A-Level Biology Practice Test 8 – 60 Questions with Answers (Cambridge 9700)
This test revisits every A-Level topic with new questions, emphasising data handling, quantitative reasoning and the finer detail of gene control, transport and energy transfer. Read each stem carefully before choosing.
Cell structure
Q1. Which organelle is present in plant cells but absent from most animal cells?
- (A) Mitochondrion
- (B) Chloroplast
- (C) Golgi body
- (D) Nucleus
Show Answer
Answer: B – Chloroplasts carry out photosynthesis and are found in plant cells, not animal cells.
Q2. Which structure allows direct cytoplasmic continuity between adjacent plant cells?
- (A) Tight junction
- (B) Desmosome
- (C) Gap junction in animals only
- (D) Plasmodesma
Show Answer
Answer: D – Plasmodesmata are channels through cell walls linking the cytoplasm of neighbouring plant cells.
Q3. The rough endoplasmic reticulum is studded with ribosomes. What does this suggest about its function?
- (A) It synthesises and transports proteins
- (B) It synthesises lipids for membranes
- (C) It breaks down hydrogen peroxide
- (D) It produces ATP
Show Answer
Answer: A – Ribosomes on its surface translate proteins that enter the lumen for folding and transport.
Biological molecules
Q4. Which monosaccharides combine to form lactose?
- (A) Glucose and fructose
- (B) Two glucose molecules
- (C) Glucose and galactose
- (D) Glucose and ribose
Show Answer
Answer: C – Lactose is a disaccharide of glucose and galactose joined by a glycosidic bond.
Q5. Why is cellulose suitable as a structural material in plant walls?
- (A) It is highly branched and soluble
- (B) Its beta-glucose chains form strong hydrogen-bonded microfibrils
- (C) It is easily hydrolysed by plant enzymes
- (D) Its chains coil into compact granules
Show Answer
Answer: B – Straight chains pack together and cross-link, giving great tensile strength.
Q6. Which type of lipid forms the bulk of cell membranes?
- (A) Triglyceride
- (B) Cholesterol alone
- (C) Wax alone
- (D) Phospholipid
Show Answer
Answer: D – Phospholipids form a bilayer with hydrophilic heads outward and hydrophobic tails inward.
Enzymes
Q7. What does Km represent in Michaelis-Menten kinetics?
- (A) The substrate concentration giving half of Vmax
- (B) The maximum rate of reaction
- (C) The enzyme concentration at saturation
- (D) The pH optimum of the enzyme
Show Answer
Answer: A – A low Km indicates high affinity, since half-maximal rate is reached at low substrate concentration.
Q8. How does a competitive inhibitor affect Km and Vmax?
- (A) Km decreases, Vmax decreases
- (B) Km unchanged, Vmax increases
- (C) Km increases, Vmax unchanged
- (D) Both Km and Vmax increase
Show Answer
Answer: C – More substrate is needed to reach half Vmax, but high substrate can still saturate the enzyme.
Q9. An enzyme catalyses the breakdown of maltose but not sucrose, although both are disaccharides. Which property best explains this observation?
- (A) One enzyme catalyses all reactions in a metabolic pathway
- (B) The active site is complementary in shape and chemistry only to maltose
- (C) Any disaccharide can fit into any enzyme active site
- (D) Specificity is lost whenever temperature falls slightly
Show Answer
Answer: B – Enzyme specificity arises because only a substrate complementary to the active site can bind and react effectively.
Q10. In a metabolic pathway, the end product inhibits the first enzyme. What is this called?
- (A) Competitive activation
- (B) Denaturation
- (C) Substrate saturation
- (D) End-product inhibition, a form of negative feedback
Show Answer
Answer: D – Accumulation of product slows its own synthesis, preventing wasteful overproduction.
Cell membranes and transport
Q11. Which protein type spans the membrane and provides a hydrophilic channel?
- (A) Intrinsic protein forming a channel
- (B) Peripheral protein on the surface only
- (C) Glycolipid
- (D) Cholesterol molecule
Show Answer
Answer: A – Intrinsic proteins extend through the bilayer and can form pores for ions or water.
Q12. A cell is placed in a solution with a higher water potential than the cell. What is the net movement of water?
