Medical University of Lublin Entrance Exam Practice Paper with Answers (2027)

Answer: A

Complementary bases pair by hydrogen bonds: two between adenine and thymine, three between guanine and cytosine, which is why the strands can be separated by heat or by helicase. Phosphodiester bonds join nucleotides along each strand (the sugar–phosphate backbone), not the two strands to each other. Glycosidic bonds link each base to its deoxyribose; peptide bonds join amino acids and disulfide bonds link cysteines in proteins.

Answer: B

Secretory proteins are made by ribosomes bound to the rough endoplasmic reticulum, which thread the growing chain into the ER lumen. They then travel in vesicles to the Golgi apparatus, which modifies, sorts and packages them but does not synthesise them. The smooth ER makes lipids and detoxifies; lysosomes digest material and peroxisomes break down fatty acids and hydrogen peroxide.

Answer: C

The solution is hypertonic to the cell, so water moves out across the membrane by osmosis, from the region of lower solute concentration (the cytoplasm) to the region of higher solute concentration, and the cell shrinks (crenates). Swelling and bursting happen in a hypotonic solution. Osmosis is the movement of water, not of solute, and it is passive: no pump moves water.

Answer: D

Codon and anticodon pair antiparallel and complementary. Against 5′-A-U-G-3′ the anticodon reads 3′-U-A-C-5′, which written in the 5′ to 3′ direction is 5′-CAU-3′. 5′-UAC-3′ is the complementary sequence written in the wrong direction, the most common slip. RNA contains no thymine, so TAC cannot be an anticodon, and AUG is the codon itself.

Answer: E

The heterozygote gives A or a gametes in equal numbers, and the recessive parent gives only a. The offspring are therefore Aa and aa in a 1 : 1 ratio, so half show the recessive phenotype. This is a test cross. 25% is the proportion of aa from a cross of two heterozygotes (Aa × Aa), and 75% is the dominant proportion in that cross.

Answer: A

A son receives his Y chromosome from his father and one of his mother's two X chromosomes. The mother is a carrier (one affected X, one normal X), so each son has an even chance of receiving the affected X and, having no second X to mask it, of being colour-blind: 1/2. A quarter is the probability that any child, son or daughter, is a colour-blind son; the daughters receive the father's normal X and none is colour-blind.

Answer: B

Homologous structures share an origin inherited from a common ancestor, even when they now do different jobs: the human arm and the whale's flipper are built on the same pentadactyl bone pattern (humerus, radius and ulna, carpals, digits). The other pairs are analogous: they look alike or do the same job because of convergent evolution, but evolved separately (insect and bird wings, octopus and vertebrate eyes, the streamlined bodies of sharks and dolphins, plant and animal spines).

Answer: C

With q = 0.3, p = 1 − 0.3 = 0.7, and the heterozygote frequency is 2pq = 2 × 0.7 × 0.3 = 0.42. 0.09 is q², the frequency of homozygous recessives; 0.49 is p², the homozygous dominants; 0.21 is pq without the factor of 2; and 0.70 is p, an allele frequency rather than a genotype frequency. As a check, 0.49 + 0.42 + 0.09 = 1.

Answer: D

Bacteria are prokaryotes: their chromosome is a single circular DNA molecule lying in the nucleoid, not in a nucleus, and their ribosomes are the smaller 70S type (eukaryotic cytoplasmic ribosomes are 80S). They have no mitochondria, making ATP on their plasma membrane; their walls are made of peptidoglycan (chitin is the fungal wall); and they divide by binary fission, not mitosis.

Answer: E

Fungal cell walls are built mainly of chitin, a polysaccharide of N-acetylglucosamine, the same material as the exoskeleton of insects. Cellulose is the main component of plant cell walls (lignin strengthens woody plant walls), peptidoglycan forms the walls of bacteria, and silica forms the walls of diatoms.

Answer: A

In deuterostomes the first opening of the embryo, the blastopore, becomes the anus and the mouth forms second; this group includes the echinoderms (starfish, sea urchins) and the chordates, among them vertebrates. Molluscs, annelids, flatworms, arthropods and nematodes are protostomes, in which the blastopore usually becomes the mouth. Sponges have no true tissues and cnidarians have only two germ layers, so neither is classed in either group.

Answer: B

Negative feedback from the hypothalamus switches on heat loss: sweat glands secrete sweat, whose evaporation cools the skin, and the skin arterioles dilate so more warm blood flows near the surface and loses heat. Shivering, vasoconstriction in the skin, a higher metabolic rate and raised hairs all conserve or generate heat; they are the responses to a fall in temperature.

