Phytochemistry studies plant chemicals—their structures, biosynthesis, extraction, analysis, and pharmacological relevance. This concise MCQ set focuses on basics of phytochemistry for B.Pharm students, covering secondary metabolites such as alkaloids, glycosides, flavonoids, terpenes, phenolics and saponins; biosynthetic pathways (shikimate, acetate-mevalonate, MEP); qualitative tests and chromatographic and spectroscopic methods (TLC, HPLC, GC, UV, MS); extraction techniques and factors affecting stability and standardization. Questions emphasize identification, functional groups, screening reagents, and analytical interpretation to strengthen applied knowledge for pharmacognosy, formulation, and quality control. Clear explanations and keyword-rich content help exam prep and practical understanding. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary classification criterion for secondary metabolites in phytochemistry?
- Chemical structure and biosynthetic origin
- Color of plant extract
- Plant height and habitat
- Harvesting season
Correct Answer: Chemical structure and biosynthetic origin
Q2. Which biosynthetic pathway is mainly responsible for aromatic amino acids and many phenolic compounds?
- Shikimate pathway
- Mevalonate pathway
- Beta-oxidation pathway
- Glycolysis
Correct Answer: Shikimate pathway
Q3. Which class of phytochemicals is characterized by a C6–C3–C6 skeleton?
- Flavonoids
- Terpenes
- Alkaloids
- Saponins
Correct Answer: Flavonoids
Q4. Which reagent is commonly used for the qualitative detection of alkaloids?
- Mayer’s reagent
- Ferric chloride
- Bornträger’s reagent
- Salkowski’s reagent
Correct Answer: Mayer’s reagent
Q5. Which test gives a green or blue color with phenolic compounds?
- Ferric chloride test
- Foam test
- Molisch’s test
- Keller-Kiliani test
Correct Answer: Ferric chloride test
Q6. Which secondary metabolite group is biosynthesized via the mevalonate (MVA) and MEP pathways?
- Terpenoids
- Alkaloids
- Flavonoids
- Tannins
Correct Answer: Terpenoids
Q7. What is the distinguishing structural feature of alkaloids?
- Presence of nitrogen atom, often in heterocyclic form
- Polyphenolic rings without nitrogen
- Long aliphatic chains with ester linkages
- Multiple sugar moieties attached
Correct Answer: Presence of nitrogen atom, often in heterocyclic form
Q8. Which extraction technique is best for continuous hot extraction of plant material in a laboratory?
- Soxhlet extraction
- Maceration at room temperature
- Cold percolation
- Supercritical CO2 extraction without heat
Correct Answer: Soxhlet extraction
Q9. Which chromatographic technique is most commonly used for rapid fingerprinting of herbal extracts in pharmacognosy labs?
- Thin layer chromatography (TLC)
- Gas chromatography with no derivatization
- Gel permeation chromatography
- Paper chromatography
Correct Answer: Thin layer chromatography (TLC)
Q10. Which compound is an example of a cardiac glycoside used as a marker in standardization?
- Digitoxin
- Quercetin
- Menthol
- Gallic acid
Correct Answer: Digitoxin
Q11. The foam test is used for preliminary detection of which class of phytochemicals?
- Saponins
- Tannins
- Alkaloids
- Flavonoids
Correct Answer: Saponins
Q12. Which analytical method is preferred for volatile essential oil profiling?
- Gas chromatography-mass spectrometry (GC-MS)
- High performance liquid chromatography (HPLC)
- UV-Visible spectrophotometry
- Polarimetry
Correct Answer: Gas chromatography-mass spectrometry (GC-MS)
Q13. What structural unit defines monoterpenes?
- Two isoprene units (C10)
- Three isoprene units (C15)
- Four isoprene units (C20)
- One isoprene unit (C5)
Correct Answer: Two isoprene units (C10)
Q14. Bornträger’s test is used to detect which group of compounds?
- Anthraquinone glycosides
- Cardiac glycosides
- Alkaloids
- Saponins
Correct Answer: Anthraquinone glycosides
Q15. Which compound is a common flavonoid used as an analytical reference standard?