- (A) Out of the cell
- (B) No net movement
- (C) Into the cell
- (D) Into the cell by active transport only
Show Answer
Answer: C – Water moves by osmosis from higher to lower water potential.
Q13. Which transport process requires ATP and a carrier protein, but moves only one type of solute?
- (A) Facilitated diffusion
- (B) Active transport by a pump
- (C) Simple diffusion
- (D) Osmosis
Show Answer
Answer: B – Pumps such as the sodium-potassium pump use ATP to move ions against a gradient.
Q14. Why do carrier proteins show saturation kinetics?
- (A) They are denatured at high solute concentration
- (B) They only work in one direction
- (C) They require light energy
- (D) All binding sites become occupied at high concentration
Show Answer
Answer: D – Like enzymes, carriers have a finite number of binding sites.
The mitotic cell cycle
Q15. What happens during prophase of mitosis?
- (A) Chromosomes condense and the spindle forms
- (B) Chromatids separate to opposite poles
- (C) The nuclear envelope reforms
- (D) DNA replicates
Show Answer
Answer: A – Chromatin condenses into visible chromosomes and the spindle begins to assemble.
Q16. Which cells in a plant divide by mitosis to increase length?
- (A) Xylem vessel elements only
- (B) Guard cells only
- (C) Meristem cells at root and shoot tips
- (D) Sieve tube elements
Show Answer
Answer: C – Apical meristems contain dividing, unspecialised cells that drive growth.
Q17. A cell has 2n equals 6. How many chromosomes will each daughter cell have after mitosis?
- (A) 3
- (B) 6
- (C) 12
- (D) 9
Show Answer
Answer: B – Mitosis preserves chromosome number, so daughters are genetically identical with 2n equals 6.
Q18. In plant cells, cytokinesis differs from animal cells because a cell plate forms across the equator. Why is a cell plate needed in plant cells?
- (A) The nucleus divides differently in plant cells
- (B) DNA is not replicated before plant cell division
- (C) Chromosomes do not condense in plant cells
- (D) The rigid cell wall cannot be pinched inward, so vesicles fuse to build a new wall across the cell
Show Answer
Answer: D – Animal cells divide their cytoplasm with a cleavage furrow, but a rigid wall prevents this, so plants build a cell plate from Golgi vesicles.
Nucleic acids and protein synthesis
Q19. Which molecule is produced by transcription?
- (A) A single-stranded mRNA copy of a gene
- (B) A new DNA double helix
- (C) A polypeptide chain
- (D) A tRNA anticodon only
Show Answer
Answer: A – RNA polymerase synthesises mRNA complementary to the template strand.
Q20. Where does translation occur in a eukaryotic cell?
- (A) In the nucleus
- (B) In the Golgi body only
- (C) At ribosomes in the cytoplasm or on rough endoplasmic reticulum
- (D) In the lysosome
Show Answer
Answer: C – Ribosomes read mRNA codons and assemble amino acids into a polypeptide.
Q21. In eukaryotes, what happens to pre-mRNA before it leaves the nucleus?
- (A) It is translated immediately
- (B) Introns are removed and exons are spliced together
- (C) It is copied back into DNA
- (D) Its bases are all changed to thymine
Show Answer
Answer: B – Splicing removes non-coding introns, leaving a mature mRNA of coding exons.
Transport in plants
Q22. Which process explains how water moves from root hairs into the xylem?
- (A) Active transport of water itself
- (B) Mass flow in phloem
- (C) Diffusion of sucrose only
- (D) Osmosis along a water potential gradient through the cortex
Show Answer
Answer: D – Root hair cells take up water by osmosis, and it moves across the cortex to the xylem.
Q23. At a sink, sucrose is removed from phloem. What follows?
- (A) Water potential in phloem rises, water leaves by osmosis, and pressure falls
- (B) Water potential falls and water enters, raising pressure further
- (C) Xylem pressure increases directly
- (D) Sucrose diffuses back to the source
Show Answer
Answer: A – Unloading lowers solute concentration, so water leaves and hydrostatic pressure drops, driving mass flow.
Q24. Which environmental factor would most increase transpiration rate?
- (A) High humidity and still air
- (B) Low temperature and darkness
- (C) Low humidity and wind
- (D) High humidity and low temperature
Show Answer
Answer: C – Dry, moving air maintains a steep water vapour gradient from leaf to air.
