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FMRDA Medicine Admission practice questions

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Question 1Biology

Which organelle is the primary site of ATP synthesis by oxidative phosphorylation in a eukaryotic cell?

  1. Golgi apparatus
  2. Mitochondrion Correct answer.
  3. Lysosome
  4. Smooth endoplasmic reticulum

Explanation

The inner mitochondrial membrane hosts the electron transport chain and ATP synthase, which couple proton gradient dissipation to ATP production. The other listed organelles perform modification, degradation, or lipid synthesis rather than bulk oxidative ATP generation.

Question 2Biology

A patient's red blood cells are placed in a strongly hypertonic saline solution. What is the expected osmotic response of the cells?

  1. They shrink as water leaves the cell Correct answer.
  2. They remain unchanged in volume
  3. They actively pump in water to restore volume
  4. They swell and may lyse

Explanation

In a hypertonic solution the external solute concentration exceeds that inside the cell, so water moves out by osmosis and the cell shrinks (crenates). Cells cannot actively pump water; water movement is passive along its osmotic gradient.

Question 3Biology

During which phase of the cell cycle does DNA replication occur?

  1. G2 phase
  2. M phase
  3. G1 phase
  4. S phase Correct answer.

Explanation

The S phase (synthesis phase) of interphase is when chromosomal DNA is duplicated so each daughter cell receives a full complement. G1 and G2 are gap phases of growth and checkpoint control, while M phase is mitosis itself.

Question 4Biology

Which molecule serves as the direct energy currency that powers most cellular reactions?

  1. ATP Correct answer.
  2. NADH
  3. Cholesterol
  4. Glucose

Explanation

ATP hydrolysis releases free energy that is coupled to endergonic reactions throughout the cell, making it the universal energy currency. Glucose and NADH are energy-rich but must first be oxidized or converted to drive ATP production.

Question 5Biology

Which blood vessel type has the thinnest walls and is the principal site of exchange between blood and tissue fluid?

  1. Vein
  2. Capillary Correct answer.
  3. Arteriole
  4. Artery

Explanation

Capillaries consist of a single endothelial layer, minimizing diffusion distance for gases, nutrients, and wastes. Arteries and veins have thick muscular and fibrous walls suited to conduction, and arterioles regulate flow resistance.

Question 6Biology

In Mendelian genetics, a cross between two heterozygous individuals (Aa x Aa) produces offspring in what expected phenotypic ratio for a completely dominant trait?

  1. 3:1 Correct answer.
  2. 1:2:1
  3. 9:3:3:1
  4. 1:1

Explanation

A monohybrid cross of two heterozygotes yields genotypes in a 1 AA : 2 Aa : 1 aa ratio, so the dominant phenotype appears in three of four offspring. The 1:2:1 ratio describes genotypes, not phenotypes, for a completely dominant trait.

Question 7Biology

Which process produces genetically diverse haploid gametes by halving the chromosome number?

  1. Meiosis Correct answer.
  2. Mitosis
  3. Binary fission
  4. Budding

Explanation

Meiosis involves one round of DNA replication followed by two divisions, producing haploid cells with recombined chromosomes. Crossing over and independent assortment during meiosis generate genetic diversity.

Question 8Biology

Which enzyme unwinds the DNA double helix ahead of the replication fork during DNA replication?

  1. Ligase
  2. DNA helicase Correct answer.
  3. Primase
  4. DNA polymerase

Explanation

DNA helicase breaks the hydrogen bonds between complementary bases to separate the strands at the replication fork. DNA polymerase then synthesizes new strands, primase lays RNA primers, and ligase joins Okazaki fragments.

Question 9Biology

A person with blood group A receives a transfusion of group B blood. Which immune reaction is most likely?

  1. No reaction, because A and B are compatible
  2. Anti-A antibodies in the donor plasma destroy recipient cells
  3. The recipient's Rh factor neutralizes the B antigen
  4. Anti-B antibodies in the recipient agglutinate the donor red cells Correct answer.

Explanation

Group A individuals carry anti-B antibodies in their plasma, which recognize the B antigen on donor red cells and cause agglutination and hemolysis. ABO compatibility requires that the recipient lack antibodies against the donor's antigens.

