NEET PG Biochemistry PYQs 2026: Most Important Questions With Answers

NEET PG Biochemistry PYQ Trend Analysis

Biochemistry prefers this kind of analysis more than most subjects. Its syllabus is concise compared to Medicine or Surgery. So, the same core pathways and disorders come up repeatedly, just designed differently in questions each year. A question on the urea cycle might appear as a direct enzyme question one year and as a clinical vignette about hyperammonemia the next. The underlying concept being tested barely changes.

Recognising this pattern changes how you revise. Instead of treating each year's paper as unrelated to the last, you start to notice the handful of ideas doing most of the work across multiple cycles.

Most Repeated NEET PG Biochemistry PYQ Topics

Questions are designed from a few topics consistently across recent years. Vitamin deficiency disorders are one of the most reliable, since they translate easily into short clinical scenarios, a patient with a specific set of symptoms, and a single vitamin behind it. Enzyme deficiency disorders follow a similar pattern, PKU, Tay-Sachs disease, and Gaucher's disease all show up in various forms because each maps cleanly to one missing enzyme and one clear clinical picture.

Metabolic pathway regulation is another repeated topic, particularly questions on rate-limiting enzymes across glycolysis, glycogen metabolism, and fatty acid synthesis. Molecular biology basics, DNA replication, RNA types, and lab techniques like PCR also repeat consistently, since they form the foundation for genetics questions tested elsewhere in the paper. Clinical enzymology, using enzyme levels to diagnose conditions like pancreatitis or myocardial infarction, ties biochemistry directly into Medicine and shows up under both subjects.

NEET PG Biochemistry PYQ-Based Practice Questions

Q1. What is the rate-limiting enzyme of glycogenolysis?

A) Glycogen synthase

B) Glycogen phosphorylase

C) Phosphoglucomutase

D) Debranching enzyme

Answer: B) Glycogen phosphorylase. This enzyme breaks down glycogen to release glucose-1-phosphate and is the key regulated step in glycogen breakdown.

Q2. The Cori cycle describes the conversion of lactate back into glucose in which organ?

A) Muscle

B) Liver

C) Kidney

D) Adipose tissue

Answer: B) Liver. Lactate produced by exercising muscle travels to the liver, where it is converted back into glucose through gluconeogenesis.

Q3. Deficiency of which vitamin causes xerophthalmia and night blindness?

A) Vitamin A

B) Vitamin C

C) Vitamin D

D) Vitamin E

Answer: A) Vitamin A. Vitamin A is essential for the visual cycle in the retina, and its deficiency leads to night blindness and, if prolonged, xerophthalmia.

Q4. Which enzyme is deficient in Tay-Sachs disease?

A) Glucocerebrosidase

B) Hexosaminidase A

C) Sphingomyelinase

D) Alpha-galactosidase A

Answer: B) Hexosaminidase A. Its deficiency leads to accumulation of GM2 ganglioside in neurons, causing the progressive neurological decline seen in Tay-Sachs disease.

Q5. Which amino acid is the direct precursor for melanin synthesis?

A) Phenylalanine

B) Tyrosine

C) Tryptophan

D) Histidine

Answer: B) Tyrosine. Tyrosine is converted through a series of steps into melanin, the pigment responsible for skin, hair, and eye colour.

Q6. FAD and FMN are coenzymes derived from which vitamin?

A) Vitamin B1 (Thiamine)

B) Vitamin B2 (Riboflavin)

C) Vitamin B3 (Niacin)

D) Vitamin B6 (Pyridoxine)

Answer: B) Vitamin B2 (Riboflavin). Riboflavin is the precursor for both FAD and FMN, coenzymes central to the electron transport chain and multiple oxidation reactions.

Q7. What is the rate-limiting enzyme of fatty acid synthesis?

A) Fatty acid synthase

B) Acetyl-CoA carboxylase

C) Citrate lyase

D) Malonyl-CoA decarboxylase

Answer: B) Acetyl-CoA carboxylase. This enzyme converts acetyl-CoA to malonyl-CoA, the committed and rate-limiting step of fatty acid synthesis.

Q8. Which enzyme catalyses the rate-limiting step of the TCA cycle?

A) Citrate synthase

B) Isocitrate dehydrogenase

C) Succinate dehydrogenase

D) Malate dehydrogenase

Answer: B) Isocitrate dehydrogenase. This step is tightly regulated and considered the rate-limiting point of the TCA cycle, responding to the cell's energy status.

Q9. Deficiency of which vitamin causes pellagra, marked by dermatitis, diarrhoea, and dementia?

A) Vitamin B1

B) Vitamin B3 (Niacin)

C) Vitamin B6

D) Vitamin B12

Answer: B) Vitamin B3 (Niacin). The classic "3 D's" of pellagra, dermatitis, diarrhoea, and dementia, result from niacin deficiency.

Q10. Which laboratory technique is used to amplify a specific segment of DNA?

A) Gel electrophoresis

B) Polymerase Chain Reaction (PCR)

C) Southern blotting

D) ELISA

Answer: B) Polymerase Chain Reaction (PCR). PCR uses repeated cycles of denaturation, annealing, and extension to amplify a targeted DNA sequence millions of times over.

Q11. Which enzyme is deficient in Gaucher's disease?

A) Glucocerebrosidase

B) Hexosaminidase A

C) Arylsulfatase A

D) Alpha-L-iduronidase

Answer: A) Glucocerebrosidase. Its deficiency causes glucocerebroside to accumulate in macrophages, producing the characteristic Gaucher cells seen in this disorder.

Q12. In zero-order enzyme kinetics, how does reaction rate relate to substrate concentration?

A) Rate increases proportionally with substrate concentration

B) Rate is independent of substrate concentration

C) Rate decreases as substrate concentration rises

D) Rate depends only on enzyme concentration, never substrate

Answer: B) Rate is independent of substrate concentration. In zero-order kinetics, the enzyme is already saturated with substrate, so adding more substrate does not change the reaction rate.

Q13. Which fat-soluble vitamin functions primarily as an antioxidant in cell membranes?

A) Vitamin A

B) Vitamin D

C) Vitamin E

D) Vitamin K

Answer: C) Vitamin E. Vitamin E protects cell membranes from oxidative damage by neutralising free radicals within the lipid bilayer.

Q14. Which enzymes are classically elevated in acute pancreatitis?

A) AST and ALT

B) Serum amylase and lipase

C) Alkaline phosphatase and GGT

D) CK-MB and troponin

Answer: B) Serum amylase and lipase. Both enzymes leak into the bloodstream when the pancreas is inflamed, and lipase is generally considered more specific to pancreatic injury.

Q15. Which type of RNA is responsible for carrying amino acids to the ribosome during protein synthesis?

A) mRNA

B) rRNA

C) tRNA

D) snRNA

Answer: C) tRNA. Transfer RNA (tRNA) reads the codon on mRNA and delivers the corresponding amino acid to the growing polypeptide chain at the ribosome.

How to Use This PYQ Trend Analysis

Treat the topic list above as a priority base, not a complete syllabus replacement. These are the topics from which questions are asked most consistently, so they deserve priority when your revision time is limited. However, Biochemistry's complete syllabus still matters for a well-rounded score.

Once you've worked through these fifteen questions, cross-check your accuracy by topic, not just your overall score. If you missed both vitamin questions but got every enzyme question right, that tells you exactly where to spend your next revision session, which is the entire point of trend-based practice over random question sets.