Transport in mammals
Q25. Which chamber of the heart has the thickest muscle wall, and why?
- (A) Right atrium, to pump to the lungs
- (B) Left ventricle, to pump blood around the whole body
- (C) Right ventricle, to pump to the brain
- (D) Left atrium, to pump to the ventricle
Show Answer
Answer: B – The left ventricle generates the high pressure needed for systemic circulation.
Q26. Why does tissue fluid contain glucose and amino acids but almost no plasma proteins or red blood cells?
- (A) Because lymph nodes filter proteins and cells out of tissue fluid
- (B) Because capillaries actively pump all proteins back into the blood
- (C) Because red blood cells dissolve as they pass through capillaries
- (D) Because gaps in the capillary endothelium allow small molecules through but retain large proteins and cells
Show Answer
Answer: D – Small solutes pass out with water under hydrostatic pressure, while large proteins and cells are too big to leave the capillary.
Q27. Which feature of capillaries suits exchange?
- (A) Walls one cell thick, narrow lumen and slow flow
- (B) Thick walls and fast flow
- (C) Valves and thick muscle
- (D) No endothelial lining
Show Answer
Answer: A – Thin walls shorten diffusion distance and slow flow gives time for exchange.
Gas exchange
Q28. In a fish gill, what is the function of gill filaments and lamellae?
- (A) They pump water actively
- (B) They filter food particles
- (C) They greatly increase surface area for diffusion
- (D) They store oxygen
Show Answer
Answer: C – Filaments bear many thin lamellae, giving a huge area in a small volume.
Q29. Which mechanism ventilates the mammalian lung during inspiration?
- (A) Diaphragm relaxes and ribs move down
- (B) Diaphragm contracts and external intercostal muscles raise the ribs
- (C) Abdominal muscles force air out
- (D) Alveoli actively pump air in
Show Answer
Answer: B – Increased thoracic volume lowers pressure, so air flows in.
Q30. Why is the trachea supported by C-shaped cartilage rings?
- (A) To allow gas exchange through its wall
- (B) To secrete mucus
- (C) To contract during breathing
- (D) To keep the airway open while allowing the oesophagus to expand behind it
Show Answer
Answer: D – The incomplete rings prevent collapse without blocking food passage.
Infectious diseases
Q31. Which disease is caused by a virus and spread by the bite of an infected mosquito?
- (A) Dengue fever
- (B) Cholera
- (C) Tuberculosis
- (D) Malaria
Show Answer
Answer: A – Dengue virus is transmitted by Aedes mosquitoes; malaria is caused by a protoctist.
Q32. How does the cholera toxin cause diarrhoea?
- (A) It destroys red blood cells
- (B) It blocks nerve impulses to the gut
- (C) It causes intestinal cells to secrete chloride ions and water into the gut lumen
- (D) It prevents absorption of fats only
Show Answer
Answer: C – Chloride secretion draws water by osmosis, producing profuse watery diarrhoea.
Q33. Why is drug resistance a growing problem in tuberculosis treatment?
- (A) The bacterium is a virus
- (B) Patients often stop treatment early, selecting resistant bacteria
- (C) Antibiotics cannot reach the lungs
- (D) Vaccines cause resistance
Show Answer
Answer: B – Incomplete courses leave resistant survivors to multiply and spread.
Immunity
Q34. Which cells present antigens to helper T cells?
- (A) Plasma cells
- (B) Red blood cells
- (C) Platelets
- (D) Phagocytes such as macrophages
Show Answer
Answer: D – Macrophages display antigen fragments on their surface to activate helper T cells.
Q35. What is the role of helper T cells in the immune response?
- (A) They stimulate B cells and cytotoxic T cells
- (B) They directly produce antibodies
- (C) They phagocytose bacteria directly
- (D) They block all inflammation
Show Answer
Answer: A – Helper T cells release cytokines that activate B cells and killer T cells.
Q36. A child receives a vaccine containing a weakened virus. Two weeks later, a blood test shows antibodies specific to that virus but no virus in the blood. What does this result show?
- (A) The child received ready-made antibodies for long-term protection
- (B) Existing memory cells were destroyed by the vaccine
- (C) A primary immune response occurred and memory cells formed, without the child developing the disease
- (D) The vaccine works only against bacteria
Show Answer
Answer: C – A harmless antigen form stimulates clonal selection and memory, so later infection is met rapidly without causing disease.