Question 10Biology

In a hypothetical population at Hardy-Weinberg equilibrium, the frequency of the recessive allele is 0.2. What is the expected frequency of heterozygous individuals?

  1. 0.16
  2. 0.32 Correct answer.
  3. 0.04
  4. 0.64

Explanation

With q = 0.2, p = 0.8, and the heterozygote frequency is 2pq = 2(0.8)(0.2) = 0.32. The 0.04 value is q squared (homozygous recessive frequency).

Question 11Biology

Which statement best explains why an enzyme increases the rate of a biochemical reaction?

  1. It lowers the activation energy by stabilizing the transition state Correct answer.
  2. It raises the activation energy of the reaction
  3. It increases the free energy change of the reaction
  4. It permanently consumes itself to drive the reaction

Explanation

Enzymes lower the activation energy barrier by binding and stabilizing the transition state, so more substrate molecules can react at a given temperature. They do not alter the overall free energy change of the reaction.

Question 12Biology

Which feature distinguishes prokaryotic cells from eukaryotic cells?

  1. Prokaryotes lack a plasma membrane
  2. Prokaryotes lack a membrane-bound nucleus Correct answer.
  3. Prokaryotes lack nucleic acids
  4. Prokaryotes lack ribosomes

Explanation

Prokaryotes keep their DNA in a nucleoid region without a nuclear envelope, whereas eukaryotes enclose DNA within a membrane-bound nucleus. Prokaryotes still possess ribosomes, a plasma membrane, and DNA or RNA.

Question 13Biology

A mutation changes a single DNA base but the encoded amino acid remains the same. What type of mutation is this?

  1. Silent mutation Correct answer.
  2. Frameshift mutation
  3. Missense mutation
  4. Nonsense mutation

Explanation

A silent mutation alters a codon but, due to the degeneracy of the genetic code, specifies the same amino acid, leaving the protein sequence unchanged. Missense and nonsense mutations change or truncate the protein.

Question 14Biology

Which component of the human immune system provides a rapid, non-specific first line of defense against pathogens?

  1. T lymphocytes mediating cell-mediated responses
  2. Innate immunity including phagocytes and barriers Correct answer.
  3. B lymphocytes producing specific antibodies
  4. Memory cells generated after prior exposure

Explanation

Innate immunity acts immediately and non-specifically through physical barriers, phagocytes, complement, and inflammation. Adaptive immunity, involving B and T lymphocytes and memory cells, is slower on first exposure but highly specific.

Question 15Biology

In human gas exchange, which structure is the primary site of oxygen diffusion into the blood?

  1. Trachea
  2. Alveoli Correct answer.
  3. Bronchi
  4. Pleural cavity

Explanation

Alveoli provide a thin, moist, highly vascularized surface where oxygen diffuses into pulmonary capillaries and carbon dioxide diffuses out. Conducting airways such as the trachea and bronchi move air but contribute little to gas exchange.

Question 16Biology

A child inherits an X-linked recessive disorder. The father is unaffected and the mother is a carrier. What is the probability that a son will be affected?

  1. 0 percent
  2. 50 percent Correct answer.
  3. 100 percent
  4. 25 percent

Explanation

Sons receive their single X chromosome from the mother, who as a carrier has one affected allele, giving each son a 50 percent chance of inheriting it. Because males are hemizygous, one copy of the recessive allele is sufficient to cause the disorder.

Question 17Biology

Which statement correctly describes the role of tRNA in translation?

  1. It carries amino acids to the ribosome and pairs with mRNA codons Correct answer.
  2. It forms the catalytic core of the ribosome
  3. It stores genetic information in the nucleus
  4. It splices introns from pre-mRNA

Explanation

Each tRNA carries a specific amino acid and has an anticodon that base-pairs with the complementary mRNA codon at the ribosome. This pairing ensures the correct amino acid is added to the growing polypeptide.

Question 18Biology

During which stage of aerobic respiration is the majority of ATP produced?

  1. Pyruvate oxidation
  2. Glycolysis
  3. Oxidative phosphorylation Correct answer.
  4. The Krebs cycle

Explanation

Most ATP is generated by oxidative phosphorylation, where the electron transport chain builds a proton gradient that ATP synthase uses to phosphorylate ADP. Glycolysis and the Krebs cycle yield only small amounts of direct ATP.

