A-Level Biology Practice Test 15 – 60 Questions with Answers (Cambridge 9700)
This test completes the set with a full-syllabus check, so use it to find any remaining gaps before exam-style practice.
Cell structure
Q1. Which statement about the rough endoplasmic reticulum is correct?
- (A) It synthesises lipids and detoxifies drugs
- (B) It is smooth because it lacks membranes
- (C) It is studded with ribosomes and is involved in synthesis of proteins for secretion or membranes
- (D) It is found only in prokaryotic cells
Show Answer
Answer: C – Proteins made here enter the lumen of the reticulum and are transported to the Golgi apparatus in vesicles.
Q2. Which statement about the cytoskeleton is correct?
- (A) It is a rigid wall outside the cell
- (B) It is made of cellulose microfibrils only
- (C) It is a network of protein fibres that supports the cell, moves organelles, and helps in cell division
- (D) It prevents all movement inside the cell
Show Answer
Answer: C – Microtubules, microfilaments and intermediate filaments together give the cell shape and internal organisation.
Q3. A student measures a cell as 20 micrometres long in real life. In a drawing it is 40 mm long. What is the magnification?
- (A) x2
- (B) x20
- (C) x200
- (D) x2000
Show Answer
Answer: D – 40 mm equals 40000 micrometres, and 40000 divided by 20 gives x2000.
Biological molecules
Q4. Why is glycogen well suited as an energy store in animals?
- (A) It is made of beta-glucose and is insoluble in water
- (B) It is a structural polysaccharide in plant cell walls
- (C) It is a storage polysaccharide in animals, made of alpha-glucose with frequent branching for rapid mobilisation
- (D) It is a protein found in muscle only
Show Answer
Answer: C – Many branch ends allow many glucose molecules to be released at once when energy is needed.
Q5. Which statement about the structure of a phospholipid is correct?
- (A) It is made of three fatty acids joined to glycerol
- (B) It has two hydrophilic heads and one hydrophobic tail
- (C) It has a hydrophilic phosphate head and two hydrophobic fatty acid tails
- (D) It has no polar region at all
Show Answer
Answer: C – This dual nature causes phospholipids to form bilayers in water, with tails facing inwards.
Q6. Which statement about hydrogen bonds in biological molecules is correct?
- (A) They are strong covalent bonds within a molecule
- (B) They occur only in water
- (C) They are weak attractions between a hydrogen atom with a partial positive charge and an electronegative atom, important in water, DNA and proteins
- (D) They join amino acids in a polypeptide chain
Show Answer
Answer: C – Individually weak, hydrogen bonds are collectively strong in large molecules and in the DNA double helix.
Enzymes
Q7. Which statement about enzyme denaturation is correct?
- (A) Denaturation breaks peptide bonds and splits the enzyme into amino acids
- (B) Denaturation increases enzyme activity
- (C) Denaturation changes the tertiary structure and active site shape, usually irreversibly, without breaking peptide bonds
- (D) Denaturation occurs only at low temperatures
Show Answer
Answer: C – The primary structure remains intact, but the enzyme can no longer bind its substrate effectively.
Q8. Which statement about the effect of pH on enzyme activity is correct?
- (A) All enzymes have the same optimum pH of 7
- (B) pH affects only the substrate, never the enzyme
- (C) Each enzyme has an optimum pH, and activity falls on either side as charges and bonds in the active site are affected
- (D) Enzyme activity increases indefinitely as pH rises
Show Answer
Answer: C – Pepsin, for example, works best in acidic conditions in the stomach, while trypsin works best in alkaline conditions.
Q9. An enzyme is immobilised for industrial use. Which advantage does this give?
- (A) The enzyme can no longer catalyse any reaction
- (B) The enzyme becomes denatured more quickly
- (C) The enzyme can be reused and easily separated from the product
- (D) The product becomes contaminated with enzyme in every batch
Show Answer
Answer: C – Immobilised enzymes are used in processes such as lactose-free milk production and biosensors.
Cell membranes and transport
Q10. What is osmosis, in terms of water potential?
- (A) Osmosis is the diffusion of solutes across a partially permeable membrane
- (B) Osmosis requires ATP in all cases
- (C) Osmosis is the diffusion of water from a higher water potential to a lower water potential across a partially permeable membrane
- (D) Osmosis occurs only in animal cells
Show Answer
Answer: C – Water potential is lowered by dissolved solutes, so pure water has the highest water potential.
