A-Level Biology Practice Test 10 – 60 Questions with Answers (Cambridge 9700)
The final test in this set covers the whole syllabus once more, with questions on experimental design, quantitative data and applied contexts. Use it as a complete mock before moving on to past papers.
Cell structure
Q1. Which microscope is best for viewing the three-dimensional surface of a cell?
- (A) Transmission electron microscope
- (B) Light microscope with a low-power objective only
- (C) Confocal microscope for living cells only
- (D) Scanning electron microscope
Show Answer
Answer: D – Scanning electron microscopy builds an image from electrons scattered from the specimen surface.
Q2. Which organelle contains hydrolytic enzymes for breaking down worn-out organelles?
- (A) Chloroplast
- (B) Lysosome
- (C) Nucleus
- (D) Ribosome
Show Answer
Answer: B – Lysosomes fuse with vesicles containing material to be digested.
Q3. Why must specimens for transmission electron microscopy be thin and dehydrated?
- (A) Light cannot pass through thin specimens
- (B) Dehydration increases magnification directly
- (C) Electrons cannot pass through thick, wet material to form an image
- (D) Thin specimens are always living
Show Answer
Answer: C – The electron beam must transmit through the section, and the microscope operates under vacuum.
Biological molecules
Q4. Which test gives a brick-red precipitate for a reducing sugar?
- (A) Benedict’s test after heating
- (B) Iodine test
- (C) Biuret test
- (D) Emulsion test
Show Answer
Answer: A – Reducing sugars reduce copper(II) ions to copper(I) oxide on heating with Benedict’s reagent.
Q5. Starch gives a blue-black colour with iodine. Which component is mainly responsible?
- (A) Amylopectin only
- (B) Cellulose
- (C) Glycogen
- (D) Amylose, whose helix traps iodine molecules
Show Answer
Answer: D – Iodine fits inside the amylose helix, producing the characteristic colour.
Q6. Which molecule is a polymer of amino acids joined by peptide bonds?
- (A) A triglyceride
- (B) A polypeptide
- (C) A polynucleotide
- (D) A disaccharide
Show Answer
Answer: B – Condensation between amino groups and carboxyl groups builds a polypeptide chain.
Enzymes
Q7. Which graph shape describes reaction rate against substrate concentration for an enzyme?
- (A) A straight line increasing indefinitely
- (B) A curve falling steadily
- (C) A curve rising steeply then levelling off at Vmax
- (D) A bell-shaped curve peaking at low concentration
Show Answer
Answer: C – Rate rises as more active sites are occupied, then plateaus at saturation.
Q8. Why do enzymes have an optimum pH?
- (A) pH alters charges on R groups, changing active site shape and binding
- (B) pH changes the substrate concentration only
- (C) pH destroys the substrate completely at all values
- (D) pH has no effect on protein structure
Show Answer
Answer: A – Away from the optimum, ionic bonds break or form incorrectly, reducing activity.
Q9. A student investigates catalase activity using potato discs. Which variable should be kept constant when testing pH?
- (A) pH itself
- (B) The dependent variable only
- (C) The volume of gas collected as the independent variable
- (D) Temperature, substrate concentration and disc size
Show Answer
Answer: D – Control variables must be held constant so only pH affects the measured rate.
Cell membranes and transport
Q10. Which membrane component acts as a receptor for hormones or cell recognition?
- (A) Phospholipid tail
- (B) Glycoprotein on the outer surface
- (C) Cholesterol in the interior
- (D) Water channel alone
Show Answer
Answer: B – Glycoproteins on the cell surface bind signalling molecules and identify the cell.
Q11. Which channel protein would be most abundant in the membranes of kidney collecting duct cells when the body needs to conserve water?
- (A) A sodium-potassium pump
- (B) A glucose co-transporter
- (C) Aquaporins, which allow rapid facilitated diffusion of water
- (D) ATP synthase
Show Answer
Answer: C – Aquaporins greatly increase membrane water permeability, allowing water reabsorption from the collecting duct when ADH is present.
Q12. Which process describes uptake of a whole bacterium by a white blood cell?