Question 19Biology

A geneticist observes a trait controlled by two genes where one gene masks the expression of another. Which interaction is this?

  1. Incomplete dominance
  2. Epistasis Correct answer.
  3. Pleiotropy
  4. Codominance

Explanation

Epistasis occurs when the allele of one gene suppresses or masks the phenotypic effect of alleles at a different gene. Codominance and incomplete dominance describe interactions between alleles of a single gene.

Question 20Biology

Which hormone is released by the posterior pituitary and increases water reabsorption in the kidneys?

  1. Thyroxine
  2. Adrenaline
  3. Insulin
  4. Antidiuretic hormone Correct answer.

Explanation

Antidiuretic hormone, released by the posterior pituitary, increases the permeability of kidney collecting ducts to water, reducing urine output. Insulin regulates glucose, thyroxine regulates metabolism, and adrenaline mediates the fight-or-flight response.

Question 21Biology

In a food chain, only about 10 percent of energy is transferred from one trophic level to the next. What happens to the remaining energy?

  1. It is lost mainly as heat through metabolism Correct answer.
  2. It is converted entirely into biomass
  3. It is stored indefinitely in the next trophic level
  4. It returns directly to the sun

Explanation

Most energy is dissipated as heat during respiration and lost in waste and uneaten material, so only a small fraction becomes new biomass. This explains why food chains rarely exceed four or five trophic levels.

Question 22Biology

A bacterial population is exposed to an antibiotic, and a few cells survive because of a pre-existing resistance mutation. Over generations the population becomes largely resistant. This best illustrates which concept?

  1. Artificial selection by humans
  2. Natural selection acting on existing variation Correct answer.
  3. Lamarckian inheritance of acquired traits
  4. Genetic drift in a small population

Explanation

The antibiotic acts as a selective pressure: cells already carrying resistance alleles survive and reproduce, increasing the frequency of those alleles. The mutation existed before exposure, so it is not acquired in response to the drug.

Question 23Biology

A woman who is a carrier of a recessive autosomal disorder mates with an affected man. What proportion of their children is expected to be affected?

  1. 75 percent
  2. 50 percent Correct answer.
  3. 25 percent
  4. 0 percent

Explanation

Let the carrier be Aa and the affected man aa. The cross Aa x aa yields offspring in a 1 Aa : 1 aa ratio, so half are affected (aa). An affected child inherits the recessive allele from each parent.

Question 24Biology

A cell is treated with a drug that blocks the formation of the mitotic spindle. At which stage will mitosis most likely arrest?

  1. Prophase of the first meiotic division only
  2. Metaphase, because chromosomes cannot align at the equator Correct answer.
  3. G1 phase, because DNA cannot replicate
  4. Telophase, because nuclei cannot reform

Explanation

The spindle is required to attach to kinetochores and align chromosomes at the metaphase plate; without it, the spindle assembly checkpoint halts the cell in metaphase. Spindle formation is not required for DNA replication in G1.

Question 25Biology

Two enzymes act on the same substrate, but enzyme X has a much lower Michaelis constant (Km) than enzyme Y. What does this indicate about enzyme X?

  1. It has a higher affinity for the substrate than enzyme Y Correct answer.
  2. It is denatured at physiological temperature
  3. It has a lower maximum reaction velocity than enzyme Y
  4. It requires more substrate to reach half-maximal velocity

Explanation

Km is the substrate concentration at which the reaction reaches half of Vmax; a lower Km reflects a higher substrate affinity. Vmax, not Km, describes the maximum rate, so velocity comparisons cannot be inferred from Km alone.

Question 26Biology

Which property of the plasma membrane is best described by the fluid mosaic model?

  1. A double layer of nucleic acid with attached carbohydrates
  2. A phospholipid bilayer with embedded proteins that can move laterally Correct answer.
  3. A continuous protein sheet that prevents any molecule from crossing
  4. A rigid layer of cellulose surrounding the cytoplasm

Explanation

The fluid mosaic model describes the membrane as a phospholipid bilayer in which proteins and other components are embedded and able to move laterally, giving the membrane a fluid character. The hydrophobic core of the bilayer restricts free passage of polar and charged substances, which is why transport proteins are needed.

