A-Level Biology Practice Test 5 – 60 Questions with Answers (Cambridge 9700)
Test your A-Level understanding across all 19 topics, using each answer explanation to close any gaps before the next test.
Cell structure
Q1. A muscle cell contains many mitochondria, while a skin cell contains far fewer. Why does this difference make functional sense?
- (A) The chloroplast is the site of aerobic respiration
- (B) Mitochondria are the site of aerobic respiration, producing ATP needed for muscle contraction
- (C) The Golgi apparatus produces most ATP
- (D) The nucleus produces most ATP
Show Answer
Answer: B – Mitochondria produce most ATP in aerobic respiration, so energy-demanding cells contain more of them.
Q2. What is the function of the cell surface membrane?
- (A) It synthesises proteins
- (B) It stores starch
- (C) It carries out photosynthesis
- (D) It controls entry and exit of substances
Show Answer
Answer: D – The membrane regulates transport and cell recognition.
Q3. Which structure joins plant cells for communication?
- (A) Plasmodesmata
- (B) Tight junctions
- (C) Desmosomes only
- (D) Gap junctions in plants
Show Answer
Answer: A – Plasmodesmata are cytoplasmic channels through cell walls.
Biological molecules
Q4. Which polysaccharide forms plant cell walls?
- (A) Glycogen
- (B) Starch
- (C) Cellulose
- (D) Chitin
Show Answer
Answer: C – Cellulose microfibrils give strength to plant walls.
Q5. What is a peptide bond?
- (A) A bond between sugars
- (B) A bond between fatty acids and glycerol
- (C) A bond between amino acids formed by condensation
- (D) A bond between nucleotides
Show Answer
Answer: C – Peptide bonds link amino acids into polypeptides.
Q6. Which molecule has a hydrophilic head and hydrophobic tails?
- (A) A phospholipid
- (B) A triglyceride
- (C) A disaccharide
- (D) An amino acid
Show Answer
Answer: A – Phospholipid structure allows bilayer formation.
Enzymes
Q7. What is activation energy?
- (A) Energy released by a reaction
- (B) Energy stored in ATP only
- (C) Energy of the products
- (D) Energy needed to start a reaction
Show Answer
Answer: D – Enzymes lower activation energy, speeding reactions.
Q8. Which statement about enzyme inhibitors is correct?
- (A) Non-competitive inhibitors increase Vmax
- (B) Competitive inhibitors bind the active site
- (C) All inhibitors denature enzymes
- (D) Inhibitors are always permanent
Show Answer
Answer: B – Competitive inhibition can be overcome by more substrate.
Q9. What is the optimum temperature for most human enzymes?
- (A) Around 0 degrees Celsius
- (B) Around 100 degrees Celsius
- (C) Around 20 degrees Celsius
- (D) Around 37 degrees Celsius
Show Answer
Answer: D – Human enzymes are adapted to body temperature.
Cell membranes and transport
Q10. Which process requires a carrier protein and ATP?
- (A) Simple diffusion
- (B) Facilitated diffusion
- (C) Active transport
- (D) Osmosis
Show Answer
Answer: C – Active transport moves substances against a gradient.
Q11. What is the function of aquaporins?
- (A) They pump ions against a gradient
- (B) They allow rapid water movement across membranes
- (C) They synthesise ATP
- (D) They carry glucose only
Show Answer
Answer: B – Aquaporins are water channel proteins.
Q12. A single-celled organism relies on diffusion for gas exchange, but a large multicellular animal cannot. Why does size matter for diffusion?
- (A) Large organisms have a small surface area to volume ratio and long diffusion distances, so diffusion alone is too slow
- (B) Diffusion requires ATP in large animals
- (C) Diffusion only occurs in gases in large animals
- (D) Diffusion moves substances against a gradient in large animals
Show Answer
Answer: A – Diffusion rate depends on gradient, area and distance, so large organisms need specialised exchange surfaces and transport systems.
The mitotic cell cycle
Q13. What is interphase?
- (A) The period of growth and DNA replication between divisions
- (B) The stage of chromosome separation
- (C) The stage of cytokinesis only
- (D) A type of meiosis
Show Answer
Answer: A – Most of the cell cycle is spent in interphase.
Q14. Which event occurs in prophase?
- (A) Chromatids separate
- (B) Chromosomes condense and the nuclear envelope breaks down
- (C) Chromosomes align at the equator
- (D) Two nuclei form
Show Answer
Answer: B – Condensation makes chromosomes visible under a microscope.