Answer: C

The β cells of the islets of Langerhans sense the rise in glucose and secrete insulin, which makes muscle and fat cells take up glucose and the liver store it as glycogen, lowering blood glucose. The α cells secrete glucagon, which raises blood glucose; adrenaline and cortisol also raise it. Insulin does not come from α cells.

Answer: D

Bile is made by the liver, stored and concentrated in the gall bladder, and released into the duodenum. Its bile salts emulsify fats into small droplets, giving pancreatic lipase a larger surface to work on; bile itself contains no digestive enzyme. Bile is slightly alkaline and, with pancreatic bicarbonate, helps neutralise the acid chyme leaving the stomach.

Answer: E

The pulmonary veins return oxygenated blood from the lungs to the left atrium; they are the only veins in the adult that carry oxygenated blood. The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs, the aorta carries oxygenated blood away from the left ventricle to the body, and the venae cavae and the coronary sinus return deoxygenated blood to the right atrium.

Answer: A

ADH, made in the hypothalamus and released from the posterior pituitary when the blood becomes too concentrated, inserts water channels (aquaporins) into the walls of the collecting ducts. More water is reabsorbed into the blood, and a smaller volume of concentrated urine is produced. It makes the ducts more permeable, not less; aldosterone, from the adrenal cortex, is the hormone that acts on sodium reabsorption.

Answer: B

The brain, spinal cord and nerves come from the ectoderm: during neurulation a strip of it, the neural plate, folds into the neural tube. The ectoderm also forms the epidermis. The endoderm forms the lining of the gut and its glands and the lungs, and the mesoderm forms muscle, bone, blood, the heart and the kidneys. The trophoblast forms part of the placenta, and the hypoblast contributes to extra-embryonic tissues.

Answer: C

Antibodies are secreted by plasma cells, which develop from B lymphocytes activated by their antigen (usually with help from helper T cells). Helper T cells coordinate the response with cytokines, cytotoxic T cells kill infected cells directly, and neutrophils and macrophages are phagocytes; none of them makes antibodies.

Answer: D

When the membrane reaches threshold, voltage-gated sodium channels open and Na⁺ rushes in down its concentration and electrical gradients, driving the potential from about −70 mV towards +30 mV. Potassium leaving the cell through voltage-gated K⁺ channels causes the repolarisation that follows. The Na⁺/K⁺-ATPase moves sodium out of the cell, not in, and keeps up the gradients over time rather than firing the spike; chloride entering would make the inside more negative.

Answer: E

Primary consumers receive about 10% of what the producers fix, 2,000 kJ m⁻², and secondary consumers about 10% of that, 200 kJ m⁻². The rest is lost at each step, mostly as heat from respiration and in material not eaten or not digested. 2,000 is the primary consumers' share; 20 would be the tertiary consumers'.

Answer: A

The atomic number gives the protons, 17, and in a neutral atom the electrons equal the protons, 17. The mass number, 37, counts protons plus neutrons, so there are 37 − 17 = 20 neutrons. Taking the mass number as the neutron count gives 37; 18 electrons would be the chloride ion, Cl⁻, not the neutral atom.

Answer: B

Magnesium, a metal, gives two electrons to oxygen, a non-metal, forming Mg²⁺ and O²⁻ ions held in a lattice by ionic bonds; the large difference in electronegativity between them is the sign. The other four are compounds of non-metals only, whose atoms share electrons in covalent bonds: polar in HCl, NH₃ and the C=O bonds of CO₂, and almost non-polar in the C–H bonds of CH₄. HCl ionises when it dissolves in water, but the molecule itself is covalent.

Answer: C

The equation gives 2 mol of water for every 1 mol of methane, so 2 mol of methane give 4 mol of water. The molar mass of water is 2 × 1 + 16 = 18 g mol⁻¹, so 4 × 18 = 72 g. 36 g forgets that there are 2 mol of methane, and 88 g is the mass of carbon dioxide (2 mol × 44 g mol⁻¹), not of water.

Answer: D

By Le Chatelier's principle, raising the temperature favours the endothermic direction, which here is the reverse reaction, so the equilibrium shifts to the left and less ammonia is present; for an exothermic reaction the equilibrium constant falls as the temperature rises. A higher temperature does make equilibrium arrive faster, which is why industry uses a compromise temperature, but the reaction never stops: forward and back reactions go on at equal rates.

