MU-Plovdiv Entrance Exam Practice Paper 1: Biology & Chemistry, with Answers

Answer: B

Aerobic respiration after glycolysis happens in the mitochondrion: the Krebs cycle in the matrix and oxidative phosphorylation on the inner membrane (the cristae), which is where most of the cell's ATP is made. The Golgi apparatus modifies and packages proteins, lysosomes digest material with hydrolytic enzymes, and the smooth endoplasmic reticulum makes lipids and detoxifies.

Answer: C

Monosaccharides are joined by a glycosidic bond, formed by condensation (a molecule of water is released): glucose and fructose make sucrose. Peptide bonds join amino acids, phosphodiester bonds join nucleotides in DNA and RNA, and ester bonds join glycerol to fatty acids in lipids.

Answer: B

Enzymes are biological catalysts: they bind the substrate at the active site and provide a pathway with a lower activation energy, so the reaction runs faster at body temperature. A catalyst does not change the position of equilibrium or supply energy; it reaches the same equilibrium sooner.

Answer: A

DNA polymerase can only add nucleotides to the free 3' end of a growing strand, so every new strand grows 5' → 3'. That is why the lagging strand is made in short Okazaki fragments, later joined by DNA ligase. Replication starts at origins of replication, not at the centromere.

Answer: C

Each transfer RNA carries one amino acid and an anticodon that pairs with a complementary codon on the messenger RNA during translation. The codon is on the mRNA; rRNA forms the ribosome together with proteins; the DNA template strand is read during transcription, not translation.

Answer: C

In anaphase the centromeres split and the spindle fibres pull the sister chromatids, now separate chromosomes, to opposite poles. In prophase chromatin condenses, in metaphase the chromosomes line up on the equatorial plate, and in telophase the nuclear envelopes re-form around the two sets.

Answer: B

Meiosis I separates the homologous chromosomes, not the chromatids, so each cell receives one of each pair: 23 chromosomes, each still made of two sister chromatids. The chromatids separate only in meiosis II, which gives 23 single-chromatid chromosomes per cell.

Answer: D

Antibodies (immunoglobulins) are secreted by plasma cells, which develop from B lymphocytes after they meet their antigen. T helper cells coordinate the response with cytokines, macrophages engulf and present antigens, and erythrocytes carry oxygen.

Answer: C

A virus particle has a single type of nucleic acid, DNA or RNA, inside a protein coat (the capsid), sometimes with a lipid envelope. It has no ribosomes and no cell wall, which is why it can multiply only inside a host cell, using the host's machinery.

Answer: B

Gas exchange needs the shortest possible distance, so the alveoli are lined by a single layer of flat cells, a simple squamous epithelium. Stratified squamous epithelium protects surfaces under friction (skin, oesophagus), simple columnar lines the stomach and intestine, and transitional epithelium lines the urinary bladder.

Answer: A

Pepsin, secreted as inactive pepsinogen and activated by hydrochloric acid, starts protein digestion in the stomach. Salivary amylase digests starch in the mouth, lipase digests fats (mainly in the small intestine), and trypsin continues protein digestion in the small intestine, from the pancreas.

Answer: B

The diaphragm is dome-shaped at rest; when it contracts it flattens and moves down, enlarging the chest cavity, so the pressure in the lungs falls and air flows in. In quiet expiration it relaxes and rises back into its dome.

Answer: C

Filtration happens in the renal corpuscle: blood pressure in the glomerular capillaries pushes plasma into Bowman's capsule, forming the primary urine. The tubules and the loop of Henle then reabsorb and secrete, and the collecting duct concentrates the urine.

Answer: D

The left atrioventricular valve has two cusps and is called the mitral or bicuspid valve. The tricuspid valve is the right atrioventricular valve; the pulmonary and aortic valves are the semilunar valves at the exits of the right and left ventricles.

Answer: A

Mature red blood cells lose their nucleus (and their organelles) while they develop in the bone marrow, which leaves more room for haemoglobin and gives them their biconcave shape. Lymphocytes, neutrophils and monocytes are white blood cells and keep their nuclei.