Q11. Which statement about active transport in root hair cells is correct?
- (A) Water is taken up by active transport
- (B) Mineral ions diffuse passively into roots at all concentrations
- (C) Mineral ions are taken up against their concentration gradient using ATP
- (D) Root hair cells have no mitochondria for ATP production
Show Answer
Answer: C – This allows roots to accumulate ions even when soil concentrations are very low.
Q12. Which statement about exocytosis is correct?
- (A) Molecules diffuse directly through the bilayer
- (B) The cell membrane wraps around a particle to bring it inside
- (C) Vesicles fuse with the cell surface membrane and release their contents outside the cell
- (D) Vesicles move substances from the nucleus to the ribosomes
Show Answer
Answer: C – Exocytosis is used to secrete hormones, enzymes and neurotransmitters.
The mitotic cell cycle
Q13. Which statement about the cell cycle in cancer is correct?
- (A) Cancer cells divide in a fully controlled way with normal checkpoints
- (B) Cancer cells never undergo mitosis
- (C) Cancer cells divide uncontrollably because checkpoint genes are mutated, allowing damaged cells to keep dividing
- (D) Cancer is caused only by viruses and never by mutations
Show Answer
Answer: C – Tumours form when cell division outpaces cell death and normal regulation is lost.
Q14. A cell in G1 has 8 chromosomes. How many chromatids are present in a single chromosome during metaphase of mitosis in this cell?
- (A) 1
- (B) 4
- (C) 2
- (D) 8
Show Answer
Answer: C – After S phase, each chromosome consists of two sister chromatids joined at the centromere.
Q15. In a plant root tip, cells in the meristem divide repeatedly while cells further back elongate and specialise. What does this show about stem cells in plants?
- (A) Meristem cells are fully specialised and cannot divide
- (B) Meristem cells are found only in animals
- (C) Meristem cells remain unspecialised, divide by mitosis, and their daughter cells differentiate
- (D) Meristem cells have no nucleus
Show Answer
Answer: C – Plant meristems contain stem cells that self-renew and produce cells that go on to specialise for growth.
Q16. Which statement about the significance of mitosis in asexual reproduction is correct?
- (A) It produces offspring with new gene combinations
- (B) It halves the chromosome number in offspring
- (C) It produces offspring genetically identical to the parent, which is advantageous in a stable environment
- (D) It requires two parents
Show Answer
Answer: C – The lack of variation is a disadvantage if the environment changes rapidly.
Nucleic acids and protein synthesis
Q17. Which statement about the structure of DNA is correct?
- (A) Its strands run parallel in the same direction
- (B) It is a single helix with bases on the outside
- (C) Its backbone is made of amino acids
- (D) It is a double helix with sugar-phosphate backbones on the outside and bases paired inside
Show Answer
Answer: D – The two strands are antiparallel, which is important for replication and transcription.
Q18. Which statement about mRNA is correct?
- (A) mRNA remains in the nucleus throughout translation
- (B) mRNA carries amino acids to ribosomes
- (C) mRNA is double-stranded and contains thymine
- (D) mRNA carries the genetic code from the nucleus to ribosomes in the cytoplasm
Show Answer
Answer: D – Its codons are read in sequence at the ribosome to assemble a polypeptide.
Q19. Which statement about the genetic code is correct?
- (A) It is overlapping, so each base belongs to several codons
- (B) It uses four-base codons in eukaryotes
- (C) It varies completely between species
- (D) It is non-overlapping, with each base belonging to only one codon, and it is read in triplets
Show Answer
Answer: D – The code is also described as universal, because the same codons specify the same amino acids in almost all organisms.
Q20. A mutation substitutes one base in a codon, but the amino acid produced stays the same. What explains this?
- (A) The mutation occurred in an intron
- (B) The ribosome corrects all substitutions
- (C) The mutation was a frameshift
- (D) The genetic code is degenerate, so a different codon can specify the same amino acid
Show Answer
Answer: D – Such silent mutations have no effect on the protein, although they may affect other processes.
