NEET PG Biochemistry Questions 2026: Important MCQs with Answers

NEET PG Biochemistry Questions for 2026

Biochemistry looks small on paper, but it is connected to almost every other subject. Metabolism links to Medicine. Enzyme concepts link to Pathology. Vitamin deficiencies link to Paediatrics and Medicine both. That overlap is exactly why NEET PG likes to frame biochemistry questions as short clinical cases rather than direct theory lines.

There is another reason to take this subject seriously: the mark obtained on time invested. Compared with a subject like Medicine, the Biochemistry topic list is short and well-defined. A candidate who revises it properly can master it less time than a large clinical subject demands. If you're still deciding which books to pick up for this round of revision, check our guide on the best books for NEET PG.

Solving questions also does something reading alone cannot. It builds recall speed, and it shows you exactly how NEET PG twists a concept into a question stem. Reading a chapter and solving a question on that same chapter are two different skills. NEET PG rewards the second one.

NEET PG Biochemistry High-Scoring Topics

Before you start solving, know where the marks actually come from. These topics repeat the most in NEET PG Biochemistry questions year after year:

• Carbohydrate metabolism (glycolysis, gluconeogenesis, glycogen storage disorders)

• Lipid metabolism (beta-oxidation, cholesterol synthesis, lipoproteins)

• Amino acid metabolism (urea cycle, inborn errors like PKU)

• Enzymes and enzyme kinetics

• Vitamins and their deficiency disorders

• Molecular biology (DNA replication, genetic code)

Now let's go through NEET PG Biochemistry important questions from each of these areas.

NEET PG Biochemistry Questions 2026 with Answers

Carbohydrate Metabolism

Q1. Which enzyme catalyses the rate-limiting step of glycolysis?

A) Hexokinase B) Phosphofructokinase-1 C) Pyruvate kinase D) Aldolase

Answer: B) Phosphofructokinase-1. PFK-1 catalyses the committed, rate-limiting step of glycolysis and is tightly regulated by ATP and AMP levels.

Q2. Which enzyme is deficient in Von Gierke disease (Glycogen Storage Disease Type I)?

A) Glucose-6-phosphatase B) Debranching enzyme C) Muscle phosphorylase D) Branching enzyme

Answer: A) Glucose-6-phosphatase. Its deficiency blocks the final step of glycogenolysis and gluconeogenesis, causing severe fasting hypoglycaemia.

Q3. What is the final electron acceptor in the electron transport chain?

A) NAD+ B) Oxygen C) Cytochrome c D) Coenzyme Q

Answer: B) Oxygen. Oxygen accepts electrons at Complex IV, combining with protons to form water.

Q4. PFK-1, the key regulatory enzyme of glycolysis, is allosterically activated by which molecule?

A) ATP B) Citrate C) AMP D) Acetyl-CoA

Answer: C) AMP. AMP signals low energy status and activates PFK-1, while ATP and citrate act as inhibitors when energy is abundant.

Lipid Metabolism

Q5. What is the rate-limiting enzyme of cholesterol synthesis?

A) HMG-CoA reductase B) HMG-CoA synthase C) Squalene synthase D) Acetyl-CoA carboxylase

Answer: A) HMG-CoA reductase. This enzyme is the target of statin drugs, which lower cholesterol by inhibiting it.

Q6. Which lipoprotein carries the highest proportion of triglycerides?

A) LDL B) HDL C) Chylomicrons D) VLDL

Answer: C) Chylomicrons. Chylomicrons transport dietary triglycerides from the intestine to tissues and carry the highest triglyceride content of all lipoproteins.

Q7. Beta-oxidation of fatty acids mainly takes place in which cell organelle?

A) Cytoplasm B) Mitochondria C) Peroxisome only D) Golgi apparatus

Answer: B) Mitochondria. Fatty acids are transported into the mitochondrial matrix via the carnitine shuttle, where beta-oxidation occurs.

Amino Acid Metabolism

Q8. What is the rate-limiting enzyme of the urea cycle?

A) Ornithine transcarbamoylase B) Arginase C) Carbamoyl phosphate synthetase I D) Argininosuccinate synthetase

Answer: C) Carbamoyl phosphate synthetase I. This mitochondrial enzyme catalyses the first, committed step of the urea cycle.

Q9. Which enzyme is deficient in phenylketonuria (PKU)?

