NBME CBSE — Full Syllabus 2026/2027
Forms 1–8 Integrated Practice Exam
400 Comprehensive Questions with Verified Answers
Comprehensive Basic Science Examination — Full Content Outline
Forms 1 through 8 Integration with Progressive Difficulty
Cognitive Levels: 30% Recall | 50% Application | 20% Analysis
Format: 85% Clinical Vignette-Based | 15% Direct Recall
Coverage: Biochemistry, Microbiology, Pathology, Pharmacology,
Physiology, Anatomy, Behavioral Science, Biostatistics, Ethics
Medical Education | Pathophysiological Rationales | NBME-Style Reasoning Complete Exam | 400 Questions | Forms 1-8 Full Syllabus
,NBME CBSE Full Syllabus 2026/2027 | Forms 1-8 | 400-Question Practice Exam Verified Answers
NBME CBSE — FULL SYLLABUS 2026/2027
400 Verified Questions & Answers — Forms 1-8 Integration
Aligned with the NBME CBSE Content Outline and Current Medical Standards
Cognitive Levels: 30% Recall | 50% Application | 20% Analysis
Format: 85% Clinical Vignette-Based | 15% Direct Recall
Coverage: Biochemistry, Microbiology, Immunology, Pathology, Pharmacology, Physiology, Anatomy,
Behavioral Science, Biostatistics, Ethics
BLOCK 1 — CBSE Forms 1 & 2: Foundations
Section 1A: Biochemistry and Molecular Biology
Focus: Enzyme Kinetics, Metabolic Pathways, Vitamins, DNA/RNA, Replication, Transcription, Translation, & Molecular
Techniques (Q1–Q15)
Q1: A 6-week-old infant presents with failure to thrive, cataracts, and hepatomegaly. Reducing
substances are detected in the urine after a lactose-containing feeding. Which enzyme
deficiency is most likely responsible?
A. Galactokinase
B. Galactose-1-phosphate uridyltransferase (GALT) [CORRECT]
C. Glucose-6-phosphatase
D. Fructokinase
Correct Answer: B
Rationale: Classic galactosemia results from GALT deficiency causing accumulation of galactose-1-phosphate,
with hepatomegaly, cataracts, and failure to thrive. Galactokinase deficiency causes only cataracts.
Glucose-6-phosphatase deficiency causes von Gierke disease. Fructokinase deficiency is benign fructosuria.
Q2: A Lineweaver-Burk plot of an enzyme in the presence of a competitive inhibitor shows which
effect compared to the uninhibited reaction?
A. Increased Km and increased Vmax
B. Increased Km with no change in Vmax [CORRECT]
C. No change in Km and decreased Vmax
D. Decreased Km and decreased Vmax
Correct Answer: B
Rationale: Competitive inhibitors bind the active site and increase apparent Km (lower substrate affinity)
without changing Vmax (can be overcome with high substrate). Noncompetitive inhibitors decrease Vmax
without changing Km. Test-taking strategy: competitive = Km up, Vmax same.
Page 2 | NBME CBSE Forms 1-8 Practice Exam
,NBME CBSE Full Syllabus 2026/2027 | Forms 1-8 | 400-Question Practice Exam Verified Answers
Q3: A 45-year-old alcoholic presents with confusion, ataxia, and ophthalmoplegia.
Administration of glucose without which vitamin can precipitate or worsen this condition?
A. Vitamin B12 (cobalamin)
B. Thiamine (B1) [CORRECT]
C. Folate (B9)
D. Niacin (B3)
Correct Answer: B
Rationale: Wernicke encephalopathy results from thiamine deficiency. Glucose infusion without thiamine can
precipitate or worsen the syndrome because thiamine is a cofactor for pyruvate dehydrogenase; glucose
metabolism further depletes thiamine stores. Always give thiamine before glucose in alcoholics.
Q4: A molecular biologist uses a restriction enzyme that cuts at the sequence 5'-GAATTC-3'. This
enzyme most likely belongs to which class of enzymes?
A. DNA ligases
B. Endonucleases [CORRECT]
C. Topoisomerases
D. Helicases
Correct Answer: B
Rationale: Restriction enzymes (e.g., EcoRI) are bacterial endonucleases that cut double-stranded DNA at
specific recognition sequences, often producing sticky ends. They are essential tools in molecular cloning.