Transport in plants
Q21. In a plant, water moves from roots to leaves while sugars move from leaves to roots at the same time. Which pair of tissues carries these two flows?
- (A) Xylem transports sugars and phloem transports water
- (B) Xylem is living tissue and phloem is dead tissue
- (C) Both tissues transport only water
- (D) Xylem transports water and mineral ions upwards, while phloem transports assimilates from sources to sinks
Show Answer
Answer: D – Xylem vessels are dead, while phloem sieve tubes are living but depend on companion cells for loading.
Q22. Which statement about the cohesion of water is correct?
- (A) Cohesion is attraction between water molecules and the walls of xylem vessels
- (B) Cohesion prevents water from evaporating from leaves
- (C) Cohesion is the active pumping of water by roots
- (D) Cohesion is attraction between water molecules due to hydrogen bonding, helping to maintain a continuous column
Show Answer
Answer: D – Adhesion, by contrast, is attraction between water and the vessel walls, which also helps support the column.
Q23. A plant is placed in a humid, still environment. What happens to transpiration and to water uptake?
- (A) Transpiration increases and water uptake increases
- (B) Transpiration decreases and water uptake increases
- (C) Transpiration stays the same but water uptake stops
- (D) Transpiration decreases because the water vapour gradient is smaller, so water uptake also decreases
Show Answer
Answer: D – Transpiration pull is the main driver of water movement up the xylem in most conditions.
Q24. Which statement about loading at a source is correct?
- (A) Water leaves the phloem at the source, lowering pressure
- (B) Sucrose is unloaded at sources and loaded at sinks
- (C) Loading requires no energy at any stage
- (D) Sucrose is loaded into sieve tubes, lowering water potential there and drawing water in by osmosis, which raises hydrostatic pressure
Show Answer
Answer: D – The pressure gradient from source to sink drives bulk flow of sap in the phloem.
Transport in mammals
Q25. Which statement about the cardiac cycle is correct?
- (A) The atria and ventricles contract at exactly the same time
- (B) The heart rests during atrial systole
- (C) The ventricles contract first, then the atria
- (D) The atria contract first, pushing blood into the ventricles, then the ventricles contract to pump blood out
Show Answer
Answer: D – A short delay at the atrioventricular node ensures the ventricles fill before they contract.
Q26. Which statement about oxygen dissociation curves is correct?
- (A) A curve shifted to the right shows a higher affinity for oxygen
- (B) The curve shows oxygen uptake against temperature
- (C) All respiratory pigments have identical curves
- (D) A curve shifted to the right shows a lower affinity, so oxygen is released more readily
Show Answer
Answer: D – Myoglobin has a curve far to the left, reflecting its role in storing oxygen in muscle.
Q27. Which statement about lymph is correct?
- (A) Lymph is produced only in the liver
- (B) Lymph is blood that has left the capillaries permanently
- (C) Lymph carries oxygen to tissues
- (D) Lymph is tissue fluid that has entered lymph vessels and is returned to the blood near the heart
Show Answer
Answer: D – Lymph nodes filter lymph and contain lymphocytes that respond to pathogens.
Gas exchange
Q28. Which statement about the ventilation of a mammal during exercise is correct?
- (A) Only the diaphragm contracts, with no change in rate
- (B) Rate increases but depth decreases so total ventilation stays the same
- (C) Breathing stops to conserve energy
- (D) Both rate and depth of breathing increase to meet higher oxygen demand and remove carbon dioxide
Show Answer
Answer: D – Chemoreceptors detect rising carbon dioxide and falling pH in the blood and stimulate the breathing centre.
Q29. Which statement about gill lamellae is correct?
- (A) Lamellae are found only in mammals
- (B) Lamellae decrease surface area to reduce water loss
- (C) Lamellae are thick and muscular
- (D) Lamellae increase surface area and have a rich blood supply and thin walls for efficient diffusion
Show Answer
Answer: D – Gill filaments support many lamellae, giving a very large total area for exchange.
Q30. Which statement about the tracheoles of an insect is correct?
- (A) Tracheoles are air-filled tubes that end close to cells and may contain fluid that is withdrawn during activity to shorten the diffusion distance
- (B) Tracheoles carry blood to the tissues
- (C) Tracheoles are found only in aquatic insects
- (D) Tracheoles open directly to the outside through the mouth
Show Answer
Answer: A – This direct delivery system supports the high metabolic rate of flying insects.