A) Tyrosinase B) Phenylalanine hydroxylase C) Homogentisate oxidase D) Tyrosine aminotransferase

Answer: B) Phenylalanine hydroxylase. Its deficiency prevents conversion of phenylalanine to tyrosine, leading to toxic phenylalanine build-up.

Q10. Which amino acid is both glucogenic and ketogenic?

A) Leucine B) Lysine C) Phenylalanine D) Alanine

Answer: C) Phenylalanine. Phenylalanine breaks down into products that feed both gluconeogenesis and ketone body formation.

Q11. Which amino acid is the direct precursor for serotonin synthesis?

A) Tyrosine B) Tryptophan C) Histidine D) Glutamate

Answer: B) Tryptophan. Tryptophan is hydroxylated and decarboxylated to form serotonin.

Enzymes and Enzyme Kinetics

Q12. A Lineweaver-Burk plot is used to determine which two enzyme kinetic parameters?

A) pH and temperature B) Km and Vmax C) Substrate concentration and time D) Enzyme concentration and pH

Answer: B) Km and Vmax. This double-reciprocal plot gives a straight line, making it easy to calculate Km and Vmax accurately.

Q13. In competitive enzyme inhibition, what happens to Km and Vmax?

A) Km increases, Vmax unchanged B) Km unchanged, Vmax decreases C) Both increase D) Both decrease

Answer: A) Km increases, Vmax unchanged. Competitive inhibitors compete with substrate at the active site, so more substrate can still reach Vmax, but a higher concentration is needed.

Q14. Which LDH isoenzyme is classically elevated after a myocardial infarction?

A) LDH5 B) LDH1 C) LDH3 D) LDH4

Answer: B) LDH1. LDH1 is the predominant isoenzyme in cardiac muscle and rises after myocardial injury.

Vitamins and Deficiency Disorders

Q15. Deficiency of which vitamin causes beriberi?

A) Vitamin B1 (Thiamine) B) Vitamin B2 (Riboflavin) C) Vitamin B3 (Niacin) D) Vitamin B6 (Pyridoxine)

Answer: A) Vitamin B1 (Thiamine). Thiamine is essential for carbohydrate metabolism, and its deficiency causes beriberi and Wernicke-Korsakoff syndrome.

Q16. Which vitamin is required for carboxylation of clotting factors II, VII, IX, and X?

A) Vitamin A B) Vitamin K C) Vitamin D D) Vitamin E

Answer: B) Vitamin K. Vitamin K acts as a cofactor for the gamma-carboxylation of glutamate residues on these clotting factors.

Q17. Deficiency of Vitamin B12 typically causes which type of anaemia?

A) Microcytic anaemia B) Megaloblastic anaemia C) Haemolytic anaemia D) Aplastic anaemia

Answer: B) Megaloblastic anaemia. B12 deficiency impairs DNA synthesis in red cell precursors, producing large, immature megaloblasts.

Molecular Biology

Q18. Who demonstrated that DNA replication is semi-conservative?

A) Watson and Crick B) Meselson and Stahl C) Okazaki D) Kornberg

Answer: B) Meselson and Stahl. Their classic experiment using labelled nitrogen isotopes confirmed the semi-conservative model of DNA replication.

Q19. Which enzyme unwinds the DNA double helix during replication?

A) DNA polymerase B) Helicase C) Ligase D) Primase

Answer: B) Helicase. Helicase breaks the hydrogen bonds between base pairs, unwinding the double helix ahead of the replication fork.

Q20. The genetic code is described as degenerate. What does this mean?

A) Some amino acids have no codon B) More than one codon can code for the same amino acid C) The code differs between species D) Codons overlap each other

Answer: B) More than one codon can code for the same amino acid. This redundancy helps protect against the effects of certain point mutations.

How to Use These NEET PG Biochemistry MCQs

Don't jump straight to the answer. Attempt each question on your own first, then check. This is the part that actually create recall for exam day. Do not do passive reading.

If you get one wrong, go back to that topic in your book. Don't just memorise the correct option and move on. Look at why the other three options are wrong as well. NEET PG likes to rephrase the same concept in a different way the next time, so understanding the "why" protects you from getting tricked later.

Once you've been through all 20, revisit them again after a few days instead of filing them away. Spaced revision beats a single read-through by a wide margin. Pair this set with full previous year papers to understand how the exam sets its questions; our NEET PG question paper page has year-wise papers with solutions. When you're ready for timed, full-length practice, try the NEET PG mock test.