- (A) Phagocytosis, a form of endocytosis
- (B) Exocytosis
- (C) Facilitated diffusion
- (D) Osmosis
Show Answer
Answer: A – The membrane engulfs the bacterium into a phagosome for digestion.
The mitotic cell cycle
Q13. Which stage of the cell cycle involves growth and synthesis of organelles before DNA replication?
- (A) S phase
- (B) G2 phase
- (C) M phase
- (D) G1 phase
Show Answer
Answer: D – In G1 the cell grows and makes proteins and organelles needed for replication.
Q14. Why is mitosis important in asexual reproduction?
- (A) It produces genetically varied offspring
- (B) It produces genetically identical offspring, preserving successful genotypes
- (C) It halves chromosome number
- (D) It requires fertilisation
Show Answer
Answer: B – Asexual reproduction by mitosis clones the parent genotype.
Q15. A root tip squash shows many cells in interphase and few in mitosis. What does this suggest?
- (A) Mitosis is the longest part of the cycle
- (B) Cells are not dividing at all
- (C) Interphase occupies most of the cell cycle
- (D) All cells are in anaphase
Show Answer
Answer: C – The proportion of cells in a stage reflects the time spent in that stage.
Nucleic acids and protein synthesis
Q16. Which base is found in RNA but not DNA, and which sugar is found in RNA?
- (A) Uracil and ribose
- (B) Thymine and deoxyribose
- (C) Adenine and deoxyribose
- (D) Cytosine and ribose only
Show Answer
Answer: A – RNA uses uracil in place of thymine and ribose in place of deoxyribose.
Q17. During translation, what happens at a stop codon?
- (A) A new amino acid is added
- (B) The ribosome copies DNA again
- (C) mRNA is spliced
- (D) No tRNA binds, and the polypeptide is released
Show Answer
Answer: D – Release factors recognise stop codons and free the completed polypeptide.
Q18. Which mutation involves insertion or deletion of a base, shifting the reading frame?
- (A) Silent mutation
- (B) Frameshift mutation
- (C) Substitution that changes one codon only
- (D) Chromosome duplication
Show Answer
Answer: B – Adding or removing a base changes every downstream codon.
Transport in plants
Q19. Which tissue in a stem is responsible for secondary growth in dicotyledons?
- (A) Epidermis
- (B) Pith
- (C) Vascular cambium
- (D) Root cap
Show Answer
Answer: C – Cambium divides to produce new xylem and phloem, thickening the stem.
Q20. Guard cells are treated with a chemical that blocks potassium ion uptake. What happens to the stoma, and why?
- (A) Guard cells remain flaccid because water does not enter by osmosis, so the stoma stays closed
- (B) Guard cells become turgid and bow outward, opening the stoma
- (C) Guard cells actively pump water out only
- (D) Guard cells divide by mitosis
Show Answer
Answer: A – Turgid guard cells curve apart because their inner walls are thicker than outer walls, but without potassium uptake they cannot become turgid.
Q21. Which factor would reduce water uptake by roots?
- (A) Well-aerated, moist soil
- (B) A large root hair surface area
- (C) A steep water potential gradient
- (D) Waterlogged soil with low oxygen for respiration
Show Answer
Answer: D – Without oxygen, active uptake of mineral ions falls, reducing the gradient for water entry.
Transport in mammals
Q22. Which heart valve prevents backflow from the aorta into the left ventricle?
- (A) Bicuspid valve
- (B) Semilunar valve of the aorta
- (C) Tricuspid valve
- (D) Pulmonary valve on the right side
Show Answer
Answer: B – Semilunar valves close when arterial pressure exceeds ventricular pressure.
Q23. What initiates the heartbeat?
- (A) The atrioventricular node alone
- (B) Nerves from the brain only
- (C) The sinoatrial node acting as pacemaker
- (D) Blood pressure in the aorta
Show Answer
Answer: C – The sinoatrial node generates regular impulses that spread across the atria.
Q24. A pulse is felt in the wrist artery immediately after each heartbeat, yet blood flow in nearby capillaries is steady rather than pulsing. Which property of arteries explains the steady capillary flow?
