Introduction to primary metabolites MCQs With Answer

Introduction to primary metabolites MCQs With Answer
In this concise introduction, B. Pharm students will review primary metabolites — essential small molecules such as carbohydrates, proteins, lipids, nucleic acids and amino acids that participate directly in growth, development and basic cellular metabolism. Understanding metabolic pathways, biosynthesis routes, regulation and physiological roles of primary metabolites is vital for pharmacology, drug formulation, biopharmaceutics and biotechnology. This topic covers central metabolism, energy flow, precursor roles in secondary metabolite production, and analytical identification techniques often relevant for quality control. Mastery of primary metabolites helps in grasping drug–metabolite interactions, enzyme targets and formulation stability. Clear conceptual knowledge supports exam success and professional practice. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which of the following is NOT considered a primary metabolite?

• Glucose
• Amino acids
• Antibiotic produced by bacteria
• Ribosomal RNA

Correct Answer: Antibiotic produced by bacteria

Q2. Primary metabolites are primarily involved in which cellular functions?

• Cell growth, energy production and basic metabolism
• Defense against predators
• Secondary signaling for quorum sensing only
• External environmental sensing exclusively

Correct Answer: Cell growth, energy production and basic metabolism

Q3. Which metabolic pathway is the central route for glucose catabolism and provides precursors for many primary metabolites?

• Glycolysis
• Shikimate pathway
• Polyketide synthesis
• Methylerythritol phosphate (MEP) pathway

Correct Answer: Glycolysis

Q4. Which compound is the common two‑carbon donor used in fatty acid biosynthesis?

• Oxaloacetate
• Acetyl‑CoA
• Succinyl‑CoA
• Phosphoenolpyruvate

Correct Answer: Acetyl‑CoA

Q5. Which of the following amino acids is strictly ketogenic?

• Leucine
• Alanine
• Glutamate
• Serine

Correct Answer: Leucine

Q6. Which primary metabolite pool directly supplies nucleotides for DNA and RNA synthesis?

• Carbohydrate pool via glycolytic intermediates and pentose phosphate pathway
• Lipid pool via beta‑oxidation
• Secondary metabolite pool
• Extracellular matrix proteins

Correct Answer: Carbohydrate pool via glycolytic intermediates and pentose phosphate pathway

Q7. The pentose phosphate pathway is especially important because it generates:

• NADPH and ribose‑5‑phosphate
• ATP and acetyl‑CoA
• FADH2 and CO2
• Urea and ammonia

Correct Answer: NADPH and ribose‑5‑phosphate

Q8. Which primary metabolite class includes cholesterol and triglycerides?

• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

Correct Answer: Lipids

Q9. Essential amino acids must be obtained from the diet because:

• Humans lack pathways to synthesize them de novo
• They are toxic if synthesized endogenously
• They are only produced by gut microbiota
• They are only needed in early development

Correct Answer: Humans lack pathways to synthesize them de novo

Q10. Which enzyme catalyzes the committed step of glycolysis?

• Hexokinase
• Phosphofructokinase‑1 (PFK‑1)
• Pyruvate kinase
• Glucose‑6‑phosphate isomerase

Correct Answer: Phosphofructokinase‑1 (PFK‑1)

Q11. Transamination reactions in amino acid metabolism require which coenzyme?

• NAD+
• Pyridoxal phosphate (PLP)
• Coenzyme A
• Biotin

Correct Answer: Pyridoxal phosphate (PLP)

Q12. Which primary metabolite is the immediate product of photosynthetic carbon fixation in plants?

• Sucrose
• 3‑Phosphoglycerate (3‑PG)
• Acetyl‑CoA
• Ribulose‑1,5‑bisphosphate

Correct Answer: 3‑Phosphoglycerate (3‑PG)

Q13. Which class of primary metabolites provides structural components like cellulose and chitin?

• Proteins
• Carbohydrates (polysaccharides)
• Lipids
• Nucleotides

Correct Answer: Carbohydrates (polysaccharides)

Q14. Which metabolite is the major nitrogen carrier in mammals for safe transport to the liver?

• Ammonia
• Alanine and glutamine
• Urea
• Nitrite

Correct Answer: Alanine and glutamine

Q15. Which pathway provides erythrose‑4‑phosphate and phosphoenolpyruvate for aromatic amino acid biosynthesis in microbes?