Infectious diseases
Q31. Which statement about the treatment of bacterial infections is correct?
- (A) Antibiotics kill bacteria or prevent their growth, but they do not work against viruses
- (B) Antibiotics work equally well against viruses and bacteria
- (C) Antibiotics are effective only if taken for one day
- (D) Antibiotics strengthen viruses
Show Answer
Answer: A – Different antibiotics target bacterial cell walls, protein synthesis or DNA replication.
Q32. Which statement about cholera treatment is correct?
- (A) The priority is replacing lost water and salts with oral rehydration solution
- (B) The priority is giving antibiotics alone, with no fluids
- (C) Cholera cannot be treated at all
- (D) Treatment involves removing the small intestine
Show Answer
Answer: A – Rehydration saves lives, while antibiotics can shorten the illness in severe cases.
Q33. Which statement about the human immunodeficiency virus is correct?
- (A) HIV infects and destroys helper T cells, progressively weakening cell-mediated immunity
- (B) HIV infects only red blood cells
- (C) HIV is a bacterium that can be killed by antibiotics
- (D) HIV infection always causes immediate symptoms and death
Show Answer
Answer: A – Without treatment, the loss of helper T cells leaves the person vulnerable to opportunistic infections.
Immunity
Q34. Which statement about phagocytes is correct?
- (A) Phagocytes are part of the non-specific immune response and engulf pathogens
- (B) Phagocytes produce antibodies
- (C) Phagocytes are found only in the blood, never in tissues
- (D) Phagocytes form memory cells
Show Answer
Answer: A – Neutrophils and macrophages are the main phagocytes, and macrophages also present antigens to lymphocytes.
Q35. Which statement about the structure of an antibody is correct?
- (A) An antibody has a variable region that binds antigen and a constant region that determines its class and function
- (B) An antibody is a single polypeptide chain with no variable region
- (C) An antibody binds antigen with its constant region
- (D) All antibodies have the same variable region
Show Answer
Answer: A – The variable region differs between antibodies, giving the huge diversity of antigen binding.
Q36. Which statement about natural passive immunity is correct?
- (A) Antibodies are passed from mother to child across the placenta and in breast milk
- (B) The child produces its own antibodies after vaccination
- (C) Antibodies are injected by a doctor
- (D) Passive immunity lasts for life
Show Answer
Answer: A – This protection is temporary, lasting only while maternal antibodies remain in the baby’s blood.
Energy and respiration
Q37. Where does the Krebs cycle take place, and what are its main products?
- (A) It occurs in the cytoplasm and produces glucose
- (B) It produces most of the ATP of aerobic respiration directly
- (C) It uses oxygen directly to make water
- (D) It occurs in the mitochondrial matrix, oxidises acetyl groups, and produces reduced coenzymes and carbon dioxide
Show Answer
Answer: D – The reduced coenzymes then feed electrons into the electron transport chain.
Q38. Which statement about chemiosmosis is correct?
- (A) ATP is made when protons diffuse down their gradient through ATP synthase in the inner mitochondrial membrane
- (B) ATP is made when electrons diffuse through ATP synthase
- (C) Chemiosmosis occurs only in chloroplasts
- (D) Chemiosmosis requires no membrane at all
Show Answer
Answer: A – A similar chemiosmotic process makes ATP in photosynthesis, using a proton gradient across the thylakoid membrane.
Q39. Which statement about anaerobic respiration is correct?
- (A) It produces much more ATP than aerobic respiration
- (B) It produces less ATP because glucose is only partly broken down, but it allows ATP production without oxygen
- (C) It produces water as its main product
- (D) It occurs only in yeast, never in animals
Show Answer
Answer: B – The waste products, lactate or ethanol, still contain much of the energy of glucose.
Photosynthesis
Q40. Which statement about the light-dependent stage is correct?
- (A) It occurs in the stroma and fixes carbon dioxide
- (B) It occurs in the thylakoid membranes, splits water, and produces ATP and reduced NADP
- (C) It produces glucose directly
- (D) It occurs only in the dark
Show Answer
Answer: B – Oxygen released here comes from water, not from carbon dioxide.
Q41. How does a limiting factor control the rate of photosynthesis?