Ligases join DNA fragments; topoisomerases alter supercoiling; helicases unwind DNA.
Q5: During DNA replication, which enzyme relieves supercoiling ahead of the replication fork by
cutting and resealing one or both strands?
A. Primase
B. DNA polymerase III
C. Topoisomerase (DNA gyrase in prokaryotes) [CORRECT]
D. Ligase
Correct Answer: C
Rationale: Topoisomerases relieve torsional strain from unwinding; DNA gyrase (a bacterial topoisomerase II)
is the target of fluoroquinolones. Primase synthesizes RNA primers; DNA polymerase III extends the new
strand; ligase seals Okazaki fragments.
Q6: A 23-year-old man has recurrent episodes of deep vein thrombosis. Homocysteine levels are
elevated. Which vitamin supplementation is most appropriate to reduce homocysteine levels?
A. Vitamin C and D
B. Vitamins B6, B12, and folate [CORRECT]
C. Vitamin E and K
D. Thiamine and riboflavin
Correct Answer: B
Rationale: Homocystinuria (often due to cystathionine β-synthase deficiency) is managed with vitamins B6,
B12, and folate, which serve as cofactors in the transsulfuration and remethylation pathways. Vitamin C
deficiency causes scurvy; vitamin K affects clotting factors.
Page 3 | NBME CBSE Forms 1-8 Practice Exam
, NBME CBSE Full Syllabus 2026/2027 | Forms 1-8 | 400-Question Practice Exam Verified Answers
Q7: A patient with diabetes has elevated levels of fructosamine. Compared to hemoglobin A1c,
fructosamine reflects blood glucose over what time period?
A. 1-3 weeks [CORRECT]
B. 2-3 months
C. 6-12 hours
D. 1 year
Correct Answer: A
Rationale: Fructosamine reflects average glucose over the past 1-3 weeks because it measures glycation of
serum proteins (e.g., albumin) with shorter half-lives than hemoglobin (2-3 months for HbA1c). Useful for
monitoring short-term glycemic changes or in conditions affecting RBC lifespan.
Q8: A newborn screening test is positive for phenylketonuria (PKU). Which enzyme is deficient
in classic PKU?
A. Phenylalanine hydroxylase [CORRECT]
B. Tyrosinase
C. Homogentisate oxidase
D. Branched-chain alpha-ketoacid dehydrogenase
Correct Answer: A
Rationale: Classic PKU is caused by deficiency of phenylalanine hydroxylase, which converts phenylalanine to
tyrosine. Untreated PKU causes intellectual disability, fair skin, and a mousy body odor. Treatment is a
low-phenylalanine diet. Tyrosinase deficiency causes albinism; homogentisate oxidase deficiency causes
alkaptonuria.
Q9: In the electron transport chain, complex IV transfers electrons to which final acceptor?
A. NAD+
B. FAD
C. Oxygen (O2) [CORRECT]
D. Coenzyme Q
Correct Answer: C
Rationale: Complex IV (cytochrome c oxidase) transfers electrons to molecular oxygen, reducing it to water.
This final electron acceptor step is essential for aerobic respiration; without oxygen, oxidative phosphorylation
halts. NAD+ and FAD are electron carriers; CoQ shuttles electrons between complexes I/II and III.
Q10: A 3-month-old infant presents with hypoglycemia, lactic acidosis, and hyperuricemia after
fasting. Liver biopsy shows marked glycogen accumulation. Deficiency of which enzyme is most
likely?
A. Lysosomal α-1,4-glucosidase
B. Glucose-6-phosphatase [CORRECT]
C. Muscle phosphorylase
D. Hepatic fructokinase
Correct Answer: B
Rationale: Von Gierke disease (type I glycogen storage disease) results from glucose-6-phosphatase deficiency,
causing hepatomegaly, severe fasting hypoglycemia, lactic acidosis, and hyperuricemia. α-1,4-glucosidase
deficiency (Pompe) affects lysosomes; muscle phosphorylase deficiency (McArdle) causes exercise intolerance.