Energy and respiration
Q37. Which stage of aerobic respiration produces the most ATP per glucose molecule?
- (A) Glycolysis
- (B) The Krebs cycle and oxidative phosphorylation together
- (C) The link reaction alone
- (D) Anaerobic fermentation
Show Answer
Answer: B – Reduced coenzymes from the Krebs cycle feed oxidative phosphorylation, yielding most ATP.
Q38. What happens to pyruvate in anaerobic respiration in mammalian muscle?
- (A) It is converted to ethanol
- (B) It enters the Krebs cycle only
- (C) It is oxidised to water directly
- (D) It is reduced to lactate, regenerating NAD
Show Answer
Answer: D – Lactate formation oxidises reduced NAD so glycolysis can continue without oxygen.
Q39. Chemiosmosis in mitochondria depends on which gradient?
- (A) A proton gradient across the inner membrane
- (B) A sodium gradient across the outer membrane
- (C) A glucose gradient across the cristae
- (D) An oxygen gradient in the matrix
Show Answer
Answer: A – Protons accumulate in the intermembrane space and flow through ATP synthase.
Photosynthesis
Q40. Which pigment absorbs light most strongly in the blue and red regions?
- (A) Carotene only
- (B) Xanthophyll only
- (C) Chlorophyll a and b
- (D) Anthocyanin in leaves
Show Answer
Answer: C – Chlorophylls absorb blue and red light, reflecting green, which is why leaves appear green.
Q41. In cyclic photophosphorylation, what is produced?
- (A) ATP and reduced NADP, with oxygen
- (B) ATP only, with no reduced NADP or oxygen
- (C) Glucose directly
- (D) Water only
Show Answer
Answer: B – Electrons cycle back to photosystem I, generating ATP without photolysis or NADP reduction.
Q42. Why is triose phosphate an important product of the Calvin cycle?
- (A) It is a waste product excreted from the leaf
- (B) It directly splits water
- (C) It stores light energy as ATP
- (D) It is used to regenerate ribulose bisphosphate and to make glucose, amino acids and lipids
Show Answer
Answer: D – Most triose phosphate regenerates the acceptor; the remainder feeds biosynthesis.
Homeostasis
Q43. Which structure in the kidney creates the water potential gradient in the medulla?
- (A) The loop of Henle with its hairpin countercurrent system
- (B) The glomerulus alone
- (C) The Bowman’s capsule
- (D) The ureter
Show Answer
Answer: A – Ion transport in the ascending limb and water loss in the descending limb build a medullary gradient.
Q44. In diabetes mellitus, why does glucose appear in urine?
- (A) The glomerulus is blocked completely
- (B) ADH secretion stops
- (C) Blood glucose exceeds the reabsorption capacity of the proximal tubule
- (D) The collecting duct becomes impermeable to glucose
Show Answer
Answer: C – When the transport maximum is exceeded, glucose remains in filtrate and is excreted.
Q45. Which is an example of negative feedback in thermoregulation?
- (A) A rise in temperature triggers shivering
- (B) A rise in core temperature triggers sweating, which cools the body back toward normal
- (C) A fall in temperature triggers vasodilation
- (D) Sweating increases temperature further
Show Answer
Answer: B – The response opposes the original change, restoring the set point.
Control and coordination
Q46. How does myelination increase conduction speed?
- (A) It allows continuous depolarisation along the whole axon
- (B) It increases axon diameter to zero
- (C) It blocks all ion movement
- (D) It restricts depolarisation to nodes of Ranvier, so impulses jump between nodes
Show Answer
Answer: D – Saltatory conduction is faster because only nodes need to depolarise.
Q47. Which plant response is controlled by auxin redistribution in roots?
- (A) Positive gravitropism, with growth inhibited on the lower side
- (B) Positive phototropism only
- (C) Negative gravitropism in shoots only
- (D) Flowering in short days
Show Answer
Answer: A – In roots, high auxin on the lower side inhibits elongation, so the root bends downward.
Q48. At a neuromuscular junction, what removes acetylcholine from the synaptic cleft?
- (A) It diffuses into the muscle fibre nucleus
- (B) It is stored in the postsynaptic membrane
- (C) Acetylcholinesterase breaks it down
- (D) Calcium ions destroy it
Show Answer
Answer: C – The enzyme hydrolyses acetylcholine to acetate and choline, ending stimulation.