Q15. What is the result of mitosis?
- (A) Four haploid cells
- (B) Two genetically different cells
- (C) Two genetically identical diploid daughter cells
- (D) One cell with double chromosomes
Show Answer
Answer: C – Mitosis preserves chromosome number and genetic identity.
Nucleic acids and protein synthesis
Q16. Which nitrogenous base is found in RNA but not DNA?
- (A) Thymine
- (B) Adenine
- (C) Guanine
- (D) Uracil
Show Answer
Answer: D – RNA uses uracil instead of thymine.
Q17. What is translation?
- (A) Synthesis of mRNA from DNA
- (B) Replication of DNA
- (C) Splicing of pre-mRNA
- (D) Synthesis of a polypeptide from an mRNA template
Show Answer
Answer: D – Translation occurs at ribosomes in the cytoplasm.
Q18. A mutation changes one base in a DNA sequence, altering the amino acid sequence of the resulting polypeptide. Which level of organisation was directly changed by the mutation?
- (A) A gene, a sequence of DNA coding for a polypeptide or functional RNA
- (B) A whole chromosome
- (C) A protein only
- (D) A type of ribosome
Show Answer
Answer: A – Genes are units of inheritance on chromosomes, and changing a gene can change the polypeptide it codes for.
Transport in plants
Q19. Which tissue in a leaf is the main site of photosynthesis?
- (A) Epidermis
- (B) Xylem
- (C) Palisade mesophyll
- (D) Phloem
Show Answer
Answer: C – Palisade cells contain many chloroplasts.
Q20. What is the function of stomata?
- (A) They absorb water from soil
- (B) They allow gas exchange and control water loss
- (C) They transport sucrose
- (D) They support the leaf
Show Answer
Answer: B – Guard cells open and close stomata.
Q21. Which factor reduces transpiration on a cloudy day?
- (A) Higher wind speed
- (B) Lower light intensity closing stomata partly
- (C) Lower humidity
- (D) Higher temperature
Show Answer
Answer: B – Reduced light lowers stomatal opening and evaporation.
Transport in mammals
Q22. What is the function of capillaries?
- (A) Carrying blood at high pressure
- (B) Returning blood to the heart
- (C) Exchange of materials between blood and tissues
- (D) Preventing backflow
Show Answer
Answer: C – Thin walls and slow flow aid exchange.
Q23. What is lymph?
- (A) Tissue fluid drained into lymph vessels
- (B) Blood plasma in arteries
- (C) Fluid inside red blood cells
- (D) Fluid in the kidney tubules
Show Answer
Answer: A – Lymph returns excess tissue fluid to the blood.
Q24. Which heart valve prevents backflow into the left atrium?
- (A) The tricuspid valve
- (B) The semilunar valve
- (C) The pulmonary valve
- (D) The bicuspid valve
Show Answer
Answer: D – The bicuspid valve separates left atrium and ventricle.
Gas exchange
Q25. What is the breathing centre controlled by?
- (A) Oxygen concentration only
- (B) Heart rate only
- (C) Carbon dioxide concentration in the blood
- (D) Blood glucose level
Show Answer
Answer: C – Chemoreceptors detect carbon dioxide and pH changes.
Q26. Which structure increases surface area for gas exchange in lungs?
- (A) Bronchi
- (B) Trachea
- (C) Diaphragm
- (D) Alveoli
Show Answer
Answer: D – Millions of alveoli provide a huge exchange surface.
Q27. Why is carbon monoxide dangerous?
- (A) It destroys alveoli
- (B) It binds haemoglobin more strongly than oxygen
- (C) It blocks the trachea
- (D) It prevents ventilation
Show Answer
Answer: B – Carbon monoxide reduces oxygen carriage by haemoglobin.
Infectious diseases
Q28. Which pathogen is a fungus that causes disease in humans?
- (A) A dermatophyte causing ringworm is one example
- (B) Vibrio cholerae
- (C) Plasmodium
- (D) HIV
Show Answer
Answer: A – Fungal pathogens can infect skin and other tissues.
Q29. What is the incubation period?
- (A) Time between infection and symptom appearance
- (B) Time to cure a disease
- (C) Time a vaccine lasts
- (D) Time between vaccinations
Show Answer
Answer: A – Pathogens multiply during incubation before symptoms appear.
Q30. Which practice reduces spread of respiratory infections?