- (A) Their elastic walls stretch during systole and recoil during diastole, smoothing out the pulse
- (B) Their walls allow exchange with surrounding tissues
- (C) Their valves prevent backflow of blood
- (D) They carry blood at uniformly low pressure
Show Answer
Answer: A – Elastic recoil maintains pressure between heartbeats, converting pulsatile flow from the heart into steadier flow in capillaries.
Gas exchange
Q25. Which condition increases the rate of diffusion across a gas exchange surface?
- (A) A thicker barrier and smaller area
- (B) A lower temperature only
- (C) A longer diffusion distance
- (D) A larger surface area and a steeper concentration gradient
Show Answer
Answer: D – Fick’s law shows rate increases with area and gradient and decreases with distance.
Q26. What is the role of surfactant in alveoli?
- (A) To increase surface tension and collapse alveoli
- (B) To reduce surface tension and prevent alveolar collapse
- (C) To trap all inhaled particles
- (D) To carry oxygen in blood
Show Answer
Answer: B – Surfactant lowers the force that would otherwise collapse small air sacs on exhalation.
Q27. Why is ventilation important even when diffusion is efficient?
- (A) It replaces diffusion entirely
- (B) It thickens the exchange surface
- (C) It maintains concentration gradients by renewing air at the surface
- (D) It stops blood flow
Show Answer
Answer: C – Without ventilation, oxygen would fall and carbon dioxide would rise at the surface until gradients vanished.
Q28. In which organism would gas exchange occur mainly by diffusion across a moist body surface?
- (A) A small flatworm with a large surface area to volume ratio
- (B) A large mammal
- (C) An active insect
- (D) A fish with gills
Show Answer
Answer: A – Small, thin organisms have short diffusion distances and low metabolic demand.
Infectious diseases
Q29. Which statement about HIV transmission is correct?
- (A) It spreads by casual contact and sharing food
- (B) It spreads through drinking water
- (C) It spreads by mosquito bites
- (D) It spreads through blood and sexual fluids, not by casual contact
Show Answer
Answer: D – HIV requires exchange of infected body fluids; it is not airborne or waterborne.
Q30. Which stage of the Plasmodium life cycle is taken up by a mosquito?
- (A) Sporozoites from liver cells
- (B) Gametocytes from human blood
- (C) Merozoites from red cells only
- (D) Oocysts from human skin
Show Answer
Answer: B – A mosquito ingests gametocytes, which fuse in its gut to continue the cycle.
Q31. Why is tuberculosis difficult to treat?
- (A) It is caused by a virus
- (B) Antibiotics work in one day only
- (C) The bacterium has a waxy cell wall and treatment takes many months
- (D) The bacterium cannot be cultured
Show Answer
Answer: C – The lipid-rich wall resists drugs, and slow growth requires prolonged combination therapy.
Q32. Which public health measure best controls a waterborne disease outbreak?
- (A) Treating water supplies and improving sanitation
- (B) Closing schools only
- (C) Mass vaccination against all viruses
- (D) Using bed nets alone
Show Answer
Answer: A – Safe water and sewage disposal remove the transmission route for faecal-oral pathogens.
Immunity
Q33. Why can the same pathogen trigger a much faster immune response on second exposure than on first exposure?
- (A) Because antibodies remain at peak level in the blood forever
- (B) Because white blood cells change their type permanently
- (C) Because a vaccine kills all pathogens on first contact
- (D) Because memory lymphocytes formed during the first response divide rapidly to produce effector cells and antibodies
Show Answer
Answer: D – Memory cells are the basis of long-term immunity: they recognise the antigen quickly and mount a stronger secondary response.
Q34. Which process increases antibody diversity before infection?
- (A) Mutation caused by the pathogen
- (B) Random rearrangement of antibody gene segments during lymphocyte development
- (C) Vaccination alone
- (D) Cloning of one B cell only
Show Answer
Answer: B – Gene rearrangement creates millions of different antigen receptors.
Q35. In an allergic response, which substance causes inflammation and itching?
- (A) Insulin
- (B) Adrenaline
- (C) Histamine released by mast cells
- (D) Haemoglobin
Show Answer
Answer: C – Histamine increases blood vessel permeability and stimulates nerve endings.
Q36. Why does passive immunity not give long-term protection?