Answer: E

Oxygen is far more electronegative than sulfur, so each water molecule can form hydrogen bonds to its neighbours, much stronger attractions than the weak forces between H₂S molecules; more energy is needed to separate the molecules, and the boiling point is far higher. H₂S is the heavier molecule (34 against 18 g mol⁻¹), water is strongly polar, and boiling separates molecules without breaking any covalent bond.

Answer: A

Moles needed = concentration × volume = 0.20 mol L⁻¹ × 0.500 L = 0.10 mol, and mass = 0.10 mol × 58.5 g mol⁻¹ = 5.85 g. 11.7 g is the mass for a whole litre, the usual slip of forgetting to convert 500 mL; 58.5 g is one mole.

Answer: B

Sodium hydroxide is a strong base and dissociates completely, so [OH⁻] = 0.001 = 10⁻³ mol L⁻¹ and pOH = 3. At 25 °C pH + pOH = 14, so pH = 14 − 3 = 11. A pH of 3 is the pOH, or the pH of a 0.001 mol L⁻¹ strong acid.

Answer: C

A buffer is a weak acid with its conjugate base (or a weak base with its conjugate acid): ethanoic acid, CH₃COOH, and the ethanoate ion from sodium ethanoate. Added H⁺ is taken up by CH₃COO⁻ and added OH⁻ by CH₃COOH, so the pH barely changes. The other mixtures pair a strong acid or base with a neutral salt, and nothing in them can absorb added acid or base without a large change in pH.

Answer: D

The C=C double bond makes alkenes unsaturated, and their characteristic reaction is addition: bromine adds across the double bond (CH₂=CH₂ + Br₂ → CH₂Br–CH₂Br), and the orange bromine water turns colourless, the standard test for an alkene. Radical substitution in UV light is typical of alkanes, and electrophilic substitution of aromatic compounds such as benzene; alkenes burn readily.

Answer: E

Propan-2-ol is a secondary alcohol: its –OH is on a carbon bonded to two other carbons, and oxidation turns that carbon into a ketone carbonyl, giving propanone, CH₃–CO–CH₃ (acetone). A ketone cannot be oxidised further without breaking C–C bonds. Propanal and then propanoic acid come from the primary alcohol propan-1-ol; propene would come from dehydration, not oxidation.

Answer: A

A carboxylic acid and an alcohol react, with an acid catalyst, in a condensation (esterification): CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O, giving the ester ethyl ethanoate and water. Ethanal would need an oxidising agent; diethyl ether and ethene come from ethanol and sulfuric acid alone; an amide needs ammonia or an amine, not an alcohol.

Answer: B

Sucrose, cane or beet sugar, is glucose joined to fructose. Lactose, milk sugar, is glucose plus galactose, and maltose is two glucose units. Cellulose and glycogen are polysaccharides, long chains of glucose, not disaccharides.

Answer: C

A triglyceride is an ester of glycerol (propane-1,2,3-triol) with three fatty acids. Alkaline hydrolysis breaks the three ester bonds, giving glycerol and, because the solution is alkaline, the sodium salts of the fatty acids rather than the free acids: these salts are soap. There is no glucose, amino acid, cholesterol or ethanol in a triglyceride.

Answer: D

Each peptide bond forms by condensation between the –COOH of one amino acid and the –NH₂ of the next, releasing one molecule of water. A chain of three amino acids has two peptide bonds, so two molecules of water are released; in general, n amino acids in a line give n − 1 water molecules. Three would be the number of amino acids, not of bonds.

Answer: E

Move the decimal point four places to the right to give 4.5, a number between 1 and 10, so the power of ten is −4: 4.5 × 10⁻⁴. 45 × 10⁻³ is 0.045 and is not in standard form anyway, 4.5 × 10⁻³ is 0.0045, 0.45 × 10⁻⁵ is 0.0000045, and 4.5 × 10⁴ is 45,000.

Answer: B

Pressure is force per area: 1 Pa = 1 N m⁻², and 1 N = 1 kg m s⁻², so 1 Pa = kg m s⁻² ÷ m² = kg m⁻¹ s⁻². The tempting kg m s⁻² is the newton itself (force, not pressure); kg m² s⁻² is the joule (energy); kg m⁻³ is the unit of density.