Answer: C

The vertebral column has 7 cervical, 12 thoracic and 5 lumbar vertebrae, then the sacrum (5 fused) and the coccyx (about 4 fused). The first two cervical vertebrae, the atlas and the axis, allow the head to nod and turn.

Answer: C

The secondary oocyte is released into the uterine tube, and fertilisation normally happens in its widest part, the ampulla. The zygote then divides as it travels to the uterus, where the blastocyst implants about a week later.

Answer: D

The cerebellum coordinates posture, balance and smooth, accurate movement. The medulla oblongata holds the breathing and cardiovascular centres, the hypothalamus regulates temperature, hunger and the pituitary, and the thalamus relays sensory signals to the cortex.

Answer: B

Calcitonin lowers blood calcium, mainly by slowing bone resorption. Parathyroid hormone does the opposite and raises it; thyroxine, from the thyroid follicles, raises the metabolic rate; aldosterone, from the adrenal cortex, increases sodium reabsorption in the kidney.

Answer: A

Cones work in bright light and, with three types sensitive to different wavelengths, give colour vision; they are concentrated in the fovea. Rods are more sensitive and serve vision in dim light, without colour. Bipolar and ganglion cells are neurons that carry the signal on, not photoreceptors.

Answer: B

Antidiuretic hormone, made in the hypothalamus and released by the posterior pituitary, makes the collecting ducts more permeable to water, so less urine is produced. Oxytocin is also released by the posterior pituitary but acts on the uterus and breast; aldosterone (adrenal cortex) acts on sodium; prolactin (anterior pituitary) on milk production.

Answer: C

S stands for synthesis: the DNA is copied, so each chromosome comes to consist of two sister chromatids. G1 is growth before replication, G2 is preparation for division after it, and M is mitosis itself.

Answer: D

A tendon connects muscle to bone and transmits the muscle's pull. A ligament connects bone to bone at a joint, cartilage covers joint surfaces and forms flexible supports, and fascia wraps muscles and groups of muscles.

Answer: B

The pleura has two layers, the visceral pleura on the lung and the parietal pleura lining the thoracic wall, with a thin film of fluid between them. The peritoneum lines the abdominal cavity, the pericardium surrounds the heart and the meninges cover the brain and spinal cord.

Answer: C

Macrophages, which develop from monocytes, are phagocytes: they engulf and digest microbes and debris and show pieces of the antigens to T lymphocytes. Lymphocytes carry out specific immunity, plasma cells secrete antibodies, and platelets take part in clotting.

Answer: A

The epiglottis folds over the entrance to the larynx when we swallow, so food goes into the oesophagus and not the airway. The uvula hangs from the soft palate and helps close the nasopharynx, the glottis is the opening between the vocal folds, and the palatine tonsils are lymphoid tissue.

Answer: B

The kidneys lie against the posterior abdominal wall, behind the peritoneum (retroperitoneally), on either side of the vertebral column. They are paired organs, and they are in the abdomen, not the thorax.

Answer: D

Most reabsorption, including about two thirds of the water and sodium and, normally, all of the glucose and amino acids, happens in the proximal convoluted tubule. The distal tubule and collecting duct fine-tune what is left under hormonal control. Urea is not mostly reabsorbed, and plasma proteins are not filtered in the first place.

Answer: A

Each kidney drains through its own ureter into the urinary bladder; the urethra carries urine from the bladder out of the body. The renal pelvis is where the urine collects before it enters the ureter, so 'pelvis' is right.

Answer: C

Antidiuretic hormone increases water reabsorption in the collecting ducts by inserting water channels (aquaporins) into their cells; the name itself means 'against urine production'. Sentences (2) and (3) are correct: each kidney has about a million nephrons, and filtration happens from the glomerulus into Bowman's capsule.