Question 27Biology

A solution of 0.9% sodium chloride is described as isotonic with human red blood cells. What happens when red blood cells are placed in distilled water?

  1. They remain unchanged because the solute concentration is equal
  2. They shrink because water leaves the cells by osmosis
  3. They swell and may burst because water enters by osmosis Correct answer.
  4. They lose their membrane proteins and become rigid

Explanation

Distilled water has a lower solute concentration than the cytoplasm, so it is hypotonic relative to the cell. Water moves by osmosis from the dilute external solution into the cell, causing swelling and potentially lysis because animal cells lack a rigid wall.

Question 28Biology

Which organelle contains hydrolytic enzymes and functions in the intracellular digestion of engulfed material?

  1. Ribosome
  2. Lysosome Correct answer.
  3. Mitochondrion
  4. Golgi apparatus

Explanation

Lysosomes are membrane-bound vesicles containing hydrolytic enzymes maintained at an acidic pH, and they digest material taken in by endocytosis as well as worn-out organelles. Their interior is kept separate from the cytosol so that the enzymes do not digest the cell's own components indiscriminately.

Question 29Biology

In the light-dependent reactions of photosynthesis, which process directly generates the proton gradient used by ATP synthase?

  1. Fixation of carbon dioxide by rubisco
  2. Hydrolysis of ATP in the stroma
  3. Splitting of glucose during glycolysis
  4. Electron transport along the thylakoid membrane Correct answer.

Explanation

Electron transport along the thylakoid membrane pumps protons into the thylakoid lumen, and the resulting electrochemical gradient drives ATP synthesis as protons return to the stroma. This chemiosmotic mechanism is analogous to the process in the inner mitochondrial membrane.

Question 30Biology

Which blood vessel carries oxygenated blood away from the heart to the body tissues?

  1. Pulmonary artery
  2. Vena cava
  3. Pulmonary vein
  4. Aorta Correct answer.

Explanation

The aorta is the major systemic artery and carries oxygenated blood from the left ventricle to the body. In the pulmonary circuit the usual pattern is reversed, with the pulmonary artery carrying deoxygenated blood to the lungs.

Question 31Biology

Which molecule is the immediate energy source used directly by the contractile proteins of a muscle fibre during contraction?

  1. Glucose
  2. Glycogen
  3. Creatine phosphate
  4. ATP Correct answer.

Explanation

ATP is hydrolysed directly to power the cross-bridge cycle of myosin and actin. Creatine phosphate and glycogen serve as reserves that regenerate ATP, but they are not the molecule hydrolysed by the contractile apparatus itself.

Question 32Biology

Which feature is common to all viruses and explains why they are considered obligate intracellular parasites?

  1. They possess their own ribosomes for protein synthesis
  2. They can reproduce only inside a living host cell Correct answer.
  3. They generate ATP through aerobic respiration
  4. They contain both DNA and RNA in the same particle

Explanation

Viruses lack the machinery for independent metabolism and replication, so they must use a host cell's ribosomes and enzymes to produce their components. This dependence on a living cell defines them as obligate intracellular parasites.

Question 33Biology

Which process converts atmospheric nitrogen gas into ammonia that can be used by plants?

  1. Ammonification
  2. Denitrification
  3. Nitrification
  4. Nitrogen fixation Correct answer.

Explanation

Nitrogen fixation is the reduction of atmospheric N2 to ammonia, carried out by bacteria such as Rhizobium in root nodules and by free-living soil bacteria. The ammonia can then be assimilated into organic compounds by plants.

Question 34Biology

In a dihybrid cross between plants heterozygous for both seed shape and seed colour (RrYy x RrYy), what proportion of offspring is expected to show both recessive traits?

  1. 3/16
  2. 1/16 Correct answer.
  3. 1/4
  4. 9/16

Explanation

Assuming independent assortment, each recessive trait appears in one quarter of offspring, so the probability of both recessive phenotypes is 1/4 x 1/4 = 1/16. This corresponds to the rryy class in the classic 9:3:3:1 ratio.

Question 35Biology

A woman with normal colour vision whose father was colour-blind marries a man with normal colour vision. Colour blindness is X-linked recessive. What proportion of their sons is expected to be colour-blind?

