Introduction: Quantitative microscopy of crude drugs is a key pharmacognosy skill for B. Pharm students, combining microscopy and numerical analysis to authenticate plant materials. This topic covers powder microscopy, micrometry with ocular and stage micrometers, and quantitative indices such as stomatal index, stomatal number, palisade ratio, vein islet number and vein termination number. Students learn sample preparation, clearing, staining, mounting methods, and counting protocols to obtain reproducible measurements and diagnostic data. Mastery of micrometry, calibration, and result interpretation helps detect adulteration, assess quality, and support pharmacopoeial standards. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What does “quantitative microscopy” of crude drugs primarily involve?
- Measuring concentrations of alkaloids using titration
- Counting and measuring microscopic features and calculating diagnostic indices
- Assessing smell and taste of powdered drugs
- Recording macroscopic appearance only
Correct Answer: Counting and measuring microscopic features and calculating diagnostic indices
Q2. Which instrument is used to calibrate an ocular micrometer?
- Analytical balance
- Spectrophotometer
- Stage micrometer
- pH meter
Correct Answer: Stage micrometer
Q3. Stomatal index is defined as:
- (Number of stomata / Number of epidermal cells) × 100
- (Number of epidermal cells / Number of stomata) × 100
- (Number of stomata / (Number of stomata + Number of epidermal cells)) × 100
- (Number of stomata × Number of epidermal cells) / 100
Correct Answer: (Number of stomata / (Number of stomata + Number of epidermal cells)) × 100
Q4. Palisade ratio refers to:
- Average number of stomata per mm²
- Average number of palisade cells beneath one epidermal cell
- Number of vein islets per cm²
- Ratio of upper to lower epidermal thickness
Correct Answer: Average number of palisade cells beneath one epidermal cell
Q5. Vein islet number is reported as:
- Number of vein islets per mm²
- Number of stomata per leaf
- Average palisade cell length
- Percentage of epidermal cells
Correct Answer: Number of vein islets per mm²
Q6. Which mounting medium is commonly used for permanent slides in pharmacognostic microscopy?
- Distilled water
- Glycerin jelly
- DPX (distyrene plasticizer xylene)
- Phenol
Correct Answer: DPX (distyrene plasticizer xylene)
Q7. To prepare a cleared leaf for epidermal study, which reagent is frequently used?
- Concentrated HCl without prior treatment
- Petroleum ether
- 10% NaOH (clearing agent)
- Silver nitrate
Correct Answer: 10% NaOH (clearing agent)
Q8. If a stage micrometer of 1 mm equals 100 divisions and an ocular division reads 20 units across the same length, the value of one ocular division is:
- 0.05 mm
- 0.2 mm
- 0.01 mm
- 0.1 mm
Correct Answer: 0.05 mm
Q9. Stomatal number is usually expressed as:
- Number of stomata per leaf
- Number of stomata per mm²
- Number of stomata per cell
- Percentage of stomata among trichomes
Correct Answer: Number of stomata per mm²
Q10. Which of the following best describes vein termination number?
- Number of vein terminations per mm²
- Number of trichomes per mm of margin
- Ratio of major to minor veins
- Palisade cells under each stomata
Correct Answer: Number of vein terminations per mm²
Q11. Powder microscopy quantitative data are important for:
- Estimating moisture content only
- Authenticating botanical origin and detecting adulteration
- Measuring pH of crude drugs
- Quantifying active constituents by weight
Correct Answer: Authenticating botanical origin and detecting adulteration
Q12. When using an ocular micrometer, calibration should be repeated when:
- The microscope magnification or objective is changed
- The slide color changes
- The room temperature varies by 1°C
- The specimen is humid
Correct Answer: The microscope magnification or objective is changed
Q13. Which staining reagent is commonly used to highlight lignified tissues during microscopic analysis?
- Phloroglucinol with HCl
- Sudan III
- Acid fuchsin only
- Silver nitrate
Correct Answer: Phloroglucinol with HCl
Q14. For accurate stomatal index determination, the epidermal peels should be observed from:
- Only the midrib region
- Randomly selected fields avoiding major veins
- Only the leaf margin
- The petiole surface
Correct Answer: Randomly selected fields avoiding major veins
Q15. Which parameter differentiates species with similar macroscopic appearance using quantitative microscopy?