Answer: D

Under constant deceleration the average speed is (20 + 0)/2 = 10 m s⁻¹, so the distance is 10 m s⁻¹ × 4.0 s = 40 m. Check: a = 20/4.0 = 5 m s⁻² and s = v²/(2a) = 400/10 = 40 m. 80 m comes from multiplying the initial speed by the time, as if the ambulance had not slowed down at all.

Answer: A

The scale reads the normal force N. Newton's second law upwards: N − mg = ma, so N = m(g + a) = 70 × (10 + 2.0) = 840 N. 700 N is the reading at rest or at constant velocity; 560 N, m(g − a), is the reading when the lift accelerates downwards; 140 N is only the resultant force ma.

Answer: C

Take moments about the elbow. The load's weight is 2.0 × 10 = 20 N at 0.30 m, a moment of 6.0 N m. The biceps acts at 0.030 m, so F × 0.030 = 6.0 and F = 200 N. The muscle works at a mechanical disadvantage of 10: its lever arm is a tenth of the load's, so it must pull ten times harder. 20 N is just the weight of the load.

Answer: E

Momentum is conserved: 2.0 × 3.0 = (2.0 + 1.0)v, so v = 6.0/3.0 = 2.0 m s⁻¹. Kinetic energy is not conserved in a collision where the bodies stick together: it falls from 9.0 J to 6.0 J. 6.0 m s⁻¹ is the momentum in kg m s⁻¹, not a speed.

Answer: B

For small swings T = 2π√(L/g), so the period is proportional to the square root of the length. Four times the length gives √4 = 2 times the period, 2T. 4T forgets the square root; the mass of the bob and (for small angles) the amplitude do not affect the period.

Answer: A

v = fλ, so λ = v/f = 1500 / (2.0 × 10⁶) = 7.5 × 10⁻⁴ m = 0.75 mm. 7.5 mm is a slip of one power of ten when converting from metres. The short wavelength is why ultrasound can resolve millimetre-scale structures.

Answer: D

By the continuity equation the volume flow rate Av is the same in both parts. The area is πr², so halving the radius makes the area a quarter, and the speed must rise four times. 'Twice' halves the area instead of quartering it; 'sixteen times' confuses continuity with Poiseuille's r⁴ law, which concerns the resistance to flow, not the speed at a fixed flow rate.

Answer: C

At constant volume p/T is constant, with T in kelvin. 27 °C is 300 K and 327 °C is 600 K, so the absolute temperature doubles and so does the pressure. 'About twelvefold' comes from dividing the Celsius temperatures (327/27), which is wrong because the Celsius scale does not start at absolute zero.

Answer: E

Q = mcΔT = 2.0 × 4200 × 10 = 84 000 J = 84 kJ. A rise of 10 °C is a rise of 10 K, so no conversion is needed for the temperature difference. 42 kJ uses 1.0 kg; 840 kJ is a slip of a factor of ten.

Answer: A

Coulomb's law: F = kq₁q₂/r². Doubling one charge doubles the force; doubling the distance divides it by 2² = 4. Together: F × 2/4 = F/2. 'F' assumes the two changes cancel, forgetting that the distance enters squared.

Answer: B

In parallel, 1/R = 1/6.0 + 1/6.0 = 1/3.0, so R = 3.0 Ω and I = V/R = 12/3.0 = 4.0 A. Each resistor carries 2.0 A, which is the tempting answer if you forget to add the branches; 1.0 A would be the current with the resistors in series (12 Ω).

Answer: E

In order of decreasing wavelength the spectrum runs radio, microwave, infrared, visible, ultraviolet, X-rays, gamma rays. Gamma rays from nuclear decay typically have the shortest wavelengths (and highest photon energies) of the five. All five travel at the same speed in a vacuum, about 3 × 10⁸ m s⁻¹.

Answer: D

Using 1/f = 1/u + 1/v with real distances positive: 1/v = 1/10 − 1/30 = 3/30 − 1/30 = 2/30, so v = 15 cm, a real image on the far side of the lens. Its magnification is v/u = 0.5, so it is inverted and half the size. 7.5 cm comes from adding 1/10 and 1/30 instead of subtracting.

Answer: C

24 hours is 24/6 = 4 half-lives, so the activity falls to (1/2)⁴ = 1/16 of its starting value: 160/16 = 10 MBq. 40 MBq treats 24 hours as two half-lives; radioactive decay never reaches zero in a finite number of half-lives.

