Analysis of phytoconstituents MCQs With Answer is an essential study area for B. Pharm students focused on phytochemistry, pharmacognosy, and natural product analysis. This introduction covers phytoconstituents such as alkaloids, flavonoids, terpenoids, glycosides, tannins and saponins, and highlights extraction techniques, qualitative tests, chromatographic methods (TLC, HPLC, GC), spectroscopic identification, and structure–activity relationships important for drug discovery and quality control. Emphasis on bioactivity, solubility, and standardization prepares students for practical lab work and research. These keyword-rich concepts strengthen understanding of plant-derived therapeutics, analytical strategy, and regulatory aspects critical to pharmaceutical sciences.
‘Now let’s test your knowledge with 30 MCQs on this topic.’
Q1. Which class of phytoconstituents is typically basic, contains nitrogen, and often shows pharmacological activity?
- Alkaloids
- Flavonoids
- Terpenoids
- Tannins
Correct Answer: Alkaloids
Q2. Which chromatographic technique is most commonly used for preliminary fingerprinting of plant extracts in pharmacognosy labs?
- Gas chromatography (GC)
- Thin layer chromatography (TLC)
- High performance liquid chromatography (HPLC)
- Capillary electrophoresis (CE)
Correct Answer: Thin layer chromatography (TLC)
Q3. Which biosynthetic pathway is primarily responsible for the formation of aromatic amino acids and many phenolic phytoconstituents?
- Mevalonate pathway
- Shikimic acid pathway
- Methylerythritol phosphate (MEP) pathway
- Polyketide pathway
Correct Answer: Shikimic acid pathway
Q4. Which qualitative test is classically used to detect alkaloids in plant extracts?
- Shinoda test
- Dragendorff’s test
- Ferric chloride test
- Salkowski test
Correct Answer: Dragendorff’s test
Q5. Flavonoid glycosides differ from their aglycones mainly by which structural feature?
- Presence of a glycosidic sugar moiety
- Additional nitrogen atom
- Long aliphatic side chain
- Extra aromatic ring
Correct Answer: Presence of a glycosidic sugar moiety
Q6. Which solvent or solvent system is generally best for extracting polar glycosides from plant material?
- Hexane
- Methanol or aqueous methanol
- Chloroform
- Petroleum ether
Correct Answer: Methanol or aqueous methanol
Q7. In structure–activity relationship (SAR) studies of phytoconstituents, which modification commonly alters lipophilicity and membrane permeability?
- Changing aromaticity to aliphatic chain
- Glycosylation or deglycosylation
- Replacing hydrogen with deuterium
- Removing all double bonds
Correct Answer: Glycosylation or deglycosylation
Q8. Which phytochemical class is characterized by isoprene (C5) units and includes monoterpenes, sesquiterpenes, and diterpenes?
- Alkaloids
- Terpenoids
- Flavonoids
- Glycosides
Correct Answer: Terpenoids
Q9. Which spectroscopic technique is most informative for determining molecular weight and fragmentation pattern of a phytoconstituent?
- Infrared spectroscopy (IR)
- Mass spectrometry (MS)
- Ultraviolet-visible spectroscopy (UV-Vis)
- Polarimetry
Correct Answer: Mass spectrometry (MS)
Q10. Tannins are known for their protein-precipitating ability. Which class of tannins are hydrolyzable and yield phenolic acids on hydrolysis?
- Condensed tannins (proanthocyanidins)
- Hydrolyzable tannins
- Phlorotannins
- Lipid tannins
Correct Answer: Hydrolyzable tannins
Q11. Which reagent is commonly used in the Liebermann–Burchard reaction to test for steroids and triterpenoids?
- Bromine water
- Conc. sulfuric acid and acetic anhydride mixture
- Dragendorff’s reagent
- Ferric chloride
Correct Answer: Conc. sulfuric acid and acetic anhydride mixture
Q12. Which property best explains why many alkaloids are extracted into acidic aqueous solutions during isolation?
- They are nonpolar and lipophilic
- They form water-soluble salts under acidic conditions
- They undergo oxidation in acid
- They precipitate as free bases in acid
Correct Answer: They form water-soluble salts under acidic conditions
Q13. Which class of phytoconstituents commonly exhibits UV absorbance maxima around 250–280 nm and 340–380 nm due to conjugated aromatic systems?
- Saponins
- Flavonoids
- Carotenoids
- Alkaloids
Correct Answer: Flavonoids
Q14. HPLC-UV quantification of a flavonoid glycoside requires which critical step for accurate results?
- Using a nonpolar stationary phase only
- Validated method with appropriate standard and calibration
- Heating the column to 200 °C
- Derivatizing the sample with bromine
Correct Answer: Validated method with appropriate standard and calibration
Q15. Which phytochemical test indicates presence of phenolic hydroxyl groups by forming a colored complex with Fe3+?