- Color of powder under daylight
- Vein islet number and stomatal index
- Odor intensity
- Drying time in oven
Correct Answer: Vein islet number and stomatal index
Q16. How is palisade ratio practically determined?
- Counting stomata per epidermal cell
- Counting palisade cells under several epidermal cells and averaging
- Measuring vein thickness only
- Calculating leaf area to mass ratio
Correct Answer: Counting palisade cells under several epidermal cells and averaging
Q17. Which microscopic feature is quantified when reporting “stomatal number” for a leaf?
- Total epidermal cell count per leaf
- Average stomata per mm² of epidermis
- Length of stomatal guard cells in mm
- Number of trichomes per vein islet
Correct Answer: Average stomata per mm² of epidermis
Q18. A common clearing technique to study internal leaf anatomy involves boiling in:
- Saturated sodium chloride
- 10% KOH or NaOH followed by washing and staining
- Absolute ethanol only
- Acetone to dehydrate permanently
Correct Answer: 10% KOH or NaOH followed by washing and staining
Q19. When recording vein islet number, the standard area examined is usually:
- Per leaf basis without area control
- Per mm² of leaf surface
- Per cm of vein length
- Per epidermal cell
Correct Answer: Per mm² of leaf surface
Q20. Which error most affects quantitative microscopy results?
- Using calibrated micrometer
- Poor calibration or inconsistent magnification
- Using stained preparations
- Counting multiple fields and averaging
Correct Answer: Poor calibration or inconsistent magnification
Q21. Which mountant is suitable for temporary wet mounts in powder microscopy?
- Canada balsam
- Glycerin-water mixture
- Epoxy resin
- DPX permanently
Correct Answer: Glycerin-water mixture
Q22. Micrometry measurements are usually reported in:
- Grams
- Micrometers (µm) or millimeters (mm)
- Mol/L
- Degrees Celsius
Correct Answer: Micrometers (µm) or millimeters (mm)
Q23. Which of the following is NOT a quantitative microscopic parameter used in leaf evaluation?
- Stomatal index
- Palisade ratio
- Vein islet number
- Moisture absorption index
Correct Answer: Moisture absorption index
Q24. For reproducibility, how many fields are commonly counted and averaged for stomatal number or epidermal counts?
- 1 field
- 3–10 randomly selected fields
- Only the largest field
- 100 fields always
Correct Answer: 3–10 randomly selected fields
Q25. Which crystal type commonly observed in crude plant drugs can be quantified microscopically?
- Calcium oxalate crystals (raphides, druses)
- Sodium chloride crystals
- Silica only in roots
- Protein crystals in alkaloids
Correct Answer: Calcium oxalate crystals (raphides, druses)
Q26. During ocular micrometer calibration, if 1 ocular division equals 10 µm at a given magnification, how many micrometers are 15 ocular divisions?
- 1.5 µm
- 150 µm
- 15 µm
- 0.15 µm
Correct Answer: 150 µm
Q27. Which preparation step improves visibility of cell walls and lignified structures for counting?
- Dehydration in acetone only
- Treating with clearing agent followed by staining with phloroglucinol or safranin
- Air drying without any reagent
- Freezing the sample immediately
Correct Answer: Treating with clearing agent followed by staining with phloroglucinol or safranin
Q28. Quantitative microscopy data in pharmacopoeial monographs are used to:
- Replace chemical assays entirely
- Support identification and quality control alongside chemical tests
- Measure drug potency in vivo
- Determine the pH of the extract
Correct Answer: Support identification and quality control alongside chemical tests
Q29. Which of the following is a correct formula for palisade ratio calculation?
- Total palisade cells counted / Number of epidermal cells observed
- Number of stomata × number of epidermal cells
- Palisade cell length / epidermal cell length
- Number of veins per leaf area
Correct Answer: Total palisade cells counted / Number of epidermal cells observed
Q30. When reporting quantitative microscopy results, good laboratory practice requires:
- Omitting magnification and calibration details
- Documenting magnification, calibration, method, number of fields and mean values
- Only providing a photograph without counts
- Using different magnifications for each count without noting them
Correct Answer: Documenting magnification, calibration, method, number of fields and mean values
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.
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