Answer: B

The mass number (39) counts protons and neutrons; the atomic number (19) counts protons. Neutrons = 39 − 19 = 20. 19 is the number of protons (and electrons in the neutral atom); 58 adds the two numbers instead of subtracting.

Answer: D

Electronegativity increases across a period, as the nuclear charge grows while the electrons stay in the same shell, and decreases down a group. Fluorine, at the end of period 2 (before the noble gas neon), is the most electronegative element of all.

Answer: C

Nitrogen is 1s² 2s² 2p³. By Hund's rule the three 2p electrons occupy the three p orbitals singly, with parallel spins, so there are 3 unpaired electrons. 5 is the number of valence electrons (2s² 2p³), not of unpaired ones.

Answer: A

A hydrogen bond needs hydrogen attached to a small, very electronegative atom with a lone pair (N, O or F). Ammonia has N–H bonds and a lone pair on nitrogen, so its molecules hydrogen-bond. In CH₄ hydrogen is bonded to carbon; sulfur is too large and not electronegative enough; CO₂ has no hydrogen.

Answer: B

The nitrogen of NH₃ donates its lone pair to the H⁺ ion, which has no electrons: a covalent bond in which both electrons come from one atom is a coordinate (dative) bond. Once formed, the four N–H bonds are identical.

Answer: C

The rate depends on the square of [B]: doubling [B] multiplies the rate by 2² = 4. Doubling [A] alone would only double it, because [A] appears to the first power.

Answer: D

A catalyst offers a reaction pathway with a lower activation energy and comes out of the reaction unchanged. It does not change the enthalpy of the reaction or the position of equilibrium: it speeds up the forward and the reverse reaction equally, so equilibrium is reached sooner.

Answer: B

By Le Chatelier's principle, raising the pressure favours the side with fewer gas molecules: 4 on the left, 2 on the right, so more ammonia forms. Raising the temperature favours the endothermic (reverse) reaction, a catalyst does not shift the equilibrium, and removing nitrogen shifts it to the left.

Answer: A

Kc is the product of the products' concentrations over the product of the reactants', each raised to the power of its coefficient: [HI]² over [H₂][I₂]. The coefficient becomes an exponent, never a multiplier, and the products go on top.

Answer: B

Moles = concentration × volume = 0.2 mol/L × 0.5 L = 0.1 mol. Mass = 0.1 mol × 40 g/mol = 4 g. 8 g is the answer for a whole litre; 40 g is one mole.

Answer: C

Freezing-point depression depends on the number of dissolved particles, not their identity. Glucose stays as 0.1 mol/kg of molecules, NaCl gives 0.2 mol/kg of ions (Na⁺ and Cl⁻), CaCl₂ gives 0.3 mol/kg (Ca²⁺ and two Cl⁻). The most particles lower the freezing point most; pure water freezes highest, at 0 °C.

Answer: D

NaOH is a strong base, fully dissociated: [OH⁻] = 0.01 = 10⁻² mol/L, so pOH = 2 and pH = 14 − 2 = 12. 2 is the pOH, the usual slip when pH is computed from [OH⁻] directly.

Answer: A

In the Brønsted-Lowry theory an acid donates a proton. Water gives H⁺ to ammonia and becomes OH⁻, so here it is the acid and ammonia the base. Water is amphiprotic: with HCl it would act as a base instead.

Answer: C

NH₄Cl is the salt of a weak base (NH₃) and a strong acid (HCl): NH₄⁺ hydrolyses, NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺, so the solution is acidic. NaCl (strong acid, strong base) is neutral; Na₂CO₃ and CH₃COONa are salts of weak acids and give basic solutions.

Answer: B

The compound is neutral: 2(+1) for potassium + 2x for chromium + 7(−2) for oxygen = 0, so 2x = 12 and x = +6. Dichromate is a strong oxidising agent and is usually reduced to Cr³⁺ (+3).

Answer: D

Cu²⁺ gains two electrons and is reduced to copper metal, so it is the oxidising agent; zinc loses two electrons, is oxidised to Zn²⁺ and is the reducing agent. The sulfate ion is a spectator and does not change.

