Can you create MCQs in this way that I can solve the Mcqs and check how much I have prepare
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I have enough solid textbook material. Let me now generate your full set of 25 mixed-difficulty Biochemistry MCQs across all major topics.
๐งช Biochemistry MCQ Quiz โ 25 Questions (Mixed Difficulty)
Instructions: All questions are listed below. Try to answer all 25 before scrolling down to the answer key at the bottom. Good luck!
SECTION A โ Carbohydrate Metabolism (Q1โ6)
Q1. During glycolysis, which enzyme catalyzes the irreversible phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate?
- A) Phosphoglucose isomerase
- B) Phosphofructokinase-1 (PFK-1)
- C) Pyruvate kinase
- D) Hexokinase
Q2. A red blood cell (RBC) lacks mitochondria. What is the fate of pyruvate produced during glycolysis in an RBC?
- A) Enters the TCA cycle
- B) Undergoes transamination to alanine
- C) Reduced to lactate by lactate dehydrogenase
- D) Converted to acetyl-CoA by pyruvate dehydrogenase
Q3. The enzyme pyruvate dehydrogenase complex requires all of the following coenzymes EXCEPT:
- A) Thiamine pyrophosphate (TPP)
- B) Lipoic acid
- C) Pyridoxal phosphate (PLP)
- D) CoA and FAD
Q4. In the TCA cycle, which step produces GTP directly (substrate-level phosphorylation)?
- A) Isocitrate โ alpha-ketoglutarate
- B) Succinyl-CoA โ succinate
- C) Malate โ oxaloacetate
- D) Fumarate โ malate
Q5. Glycogen phosphorylase cleaves glycogen by:
- A) Hydrolysis, releasing glucose-1-phosphate
- B) Phosphorolysis, releasing glucose-1-phosphate
- C) Phosphorolysis, releasing glucose-6-phosphate
- D) Hydrolysis, releasing free glucose
Q6. Which of the following is the rate-limiting enzyme of the pentose phosphate pathway?
- A) Transketolase
- B) Glucose-6-phosphate dehydrogenase (G6PD)
- C) 6-Phosphogluconate dehydrogenase
- D) Ribulose-5-phosphate epimerase
SECTION B โ Lipid Metabolism (Q7โ11)
Q7. Beta-oxidation of a saturated 18-carbon fatty acid (stearic acid) produces how many acetyl-CoA molecules?
- A) 8
- B) 9
- C) 10
- D) 6
Q8. Which lipoprotein is responsible for delivering dietary (exogenous) triglycerides from the intestine to peripheral tissues?
- A) VLDL
- B) IDL
- C) Chylomicrons
- D) HDL
Q9. Malonyl-CoA, the first committed intermediate of fatty acid synthesis, is produced by:
- A) Fatty acid synthase
- B) Acetyl-CoA carboxylase
- C) ATP-citrate lyase
- D) Malic enzyme
Q10. HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis, catalyzes which reaction?
- A) Acetyl-CoA โ HMG-CoA
- B) HMG-CoA โ Mevalonate
- C) Mevalonate โ Squalene
- D) Squalene โ Cholesterol
Q11. A patient with abdominal pain, eruptive xanthomas, and markedly elevated triglycerides is found to have absent lipoprotein lipase activity. Which condition does this represent?
- A) Type IIa familial hypercholesterolemia
- B) Type I hyperlipoproteinemia
- C) Tangier disease
- D) Abetalipoproteinemia
SECTION C โ Proteins & Amino Acid Metabolism (Q12โ16)
Q12. Phenylketonuria (PKU) results from a deficiency of which enzyme?
- A) Tyrosinase
- B) Homogentisate oxidase
- C) Phenylalanine hydroxylase
- D) Fumarylacetoacetate hydrolase
Q13. Which amino acid serves as the major carrier of nitrogen from peripheral tissues to the liver?
- A) Glutamine
- B) Alanine
- C) Glycine
- D) Aspartate
Q14. The urea cycle takes place in which cellular compartments?
- A) Cytoplasm only
- B) Mitochondria only
- C) Both mitochondria and cytoplasm
- D) Endoplasmic reticulum and mitochondria
Q15. Which vitamin is required as a coenzyme for all transamination reactions?
- A) Thiamine (B1)
- B) Riboflavin (B2)
- C) Pyridoxine (B6) as PLP
- D) Cobalamin (B12)
Q16. Maple syrup urine disease (MSUD) is caused by a defect in the metabolism of which amino acids?
- A) Phenylalanine, tyrosine, tryptophan
- B) Leucine, isoleucine, valine (branched-chain amino acids)
- C) Lysine, arginine, histidine
- D) Methionine, cysteine, homocysteine
SECTION D โ Enzymes & Molecular Biology (Q17โ20)
Q17. A competitive inhibitor of an enzyme:
- A) Increases Km and decreases Vmax
- B) Decreases Km and has no effect on Vmax
- C) Increases Km but does not change Vmax
- D) Decreases Vmax but does not change Km
Q18. DNA replication is described as "semi-conservative." This means:
- A) Each new DNA molecule contains two newly synthesized strands
- B) Each new DNA molecule contains one original and one new strand
- C) Only half the genome is replicated at a time
- D) Replication occurs only in the S phase of meiosis
Q19. Which enzyme removes the RNA primer during DNA replication in eukaryotes?