- (A) Sharing towels
- (B) Increasing crowding
- (C) Stopping hand washing
- (D) Covering coughs and improving ventilation
Show Answer
Answer: D – Reducing droplet spread lowers transmission.
Immunity
Q31. What is clonal selection?
- (A) Random production of antibodies
- (B) Division of phagocytes only
- (C) Activation of lymphocytes with receptors matching an antigen
- (D) Production of all antibodies by one cell
Show Answer
Answer: C – Specific lymphocytes are selected and expand by cloning.
Q32. What is a memory cell?
- (A) A cell that stores antibodies forever
- (B) A long-lived lymphocyte that allows a rapid secondary response
- (C) A phagocyte that never divides
- (D) A cell that produces antigens
Show Answer
Answer: B – Memory cells persist after infection or vaccination.
Q33. Which type of immunity is provided by breastfeeding?
- (A) Natural active immunity
- (B) Natural passive immunity
- (C) Artificial active immunity
- (D) Artificial passive immunity
Show Answer
Answer: B – Maternal antibodies pass to the infant in milk.
Energy and respiration
Q34. What is glycolysis?
- (A) Breakdown of glucose to pyruvate in the cytoplasm
- (B) Breakdown of pyruvate in mitochondria
- (C) Synthesis of glucose
- (D) Fixation of carbon dioxide
Show Answer
Answer: A – Glycolysis is the first stage of respiration.
Q35. What is the role of NAD in respiration?
- (A) It synthesises ATP directly
- (B) It fixes carbon dioxide
- (C) It splits water
- (D) It carries hydrogen to the electron transport chain
Show Answer
Answer: D – Reduced NAD delivers electrons for oxidative phosphorylation.
Q36. Which stage produces most ATP in aerobic respiration?
- (A) Glycolysis
- (B) The link reaction
- (C) Oxidative phosphorylation
- (D) Anaerobic fermentation
Show Answer
Answer: C – The electron transport chain generates the largest ATP yield.
Photosynthesis
Q37. What is the light-independent stage also called?
- (A) Photolysis
- (B) Chemiosmosis
- (C) Glycolysis
- (D) The Calvin cycle
Show Answer
Answer: D – The Calvin cycle fixes carbon dioxide in the stroma.
Q38. Which enzyme catalyses carbon fixation?
- (A) ATP synthase
- (B) Rubisco
- (C) DNA polymerase
- (D) Amylase
Show Answer
Answer: B – Rubisco is the most abundant enzyme on Earth.
Q39. What is the product of the Calvin cycle used to make starch?
- (A) Triose phosphate
- (B) Glycerate 3-phosphate only
- (C) Oxygen
- (D) Water
Show Answer
Answer: A – Triose phosphate can be converted to starch, sucrose or other products.
Q40. How many turns of the Calvin cycle fix six carbon dioxide molecules to make one glucose equivalent?
- (A) One turn
- (B) Three turns
- (C) Six turns
- (D) Twelve turns
Show Answer
Answer: C – Each turn fixes one carbon dioxide, so six are needed for a hexose.
Homeostasis
Q41. What is the role of the distal convoluted tubule?
- (A) It filters blood
- (B) It produces urine directly
- (C) It adjusts salt and water reabsorption under hormonal control
- (D) It stores urine
Show Answer
Answer: C – The distal tubule fine-tunes composition of tubular fluid.
Q42. A person becomes dehydrated after sweating heavily. Blood water potential falls. Which hormonal response helps restore water balance?
- (A) Insulin release increases
- (B) ADH release increases, increasing water reabsorption in the kidney
- (C) Glucagon release increases
- (D) Adrenaline release increases
Show Answer
Answer: B – ADH acts on the collecting duct to conserve water, restoring blood water potential.
Q43. What is diabetes insipidus?
- (A) A condition with high insulin
- (B) A condition with low glucagon
- (C) A condition with excess ADH
- (D) A condition with low ADH leading to large volumes of dilute urine
Show Answer
Answer: D – Without ADH, the collecting duct remains impermeable to water.
Q44. Which mechanism controls body temperature?
- (A) Negative feedback involving receptors, coordination centres and effectors
- (B) Positive feedback only
- (C) Hormonal control only
- (D) Behavioural responses only
Show Answer
Answer: A – Thermoregulation uses nervous and hormonal mechanisms.
Control and coordination
Q45. What is the function of a motor neurone?