Answer: B

Multiply the numbers and add the powers: 3 × 4 = 12 and 10⁴ × 10⁻⁶ = 10⁻², giving 12 × 10⁻², which in standard form is 1.2 × 10⁻¹. 1.2 × 10⁻² forgets to adjust the power when moving the decimal point; 7 × 10⁻² adds 3 and 4 instead of multiplying them.

Answer: D

The dose is 15 × 24 = 360 mg, and 360 ÷ 120 = 3 tablets. 2 tablets (240 mg) would correspond to a 16 kg child; 2.5 tablets would be 300 mg, which is 12.5 mg per kg.

Answer: A

30 − 5 = 25 students study at least one of the two. By inclusion–exclusion, n(B ∪ C) = n(B) + n(C) − n(B ∩ C), so 25 = 18 + 15 − n(B ∩ C) and n(B ∩ C) = 8. 3 comes from 18 + 15 − 30, which forgets the 5 who study neither.

Answer: C

√8 = 2√2, and √2 cannot be written as a ratio of two integers, so √8 is irrational. 0.25 = 1/4, √49 = 7 and −3 are rational, and 22/7 is a fraction, so it is rational by definition, even though it is a familiar approximation to the irrational number π.

Answer: E

Expand the bracket: 2x − 5 = 3x − 12. Subtract 2x and add 12 to both sides: 7 = x. Check: 2(7) − 5 = 9 and 3(7 − 4) = 9. x = −1 comes from expanding 3(x − 4) as 3x − 4.

Answer: B

Factorise: you need two numbers that multiply to 6 and add to −5, which are −2 and −3, so (x − 2)(x − 3) = 0 and x = 2 or x = 3. Check: 4 − 10 + 6 = 0 and 9 − 15 + 6 = 0. x = −2 or −3 are the numbers inside the brackets, not the roots.

Answer: A

Apply g first: g(2) = 2² = 4. Then f(4) = 2 × 4 + 3 = 11. 49 is (g ∘ f)(2) = g(f(2)) = g(7), the composition in the other order.

Answer: D

sin 30° = 1/2 and cos 60° = 1/2 (they are equal because 30° and 60° are complementary), so the sum is 1. √3 would be sin 60° + cos 30° = √3/2 + √3/2.

Answer: C

Opposite = hypotenuse × sin 30° = 10 × 1/2 = 5 cm. 5√3 cm is the side adjacent to the 30° angle (10 × cos 30°), which is opposite the 60° angle.

Answer: E

V = πr²h = π × 3² × 10 = 90π cm³. 30π uses r instead of r²; 60π cm² is the curved surface area (2πrh), a different quantity in different units.

Answer: A

Circumference = 2πr = 10π, so r = 5 cm and the area is πr² = 25π cm². 100π cm² takes 10 as the radius instead of the diameter.

Answer: B

Gradient = (change in y)/(change in x) = (11 − 2)/(4 − 1) = 9/3 = 3. 1/3 divides the change in x by the change in y; 9 forgets to divide by the change in x.

Answer: E

Perpendicular gradients multiply to −1, so the new gradient is −1/2. A line through (0, 4) has y-intercept 4, so the line is y = −½x + 4. y = 2x + 4 is parallel to the given line; y = −2x + 4 changes the sign but does not take the reciprocal; y = ½x + 4 takes the reciprocal but keeps the sign.

Answer: D

Five numbers with mean 8 add up to 5 × 8 = 40. The four known numbers add up to 4 + 7 + 9 + 13 = 33, so the fifth is 40 − 33 = 7. 8 assumes the missing number must equal the mean.

Answer: C

There are 6 × 6 = 36 equally likely outcomes. Six of them add up to 7: (1,6), (2,5), (3,4), (4,3), (5,2) and (6,1). So the probability is 6/36 = 1/6. 1/12 counts only the three unordered pairs, forgetting that (1,6) and (6,1) are different outcomes.

Answer: A

The Krebs cycle and the respiratory chain, the aerobic stages of respiration, take place in the mitochondrion, which makes most of the cell's ATP. Ribosomes make proteins, the Golgi apparatus modifies and packages them, lysosomes digest material, and the nucleolus assembles ribosomal subunits.

Answer: B

Osmosis is the net movement of water across a selectively permeable membrane towards the side with more solute. Diffusion is the general term for the spread of any substance down its concentration gradient; active transport uses energy to move substances against their gradient; endocytosis takes material in by folding the membrane; facilitated diffusion moves solutes down their gradient through carrier or channel proteins.