- A) DNA polymerase delta (ฮด)
- B) RNase H / DNA polymerase alpha
- C) Primase
- D) Topoisomerase II
Q20. The Shine-Dalgarno sequence is found in:
- A) Eukaryotic mRNA, upstream of the start codon
- B) Prokaryotic mRNA, upstream of the start codon
- C) The 5' cap structure of eukaryotic mRNA
- D) tRNA at the anticodon loop
SECTION E โ Vitamins, Minerals & Miscellaneous (Q21โ25)
Q21. A strict vegan presents with megaloblastic anemia, elevated homocysteine, and normal methylmalonic acid levels. Which deficiency is most likely?
- A) Vitamin B12 (cobalamin)
- B) Folate
- C) Iron
- D) Vitamin B6
Q22. Wernicke-Korsakoff syndrome, seen in chronic alcoholics, is caused by deficiency of which vitamin?
- A) Niacin (B3)
- B) Thiamine (B1)
- C) Pyridoxine (B6)
- D) Biotin
Q23. Which of the following correctly pairs a nucleotide base with its type?
- A) Adenine - pyrimidine
- B) Thymine - purine
- C) Guanine - purine
- D) Cytosine - purine
Q24. Scurvy occurs due to a deficiency of Vitamin C (ascorbic acid). The primary biochemical defect is the failure to:
- A) Synthesize clotting factors II, VII, IX, X
- B) Hydroxylate proline and lysine residues in collagen
- C) Absorb dietary iron from the duodenum
- D) Produce NADPH via the pentose phosphate pathway
Q25. A patient's urine turns dark brown/black on standing. Homogentisic acid is found in the urine. What is the enzyme deficiency?
- A) Phenylalanine hydroxylase
- B) Tyrosinase
- C) Homogentisate oxidase (dioxygenase)
- D) Fumarylacetoacetate hydrolase
โ STOP HERE - Write down your answers before scrolling to the answer key below!
โ ANSWER KEY WITH EXPLANATIONS
| Q# | Answer | Topic |
|---|---|---|
| 1 | B | Carbohydrate metabolism |
| 2 | C | Carbohydrate metabolism |
| 3 | C | Carbohydrate metabolism |
| 4 | B | TCA cycle |
| 5 | B | Glycogen metabolism |
| 6 | B | Pentose phosphate pathway |
| 7 | B | Lipid - beta oxidation |
| 8 | C | Lipoprotein metabolism |
| 9 | B | Fatty acid synthesis |
| 10 | B | Cholesterol synthesis |
| 11 | B | Hyperlipoproteinemia |
| 12 | C | Amino acid metabolism |
| 13 | B | Amino acid / nitrogen transport |
| 14 | C | Urea cycle |
| 15 | C | Coenzymes |
| 16 | B | Inborn errors of metabolism |
| 17 | C | Enzyme kinetics |
| 18 | B | Molecular biology - DNA |
| 19 | B | DNA replication |
| 20 | B | Translation |
| 21 | B | Vitamins |
| 22 | B | Vitamins |
| 23 | C | Nucleotide chemistry |
| 24 | B | Vitamins |
| 25 | C | Amino acid metabolism |
Detailed Explanations
Q1 - B: PFK-1 catalyzes the irreversible phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate. It is the rate-limiting enzyme of glycolysis and is regulated by AMP (activates) and ATP/citrate (inhibit).
Q2 - C: RBCs lack mitochondria, so pyruvate cannot enter the TCA cycle. Lactate dehydrogenase reduces pyruvate to lactate while regenerating NAD+, allowing glycolysis to continue (anaerobic glycolysis).
Q3 - C: Pyruvate dehydrogenase complex requires TPP (B1), lipoic acid, CoA (B5), FAD (B2), and NAD (B3). PLP (B6) is NOT required - it is needed for transamination reactions.
Q4 - B: The succinyl-CoA synthetase step (Succinyl-CoA โ succinate) directly produces GTP by substrate-level phosphorylation, the only such step in the TCA cycle.
Q5 - B: Glycogen phosphorylase uses phosphorolysis (adds inorganic phosphate Pi, not water) to cleave the alpha-1,4-glycosidic bond, releasing glucose-1-phosphate. This keeps glucose phosphorylated inside the cell.
Q6 - B: G6PD is the rate-limiting enzyme of the pentose phosphate pathway. G6PD deficiency is the most common enzyme deficiency worldwide and causes hemolytic anemia with oxidant stress.
Q7 - B: An 18-carbon saturated fatty acid undergoes 8 cycles of beta-oxidation, producing 9 acetyl-CoA molecules (one extra from the last cycle which produces 2 acetyl-CoA simultaneously).