Answer: A

Only metals above hydrogen in the reactivity series displace hydrogen from dilute acids. Magnesium, zinc and iron are above hydrogen; copper is below it, so it does not react with dilute HCl.

Answer: B

SO₃ + H₂O → H₂SO₄: an acidic oxide reacts with water to give its oxyacid, with sulfur keeping its oxidation number (+6). H₂SO₃ comes from SO₂ (+4), and H₂S is a hydride, not an oxyacid.

Answer: C

A basic oxide reacts with an acidic oxide to give a salt: CaO + CO₂ → CaCO₃. Ca(OH)₂ would form with water, not with CO₂.

Answer: B

Aluminium hydroxide reacts with acids (Al(OH)₃ + 3HCl → AlCl₃ + 3H₂O) and with strong bases (Al(OH)₃ + NaOH → Na[Al(OH)₄]), so it is amphoteric; zinc hydroxide behaves the same way. The hydroxides of sodium, magnesium and calcium are bases only.

Answer: C

Each carbon in ethene forms three σ bonds (two to H, one to C) and one π bond, so it uses three hybrid orbitals: sp², with a trigonal planar arrangement at 120°. Single-bonded carbon (alkanes) is sp³; triple-bonded carbon (alkynes) is sp.

Answer: D

Cis-trans isomerism needs a C=C double bond with two different groups on each carbon. In but-2-ene, CH₃–CH=CH–CH₃, each double-bonded carbon carries H and CH₃. But-1-ene has two H atoms on the first carbon, 2-methylpropene two CH₃ groups on one carbon, and ethene only H atoms, so none of them has cis and trans forms.

Answer: B

Alkenes undergo addition across the double bond: CH₂=CH₂ + Br₂ → CH₂Br–CH₂Br, 1,2-dibromoethane. The orange bromine is used up, which is the classic test for a C=C bond. Substitution is typical of alkanes (with light) and of benzene.

Answer: A

Sulfuric acid helps form the nitronium ion, NO₂⁺, which replaces a hydrogen on the ring: nitration is an electrophilic substitution, and the aromatic ring is kept. Benzene resists addition because addition would destroy its stable delocalised π system.

Answer: B

A secondary alcohol is oxidised to a ketone (propan-2-ol → propanone) and goes no further under normal conditions. A primary alcohol gives an aldehyde and then a carboxylic acid; a tertiary alcohol resists oxidation.

Answer: D

Phenol is a weak acid, much stronger than alcohols, because its anion (phenoxide) is stabilised by the benzene ring: C₆H₅OH + NaOH → C₆H₅ONa + H₂O. Alcohols are too weakly acidic to react with NaOH; they react with sodium metal instead.

Answer: C

Aldehydes are easily oxidised to carboxylic acids, and they reduce the Ag⁺ of Tollens' reagent to metallic silver. Ethanal is an aldehyde; propanone is a ketone and is not oxidised; ethanol and ethanoic acid do not give the test.

Answer: C

Sucrose is glucose joined to fructose by a glycosidic bond between their anomeric carbons, which is why it is a non-reducing sugar. Maltose is two glucose units and lactose is glucose plus galactose.

Answer: A

This is esterification: CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O, catalysed by acid and reversible. Sodium ethanoate and hydrogen would come from the acid and sodium metal.

Answer: D

At the isoelectric point the amino group is protonated (–NH₃⁺) and the carboxyl group deprotonated (–COO⁻): a zwitterion, with no net charge, so it does not move in an electric field. At lower pH the cation dominates, at higher pH the anion.

Answer: B

The first paragraph says sleep 'was seen simply as rest: a period in which the body and the brain switched off to save energy'. The active brain is the newer view, not the old one.

Answer: A

The second paragraph: 'During deep sleep, the brain appears to replay the experiences of the day'. Waking and naps are not mentioned.