Answer: C

Heterozygous means having two different alleles of a gene (Aa). Homozygous means two identical alleles (AA or aa); hemizygous means having only one copy, as a male has for X-linked genes; polyploid means having more than two full sets of chromosomes; recessive describes an allele, not an organism.

Answer: D

The phenotype is the set of observable traits, produced by the genotype together with the environment. The genotype is the combination of alleles an organism carries; the karyotype is its set of chromosomes as seen under the microscope; the genome is all of its DNA; an allele is one form of a gene.

Answer: E

'Hyper-' means above normal or excessive: hyperglycaemia is a raised blood glucose and hypertension a raised blood pressure. Its opposite is 'hypo-' (below normal); 'intra-' means within, 'peri-' around and 'brady-' slow.

Answer: A

Medial means nearer the midline; lateral means further from it. Proximal and distal describe positions along a limb, nearer to or further from where it attaches to the trunk, and superficial means nearer the body surface.

Answer: B

The alveoli are lined by simple squamous epithelium: a single layer of flat cells gives the shortest diffusion distance for oxygen and carbon dioxide. Stratified squamous protects surfaces that are rubbed (skin, oesophagus); simple columnar lines the stomach and intestine; transitional lines the bladder; pseudostratified ciliated columnar lines the trachea and bronchi.

Answer: C

Plasma cells, which develop from activated B lymphocytes, secrete antibodies. Helper T cells coordinate the immune response but make no antibodies; neutrophils and macrophages are phagocytes; erythrocytes carry oxygen.

Answer: D

A pathogen is an organism that causes disease. A commensal lives on or in a host without harming it; a vector, such as a mosquito, carries a pathogen from one host to another; a saprophyte feeds on dead organic matter; a symbiont lives in close association with another organism, often to the benefit of both.

Answer: E

A polymer is built from many monomers: starch from glucose, proteins from amino acids, DNA from nucleotides. Isomers share a molecular formula but differ in structure; isotopes are atoms of one element with different numbers of neutrons; an ion is a charged particle; a catalyst speeds up a reaction without being used up.

Answer: A

Proteins are chains of amino acids joined by peptide bonds. Nucleotides are the monomers of nucleic acids, monosaccharides of polysaccharides; fatty acids and glycerol make up triglycerides, which are not polymers.

Answer: B

Isotopes have the same number of protons, and so are the same element, but different numbers of neutrons, as ¹²C and ¹⁴C do. Isomers are compounds with the same formula and different structures; ions carry a charge; allotropes are different forms of the same element, such as diamond and graphite; radicals have an unpaired electron.

Answer: C

Force is measured in newtons (1 N = 1 kg m s⁻²). The joule is the unit of energy, the watt of power, the pascal of pressure and the coulomb of electric charge.

Answer: D

The mode is the most frequent value. The mean is the sum divided by the number of values, the median the middle value when they are put in order, the range the difference between the largest and smallest, and the variance a measure of spread.

Answer: E

'Tachy-' means fast and '-cardia' refers to the heart: tachycardia is a resting heart rate above the normal range, usually over 100 beats per minute in an adult. A slow heart rate is bradycardia, low blood pressure is hypotension, and inflammation of the heart muscle is myocarditis.

Answer: A

'-itis' means inflammation: appendicitis is inflammation of the appendix and hepatitis inflammation of the liver. Surgical removal is '-ectomy', a tumour '-oma', a blood condition '-aemia' and pain '-algia'.

Answer: B

In anaphase the centromeres split and the sister chromatids are pulled to opposite poles. In prophase the chromosomes condense, in metaphase they line up at the equator, and in telophase new nuclear envelopes form; interphase is the period between divisions, when DNA is replicated.

Answer: C

Transcription copies a gene's DNA into mRNA. Replication copies DNA into DNA, translation builds a protein from the mRNA on the ribosome, a mutation is a change in the DNA sequence, and recombination is the exchange of genetic material between chromosomes.

Answer: D

Homeostasis is keeping the internal environment (temperature, blood glucose, water and ion balance, pH) within narrow limits, mostly by negative feedback. The other options describe digestion, cellular respiration, synaptic transmission and growth.

Answer: E

A vector has magnitude and direction; velocity, acceleration and force are vectors. A scalar has magnitude only (mass, temperature, speed); a constant is a fixed value; a ratio compares two quantities; a coefficient is a number multiplying a variable.