  1. 1/4
  2. 0
  3. 1/2 Correct answer.
  4. All sons

Explanation

The woman is an obligatory carrier because her father contributed his only X chromosome, which carries the recessive allele. Each son receives one of her X chromosomes with probability one half, so half of the sons are expected to be affected.

Question 36Biology

A DNA template strand reads 3'-TAC GGA TTC-5'. Which mRNA sequence is transcribed from it?

  1. 5'-TAC GGA TTC-3'
  2. 5'-ATG CCT AAG-3'
  3. 5'-AUG CCU AAG-3' Correct answer.
  4. 5'-UAC GGA UUC-3'

Explanation

Transcription builds mRNA complementary and antiparallel to the template strand, with uracil replacing thymine. Complementing TAC GGA TTC gives AUG CCU AAG, written 5' to 3' in the direction of synthesis.

Question 37Biology

During which phase of meiosis does crossing over between homologous chromosomes occur?

  1. Anaphase I
  2. Metaphase II
  3. Prophase I Correct answer.
  4. Telophase II

Explanation

Crossing over takes place during prophase I, when homologous chromosomes are paired as bivalents and non-sister chromatids exchange segments at chiasmata. This recombination is a major source of genetic variation in the gametes.

Question 38Biology

A population of 500 individuals contains 180 homozygous dominant, 240 heterozygous, and 80 homozygous recessive individuals. What is the frequency of the dominant allele?

  1. 0.64
  2. 0.4
  3. 0.6 Correct answer.
  4. 0.36

Explanation

The dominant allele frequency equals the number of dominant alleles divided by the total number of alleles. There are 2(180) + 240 = 600 dominant alleles among 1000 alleles, giving 0.6.

Question 39Biology

A patient's blood plasma has a solute potential of -0.8 MPa and a pressure potential of 0.3 MPa. What is the water potential of the plasma?

  1. -1.1 MPa
  2. -0.5 MPa Correct answer.
  3. -0.24 MPa
  4. 0.5 MPa

Explanation

Water potential is the sum of solute potential and pressure potential. Adding -0.8 MPa and +0.3 MPa gives -0.5 MPa, which is the value governing the direction of water movement.

Question 40Biology

In an enzyme-catalysed reaction, a competitive inhibitor is added. Which change is expected in the kinetic parameters?

  1. Km increases while Vmax is unchanged Correct answer.
  2. Km decreases while Vmax decreases
  3. Vmax decreases while Km is unchanged
  4. Both Km and Vmax increase

Explanation

A competitive inhibitor binds the active site reversibly, so a higher substrate concentration is needed to reach half-maximal velocity, raising the apparent Km. Because inhibition can be overcome by sufficient substrate, the maximum velocity Vmax is unchanged.

Question 41Biology

A mutation inserts one extra nucleotide into the coding region of a gene. What is the most likely consequence for the encoded protein?

  1. A single amino acid substitution with no other change
  2. No change because the genetic code is degenerate
  3. A frameshift that alters all downstream amino acids Correct answer.
  4. Deletion of the entire gene from the chromosome

Explanation

Inserting one nucleotide shifts the reading frame from that point onward, so every subsequent codon is read differently and the protein sequence is usually disrupted. This typically produces a non-functional protein, often with a premature stop codon.

Question 42Biology

A respirometer shows that germinating seeds consume oxygen and release carbon dioxide in roughly equal volumes. Which substrate is being respired?

  1. Protein
  2. Lipid
  3. Nucleic acid
  4. Carbohydrate Correct answer.

Explanation

The respiratory quotient for carbohydrate is about 1.0 because glucose oxidation consumes six molecules of oxygen and releases six of carbon dioxide. Values below 1.0 suggest substrates such as lipids or proteins that are more reduced or contain more oxygen.

Question 43Biology

In a cross between a heterozygous tall pea plant and a homozygous short pea plant, tall is dominant. What phenotypic ratio is expected among the offspring?

  1. 1 tall : 3 short
  2. 3 tall : 1 short
  3. All tall
  4. 1 tall : 1 short Correct answer.

