Chemo-taxonomical classification of drugs MCQs With Answer

Chemo-taxonomical classification of drugs MCQs With Answer

Chemo-taxonomical classification of drugs is the systematic grouping of medicines based on chemical structure, biosynthetic origin and functional groups. For B.Pharm students, understanding chemotaxonomy links chemical scaffolds to pharmacological behavior, structure–activity relationships, biosynthetic pathways and natural product origins. This concise, keyword-rich review emphasizes chemical classes (alkaloids, glycosides, steroids, beta-lactams, macrolides), analytical techniques (HPLC, MS, TLC), chemotypes and bioisosterism, which are essential for drug identification, lead discovery and rational modification. Answers and explanations emphasize structural markers, representative drug examples and clinical relevance to strengthen exam preparation. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary basis of chemo-taxonomical classification of drugs?

• Grouping by therapeutic use only
• Grouping by chemical structure and biosynthetic origin
• Grouping by manufacturing process
• Grouping by brand name

Correct Answer: Grouping by chemical structure and biosynthetic origin

Q2. Which technique is most commonly used for chemotaxonomic profiling and separation of drug constituents?

• Nuclear medicine imaging
• High-performance liquid chromatography (HPLC)
• Patch testing
• Electrocardiography

Correct Answer: High-performance liquid chromatography (HPLC)

Q3. In chemotaxonomy, what is a “chemotype”?

• A molecular weight measurement
• A genetic marker for drug metabolism
• A characteristic chemical profile of a species or variety
• A pharmacological receptor binding site

Correct Answer: A characteristic chemical profile of a species or variety

Q4. Which functional group is characteristic of alkaloids?

• Acidic carboxyl group
• Basic nitrogen atom
• Sulfhydryl group
• Polyene chain

Correct Answer: Basic nitrogen atom

Q5. Which of the following is a cardiac glycoside used as an example in chemo-taxonomical classification?

• Amoxicillin
• Digoxin
• Ibuprofen
• Metformin

Correct Answer: Digoxin

Q6. The beta-lactam antibiotics are defined by which core structural feature?

• A macrolide lactone ring of 14 atoms
• A four-membered beta-lactam ring
• A steroidal tetracyclic nucleus
• An aminoglycoside cyclitol ring

Correct Answer: A four-membered beta-lactam ring

Q7. Which structural feature distinguishes cephalosporins from penicillins?

• Presence of a macrolide lactone
• Fusion of a dihydrothiazine six-membered ring to the beta-lactam
• Lack of beta-lactam ring
• Presence of a steroid nucleus

Correct Answer: Fusion of a dihydrothiazine six-membered ring to the beta-lactam

Q8. Erythromycin is classified as which type of macrolide based on its lactone ring size?

• 12-membered macrolide
• 14-membered macrolide
• 16-membered macrolide
• 20-membered macrolide

Correct Answer: 14-membered macrolide

Q9. Tetracyclines are named for which core structural characteristic?

• Three aromatic rings
• Four fused hydrocarbon rings (tetracyclic naphthacene core)
• Single benzene ring with amide
• Large macrocyclic lactone

Correct Answer: Four fused hydrocarbon rings (tetracyclic naphthacene core)

Q10. Aminoglycoside antibiotics are characterized by what structural unit?

• A macrolide lactone
• An aminocyclitol ring linked to amino sugars
• A beta-lactam nucleus
• A steroidal aglycone

Correct Answer: An aminocyclitol ring linked to amino sugars

Q11. Which analytical method provides both separation and mass identification for chemotaxonomic studies?

• Thin layer chromatography alone
• HPLC coupled with mass spectrometry (HPLC-MS)
• Simple UV-Vis spectrophotometry
• Visual colorimetry

Correct Answer: HPLC coupled with mass spectrometry (HPLC-MS)

Q12. What is bioisosterism in medicinal chemistry and chemo-taxonomy?

• Replacement of a drug by an unrelated natural product
• Replacement of one atom or group by another to retain or improve biological activity
• Grouping drugs solely by therapeutic use
• Classification based on brand names

Correct Answer: Replacement of one atom or group by another to retain or improve biological activity

Q13. Which local anesthetic is classified as an amide rather than an ester?

• Procaine
• Cocaine
• Tetracaine
• Lidocaine

Correct Answer: Lidocaine

Q14. Cardiac glycosides are chemotaxonomically grouped by which two main structural components?

• Beta-lactam ring and N-substitution
• Steroid nucleus (aglycone) and sugar moiety (glycone)
• Amino sugar and peptide chain
• Polyene chain and sulfhydryl group

Correct Answer: Steroid nucleus (aglycone) and sugar moiety (glycone)

Q15. Which NSAID belongs to the propionic acid derivative class?