- (A) It carries impulses to an effector
- (B) It carries impulses from a receptor
- (C) It connects sensory and motor neurones
- (D) It detects stimuli
Show Answer
Answer: A – Motor neurones stimulate muscles or glands.
Q46. What is summation at a synapse?
- (A) A single signal always triggering an impulse
- (B) Blocking of all signals
- (C) Combined excitatory signals reaching threshold to trigger an impulse
- (D) Reversal of an impulse
Show Answer
Answer: C – Spatial and temporal summation allow integration of inputs.
Q47. What is the role of acetylcholinesterase?
- (A) It synthesises acetylcholine
- (B) It opens sodium channels permanently
- (C) It transports acetylcholine into vesicles
- (D) It breaks down acetylcholine in the synaptic cleft
Show Answer
Answer: D – Breakdown prevents continuous stimulation of the postsynaptic membrane.
Q48. Which plant hormone inhibits growth and promotes leaf fall?
- (A) Auxin
- (B) Abscisic acid
- (C) Gibberellin
- (D) Cytokinin
Show Answer
Answer: B – Abscisic acid promotes dormancy and abscission.
Inheritance
Q49. What is sex linkage?
- (A) Inheritance of genes on autosomes only
- (B) Inheritance of genes on sex chromosomes
- (C) Inheritance through mitochondria only
- (D) Inheritance of dominant genes only
Show Answer
Answer: B – Sex-linked traits show different patterns in males and females.
Q50. What is a carrier?
- (A) A person with a dominant disorder
- (B) A person with two recessive alleles
- (C) A person who cannot pass on alleles
- (D) A heterozygote for a recessive disorder who shows no symptoms
Show Answer
Answer: D – Carriers can pass a recessive allele to offspring.
Q51. What is crossing over?
- (A) Separation of sister chromatids
- (B) Replication of DNA
- (C) Exchange of genetic material between homologous chromosomes
- (D) Fusion of gametes
Show Answer
Answer: C – Crossing over creates new allele combinations.
Selection and evolution
Q52. What is an adaptation?
- (A) An inherited feature that increases survival and reproduction
- (B) A learned behaviour only
- (C) A mutation that always harms
- (D) A temporary change in phenotype
Show Answer
Answer: A – Adaptations arise through selection over generations.
Q53. Which statement about evolution is correct?
- (A) Individuals evolve during their lifetime
- (B) Evolution always increases complexity
- (C) Evolution has a goal
- (D) Populations evolve, not individual organisms
Show Answer
Answer: D – Allele frequencies change in populations over time.
Q54. What is the founder effect?
- (A) Reduced genetic diversity when a small group starts a new population
- (B) Increased diversity from migration
- (C) Selection for founders only
- (D) Extinction of a population
Show Answer
Answer: A – Founders carry only a sample of the original gene pool.
Classification, biodiversity and conservation
Q55. What is habitat fragmentation?
- (A) Creating a new habitat
- (B) Breaking a habitat into isolated patches
- (C) Increasing habitat size
- (D) Protecting a habitat completely
Show Answer
Answer: B – Fragmentation isolates populations and reduces gene flow.
Q56. Which international agreement aims to protect biodiversity?
- (A) The Kyoto Protocol only
- (B) A local planning law only
- (C) The Convention on Biological Diversity
- (D) A fishing quota only
Show Answer
Answer: C – The convention promotes conservation and sustainable use.
Q57. What is an endemic species?
- (A) A species found only in one location
- (B) A species found worldwide
- (C) An extinct species
- (D) An introduced species
Show Answer
Answer: A – Endemic species are vulnerable to local habitat loss.
Genetic technology
Q58. What is recombinant DNA technology?
- (A) Cloning by selective breeding
- (B) Natural mutation only
- (C) Combining DNA from different sources to create new genetic combinations
- (D) Sequencing DNA only
Show Answer
Answer: C – Recombinant technology underpins genetic engineering.
Q59. What is the role of a promoter in genetic engineering?
- (A) It cuts DNA
- (B) It controls expression of an inserted gene
- (C) It joins DNA fragments
- (D) It amplifies DNA
Show Answer
Answer: B – Promoters ensure the gene is transcribed in the host.
Q60. What is a transgenic organism?
- (A) An organism produced by inbreeding
- (B) An organism with a natural mutation
- (C) An organism grown in tissue culture only
- (D) An organism containing foreign DNA from another species
Show Answer
Answer: D – Transgenic organisms express genes transferred from another species.
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