- (A) The rate of photosynthesis is always limited by light intensity alone
- (B) The factor in shortest supply relative to need limits the rate, and increasing it increases the rate until another factor limits
- (C) Increasing a limiting factor always increases the rate indefinitely
- (D) Temperature never limits photosynthesis
Show Answer
Answer: B – At high temperatures, enzymes may denature and the rate falls despite abundant light and carbon dioxide.
Q42. Which statement about triose phosphate is correct?
- (A) Triose phosphate is the first stable product of carbon fixation
- (B) Triose phosphate is produced in the Calvin cycle and can be used to make sugars, amino acids and lipids, or to regenerate RuBP
- (C) Triose phosphate is produced only in the light-dependent stage
- (D) Triose phosphate is a pigment
Show Answer
Answer: B – It is a key branch point between export from the chloroplast and regeneration of the carbon acceptor.
Homeostasis
Q43. Which statement about negative feedback is correct?
- (A) A change triggers a response that amplifies the change further
- (B) A change triggers a response that reverses the change and restores the set point
- (C) Negative feedback occurs only in blood glucose control
- (D) Negative feedback always involves hormones, never nerves
Show Answer
Answer: B – Temperature, water potential and blood glucose are all controlled by negative feedback loops.
Q44. Which statement about the kidney is correct?
- (A) The kidney filters blood in the glomerulus and selectively reabsorbs useful substances in the tubules
- (B) The kidney produces urine by filtering the whole blood, including cells and proteins
- (C) The kidney stores glucose for later use
- (D) The kidney produces red blood cells only
Show Answer
Answer: A – The nephron is the functional unit, and each kidney contains about a million nephrons.
Q45. Which statement about the control of core temperature is correct?
- (A) In cold conditions, shivering and vasoconstriction help raise or conserve core temperature
- (B) In cold conditions, sweating and vasodilation help conserve heat
- (C) In hot conditions, shivering helps cool the body
- (D) Temperature receptors are found only in the skin
Show Answer
Answer: A – In hot conditions, sweating and vasodilation increase heat loss instead.
Control and coordination
Q46. Which statement about the transmission of a nerve impulse along an axon is correct?
- (A) The impulse is an electrical current flowing inside the axon like in a wire
- (B) The impulse is a wave of depolarisation and repolarisation travelling along the membrane
- (C) The impulse travels by diffusion of neurotransmitter along the axon
- (D) The impulse travels only in myelinated neurones
Show Answer
Answer: B – Local currents ahead of the action potential bring the next region to threshold.
Q47. Which statement about the eye is correct?
- (A) Light is refracted mainly by the cornea and lens and focused onto the retina
- (B) Light is focused onto the blind spot for sharpest vision
- (C) The retina is at the front of the eye
- (D) The iris produces the image
Show Answer
Answer: A – Photoreceptors in the retina convert light into nerve impulses sent to the brain via the optic nerve.
Q48. Which statement about tropisms is correct?
- (A) Tropisms are rapid movements of a whole plant towards a stimulus
- (B) Tropisms are growth responses to a directional stimulus, such as light or gravity
- (C) Tropisms occur only in roots
- (D) Tropisms are controlled by nerve impulses
Show Answer
Answer: B – Shoots are positively phototropic and negatively gravitropic, while roots show the opposite responses.
Inheritance
Q49. Which statement about alleles is correct?
- (A) Alleles are different forms of the same gene, occupying the same locus on homologous chromosomes
- (B) Alleles are different genes on different chromosomes
- (C) Alleles are proteins produced by a gene
- (D) An organism can have only one allele of each gene
Show Answer
Answer: A – The combination of alleles is the genotype, while the observable trait is the phenotype.
Q50. Which statement about the inheritance of cystic fibrosis is correct?
- (A) It is caused by a dominant allele on an autosome
- (B) It is caused by a recessive allele on an autosome, so both parents of an affected child are usually carriers
- (C) It is caused by a recessive allele on the X chromosome
- (D) It is not inherited at all
Show Answer
Answer: B – Carrier parents have a 1 in 4 chance of having an affected child with each pregnancy.
Q51. Which statement about independent assortment is correct?