Answer: B

The text links it to the previous sentence: people who sleep after learning remember more, so staying awake costs the memory consolidation that sleep provides.

Answer: B

'The space between brain cells widens during sleep, allowing fluid to wash away waste products'. Waste builds up during the day, not during sleep.

Answer: B

'Some scientists believe ... although this has not yet been proved in humans.' The careful wording ('may contribute') signals a hypothesis, not a fact.

Answer: B

The last paragraph: 'Most adults need between seven and nine hours of sleep a night'.

Answer: B

The text names shift workers, new parents and people who use screens late in the evening. Athletes are not mentioned.

Answer: B

To delay is to make something happen later: screen light postpones the release of melatonin. It does not stop it altogether or make it stronger.

Answer: A

'Melatonin, the hormone that tells the body it is time to sleep.' The devices produce light, which delays its release; they do not produce the hormone.

Answer: A

It moves from the old view of sleep to what sleep does (memory, cleaning the brain) and ends with practical advice. It sells nothing, and the mice are one example among several.

Answer: C

'Since Monday' with a situation that continues to the present takes the present perfect: 'has been'.

Answer: C

An action in progress up to a past moment, with its duration ('for twenty minutes'), takes the past perfect continuous.

Answer: B

An action completed before a point in the future takes the future perfect: 'will have spent'.

Answer: B

A finished past event in the passive, with a past date: past simple passive, 'was discovered'.

Answer: B

'Be used to' means 'be accustomed to' and is followed by the -ing form; 'used to + infinitive' is a different structure, for past habits.

Answer: A

With a present perfect continuous and a duration in mind, the question word is 'how long'.

Answer: C

Reported questions take statement word order and, after a past reporting verb, the tense moves back: 'where I lived'.

Answer: B

A negative statement takes a positive question tag with the same auxiliary: 'have you'.

Answer: B

In reported speech 'will' becomes 'would' after a past reporting verb, and 'tomorrow' becomes 'the following day'.

Answer: A

Prohibition is 'mustn't'. 'Don't have to' and 'needn't' mean that something is not necessary, which is different.

Answer: B

A third conditional, about an unreal past: 'if + past perfect', 'would have + past participle'.

Answer: B

A logical deduction that something is impossible, about the past, is 'can't have + past participle'.

Answer: A

A general truth takes the zero conditional: present simple in both clauses.

Answer: B

'Information' is uncountable, so it takes 'much' in negative sentences; 'many', 'a few' and 'several' go with countable nouns.

Answer: C

A one-syllable adjective forms its superlative with -est and 'the': 'the largest'.

Answer: A

The reflexive pronoun for 'the students' is 'themselves'; 'theirselves' does not exist, and 'each other' would mean they helped one another.

Answer: A

The double comparative is 'the + comparative ..., the + comparative'.

Answer: B

The fixed preposition after 'responsible' is 'for'.

Answer: A

'Put off' means postpone. 'Put on' is to dress or to switch on, 'put up' to raise or to host, 'put out' to extinguish.

Answer: A

'Get over' an illness means to recover from it. 'Get by' is to manage, 'get on' to make progress or have a good relationship, 'get through to' to reach someone by phone.

Answer: C

Dates and days take 'on'; months and years alone take 'in'; times take 'at'.

Answer: B

One complains 'about' something and 'to' someone.

Answer: C

The collocation is 'sign a form'.

Answer: A

The usual collocation is 'reduce the risk'. 'Decline' is intransitive here, and 'lower down' is not used this way.

Answer: A

The set phrase is 'do my best'.

Answer: B

The collocation is 'make a difference'.

Answer: A

Paediatrics is the medicine of children. A geriatrician treats older people, a dermatologist the skin, a radiologist reads images.

Answer: B

A fever is a raised body temperature, so the nurse takes his temperature.

Answer: B

A prescription is the doctor's written order for a medicine. A 'recipe' is for cooking (a common false friend), and a receipt proves payment.

Answer: A

The hospital department is called the emergency department (also accident and emergency, A&E, in British English).