• Aspirin
• Diclofenac
• Ibuprofen
• Indomethacin

Correct Answer: Ibuprofen

Q16. Morphine is structurally classified as which type of alkaloid?

• Isoquinoline alkaloid
• Phenanthrene alkaloid
• Indole alkaloid
• Pyrrolidine alkaloid

Correct Answer: Phenanthrene alkaloid

Q17. Which group defines sulfonamide antibiotics structurally?

• Thiol group linked to aromatic ring
• Sulfonyl group attached to an amide nitrogen (–SO2–NH–)
• Beta-lactam ring
• Macrolide lactone

Correct Answer: Sulfonyl group attached to an amide nitrogen (–SO2–NH–)

Q18. Phenothiazine antipsychotics are recognized by what core scaffold?

• A macrolide lactone
• A tricyclic ring containing sulfur and nitrogen (phenothiazine nucleus)
• A steroidal tetracyclic nucleus
• An aminocyclitol core

Correct Answer: A tricyclic ring containing sulfur and nitrogen (phenothiazine nucleus)

Q19. Benzodiazepines possess which defining structural motif?

• A benzene ring fused to a seven-membered diazepine ring
• A macrolide 14-membered lactone
• A steroid nucleus with sugars
• An aminocyclitol linked to sugars

Correct Answer: A benzene ring fused to a seven-membered diazepine ring

Q20. In glycoside classification, what determines the subclass (e.g., cardiac glycoside vs. saponin)?

• The route of administration
• The nature and structure of the aglycone (non-sugar) part
• The color of the crude extract
• The melting point of the sugar only

Correct Answer: The nature and structure of the aglycone (non-sugar) part

Q21. Which anticancer antibiotic class is typified by a planar tetracyclic quinone nucleus with attached sugars?

• Macrolides
• Aminoglycosides
• Anthracyclines (e.g., doxorubicin)
• Beta-lactams

Correct Answer: Anthracyclines (e.g., doxorubicin)

Q22. The term “chemovar” in chemotaxonomy refers to:

• A chemical used in varicose vein treatment
• A variety of a species that differs in chemical composition
• A type of chromatography stationary phase
• A synthetic analog of a natural drug

Correct Answer: A variety of a species that differs in chemical composition

Q23. Which analgesic contains a phenolic hydroxyl group and is classified as a para-aminophenol derivative?

• Aspirin
• Paracetamol (acetaminophen)
• Ibuprofen
• Naproxen

Correct Answer: Paracetamol (acetaminophen)

Q24. Which of the following is an example of a sulfonylurea antidiabetic drug?

• Metformin
• Glibenclamide (glyburide)
• Insulin lispro
• Pioglitazone

Correct Answer: Glibenclamide (glyburide)

Q25. Which molecular modification is a common bioisosteric replacement to enhance metabolic stability?

• Replacing an aromatic ring with a carbohydrate
• Replacing hydrogen with fluorine on an aromatic ring
• Removing all heteroatoms
• Converting a carboxylate to metallic salt

Correct Answer: Replacing hydrogen with fluorine on an aromatic ring

Q26. Which antibiotic is a classic example of a first-generation cephalosporin?

• Ceftriaxone
• Cephalexin
• Imipenem
• Azithromycin

Correct Answer: Cephalexin

Q27. Which structural feature distinguishes cardiac cardenolides from bufadienolides?

• Cardenolides contain a five-membered unsaturated lactone ring, bufadienolides contain a six-membered pyrone
• Cardenolides lack sugar moieties while bufadienolides always have sugars
• Cardenolides are peptides and bufadienolides are steroids
• There is no structural difference

Correct Answer: Cardenolides contain a five-membered unsaturated lactone ring, bufadienolides contain a six-membered pyrone

Q28. Which structural class does fentanyl belong to among opioids?

• Phenanthrenes
• Phenylpiperidines
• Benzomorphans
• Alkaloid isoquinolines

Correct Answer: Phenylpiperidines

Q29. For chemotaxonomic marker identification in plant-derived drugs, which analytical approach is most informative?

• Simple boiling point measurement
• Chromatography combined with spectroscopic identification (e.g., HPLC-MS)
• Counting plant leaves visually
• Only measuring pH of extracts

Correct Answer: Chromatography combined with spectroscopic identification (e.g., HPLC-MS)

Q30. Why is chemo-taxonomical classification important in drug discovery?

• Only for legal classification of medicines
• It identifies chemical markers, biosynthetic relationships and structural leads for rational drug design
• It replaces clinical trials
• It only classifies drugs by price

Correct Answer: It identifies chemical markers, biosynthetic relationships and structural leads for rational drug design

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