Morphology and histology of Cinchona MCQs With Answer

Introduction: The morphology and histology of Cinchona are essential for B.Pharm students studying pharmacognosy and medicinal plant analysis. This topic covers macroscopic features of Cinchona trees—leaf arrangement, bark characteristics, and species identification—and microscopic structure of the bark including periderm, cortex, secondary phloem, xylem, medullary rays, sclereids and secretory elements. Emphasis on alkaloid localization (quinine and related quinoline alkaloids), powder microscopy markers, and diagnostic histological characters helps correlate plant structure with drug quality and therapeutic activity. Mastery of these keywords and microscopic traits aids in authentication, standardization and quality control of Cinchona bark drugs. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary medicinal constituent class found in Cinchona bark?

• Flavonoids
• Saponins
• Quinoline alkaloids
• Tannins

Correct Answer: Quinoline alkaloids

Q2. Which layer constitutes the outermost protective tissue in transverse section of Cinchona bark?

• Phelloderm
• Phellogen (cork cambium)
• Phellem (cork)
• Cortex parenchyma

Correct Answer: Phellem (cork)

Q3. In Cinchona bark histology, which cell type is most commonly associated with mechanical strength and appears as stone cells?

• Sclereids
• Sieve tube elements
• Parenchyma cells
• Companion cells

Correct Answer: Sclereids

Q4. Which tissue contains the sieve tubes and companion cells in Cinchona secondary structure?

• Secondary xylem
• Secondary phloem
• Phellem
• Pith

Correct Answer: Secondary phloem

Q5. Which anatomical feature is most diagnostic in powdered Cinchona bark microscopy?

• Prismatic calcium oxalate crystals only
• Numerous lignified phloem fibers and stone cells
• Abundant stomata fragments
• Multicellular glandular trichomes

Correct Answer: Numerous lignified phloem fibers and stone cells

Q6. Quinine is classed chemically as which type of alkaloid?

• Isoquinoline alkaloid
• Quinoline alkaloid
• Indole alkaloid
• Pyrrolizidine alkaloid

Correct Answer: Quinoline alkaloid

Q7. In a transverse section of Cinchona stem, medullary rays are visible as:

• Radial files of parenchyma cells extending from cortex to pith
• Concentric rings of xylem vessels
• Clusters of sclerenchyma cells in phloem
• Isolated secretory ducts filled with resin

Correct Answer: Radial files of parenchyma cells extending from cortex to pith

Q8. Which Cinchona species is traditionally recognized as a primary source of medicinal quinine?

• Cinchona pubescens
• Cinchona officinalis
• Cinchona micrantha
• Cinchona alba

Correct Answer: Cinchona officinalis

Q9. Where are alkaloids predominantly localized in Cinchona bark histologically?

• Phellem cell walls only
• Cortical and phloem parenchyma cells, including secretory cells
• Xylem vessel lumina exclusively
• Pith parenchyma

Correct Answer: Cortical and phloem parenchyma cells, including secretory cells

Q10. Which microscopic stain is commonly used to highlight lignified elements like sclereids and fibers in Cinchona sections?

• Wright’s stain
• Safranin and fast green
• Silver nitrate
• Iodine-potassium iodide (IKI)

Correct Answer: Safranin and fast green

Q11. Which macroscopic feature helps differentiate Cinchona bark from other barks?

• Distinctive red inner surface with concentric bands and bitter taste
• Presence of aerial roots
• Whitish powdery outer coating
• Fragrant citrus odor when broken

Correct Answer: Distinctive red inner surface with concentric bands and bitter taste

Q12. In stem anatomy, the vascular bundles of Cinchona are arranged as:

• Scattered amphivasal bundles
• Collateral bundles in a ring with secondary growth
• Closed concentric rings without cambium
• Single large central bundle only

Correct Answer: Collateral bundles in a ring with secondary growth

Q13. Which of the following microscopic fragments is LEAST likely to be observed in Cinchona bark powder?

• Stone cell fragments
• Prismatic crystals
• Spiral thickened tracheids typical of gymnosperms
• Bundles of lignified fibers

Correct Answer: Spiral thickened tracheids typical of gymnosperms

Q14. Lenticels on Cinchona bark are associated with which structure?

• Gas exchange through periderm
• Storage of alkaloids
• Anchorage of aerial roots
• Secretion of resin

Correct Answer: Gas exchange through periderm

Q15. Which secondary metabolite besides quinoline alkaloids is commonly found in Cinchona bark cells and may affect extraction?

• Cardiac glycosides
• Tannins (polyphenols)
• Essential oils in high concentration
• Saponins as the major component

Correct Answer: Tannins (polyphenols)

Q16. The term “periderm” in Cinchona bark anatomy includes which of the following layers?