- Quercetin
- Caffeine
- Saponin
- Digitonin
Correct Answer: Quercetin
Q16. Which test detects steroidal compounds by producing a red/pink or green color with concentrated sulfuric acid?
- Liebermann-Burchard test
- Dragendorff’s test
- Mayer’s test
- Fehling’s test
Correct Answer: Liebermann-Burchard test
Q17. What is the primary consequence of prolonged exposure of phytochemicals to light and heat?
- Degradation and loss of potency
- Polymerization into beneficial pigments
- Increased solubility in water
- Formation of stable glycosides
Correct Answer: Degradation and loss of potency
Q18. Which method is quantitative and widely used for assay of marker compounds in herbal formulations?
- HPLC (High Performance Liquid Chromatography)
- Simple TLC visualization
- Color change by spot test only
- Drying and weighing the crude extract
Correct Answer: HPLC (High Performance Liquid Chromatography)
Q19. Which phytochemical class commonly forms complexes with proteins and precipitates them, contributing to astringency?
- Tannins
- Saponins
- Terpenes
- Alkaloids
Correct Answer: Tannins
Q20. The Keller-Kiliani test is diagnostic for which group of glycosides?
- Cardiac glycosides (deoxy sugars)
- Anthraquinone glycosides
- Cyanogenic glycosides
- Flavonoid glycosides
Correct Answer: Cardiac glycosides (deoxy sugars)
Q21. Which of the following is a common phenolic acid used as an internal standard in phytochemical studies?
- Gallic acid
- Citric acid
- Acetic acid
- Lactic acid
Correct Answer: Gallic acid
Q22. Which pathway contributes to formation of isoprenoid precursors like IPP and DMAPP in plastids?
- MEP (non-mevalonate) pathway
- Shikimate pathway
- Glyoxylate pathway
- Urea cycle
Correct Answer: MEP (non-mevalonate) pathway
Q23. Which qualitative test is used to detect reducing sugars in a plant extract?
- Fehling’s or Benedict’s test
- Dragendorff’s test
- Liebermann-Burchard test
- Mayer’s test
Correct Answer: Fehling’s or Benedict’s test
Q24. Cyanogenic glycosides release which toxic compound upon hydrolysis?
- Hydrogen cyanide (HCN)
- Carbon monoxide
- Nitrous oxide
- Methane
Correct Answer: Hydrogen cyanide (HCN)
Q25. Which solvent polarity is generally best for extracting polar glycosides from plant material?
- Hydroalcoholic (water–ethanol) solvent
- Pure hexane
- Pure chloroform
- Neat diethyl ether
Correct Answer: Hydroalcoholic (water–ethanol) solvent
Q26. Which spectral technique provides information about molecular weight and fragmentation pattern of phytoconstituents?
- Mass spectrometry (MS)
- Infrared spectroscopy only
- Polarimetry
- Colorimetric spot tests
Correct Answer: Mass spectrometry (MS)
Q27. Which statement correctly contrasts hydrolyzable and condensed tannins?
- Hydrolyzable tannins yield sugars and phenolic acids on hydrolysis; condensed tannins are polymeric flavonoids
- Hydrolyzable tannins are polymers of flavonoid units; condensed tannins yield gallic acid
- Both types are identical chemically and only differ in solubility
- Condensed tannins always contain nitrogen in the structure
Correct Answer: Hydrolyzable tannins yield sugars and phenolic acids on hydrolysis; condensed tannins are polymeric flavonoids
Q28. Which phytochemical is the major volatile component of peppermint oil used in inhalants and topical rubs?
- Menthol
- Quinine
- Saponin
- Digitoxin
Correct Answer: Menthol
Q29. In TLC, which factor primarily influences Rf values of phytochemicals?
- Polarity of solute and mobile phase interaction with stationary phase
- Color of the compound only
- pH of the detection reagent only
- Size of the TLC plate alone
Correct Answer: Polarity of solute and mobile phase interaction with stationary phase
Q30. Which practice is essential for herbal product standardization and quality control?
- Use of marker compounds, chromatographic fingerprints, and validated assays
- Relying solely on organoleptic evaluation
- Using random harvests without documentation
- Avoiding quantitative assays to save cost
Correct Answer: Use of marker compounds, chromatographic fingerprints, and validated assays
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