- Dragendorff’s test
- Ferric chloride test
- Salkowski test
- Bornträger’s test
Correct Answer: Ferric chloride test
Q16. Saponins are known for their surfactant properties. What structural feature primarily imparts this property?
- Large aromatic rings
- Sugar moiety attached to a hydrophobic aglycone (glycoside nature)
- Multiple sulfate groups
- Presence of aliphatic amine groups
Correct Answer: Sugar moiety attached to a hydrophobic aglycone (glycoside nature)
Q17. Which compound class is typically detected by the Bornträger’s test after alkaline hydrolysis?
- Anthraquinones
- Steroids
- Terpenoids
- Alkaloids
Correct Answer: Anthraquinones
Q18. In HPTLC fingerprinting, which parameter is most important for reproducible Rf values?
- Ambient humidity alone
- Standardized mobile phase composition and plate development conditions
- Color of the sample
- Using any solvent system arbitrarily
Correct Answer: Standardized mobile phase composition and plate development conditions
Q19. Which phytoconstituent class often shows foam formation when shaken with water indicating its surface-active nature?
- Tannins
- Saponins
- Flavonoids
- Alkaloids
Correct Answer: Saponins
Q20. Which statement about glycosidic linkage in cardiac glycosides is correct?
- They always contain N-glycosidic linkages
- They commonly have O-glycosidic linkage between sugar and aglycone
- Glycosidic linkage is absent in cardiac glycosides
- They only have C-glycosidic linkages
Correct Answer: They commonly have O-glycosidic linkage between sugar and aglycone
Q21. Which analytical technique separates volatile phytochemicals and is often coupled with MS for identification?
- HPLC-UV
- Gas chromatography–mass spectrometry (GC-MS)
- TLC with visible light detection
- Polarimetry
Correct Answer: Gas chromatography–mass spectrometry (GC-MS)
Q22. Which structural feature is typical for flavones and flavonols?
- Isoquinoline nucleus
- Two aromatic rings joined by a three-carbon bridge forming a heterocyclic ring (C6–C3–C6)
- Linear polyisoprene chain
- Sugar polymer backbone
Correct Answer: Two aromatic rings joined by a three-carbon bridge forming a heterocyclic ring (C6–C3–C6)
Q23. Which parameter is most important when selecting solvents for successive extraction of plant material?
- Solvent color
- Polarity gradient from nonpolar to polar to fractionate compounds
- Boiling point only
- Solvent odour
Correct Answer: Polarity gradient from nonpolar to polar to fractionate compounds
Q24. Which phytoconstituent class is typically responsible for yellow-orange pigmentation and is fat-soluble?
- Anthraquinones
- Carotenoids
- Alkaloids
- Flavonoid glycosides
Correct Answer: Carotenoids
Q25. Which enzymatic process in plants commonly converts glycosides to more active aglycones?
- Hydrogenation
- Glycosidic hydrolysis by glycosidases
- Sulfation
- Phosphorylation
Correct Answer: Glycosidic hydrolysis by glycosidases
Q26. For regulatory quality control, which approach provides both identity and relative abundance information for complex herbal extracts?
- Single spot TLC only
- Chromatographic fingerprinting (e.g., HPLC or HPTLC fingerprint)
- Organoleptic evaluation only
- Microscopy alone
Correct Answer: Chromatographic fingerprinting (e.g., HPLC or HPTLC fingerprint)
Q27. Which reagent gives a positive Shinoda test indicating the presence of flavonoids?
- Magnesium turnings and concentrated hydrochloric acid
- Conc. sulfuric acid alone
- Dragendorff’s reagent
- Benedict’s reagent
Correct Answer: Magnesium turnings and concentrated hydrochloric acid
Q28. Which factor most influences the bioavailability of a plant-derived alkaloid after oral administration?
- Molar mass only
- pKa, lipophilicity, and first-pass metabolism
- Color of the extract
- Melting point only
Correct Answer: pKa, lipophilicity, and first-pass metabolism
Q29. Which phytoconstituent class often shows red or purple color with alkaline treatment in Bornträger’s test after extraction?
- Cardiac glycosides
- Anthraquinones
- Terpenoids
- Saponins
Correct Answer: Anthraquinones
Q30. Which analytical parameter should be validated for a quantitative HPLC method measuring a key phytoconstituent in a herbal formulation?
- Selectivity, linearity, accuracy, precision, and limits of detection/quantification
- Only column brand
- Only mobile phase color
- Temperature of the laboratory only
Correct Answer: Selectivity, linearity, accuracy, precision, and limits of detection/quantification
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