NBME CBSE ACTUAL EXAM COMPLETE TEST BANK
200+| HIGH-YIELD, LATEST 2026, WITH CORRECT
ANSWERS & EXPLANATIONS | (USMLE STEP 1)
1. A 16-year-old girl presents with fever, nonproductive cough, and fatigue. Her
blood spontaneously agglutinates in the lab. Which antibody is responsible?
A. IgG
B. IgA
C. IgM
D. IgE E. IgD
Answer: C. IgM
Explanation: IgM is the major agglutinating antibody, especially in cold agglutinin
disease, commonly seen in Mycoplasma pneumoniae infections.
2. A newborn presents with white forelock, heterochromia, and bilateral
sensorineural hearing loss. What is the most likely cause?
A) Abnormality of connexins
B) Deficiency of tyrosinase activity
C) Abnormal neural crest development
D) Deficiency of homogentisic acid oxidase
E) Failure of melanosome transport
Answer: C) Abnormal neural crest development
,Explanation: These findings are characteristic of Waardenburg syndrome, which
results from defective neural crest migration affecting melanocytes.
3. GIP secretion leads to increased insulin levels. Which stimulus is most likely
responsible?
A) Saline infusion
B) Gastrin
C) Glucose-dependent insulinotropic peptide
D) Somatostatin.
E) Secretin
Answer: C) Glucose-dependent insulinotropic peptide
Explanation: GIP is secreted by K cells in the duodenum and jejunum in response
to fats and carbohydrates and enhances insulin secretion.
4. In lobar pneumonia, what allows bacteria to spread rapidly between alveoli?
A) Germinal centers
B) Alveolar capillaries
C) Pores of Kohn
D) Lymphatic vessels
E) Vascular sinusoids
Answer: C) Pores of Kohn
,Explanation: Pores of Kohn are openings between adjacent alveoli, facilitating
spread of infections like Streptococcus pneumoniae.
5. A newborn with microcephaly and a mousy odor is diagnosed with PKU. What
should be supplemented?
A) DOPA
B) Dopamine
C) Tyrosine
D) Phenylalanine
E) Epinephrine
Answer: E) Common iliac
Explanation: The ureter crosses anterior to the common iliac artery, making it
vulnerable to compression from aneurysms.
7. A pregnant woman at 5 weeks gestation has rising B-hCG. What produces
progesterone at this stage?
A) Corpus albicans
B) Pituitary
C) Cytotrophoblast
D) Corpus luteum
E) Syncytiotrophoblast
Answer: D) Corpus luteum
, 8. A patient with pernicious anemia lacks intrinsic factor. Which vitamin
deficiency results?
A) Vitamin B12
B) Vitamin B6
C) Vitamin B1
D) Vitamin C
E) Folate
Answer: A) Vitamin B12
Explanation: Intrinsic factor is required for B12 absorption in the terminal ileum.
Deficiency causes megaloblastic anemia and neurologic deficits.
9. A patient with hyperthyroidism has exophthalmos. What is the mechanism?
A) Increased T3 production
B) Autoantibodies stimulating TSH receptors
C) Iodine deficiency
D) Decreased T4 conversion
E) Pituitary adenoma
Answer: B) Autoantibodies stimulating TSH receptors
Explanation: Graves disease involves TSI antibodies that stimulate TSH receptors.
200+| HIGH-YIELD, LATEST 2026, WITH CORRECT
ANSWERS & EXPLANATIONS | (USMLE STEP 1)
1. A 16-year-old girl presents with fever, nonproductive cough, and fatigue. Her
blood spontaneously agglutinates in the lab. Which antibody is responsible?
A. IgG
B. IgA
C. IgM
D. IgE E. IgD
Answer: C. IgM
Explanation: IgM is the major agglutinating antibody, especially in cold agglutinin
disease, commonly seen in Mycoplasma pneumoniae infections.
2. A newborn presents with white forelock, heterochromia, and bilateral
sensorineural hearing loss. What is the most likely cause?
A) Abnormality of connexins
B) Deficiency of tyrosinase activity
C) Abnormal neural crest development
D) Deficiency of homogentisic acid oxidase
E) Failure of melanosome transport
Answer: C) Abnormal neural crest development
,Explanation: These findings are characteristic of Waardenburg syndrome, which
results from defective neural crest migration affecting melanocytes.
3. GIP secretion leads to increased insulin levels. Which stimulus is most likely
responsible?
A) Saline infusion
B) Gastrin
C) Glucose-dependent insulinotropic peptide
D) Somatostatin.
E) Secretin
Answer: C) Glucose-dependent insulinotropic peptide
Explanation: GIP is secreted by K cells in the duodenum and jejunum in response
to fats and carbohydrates and enhances insulin secretion.
4. In lobar pneumonia, what allows bacteria to spread rapidly between alveoli?
A) Germinal centers
B) Alveolar capillaries
C) Pores of Kohn
D) Lymphatic vessels
E) Vascular sinusoids
Answer: C) Pores of Kohn
,Explanation: Pores of Kohn are openings between adjacent alveoli, facilitating
spread of infections like Streptococcus pneumoniae.
5. A newborn with microcephaly and a mousy odor is diagnosed with PKU. What
should be supplemented?
A) DOPA
B) Dopamine
C) Tyrosine
D) Phenylalanine
E) Epinephrine
Answer: E) Common iliac
Explanation: The ureter crosses anterior to the common iliac artery, making it
vulnerable to compression from aneurysms.
7. A pregnant woman at 5 weeks gestation has rising B-hCG. What produces
progesterone at this stage?
A) Corpus albicans
B) Pituitary
C) Cytotrophoblast
D) Corpus luteum
E) Syncytiotrophoblast
Answer: D) Corpus luteum
, 8. A patient with pernicious anemia lacks intrinsic factor. Which vitamin
deficiency results?
A) Vitamin B12
B) Vitamin B6
C) Vitamin B1
D) Vitamin C
E) Folate
Answer: A) Vitamin B12
Explanation: Intrinsic factor is required for B12 absorption in the terminal ileum.
Deficiency causes megaloblastic anemia and neurologic deficits.
9. A patient with hyperthyroidism has exophthalmos. What is the mechanism?
A) Increased T3 production
B) Autoantibodies stimulating TSH receptors
C) Iodine deficiency
D) Decreased T4 conversion
E) Pituitary adenoma
Answer: B) Autoantibodies stimulating TSH receptors
Explanation: Graves disease involves TSI antibodies that stimulate TSH receptors.