Inheritance
Q49. What is the expected genotypic ratio from a cross between two heterozygotes for one gene?
- (A) 3:1
- (B) 1:2:1
- (C) 9:3:3:1
- (D) 1:1
Show Answer
Answer: B – One quarter homozygous dominant, one half heterozygous, one quarter homozygous recessive.
Q50. If allele frequencies are p equals 0.6 and q equals 0.4, what is the expected frequency of homozygous recessive individuals?
- (A) 0.36
- (B) 0.48
- (C) 0.60
- (D) 0.16
Show Answer
Answer: D – Homozygous recessive frequency is q squared, which is 0.16.
Q51. Which cross would reveal whether a dihybrid organism is heterozygous at both loci?
- (A) A test cross with a homozygous recessive organism
- (B) A cross with a homozygous dominant organism
- (C) Self-fertilisation only
- (D) A cross with an unrelated species
Show Answer
Answer: A – Offspring phenotypes in a test cross reveal the gametes produced by the unknown parent.
Selection and evolution
Q52. Which process can cause speciation without geographical separation?
- (A) Allopatric speciation
- (B) Artificial selection only
- (C) Sympatric speciation, for example by polyploidy in plants
- (D) Genetic drift in a large population only
Show Answer
Answer: C – Polyploid plants may be reproductively isolated from diploid parents in the same area.
Q53. Directional selection on beak size in finches during drought is an example of what?
- (A) Selection favouring intermediates
- (B) Selection favouring one extreme phenotype as conditions change
- (C) Selection favouring both extremes
- (D) No selection acting
Show Answer
Answer: B – Larger beaks that crack tough seeds were favoured, shifting the population mean.
Q54. Why does a small founder population often have reduced genetic diversity?
- (A) Mutation stops in small populations
- (B) Natural selection stops acting
- (C) It always has more alleles
- (D) It carries only a sample of the original gene pool
Show Answer
Answer: D – The founder effect means alleles present by chance may be over- or under-represented.
Classification, biodiversity and conservation
Q55. Which taxonomic group includes all organisms descended from a common ancestor?
- (A) A monophyletic group or clade
- (B) A polyphyletic group
- (C) A kingdom only
- (D) A genus with unrelated species
Show Answer
Answer: A – A clade includes an ancestor and all its descendants.
Q56. What does species richness measure, on its own?
- (A) The evenness of species abundance
- (B) The genetic diversity within one species
- (C) The number of different species in an area
- (D) The total biomass
Show Answer
Answer: C – Richness counts species; indices like Simpson’s also include evenness.
Q57. Which is an ex situ conservation method?
- (A) A national park protecting habitat
- (B) A seed bank storing seeds away from their habitat
- (C) A marine reserve
- (D) A protected forest corridor
Show Answer
Answer: B – Ex situ methods conserve organisms or gametes outside their natural habitat.
Genetic technology
Q58. What is the function of primers in PCR?
- (A) To cut DNA into fragments
- (B) To separate DNA by size
- (C) To insert DNA into a vector
- (D) To provide a starting point for Taq polymerase on each strand
Show Answer
Answer: D – Primers anneal to complementary sequences flanking the target region.
Q59. A scientist wants to insert a human insulin gene into bacteria. Which component is first joined to the gene to form recombinant DNA before it enters the host cell?
- (A) A plasmid, acting as a vector
- (B) A restriction enzyme, acting alone
- (C) A primer sequence only
- (D) A gel used for electrophoresis
Show Answer
Answer: A – The gene is inserted into a plasmid vector, which then carries it into host cells where it can be replicated and expressed.
Q60. Which is a potential benefit of genetically modified crops?
- (A) Guaranteed elimination of all weeds
- (B) No need for any farming inputs
- (C) Increased yield or resistance to pests and herbicides
- (D) Complete immunity to drought in all climates
Show Answer
Answer: C – Inserted genes can confer pest resistance or herbicide tolerance, improving yield.
Work through any questions you missed again, then revise those areas before moving on to the next test.
📥 Prefer pen and paper? Take this test offline.
Download Printable PDF – Test 8
Free printable version: all 60 questions + answer key. Explanations stay here on the website.