- (A) No memory cells are produced
- (B) Antibodies are too large to circulate
- (C) The immune system is suppressed permanently
- (D) Antigens are not recognised
Show Answer
Answer: A – Received antibodies break down over weeks, and without memory cells there is no rapid recall.
Energy and respiration
Q37. Which molecule is oxidised in the Krebs cycle to release carbon dioxide?
- (A) Glucose directly
- (B) Pyruvate in the cytoplasm only
- (C) Oxygen
- (D) Acetyl CoA, via citrate and other intermediates
Show Answer
Answer: D – Acetyl CoA enters the cycle, and decarboxylation steps release carbon dioxide and reduced coenzymes.
Q38. What is the net ATP yield from glycolysis alone?
- (A) Zero
- (B) Two ATP
- (C) Four ATP
- (D) Thirty-two ATP
Show Answer
Answer: B – Four ATP are made but two are used initially, giving a net gain of two.
Q39. Why does anaerobic respiration yield less ATP than aerobic respiration?
- (A) Glucose is not broken down at all
- (B) No ATP is made in glycolysis
- (C) Glucose is only partly broken down, and most energy remains in lactate or ethanol
- (D) Oxygen is used up too quickly
Show Answer
Answer: C – Without oxidative phosphorylation, only the small glycolytic ATP gain is available.
Photosynthesis
Q40. Which organelle and membrane carry out the light-dependent reactions?
- (A) Chloroplast, thylakoid membrane
- (B) Mitochondrion, inner membrane
- (C) Chloroplast, outer membrane only
- (D) Nucleus, nuclear membrane
Show Answer
Answer: A – Photosystems and ATP synthase are embedded in thylakoid membranes.
Q41. How is reduced NADP regenerated for reuse in the light-dependent reactions?
- (A) It is broken down by photolysis
- (B) It is stored as starch
- (C) It is excreted from the chloroplast
- (D) It is oxidised in the Calvin cycle when it donates hydrogen
Show Answer
Answer: D – In the Calvin cycle, reduced NADP gives up hydrogen to glycerate 3-phosphate and returns as NADP.
Q42. A leaf disc experiment shows faster floating at higher light intensity. What does floating indicate?
- (A) Carbon dioxide uptake making discs heavier
- (B) Oxygen production filling intercellular spaces, making discs buoyant
- (C) Water loss from discs
- (D) Starch accumulation only
Show Answer
Answer: B – Oxygen evolved in photosynthesis displaces infiltration fluid, so discs rise.
Homeostasis
Q43. Which hormone lowers blood glucose by promoting glycogenesis?
- (A) Glucagon
- (B) Adrenaline
- (C) Insulin
- (D) ADH
Show Answer
Answer: C – Insulin increases glucose uptake by liver and muscle and conversion to glycogen.
Q44. In the kidney, where does most water reabsorption occur by osmosis following solute uptake?
- (A) Proximal convoluted tubule and loop of Henle
- (B) Glomerulus
- (C) Ureter
- (D) Renal pelvis
Show Answer
Answer: A – Solute reabsorption lowers tubular water potential, so water follows by osmosis.
Q45. Which response occurs when core temperature falls?
- (A) Sweating and vasodilation
- (B) Increased skin blood flow only
- (C) Reduced metabolic rate to zero
- (D) Vasoconstriction, shivering and piloerection
Show Answer
Answer: D – These responses reduce heat loss and increase heat production.
Control and coordination
Q46. Which part of the brain coordinates balance and fine motor control?
- (A) Cerebrum
- (B) Cerebellum
- (C) Medulla only
- (D) Hypothalamus
Show Answer
Answer: B – The cerebellum integrates sensory information to coordinate movement.
Q47. What is spatial summation?
- (A) Repeated firing from one neurone
- (B) Inhibition from a single neurone
- (C) Simultaneous firing from several presynaptic neurones summing at one postsynaptic neurone
- (D) Saltatory conduction
Show Answer
Answer: C – Multiple small generator potentials together can reach threshold.
Q48. Which hormone regulates metabolic rate?