Explanation

The heterozygote Tt produces T and t gametes in equal numbers, while the short parent tt produces only t gametes. Half the offspring are Tt and tall, and half are tt and short, giving a 1:1 ratio.

Question 44Biology

Which statement best describes the role of the loop of Henle in the mammalian kidney?

  1. It creates a solute gradient in the medulla that allows water reabsorption Correct answer.
  2. It reabsorbs all filtered water immediately in the cortex
  3. It secretes glucose into the collecting duct
  4. It filters plasma proteins into the renal capsule

Explanation

The countercurrent multiplier arrangement of the loop of Henle establishes an osmotic gradient in the medulla, which enables the collecting duct to reabsorb water under the influence of antidiuretic hormone. The descending limb is permeable to water while the ascending limb actively transports salts.

Question 45Biology

A plant is exposed to a light source from one side only. Which mechanism explains the resulting phototropic bending?

  1. Gibberellin is destroyed on the shaded side, causing cells to shorten
  2. Auxin accumulates on the shaded side and stimulates greater cell elongation there Correct answer.
  3. Auxin accumulates on the illuminated side and inhibits elongation there
  4. Ethylene causes cells on the illuminated side to divide rapidly

Explanation

Lateral redistribution of auxin in the shoot tip causes a higher concentration on the shaded side, where the hormone promotes greater cell elongation. The unequal growth makes the shoot bend toward the light.

Question 46Biology

An individual with genotype AaBb produces gametes AB, Ab, aB, and ab in equal proportions. What does this indicate about the two loci?

  1. Both loci are on the same chromosome very close together
  2. One locus is on a sex chromosome and the other is autosomal
  3. The loci assort independently on different chromosomes or are far apart Correct answer.
  4. The loci are completely linked on the same chromosome

Explanation

Equal proportions of all four gamete types indicate independent assortment, which occurs when genes are on different chromosomes or are sufficiently far apart on the same chromosome for recombination to separate them. Close linkage would produce an excess of parental combinations.

Question 47Biology

In a population at Hardy-Weinberg equilibrium, the frequency of the homozygous recessive genotype is 0.09. What is the frequency of heterozygous individuals?

  1. 0.30
  2. 0.49
  3. 0.21
  4. 0.42 Correct answer.

Explanation

The recessive genotype frequency q squared equals 0.09, so q is 0.3 and p is 0.7. The heterozygote frequency 2pq is therefore 2 x 0.7 x 0.3 = 0.42.

Question 48Biology

An experiment measures the rate of an enzyme reaction at increasing substrate concentrations. At high substrate concentration the rate plateaus. What best explains this plateau?

  1. The reaction has reached equilibrium and stops
  2. The substrate has become a competitive inhibitor of the enzyme
  3. All active sites are saturated with substrate Correct answer.
  4. The enzyme has been permanently denatured by the substrate

Explanation

At saturation every enzyme active site is occupied, so adding more substrate cannot increase the number of catalytic events per unit time. The maximum rate Vmax reflects enzyme concentration and turnover number rather than substrate availability.

Question 49Biology

A cell is placed in a solution that blocks the electron transport chain of the mitochondria but leaves glycolysis intact. Which statement best describes the effect on ATP yield from one glucose molecule?

  1. ATP yield is unchanged because glycolysis alone produces 36 ATP
  2. Only ATP from the Krebs cycle is lost while oxidative phosphorylation continues
  3. Total ATP yield falls sharply because oxidative phosphorylation stops Correct answer.
  4. ATP yield increases because glycolysis accelerates without feedback

Explanation

Most ATP from glucose oxidation comes from oxidative phosphorylation, which depends on the electron transport chain and the proton gradient. Blocking electron transport eliminates this major contribution, leaving only the smaller yield from glycolysis and substrate-level phosphorylation.

Question 50Biology

In a pedigree, an unaffected couple has an affected daughter and an affected son. Which mode of inheritance is most consistent with this pattern?

  1. X-linked recessive
  2. Autosomal recessive Correct answer.
  3. Y-linked
  4. Autosomal dominant

Explanation

Two unaffected parents producing affected offspring indicates a recessive trait carried by both parents. An affected daughter cannot have an X-linked recessive condition if her father is unaffected, because he would have to pass on an affected X chromosome, so autosomal recessive is the consistent explanation.