• Cuticle, epidermis, and hypodermis
• Phellem, phellogen and phelloderm
• Cortex, phloem and xylem
• Endodermis, exodermis and cortex

Correct Answer: Phellem, phellogen and phelloderm

Q17. Which structural change occurs in Cinchona bark during secondary growth?

• Primary phloem increases and primary xylem is lost
• Formation of cambium producing secondary xylem and phloem with annual rings
• Epidermis becomes thicker and develops stomata
• Pith differentiates into vascular bundles

Correct Answer: Formation of cambium producing secondary xylem and phloem with annual rings

Q18. Which leaf arrangement is typical for many Cinchona species and aids botanical identification?

• Alternate pinnate leaves
• Opposite simple leaves
• Whorled needle-like leaves
• Basal rosette of leaves

Correct Answer: Opposite simple leaves

Q19. In quality control, fluorescence under UV light of Cinchona extract is mainly used to detect which constituent?

• Quinine and certain quinoline alkaloids
• Tannins
• Lignin fragments
• Starch

Correct Answer: Quinine and certain quinoline alkaloids

Q20. Which anatomical character helps distinguish inner bark (phloem) from outer cortex in a transverse section of Cinchona?

• Presence of phellem in inner bark
• Phloem shows sieve tubes, companion cells and phloem fibers, while cortex has parenchyma and tannin cells
• Inner bark contains stomata
• Cortex contains xylem vessels

Correct Answer: Phloem shows sieve tubes, companion cells and phloem fibers, while cortex has parenchyma and tannin cells

Q21. Which microscopy observation suggests presence of secondary metabolites stored in cells of Cinchona?

• Empty vessel lumina only
• Darkly staining granular content in parenchyma and secretory cells
• Uniform, unstained cell walls across tissues
• Only large intercellular air spaces

Correct Answer: Darkly staining granular content in parenchyma and secretory cells

Q22. Which processing practice affects microscopic characters and alkaloid content of harvested Cinchona bark?

• Immediate sun-drying in thin layers to prevent fermentation
• Boiling the bark in water before drying
• Packing fresh bark wet for long transport
• Storing under saturated humidity without drying

Correct Answer: Immediate sun-drying in thin layers to prevent fermentation

Q23. In thin section, which cell wall feature indicates lignification in Cinchona sclereids and fibers?

• Thin primary walls with prominent plasmodesmata
• Thick secondary walls staining red with safranin
• High content of oil droplets visible in lumen
• Transparent thin walls that collapse on staining

Correct Answer: Thick secondary walls staining red with safranin

Q24. Which of the following is a true statement about the origin of medicinal Cinchona bark?

• It is the root bark harvested from herbaceous plants
• It is the stem bark obtained from small trees/shrubs of Cinchona
• It is exclusively leaf material collected during flowering
• It is derived from the fruit pericarp

Correct Answer: It is the stem bark obtained from small trees/shrubs of Cinchona

Q25. Which microscopic feature in Cinchona powder indicates xylem origin?

• Cork cell polygonal outlines
• Vessel elements with bordered pits and annular or scalariform thickenings
• Abundant epidermal stomatal complexes
• Dense clusters of companion cells

Correct Answer: Vessel elements with bordered pits and annular or scalariform thickenings

Q26. The bitterness of Cinchona bark is mainly attributed to which constituents?

• Essential oils
• Alkaloids, particularly quinoline alkaloids
• Starch breakdown products
• Pectins and mucilage

Correct Answer: Alkaloids, particularly quinoline alkaloids

Q27. Which anatomical diagnostic feature helps separate Cinchona from other bitter barks microscopically?

• Absence of sclereids throughout the bark
• Frequent isolated stone cells (sclereids) interspersed with phloem elements
• Dominance of collenchyma in inner bark
• Large secretory cavities typical of Rutaceae

Correct Answer: Frequent isolated stone cells (sclereids) interspersed with phloem elements

Q28. Which structural component is most important for mechanical protection of Cinchona stem during growth?

• Phellem (cork) and lignified sclerenchyma elements
• Sieve tube clusters
• Companion cells
• Medullary parenchyma only

Correct Answer: Phellem (cork) and lignified sclerenchyma elements

Q29. During microscopic examination, a student finds groups of cells with brown granular contents that react with FeCl3. These are most likely:

• Starch grains
• Tannin-containing cells
• Calcium oxalate druses
• Oil cells rich in essential oils

Correct Answer: Tannin-containing cells

Q30. Which practical pharmacognostic test helps estimate total alkaloid content in Cinchona samples?

• Microscopic count of sclereids per field
• Acid-base extraction followed by titration or spectrophotometric estimation of quinine
• Direct observation of cork cell size under microscope
• Determination of ash value alone

Correct Answer: Acid-base extraction followed by titration or spectrophotometric estimation of quinine

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