KMU MDCAT 2024 past paper, Code A

Answer: B. Flu virus

The genetic material of the influenza virus (Flu virus) is enclosed within a lipid envelope, which is derived from the host cell membrane. Enterovirus, Hepatitis A virus, and Poliovirus are all non-enveloped viruses, meaning their genetic material is not surrounded by a lipid membrane.

Answer: D. Used for another reaction

Enzymes are biological catalysts, meaning they speed up reactions without being consumed or permanently altered themselves. Therefore, after facilitating a reaction, the enzyme remains unchanged and can be used to catalyze subsequent reactions. Option A is incorrect because enzymes are not "reduced" to an inactive form after a reaction; they maintain their structure and function. Option B is incorrect as enzymes do not become inert; their catalytic activity is preserved. Option C is incorrect because an enzyme transforms the substrate, not itself, into a product.

Answer: D. O

Option D is correct because individuals with blood group O have both anti-A and anti-B antibodies in their serum. This is because their red blood cells lack both A and B antigens, so their immune system produces antibodies against both. Option B is tempting because AB blood group has neither antibody, but it's the opposite of what's asked.

Answer: C. Mucus cells secrete mucin

Chief cells secrete pepsinogen, not gastrin. Hormone cells, specifically enteroendocrine cells, secrete gastrin, not intrinsic factor. Parietal cells secrete hydrochloric acid and intrinsic factor, not pepsinogen. Mucus cells are specialized for secreting mucin, a component of mucus, which protects the stomach lining.

Answer: D. Perpendicular to sp² orbitals

The unhybridized p orbital in sp² hybridization is perpendicular to the plane formed by the sp² hybrid orbitals. This orientation allows the p orbital to overlap effectively with p orbitals on adjacent atoms, forming pi bonds. Options A and C are incorrect because the p orbital's orientation is distinct from the sp² orbitals, and option B, while describing its orientation relative to the plane, doesn't fully capture its directional relationship with the sp² orbitals.

Answer: D. Potassium iodide

Potassium iodide is a strong electrolyte because it is an ionic compound that fully dissociates into its constituent ions (K⁺ and I⁻) when dissolved in water. This high degree of dissociation leads to a large number of charge carriers, resulting in good electrical conductivity. Acetic acid, ammonium hydroxide, and carbonic acid are weak electrolytes, meaning they only partially ionize in water, producing fewer charge carriers.

Answer: D. Methyl cyanide

The hydrolysis of methyl cyanide (acetonitrile) yields acetic acid and ammonia. The nitrile group ($\text{C} \equiv \text{N}$) is converted to a carboxyl group ($\text{COOH}$) upon reaction with water. Ethanal can be oxidized to acetic acid, but hydrolysis of ethanal primarily yields ethanoic acid and water if performed carefully, or further products otherwise. Ethanol is an alcohol and can be oxidized to acetic acid, but its hydrolysis doesn't produce it. Methanoic acid is the simplest carboxylic acid and cannot be prepared by hydrolysis of itself.

Answer: D. The sum of the amplitudes of the individual waves

The principle of superposition states that when waves meet, their displacements add up. Therefore, the amplitude of the resultant wave is the algebraic sum of the amplitudes of the individual waves. Option A is incorrect because the resultant amplitude is not always zero; it depends on whether the waves are in phase or out of phase.

Answer: B. F = qv × B

The magnetic force on a charged particle is described by the Lorentz force law, which states that the force is the product of the charge, the velocity of the particle, and the magnetic field vector, all in a cross-product relationship. Option B directly represents this fundamental physics principle. Option A is incorrect because it equates charge to a force expression, which is dimensionally inconsistent.

Answer: D. They were playing football when it started to rain.

Option D is correct because it uses the past continuous tense ("were playing") to describe an ongoing action in