- (A) Alleles of genes on the same chromosome always assort independently
- (B) During metaphase I, homologous chromosome pairs line up independently, so alleles of genes on different chromosomes assort independently
- (C) Independent assortment occurs only in mitosis
- (D) Independent assortment prevents any genetic variation
Show Answer
Answer: B – Together with crossing over, independent assortment generates the variation on which selection acts.
Selection and evolution
Q52. Over many generations, a population of moths shifts from mostly light-coloured to mostly dark-coloured after industrial pollution darkens tree bark. Which statement best describes this change?
- (A) Allele frequencies in the population changed because dark moths survived and reproduced more successfully
- (B) Individual moths changed colour during their lifetimes and passed the change on
- (C) Evolution occurred only when a new moth species formed
- (D) The population progressed towards a perfect form
Show Answer
Answer: A – Natural selection changed allele frequencies over generations as camouflaged individuals left more offspring.
Q53. Which statement about the Hardy-Weinberg equation is correct?
- (A) In the equation p squared plus 2pq plus q squared equals 1, p squared is the frequency of heterozygotes
- (B) In the equation, 2pq is the frequency of heterozygotes, and p squared and q squared are the frequencies of the two homozygotes
- (C) The equation can only be used when one allele is dominant
- (D) The equation measures mutation rate directly
Show Answer
Answer: B – The equation assumes equilibrium conditions, so deviations from it indicate evolution is occurring.
Q54. Which statement about natural selection and antibiotic resistance is correct?
- (A) Bacteria become resistant because they need to survive
- (B) Resistant bacteria survive antibiotic treatment and reproduce, passing resistance alleles to their offspring
- (C) Antibiotics insert resistance genes into bacteria
- (D) Resistance is acquired by individual bacteria during treatment and lost afterwards
Show Answer
Answer: B – Resistance genes can also spread between bacteria by horizontal gene transfer.
Classification, biodiversity and conservation
Q55. Which statement about classification is correct?
- (A) Classification groups organisms by evolutionary relationships, so closely related organisms share a recent common ancestor
- (B) Classification is based only on where organisms live
- (C) Classification never changes as new evidence appears
- (D) All organisms in the same kingdom are equally closely related
Show Answer
Answer: A – Molecular evidence has led to reclassification, notably the separation of Archaea from Bacteria.
Q56. Which statement about biodiversity is correct?
- (A) Biodiversity refers only to the number of species in an area
- (B) Biodiversity includes genetic diversity, species diversity and ecosystem diversity
- (C) Biodiversity is the same in every habitat
- (D) Biodiversity cannot be measured
Show Answer
Answer: B – All three levels are important for the stability and functioning of ecosystems.
Q57. Which statement about conservation is correct?
- (A) Conservation aims only to preserve individual animals in zoos
- (B) Conservation aims to maintain biodiversity and ecosystem function, using both in situ and ex situ methods
- (C) Conservation prevents all human use of natural resources
- (D) Conservation is needed only for species that are already extinct
Show Answer
Answer: B – Sustainable use, habitat protection and legal measures are also part of conservation strategies.
Genetic technology
Q58. What does the polymerase chain reaction achieve, and how does it do it?
- (A) PCR amplifies a specific DNA sequence by repeated cycles of denaturation, annealing and extension
- (B) PCR translates DNA into protein
- (C) PCR requires a living cell
- (D) PCR separates DNA fragments by size
Show Answer
Answer: A – Primers define the sequence to be copied, and Taq polymerase extends them.
Q59. Which statement about genetic modification is correct?
- (A) Genetic modification always involves adding genes from the same species only
- (B) Genetic modification involves altering the genetic material of an organism, which may include adding a gene from another species
- (C) Genetic modification changes an organism without changing its DNA
- (D) Genetic modification is the same as selective breeding
Show Answer
Answer: B – Transgenic organisms carry a gene transferred from another species, such as the insulin gene in bacteria.
Q60. Which statement about the ethical issues of genetic technology is correct?
- (A) There are no ethical issues associated with genetic technology
- (B) Issues include consent for genetic testing, ownership of genetic information, and the safety of releasing genetically modified organisms
- (C) Genetic technology is banned in all countries
- (D) Ethical issues apply only to plants, never to humans
Show Answer
Answer: B – Regulation and public debate aim to balance potential benefits against these concerns.
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