Page 4 | NBME CBSE Forms 1-8 Practice Exam
Forms 1–8 Integrated Practice Exam
400 Comprehensive Questions with Verified Answers
Comprehensive Basic Science Examination — Full Content Outline
Forms 1 through 8 Integration with Progressive Difficulty
Cognitive Levels: 30% Recall | 50% Application | 20% Analysis
Format: 85% Clinical Vignette-Based | 15% Direct Recall
Coverage: Biochemistry, Microbiology, Pathology, Pharmacology,
Physiology, Anatomy, Behavioral Science, Biostatistics, Ethics
Medical Education | Pathophysiological Rationales | NBME-Style Reasoning Complete Exam | 400 Questions | Forms 1-8 Full Syllabus
,NBME CBSE Full Syllabus 2026/2027 | Forms 1-8 | 400-Question Practice Exam Verified Answers
NBME CBSE — FULL SYLLABUS 2026/2027
400 Verified Questions & Answers — Forms 1-8 Integration
Aligned with the NBME CBSE Content Outline and Current Medical Standards
Cognitive Levels: 30% Recall | 50% Application | 20% Analysis
Format: 85% Clinical Vignette-Based | 15% Direct Recall
Coverage: Biochemistry, Microbiology, Immunology, Pathology, Pharmacology, Physiology, Anatomy,
Behavioral Science, Biostatistics, Ethics
BLOCK 1 — CBSE Forms 1 & 2: Foundations
Section 1A: Biochemistry and Molecular Biology
Focus: Enzyme Kinetics, Metabolic Pathways, Vitamins, DNA/RNA, Replication, Transcription, Translation, & Molecular
Techniques (Q1–Q15)
Q1: A 6-week-old infant presents with failure to thrive, cataracts, and hepatomegaly. Reducing
substances are detected in the urine after a lactose-containing feeding. Which enzyme
deficiency is most likely responsible?
A. Galactokinase
B. Galactose-1-phosphate uridyltransferase (GALT) [CORRECT]
C. Glucose-6-phosphatase
D. Fructokinase
Correct Answer: B
Rationale: Classic galactosemia results from GALT deficiency causing accumulation of galactose-1-phosphate,
with hepatomegaly, cataracts, and failure to thrive. Galactokinase deficiency causes only cataracts.
Glucose-6-phosphatase deficiency causes von Gierke disease. Fructokinase deficiency is benign fructosuria.
Q2: A Lineweaver-Burk plot of an enzyme in the presence of a competitive inhibitor shows which
effect compared to the uninhibited reaction?
A. Increased Km and increased Vmax
B. Increased Km with no change in Vmax [CORRECT]
C. No change in Km and decreased Vmax
D. Decreased Km and decreased Vmax
Correct Answer: B
Rationale: Competitive inhibitors bind the active site and increase apparent Km (lower substrate affinity)
without changing Vmax (can be overcome with high substrate). Noncompetitive inhibitors decrease Vmax
without changing Km. Test-taking strategy: competitive = Km up, Vmax same.
Page 2 | NBME CBSE Forms 1-8 Practice Exam
,NBME CBSE Full Syllabus 2026/2027 | Forms 1-8 | 400-Question Practice Exam Verified Answers
Q3: A 45-year-old alcoholic presents with confusion, ataxia, and ophthalmoplegia.
Administration of glucose without which vitamin can precipitate or worsen this condition?
A. Vitamin B12 (cobalamin)
B. Thiamine (B1) [CORRECT]
C. Folate (B9)
D. Niacin (B3)
Correct Answer: B
Rationale: Wernicke encephalopathy results from thiamine deficiency. Glucose infusion without thiamine can
precipitate or worsen the syndrome because thiamine is a cofactor for pyruvate dehydrogenase; glucose
metabolism further depletes thiamine stores. Always give thiamine before glucose in alcoholics.
Q4: A molecular biologist uses a restriction enzyme that cuts at the sequence 5'-GAATTC-3'. This
enzyme most likely belongs to which class of enzymes?
A. DNA ligases
B. Endonucleases [CORRECT]
C. Topoisomerases
D. Helicases
Correct Answer: B
Rationale: Restriction enzymes (e.g., EcoRI) are bacterial endonucleases that cut double-stranded DNA at
specific recognition sequences, often producing sticky ends. They are essential tools in molecular cloning.
