2026 NBME CBSE (Comprehensive Basic Science Examination) Overview

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NBME CBSE Actual exam COMPREHENSIVE QUESTIONS AND VERIFIED
ANSWERS 2026 (NEW UPDATED VERSION) LATEST ACTUAL EXAM QUESTIONS
AND CORRECT ANSWERS (VERIFIED QUESTIONS AND ANSWERS)- GUARANTEED
PASS A+




NBME CBSE

Question: A 25-year-old presents with fatigue and pallor. Lab shows microcytic anemia. Which
nutrient deficiency is most likely?
Answer: Iron
Rationale: Microcytic anemia is commonly caused by iron deficiency; iron is essential for
hemoglobin synthesis.



Question: A patient with uncontrolled hypertension develops proteinuria and edema. Which
renal pathology is most likely?
Answer: Chronic glomerulonephritis
Rationale: Hypertension can cause glomerular damage leading to proteinuria and edema.



Question: Which neurotransmitter is primarily deficient in Parkinson’s disease?
Answer: Dopamine
Rationale: Degeneration of substantia nigra neurons reduces dopamine, causing bradykinesia,
rigidity, and tremor.



Question: Which bacterium is most commonly associated with peptic ulcers?
Answer: Helicobacter pylori
Rationale: H. pylori colonizes the stomach lining, causing chronic gastritis and peptic ulcer
disease.



Question: Which embryologic structure gives rise to the auditory ossicles?
Answer: Pharyngeal arches 1 and 2
Rationale: Meckel’s cartilage (arch 1) forms malleus and incus; Reichert’s cartilage (arch 2)
forms stapes.



practice exam 2026

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Question: A patient presents with polyuria, polydipsia, and high fasting glucose. Which type of
diabetes is most likely?
Answer: Type 2 diabetes mellitus
Rationale: Polyuria, polydipsia, and hyperglycemia indicate diabetes; in adults, type 2 is most
common.



Question: Which cell type is responsible for humoral immunity?
Answer: B lymphocytes
Rationale: B cells differentiate into plasma cells to produce antibodies.



Question: A patient develops painless jaundice, weight loss, and a palpable gallbladder. What is
the most likely diagnosis?
Answer: Pancreatic head carcinoma (Courvoisier sign)
Rationale: Obstruction of the common bile duct by tumor causes painless jaundice and palpable
gallbladder.



Question: Which anti-hypertensive drug class is contraindicated in pregnancy?
Answer: ACE inhibitors
Rationale: ACE inhibitors can cause fetal renal dysplasia and are teratogenic.



Question: Which vitamin deficiency causes night blindness?
Answer: Vitamin A
Rationale: Vitamin A is required for rhodopsin formation in rods; deficiency impairs vision in
low light.



Question: A patient has prolonged PT and normal aPTT. Which factor deficiency is most likely?
Answer: Factor VII
Rationale: PT assesses the extrinsic pathway; Factor VII deficiency prolongs PT selectively.



Question: A newborn has cyanosis and a holosystolic murmur at the left lower sternal border.
Most likely diagnosis?



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Answer: Ventricular septal defect (VSD)
Rationale: VSD causes left-to-right shunt, often producing a loud holosystolic murmur.



Question: Which neurotransmitter is elevated in anxiety disorders?
Answer: Norepinephrine
Rationale: Hyperactivity of noradrenergic pathways contributes to anxiety symptoms.



Question: A patient presents with fever, headache, stiff neck, and purpura. Which pathogen is
most likely?
Answer: Neisseria meningitidis
Rationale: N. meningitidis causes meningococcemia with rapid progression and petechial rash.



Question: Which enzyme deficiency causes maple syrup urine disease?
Answer: Branched-chain α-ketoacid dehydrogenase
Rationale: Deficiency leads to accumulation of branched-chain amino acids (leucine, isoleucine,
valine).



Question: A patient develops sudden-onset chest pain radiating to the back and unequal blood
pressures in both arms. Most likely diagnosis?
Answer: Aortic dissection
Rationale: Dissection can occlude branch vessels, causing asymmetrical pulses and severe pain.



Question: Which hormone is primarily responsible for calcium homeostasis?
Answer: Parathyroid hormone (PTH)
Rationale: PTH increases blood calcium by stimulating bone resorption, renal reabsorption, and
vitamin D activation.



Question: Which cranial nerve mediates corneal reflex (afferent limb)?
Answer: Trigeminal nerve (V1)
Rationale: V1 detects corneal touch; the facial nerve (VII) mediates the efferent blink.




practice exam 2026

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Question: Which enzyme is deficient in classic galactosemia?
Answer: Galactose-1-phosphate uridyltransferase (GALT)
Rationale: Deficiency leads to accumulation of galactose-1-phosphate causing liver, cataract,
and cognitive issues.



Question: Which tumor marker is elevated in hepatocellular carcinoma?
Answer: Alpha-fetoprotein (AFP)
Rationale: AFP is secreted by malignant hepatocytes and is used as a diagnostic and monitoring
tool.



Question: Which antibiotic class inhibits bacterial cell wall synthesis?
Answer: Beta-lactams (penicillins, cephalosporins)
Rationale: Beta-lactams inhibit transpeptidase enzymes, preventing peptidoglycan cross-linking.



Question: A patient presents with fatigue, weight gain, and cold intolerance. Lab shows elevated
TSH. Diagnosis?
Answer: Primary hypothyroidism
Rationale: High TSH indicates thyroid gland failure, causing hypothyroid symptoms.



Question: Which artery is most commonly affected in myocardial infarction?
Answer: Left anterior descending artery (LAD)
Rationale: LAD occlusion affects the anterior wall of the heart and is the most frequent MI site.



Question: Which immunoglobulin crosses the placenta?
Answer: IgG
Rationale: IgG provides passive immunity to the fetus during gestation.



Question: Which vitamin deficiency causes megaloblastic anemia without neurological
symptoms?
Answer: Folate (Vitamin B9)
Rationale: Folate deficiency impairs DNA synthesis, leading to megaloblastic anemia; B12
deficiency causes neurological deficits as well.




practice exam 2026