• Glycolysis alone
• Shikimate pathway precursors from pentose phosphate and glycolysis
• Beta‑oxidation
• Urea cycle

Correct Answer: Shikimate pathway precursors from pentose phosphate and glycolysis

Q16. Which primary metabolite acts as a universal energy currency in the cell?

• NADH
• ATP
• Glucose
• Oxygen

Correct Answer: ATP

Q17. Which laboratory method is commonly used to separate and quantify primary metabolites like amino acids and sugars?

• Gel electrophoresis for DNA only
• Chromatography (HPLC, GC) with appropriate detectors
• Southern blotting
• X‑ray crystallography

Correct Answer: Chromatography (HPLC, GC) with appropriate detectors

Q18. Glucogenic amino acids are those that can be converted into:

• Ketone bodies only
• Glucose via gluconeogenesis intermediates
• Fatty acids directly without modification
• Urea directly

Correct Answer: Glucose via gluconeogenesis intermediates

Q19. Beta‑oxidation of fatty acids occurs primarily in which cellular compartment?

• Cytosol
• Mitochondrial matrix
• Endoplasmic reticulum lumen
• Golgi apparatus

Correct Answer: Mitochondrial matrix

Q20. Which primary metabolite is a key precursor for nucleotide biosynthesis and is produced via the pentose phosphate pathway?

• Fructose‑6‑phosphate
• Ribose‑5‑phosphate
• Lactate
• Citrate

Correct Answer: Ribose‑5‑phosphate

Q21. Which cofactor is essential for carboxylation reactions such as pyruvate carboxylase activity?

• Thiamine pyrophosphate (TPP)
• Biotin
• NADP+
• FAD

Correct Answer: Biotin

Q22. Which metabolite accumulates during anaerobic glycolysis in muscle?

• Acetyl‑CoA
• Lactate
• Oxaloacetate
• Fructose‑1,6‑bisphosphate

Correct Answer: Lactate

Q23. Which enzyme links glycolysis to the Krebs cycle by converting pyruvate to acetyl‑CoA?

• Pyruvate carboxylase
• Pyruvate dehydrogenase complex
• Pyruvate kinase
• Lactate dehydrogenase

Correct Answer: Pyruvate dehydrogenase complex

Q24. Which primary metabolite is directly used as an osmoregulator and compatible solute in many microorganisms?

• Sucrose
• Trehalose and proline
• Cholesterol
• Deoxyribonucleic acid

Correct Answer: Trehalose and proline

Q25. Which vitamin is a precursor for NAD+ and NADP+ cofactors important in primary metabolism?

• Niacin (vitamin B3)
• Vitamin C
• Vitamin D
• Vitamin K

Correct Answer: Niacin (vitamin B3)

Q26. In amino acid biosynthesis, feedback inhibition typically controls which feature?

• Transport of amino acids only
• Activity of the first committed enzyme of the pathway
• mRNA transcription only without affecting enzymes
• Protein folding exclusively

Correct Answer: Activity of the first committed enzyme of the pathway

Q27. Which metabolite is anaplerotic when converted to oxaloacetate to replenish TCA cycle intermediates?

• Acetyl‑CoA
• Pyruvate carboxylation product from pyruvate
• Lactate only
• Cholesterol

Correct Answer: Pyruvate carboxylation product from pyruvate

Q28. Which analytical tracer technique is commonly used to follow primary metabolite fluxes in metabolism studies?

• Radiolabeled or stable isotope (13C) labeling with MS/NMR analysis
• Fluorescent protein tagging exclusively
• Southern blotting
• ELISA for DNA

Correct Answer: Radiolabeled or stable isotope (13C) labeling with MS/NMR analysis

Q29. Which of the following is a common precursor for both cholesterol and certain isoprenoids?

• Methylmalonyl‑CoA
• Acetyl‑CoA via mevalonate pathway
• Ribose‑5‑phosphate
• Sedoheptulose‑7‑phosphate

Correct Answer: Acetyl‑CoA via mevalonate pathway

Q30. Why is understanding primary metabolite pathways important for drug development and B. Pharm practice?

• They determine formulation color only
• They inform drug metabolism, enzyme targets, precursor supply and toxicity risks
• They are irrelevant to pharmacokinetics
• They only apply to plant biology and not pharmaceuticals

Correct Answer: They inform drug metabolism, enzyme targets, precursor supply and toxicity risks

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com