) It is stored in the liver
- (D) It leaves through the skin
Show Answer
Answer: A – Selective reabsorption returns most filtered water to the blood.
Q36. A urine sample contains protein. What does this most likely indicate?
- (A) Excess water intake
- (B) Damage to the kidney filter
- (C) A high-salt diet
- (D) Normal kidney function in a healthy person
Show Answer
Answer: B – Large protein molecules are normally too big to pass the filter.
Coordination and response
Q37. A person touches a hot plate and pulls away before feeling pain. Why?
- (A) The brain sends the fastest signal
- (B) Hormones act before nerves
- (C) The response is learned behaviour
- (D) The reflex arc bypasses conscious thought
Show Answer
Answer: D – Reflexes are processed in the spinal cord for a rapid protective response.
Q38. Which sense organ contains photoreceptors?
- (A) Skin
- (B) Tongue
- (C) Eye
- (D) Ear
Show Answer
Answer: C – Rods and cones in the retina detect light.
Q39. In dim light, what happens to the pupil?
- (A) It dilates to admit more light
- (B) It constricts to protect the retina from damage by bright light entering the eye
- (C) It closes completely
- (D) It stays the same size
Show Answer
Answer: A – Radial muscles of the iris contract in dim light, widening the pupil so more light reaches the retina.
Drugs
Q40. Which substance in cigarette smoke reduces oxygen transport in blood?
- (A) Tar
- (B) Carbon monoxide
- (C) Nicotine
- (D) Water vapour in cigarette smoke
Show Answer
Answer: B – Carbon monoxide binds haemoglobin more strongly than oxygen does.
Q41. Which effect does heroin have on the nervous system?
- (A) It depresses nervous activity
- (B) It speeds up reflexes permanently
- (C) It increases oxygen uptake
- (D) It strengthens heart muscle
Show Answer
Answer: A – Heroin is a depressant that slows brain and body functions.
Q42. Why can antibiotics become less effective over time?
- (A) Bacteria learn to avoid doctors
- (B) Patients develop immunity to drugs over time
- (C) Viruses destroy the antibiotics
- (D) Resistant bacteria survive and multiply
Show Answer
Answer: D – Overuse selects for resistant strains, which then spread.
Reproduction
Q43. Which method of asexual reproduction is used by potato plants?
- (A) Seed production
- (B) Growth from tubers
- (C) Pollination by insects
- (D) Spore formation
Show Answer
Answer: B – Tubers are underground stems that sprout into new plants.
Q44. What is the function of the placenta?
- (A) To produce egg cells
- (B) To trigger labour only
- (C) To allow exchange between mother and fetus blood
- (D) To protect the fetus from all infections
Show Answer
Answer: C – Nutrients and oxygen diffuse across the placenta to the fetus.
Q45. Which change occurs at puberty in males due to testosterone?
- (A) Menstruation begins
- (B) The voice deepens
- (C) Breast development occurs
- (D) Ovulation starts
Show Answer
Answer: B – Testosterone drives male secondary sexual characteristics.
Inheritance
Q46. A person has genotype IAIB. Why is their blood group AB?
- (A) The IA allele masks IB completely in all cases
- (B) The IB allele masks IA completely
- (C) Both IA and IB alleles are expressed
- (D) Neither allele is expressed
Show Answer
Answer: C – IA and IB are codominant, so both antigens appear on red cells.
Q47. A pedigree shows a trait appearing in every generation and in both sexes. What inheritance pattern does this suggest?
- (A) Recessive only
- (B) Sex-linked only
- (C) Mutation in mitochondria only
- (D) Dominant inheritance
Show Answer
Answer: D – Dominant traits typically appear in each generation when one parent carries the allele.
Q48. What is the phenotype of an organism with genotype Bb, where B is dominant?
- (A) The dominant trait
- (B) The recessive trait
- (C) A blend of both traits
- (D) No trait at all
Show Answer
Answer: A – One dominant allele is enough to show the dominant phenotype.
Variation and selection
Q49. Antibiotic-resistant bacteria become common in a hospital. Which process best explains this?
- (A) Bacteria choose to mutate
- (B) Selection for resistant variants
- (C) Direct instruction from doctors during treatment
- (D) Migration of patients only
Show Answer
Answer: B – Antibiotics kill sensitive bacteria, leaving resistant ones to reproduce.
Q50. Which source of variation introduces entirely new alleles?
- (A) Asexual reproduction
- (B) Mitosis in body cells
- (C) Environmental change alone
- (D) Mutation
Show Answer
Answer: D – Mutation changes DNA sequence and can create new alleles.
Q51. Which trait shows discontinuous variation?
- (A) Tongue rolling ability
- (B) Body mass
- (C) Height
- (D) Leaf length
Show Answer
Answer: A – Tongue rolling falls into distinct categories rather than a continuous range.
Organisms and their environment
Q52. Which organism is a producer in a food chain?
- (A) Fox
- (B) Rabbit
- (C) Grass
- (D) Earthworm
Show Answer
Answer: C – Grass is a producer because it makes its own food by photosynthesis.
Q53. Which process in the carbon cycle releases carbon dioxide from dead organisms?
- (A) Decomposition and respiration
- (B) Photosynthesis
- (C) Feeding by herbivores
- (D) Formation of fossil fuels over millions of years
Show Answer
Answer: A – Decomposers respire as they break down dead material, releasing carbon dioxide.
Q54. A food web is more stable than a single food chain because:
- (A) Each species has only one food source
- (B) Top predators are removed
- (C) Alternative food sources exist if one declines
- (D) Energy transfer becomes 100 percent efficient at every level
Show Answer
Answer: C – Multiple feeding links buffer a species against the loss of one prey type.
Human influences on ecosystems
Q55. Fertilisers washed into a river cause fish deaths downstream. What is the sequence?
- (A) Less algae, more oxygen, fish thrive
- (B) More plants, less light, fish migrate
- (C) Algae die, oxygen rises, and fish suffocate from heat
- (D) Algal bloom, decay, oxygen depletion, fish die
Show Answer
Answer: D – Decay of the bloom by bacteria consumes dissolved oxygen.
Q56. Which human activity most directly increases atmospheric methane?
- (A) Planting trees
- (B) Cattle farming and rice paddies
- (C) Using solar panels
- (D) Recycling paper
Show Answer
Answer: B – Anaerobic conditions in guts and flooded fields release methane.
Q57. Why are conservation programmes needed for endangered species?
- (A) To increase hunting quotas
- (B) To replace wild species with crops
- (C) To protect habitats and maintain biodiversity
- (D) To speed up extinction rates
Show Answer
Answer: C – Protecting habitats preserves species and the ecosystems they support.
Biotechnology and genetic modification
Q58. In a fermenter producing yoghurt, why is temperature carefully controlled?
- (A) To kill all bacteria at the start
- (B) To keep bacterial enzymes near their optimum
- (C) To prevent any respiration
- (D) To freeze the product solid
Show Answer
Answer: B – Bacteria work fastest near their optimum temperature without denaturing enzymes.
Q59. Which step comes first when genetically modifying bacteria to make insulin?
- (A) Inserting the human insulin gene into a plasmid
- (B) Growing bacteria in a large fermenter
- (C) Purifying insulin from the culture
- (D) Testing the insulin on patients
Show Answer
Answer: A – The gene must first be placed in a vector before bacteria can take it up.
Q60. What is a possible concern about genetically modified crops?
- (A) They always taste worse
- (B) They cannot grow in soil
- (C) They never produce seeds
- (D) Modified genes could spread to wild relatives
Show Answer
Answer: D – Gene flow to wild plants is a widely discussed ecological concern.
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