Ligases join DNA fragments; topoisomerases alter supercoiling; helicases unwind DNA.
Q5: During DNA replication, which enzyme relieves supercoiling ahead of the replication fork by
cutting and resealing one or both strands?
A. Primase
B. DNA polymerase III
C. Topoisomerase (DNA gyrase in prokaryotes) [CORRECT]
D. Ligase
Correct Answer: C
Rationale: Topoisomerases relieve torsional strain from unwinding; DNA gyrase (a bacterial topoisomerase II)
is the target of fluoroquinolones. Primase synthesizes RNA primers; DNA polymerase III extends the new
strand; ligase seals Okazaki fragments.
Q6: A 23-year-old man has recurrent episodes of deep vein thrombosis. Homocysteine levels are
elevated. Which vitamin supplementation is most appropriate to reduce homocysteine levels?
A. Vitamin C and D
B. Vitamins B6, B12, and folate [CORRECT]
C. Vitamin E and K
D. Thiamine and riboflavin
Correct Answer: B
Rationale: Homocystinuria (often due to cystathionine β-synthase deficiency) is managed with vitamins B6,
B12, and folate, which serve as cofactors in the transsulfuration and remethylation pathways. Vitamin C
deficiency causes scurvy; vitamin K affects clotting factors.
Page 3 | NBME CBSE Forms 1-8 Practice Exam
, NBME CBSE Full Syllabus 2026/2027 | Forms 1-8 | 400-Question Practice Exam Verified Answers
Q7: A patient with diabetes has elevated levels of fructosamine. Compared to hemoglobin A1c,
fructosamine reflects blood glucose over what time period?
A. 1-3 weeks [CORRECT]
B. 2-3 months
C. 6-12 hours
D. 1 year
Correct Answer: A
Rationale: Fructosamine reflects average glucose over the past 1-3 weeks because it measures glycation of
serum proteins (e.g., albumin) with shorter half-lives than hemoglobin (2-3 months for HbA1c). Useful for
monitoring short-term glycemic changes or in conditions affecting RBC lifespan.
Q8: A newborn screening test is positive for phenylketonuria (PKU). Which enzyme is deficient
in classic PKU?
A. Phenylalanine hydroxylase [CORRECT]
B. Tyrosinase
C. Homogentisate oxidase
D. Branched-chain alpha-ketoacid dehydrogenase
Correct Answer: A
Rationale: Classic PKU is caused by deficiency of phenylalanine hydroxylase, which converts phenylalanine to
tyrosine. Untreated PKU causes intellectual disability, fair skin, and a mousy body odor. Treatment is a
low-phenylalanine diet. Tyrosinase deficiency causes albinism; homogentisate oxidase deficiency causes
alkaptonuria.
Q9: In the electron transport chain, complex IV transfers electrons to which final acceptor?
A. NAD+
B. FAD
C. Oxygen (O2) [CORRECT]
D. Coenzyme Q
Correct Answer: C
Rationale: Complex IV (cytochrome c oxidase) transfers electrons to molecular oxygen, reducing it to water.
This final electron acceptor step is essential for aerobic respiration; without oxygen, oxidative phosphorylation
halts. NAD+ and FAD are electron carriers; CoQ shuttles electrons between complexes I/II and III.
Q10: A 3-month-old infant presents with hypoglycemia, lactic acidosis, and hyperuricemia after
fasting. Liver biopsy shows marked glycogen accumulation. Deficiency of which enzyme is most
likely?
A. Lysosomal α-1,4-glucosidase
B. Glucose-6-phosphatase [CORRECT]
C. Muscle phosphorylase
D. Hepatic fructokinase
Correct Answer: B
Rationale: Von Gierke disease (type I glycogen storage disease) results from glucose-6-phosphatase deficiency,
causing hepatomegaly, severe fasting hypoglycemia, lactic acidosis, and hyperuricemia. α-1,4-glucosidase
deficiency (Pompe) affects lysosomes; muscle phosphorylase deficiency (McArdle) causes exercise intolerance.
Page 4 | NBME CBSE Forms 1-8 Practice Exam