- (A) Thyroxine
- (B) Insulin
- (C) ADH
- (D) Auxin
Show Answer
Answer: A – Thyroxine increases oxygen consumption and metabolic activity in target tissues.
Inheritance
Q49. Two parents are both heterozygous for cystic fibrosis, a recessive condition. What is the probability of an affected child?
- (A) One half
- (B) Three quarters
- (C) One in sixteen
- (D) One quarter
Show Answer
Answer: D – One quarter of offspring receive the recessive allele from both parents.
Q50. Which term describes different forms of the same gene?
- (A) Locus
- (B) Allele
- (C) Genotype
- (D) Phenotype
Show Answer
Answer: B – Alleles occupy the same locus but may differ in DNA sequence.
Q51. In a pedigree, a trait appears in every generation and affects both sexes equally. What is most likely?
- (A) Recessive X-linked inheritance
- (B) Recessive autosomal inheritance only
- (C) Dominant autosomal inheritance
- (D) Mitochondrial inheritance only
Show Answer
Answer: C – Dominant traits appear in each generation, and autosomal traits affect both sexes equally.
Selection and evolution
Q52. Which statement about genetic drift is correct?
- (A) It is random change in allele frequencies, strongest in small populations
- (B) It is selection for advantageous alleles
- (C) It only occurs in large populations
- (D) It increases adaptation directly
Show Answer
Answer: A – Chance events in small populations can change frequencies irrespective of fitness.
Q53. Which is an example of convergent evolution?
- (A) Homologous limbs in mammals from a common ancestor
- (B) Identical DNA in clones
- (C) Speciation by geographical isolation alone
- (D) Wings in bats and birds evolving separately for flight
Show Answer
Answer: D – Similar structures evolve independently under similar selection pressures.
Q54. What is required for natural selection to act?
- (A) Identical individuals only
- (B) Variation, inheritance and differential survival and reproduction
- (C) No environmental change
- (D) Artificial breeding only
Show Answer
Answer: B – Without heritable variation and differential success, allele frequencies cannot change by selection.
Classification, biodiversity and conservation
Q55. Which classification system uses three domains?
- (A) The five-kingdom system only
- (B) Linnaean binomial system only
- (C) The three-domain system of Woese
- (D) A system based only on cell wall type
Show Answer
Answer: C – Woese divided life into Bacteria, Archaea and Eukarya based on rRNA sequences.
Q56. A survey records 40 plant species, high genetic variation within each species, and five distinct habitat types in a woodland. Which term best summarises all three levels recorded?
- (A) Biodiversity, the variety of genes, species and ecosystems in an area
- (B) The number of individuals of one species only
- (C) The biomass of producers only
- (D) The number of endangered species only
Show Answer
Answer: A – Biodiversity includes genetic, species and habitat diversity, all three levels recorded in the survey.
Q57. Which strategy best protects biodiversity in the long term?
- (A) Keeping single species in zoos only
- (B) Introducing non-native species widely
- (C) Clearing forest for monoculture
- (D) Protecting habitats and reducing threats such as pollution and overexploitation
Show Answer
Answer: D – In situ habitat protection preserves interactions and genetic diversity together.
Genetic technology
Q58. How are DNA fragments separated in gel electrophoresis?
- (A) By charge only, with no effect of size
- (B) By size, as smaller fragments move further through the gel toward the positive electrode
- (C) By colour
- (D) By temperature only
Show Answer
Answer: B – All fragments are negatively charged, so size determines how far they travel.
Q59. Which organism is commonly used to produce human insulin by genetic engineering?
- (A) A virus only
- (B) A fungus that causes disease
- (C) Genetically modified bacteria
- (D) A plant virus
Show Answer
Answer: C – Bacteria carrying the human insulin gene express it and produce insulin that can be purified.
Q60. A tomato plant has been given a gene from a bacterium that produces a protein toxic to insect pests. What is the most accurate description of this plant?
- (A) A genetically modified organism, because its genome has been altered by adding a gene
- (B) An organism produced only by selective breeding
- (C) An organism with no DNA of its own
- (D) A clone with DNA identical to the parent plant
Show Answer
Answer: A – Genetic modification directly alters DNA by adding, removing or changing genes, unlike traditional breeding alone.
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