CBSE-Style Practice Exam 2026| REAL EXAM QUESTIONS AND 100%
CORRECT DETAILED ANSWERS (USMLE STEP 1) MEDICAL EXAMINATION
1. Which of the following is the primary site of gluconeogenesis?
a) Muscle
b) Kidney
c) Liver
d) Adipose tissue
Rationale: The liver is the main organ that produces glucose from non-carbohydrate precursors.
2. Which cranial nerve is responsible for facial sensation?
a) Facial (VII)
b) Glossopharyngeal (IX)
c) Trigeminal (V)
d) Vagus (X)
Rationale: The trigeminal nerve provides sensory innervation to the face.
3. The bacteria that is most likely to cause nosocomial urinary tract infections is:
a) Streptococcus pyogenes
b) Staphylococcus aureus
c) Escherichia coli
d) Pseudomonas aeruginosa
Rationale: E. coli is the most common cause of hospital-acquired UTIs.
4. Which of the following is a beta-1 selective adrenergic blocker?
a) Propranolol
,b) Metoprolol
c) Labetalol
d) Carvedilol
Rationale: Metoprolol selectively blocks β1 receptors, primarily affecting the heart.
5. During the cardiac cycle, the first heart sound (S1) is caused by:
a) Aortic valve closure
b) Mitral and tricuspid valve closure
c) Pulmonary valve closure
d) Rapid ventricular filling
Rationale: S1 corresponds to closure of AV valves at the start of systole.
6. Which amino acid is essential and must be obtained from the diet?
a) Alanine
b) Glycine
c) Leucine
d) Glutamine
Rationale: Leucine is an essential amino acid, unlike alanine, glycine, or glutamine.
7. The most common cause of bacterial meningitis in adults is:
a) Listeria monocytogenes
b) Streptococcus pneumoniae
c) Neisseria gonorrhoeae
d) Haemophilus influenzae
Rationale: Streptococcus pneumoniae is the leading cause in adults.
8. Which enzyme is deficient in classic phenylketonuria (PKU)?
a) Tyrosinase
b) Homogentisate oxidase
c) Phenylalanine hydroxylase
d) Branched-chain α-keto acid dehydrogenase
Rationale: PKU results from a defect in phenylalanine hydroxylase, leading to high
phenylalanine levels.
, 9. A patient has hyperkalemia. Which ECG change is most characteristic?
a) Peaked T waves
b) Widened P wave
c) ST depression
d) U wave prominence
Rationale: Elevated potassium levels cause tall, peaked T waves.
10. Which part of the nephron is impermeable to water?
a) Descending loop of Henle
b) Proximal tubule
c) Collecting duct
d) Thick ascending loop of Henle
Rationale: The thick ascending limb actively reabsorbs ions but is impermeable to water.
11. Which virus is a DNA virus that can integrate into the host genome?
a) HIV
b) Influenza
c) Hepatitis B
d) Poliovirus
Rationale: Hepatitis B is a DNA virus that can integrate into host DNA, unlike HIV (RNA
retrovirus).
12. The classical triad of meningitis includes:
a) Fever, cough, rash
b) Fever, hematuria, jaundice
c) Fever, neck stiffness, altered mental status
d) Cough, dyspnea, chest pain
Rationale: These three are hallmark clinical signs of meningitis.
13. Which hormone increases during stress and stimulates gluconeogenesis?
a) Insulin
b) Cortisol
c) Growth hormone
d) Prolactin
Rationale: Cortisol promotes gluconeogenesis and protein catabolism in stress response.
CORRECT DETAILED ANSWERS (USMLE STEP 1) MEDICAL EXAMINATION
1. Which of the following is the primary site of gluconeogenesis?
a) Muscle
b) Kidney
c) Liver
d) Adipose tissue
Rationale: The liver is the main organ that produces glucose from non-carbohydrate precursors.
2. Which cranial nerve is responsible for facial sensation?
a) Facial (VII)
b) Glossopharyngeal (IX)
c) Trigeminal (V)
d) Vagus (X)
Rationale: The trigeminal nerve provides sensory innervation to the face.
3. The bacteria that is most likely to cause nosocomial urinary tract infections is:
a) Streptococcus pyogenes
b) Staphylococcus aureus
c) Escherichia coli
d) Pseudomonas aeruginosa
Rationale: E. coli is the most common cause of hospital-acquired UTIs.
4. Which of the following is a beta-1 selective adrenergic blocker?
a) Propranolol
,b) Metoprolol
c) Labetalol
d) Carvedilol
Rationale: Metoprolol selectively blocks β1 receptors, primarily affecting the heart.
5. During the cardiac cycle, the first heart sound (S1) is caused by:
a) Aortic valve closure
b) Mitral and tricuspid valve closure
c) Pulmonary valve closure
d) Rapid ventricular filling
Rationale: S1 corresponds to closure of AV valves at the start of systole.
6. Which amino acid is essential and must be obtained from the diet?
a) Alanine
b) Glycine
c) Leucine
d) Glutamine
Rationale: Leucine is an essential amino acid, unlike alanine, glycine, or glutamine.
7. The most common cause of bacterial meningitis in adults is:
a) Listeria monocytogenes
b) Streptococcus pneumoniae
c) Neisseria gonorrhoeae
d) Haemophilus influenzae
Rationale: Streptococcus pneumoniae is the leading cause in adults.
8. Which enzyme is deficient in classic phenylketonuria (PKU)?
a) Tyrosinase
b) Homogentisate oxidase
c) Phenylalanine hydroxylase
d) Branched-chain α-keto acid dehydrogenase
Rationale: PKU results from a defect in phenylalanine hydroxylase, leading to high
phenylalanine levels.
, 9. A patient has hyperkalemia. Which ECG change is most characteristic?
a) Peaked T waves
b) Widened P wave
c) ST depression
d) U wave prominence
Rationale: Elevated potassium levels cause tall, peaked T waves.
10. Which part of the nephron is impermeable to water?
a) Descending loop of Henle
b) Proximal tubule
c) Collecting duct
d) Thick ascending loop of Henle
Rationale: The thick ascending limb actively reabsorbs ions but is impermeable to water.
11. Which virus is a DNA virus that can integrate into the host genome?
a) HIV
b) Influenza
c) Hepatitis B
d) Poliovirus
Rationale: Hepatitis B is a DNA virus that can integrate into host DNA, unlike HIV (RNA
retrovirus).
12. The classical triad of meningitis includes:
a) Fever, cough, rash
b) Fever, hematuria, jaundice
c) Fever, neck stiffness, altered mental status
d) Cough, dyspnea, chest pain
Rationale: These three are hallmark clinical signs of meningitis.
13. Which hormone increases during stress and stimulates gluconeogenesis?
a) Insulin
b) Cortisol
c) Growth hormone
d) Prolactin
Rationale: Cortisol promotes gluconeogenesis and protein catabolism in stress response.