Q8 - C: Chylomicrons transport dietary (exogenous) lipids from the intestinal enterocytes via the lymphatics to peripheral tissues. VLDL transports endogenous lipids from the liver.
Q9 - B: Acetyl-CoA carboxylase (requires biotin) catalyzes the carboxylation of acetyl-CoA to malonyl-CoA. This is the rate-limiting, committed step of fatty acid synthesis. Malonyl-CoA also inhibits carnitine acyltransferase-I, preventing simultaneous beta-oxidation.
Q10 - B: HMG-CoA reductase converts HMG-CoA โ Mevalonate using 2 NADPH. This is the target of statins (competitive inhibitors), which lower cholesterol synthesis.
Q11 - B: Absent lipoprotein lipase leads to inability to hydrolyze chylomicron triglycerides, causing massive hypertriglyceridemia. This is Type I hyperlipoproteinemia (familial lipoprotein lipase deficiency).
Q12 - C: PKU is caused by deficiency of phenylalanine hydroxylase, which converts phenylalanine โ tyrosine. This requires tetrahydrobiopterin (BH4) as a cofactor.
Q13 - B: Alanine is the primary carrier of nitrogen from muscle to liver (glucose-alanine cycle). Glutamine carries nitrogen from most other peripheral tissues to the kidney and liver.
Q14 - C: The urea cycle spans both compartments. Carbamoyl phosphate synthesis and citrulline production occur in the mitochondria, while argininosuccinate synthesis and the final steps occur in the cytoplasm.
Q15 - C: PLP (pyridoxal phosphate), the active form of B6, is the coenzyme for all aminotransferases (transaminases), including AST and ALT.
Q16 - B: MSUD results from a defect in the branched-chain alpha-keto acid dehydrogenase complex, which metabolizes the keto-acids derived from leucine, isoleucine, and valine.
Q17 - C: A competitive inhibitor competes with the substrate for the active site. It increases apparent Km (reduced affinity) but Vmax is unchanged because it can be overcome with high substrate concentrations.
Q18 - B: Semi-conservative replication means each daughter DNA molecule contains one parental strand and one newly synthesized strand. Proven by Meselson-Stahl experiment.
Q19 - B: In eukaryotes, RNA primers are removed by RNase H and DNA polymerase delta/epsilon. DNA pol alpha (with primase) lays down the initial RNA primer.
Q20 - B: The Shine-Dalgarno sequence is a prokaryotic ribosome binding site on mRNA, located ~10 nucleotides upstream of the AUG start codon. It base-pairs with the 16S rRNA of the 30S subunit.
Q21 - B: Elevated homocysteine occurs in BOTH B12 and folate deficiency. However, elevated methylmalonic acid (MMA) is specific to B12 deficiency (needed for methylmalonyl-CoA mutase). Normal MMA + elevated homocysteine = folate deficiency.
Q22 - B: Thiamine (B1) deficiency in alcoholics causes Wernicke encephalopathy (confusion, ophthalmoplegia, ataxia) and Korsakoff psychosis (confabulation, amnesia). Thiamine is required by pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and transketolase.
Q23 - C: Purines = Adenine and Guanine ("PuRines are larger - the R stands for Ring-within-a-ring"). Pyrimidines = Cytosine, Thymine, Uracil ("CUT the PY").
Q24 - B: Vitamin C is required for the hydroxylation of proline and lysine by prolyl and lysyl hydroxylase in collagen synthesis. Without it, collagen triple-helix formation is defective, causing the clinical features of scurvy (bleeding gums, perifollicular hemorrhage, poor wound healing).
Q25 - C: Dark urine on standing + homogentisic aciduria = Alkaptonuria, caused by deficiency of homogentisate oxidase (dioxygenase). This leads to accumulation of homogentisic acid (an intermediate in phenylalanine/tyrosine catabolism).
๐ Score Yourself
| Score | Assessment |
|---|---|
| 23โ25 | Excellent - Well prepared! |
| 18โ22 | Good - Review weak areas |
| 12โ17 | Fair - Need focused revision |
| Below 12 | Needs significant review |
How did you do? Let me know your score, and I can generate another set focused on your weak areas, or cover a specific topic in more depth!
Can you create in a clock able format bcz I want I solve the Mcqs and click option 2 if it is correct then u give the correct answer with short explanation
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biochem mcq quiz
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What's included in the quiz:
| Feature | Details |
|---|---|
| 25 MCQs | All Biochemistry topics, mixed difficulty |
| Countdown Timer | 90 seconds per question - turns orange at 25s, red + pulsing at 10s |
| Instant Feedback | Click an option - green = correct โ , red = wrong โ |
| Correct answer revealed | If you pick wrong, the correct answer lights up green automatically |
| Short explanation | Appears immediately after every click |
| Live score tracker | Top-right updates after each question |
| Progress bar | Shows % completed at the top |
| Final results screen | Shows score, time taken, grade, and full question review |
| Restart button | Try again from the beginning |
How to use it: Download the file โ open it in Chrome/Firefox/Edge โ no internet needed, it runs fully offline!
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