General anatomy of stem (monocot & dicot) MCQs With Answer offers B. Pharm students a focused review of stem structure, essential for pharmacognosy and drug-source identification. This concise guide covers stem anatomy keywords such as monocot vs dicot stem, vascular bundles, eustele, atactostele, primary and secondary growth, vascular cambium, cortex, pith, periderm, medullary rays, and storage parenchyma. Understanding these features helps in microscopic authentication of botanical drugs, tracing transport of metabolites, and recognizing anatomical markers used in pharmacopeial standards. Clear, exam-oriented MCQs reinforce concepts and improve retention for practical lab work and theory exams. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the region of the stem located between two successive nodes called?
- Node
- Internode
- Leaf scar
- Axil
Correct Answer: Internode
Q2. Which tissue primarily provides mechanical support and flexibility to young dicot stems?
- Sclerenchyma fibers
- Collenchyma
- Xylem vessels
- Epidermis
Correct Answer: Collenchyma
Q3. In transverse section, monocot stems typically show vascular bundles that are:
- Arranged in a continuous ring
- Scattered (atactostele)
- Concentrated in the center only
- Surrounded by a conspicuous cambium in each bundle
Correct Answer: Scattered (atactostele)
Q4. Which feature distinguishes a dicot (typical) stem from a monocot stem microscopically?
- Presence of epidermis
- Vascular bundles arranged in a ring with cambium
- Presence of pith
- Presence of chlorenchyma
Correct Answer: Vascular bundles arranged in a ring with cambium
Q5. The vascular cambium in dicot stems arises from which regions?
- Only fascicular cambium
- Only interfascicular cambium
- Both fascicular and interfascicular regions forming a continuous cambium
- From the epidermis
Correct Answer: Both fascicular and interfascicular regions forming a continuous cambium
Q6. Which type of xylem maturation is typically seen in stems (primary xylem)?
- Exarch
- Endarch
- Mesarch
- Amphicribral
Correct Answer: Endarch
Q7. What is the main function of medullary rays in dicot stems?
- Conduct water longitudinally
- Store starch and facilitate radial transport
- Protect against herbivores
- Form the epidermal layer
Correct Answer: Store starch and facilitate radial transport
Q8. Which tissue makes up the outer protective layer and may be replaced by periderm during secondary growth?
- Cortex
- Pericycle
- Epidermis
- Pith
Correct Answer: Epidermis
Q9. In pharmacognosy, which stem tissue is commonly examined for identification of plant drugs due to presence of vessels, fibers, and parenchyma?
- Cork
- Phellem
- Secondary xylem (wood)
- Cuticle only
Correct Answer: Secondary xylem (wood)
Q10. Lenticels in woody stems are primarily involved in:
- Water absorption
- Gas exchange through the periderm
- Nitrogen fixation
- Photosynthesis
Correct Answer: Gas exchange through the periderm
Q11. Which one of the following best describes an ‘open vascular bundle’?
- Vascular bundle without cambium
- Bundle with a cambium between xylem and phloem capable of secondary growth
- Bundle with xylem only
- Bundle that is scattered in monocots
Correct Answer: Bundle with a cambium between xylem and phloem capable of secondary growth
Q12. The ground tissue region between the epidermis and vascular bundles in stems is called:
- Pith
- Cortex
- Periderm
- Vascular cambium
Correct Answer: Cortex
Q13. Which cell type in the stem is most important for storage of starch and other metabolites relevant to drug constituents?
- Sclerenchyma fibers
- Parenchyma cells
- Tracheids
- Companion cells
Correct Answer: Parenchyma cells
Q14. How are vascular bundles described in most dicot stems?
- Closed and scattered
- Conjoint, collateral and open arranged in a ring
- Separated xylem islands
- Siphonostele with leaf gaps
Correct Answer: Conjoint, collateral and open arranged in a ring
Q15. Which structure gives rise to the vascular cambium during secondary growth in dicot stems?
- Phloem fibers
- Pericycle only
- Meristematic cells between xylem and phloem and interfascicular parenchyma
- Epidermal cells
Correct Answer: Meristematic cells between xylem and phloem and interfascicular parenchyma
Q16. The central region of a young dicot stem composed mainly of parenchyma is called:
- Cortex
- Pith
- Periderm
- Vascular bundle
Correct Answer: Pith
Q17. Which of the following is a characteristic anatomical feature of monocot stems used in drug identification?
- Well-developed secondary xylem rings
- Atactostele with scattered vascular bundles and no true secondary growth
- Conspicuous cambial activity forming wood
- Interfascicular cambium forming medullary rays
Correct Answer: Atactostele with scattered vascular bundles and no true secondary growth
Q18. What are tyloses and where are they found?
- Fungal infections in cortex
- Outgrowths of parenchyma into vessels found in heartwood
- Stomatal pores on stems
- Secretory ducts in phloem
Correct Answer: Outgrowths of parenchyma into vessels found in heartwood
Q19. Which anatomical feature indicates annual growth rings in woody dicot stems?
- Alternating bands of collenchyma and sclerenchyma
- Differences in vessel diameter and density between earlywood and latewood
- Scattered vascular bundles
- Presence of stomata on bark
Correct Answer: Differences in vessel diameter and density between earlywood and latewood
Q20. Secretory canals or resin ducts in stems are typically lined by:
- Sclerenchyma cells
- Specialized epithelial cells
- Epidermal cells
- Companion cells
Correct Answer: Specialized epithelial cells
Q21. The presence of a hypodermis containing collenchyma in stems is mainly an adaptation for:
- Enhanced photosynthesis
- Mechanical strength and flexibility
- Salt excretion
- Seed dispersal
Correct Answer: Mechanical strength and flexibility
Q22. In monocot stems, the storage parenchyma region that may functionally replace cambial secondary growth is called:
- Secondary xylem
- Primary thickening meristem
- Interfascicular cambium
- Periderm
Correct Answer: Primary thickening meristem
Q23. Which of the following is NOT a typical component of the bark of a dicotyledonous tree?
- Periderm (cork)
- Secondary phloem
- Secondary xylem
- Outer dead cork cells
Correct Answer: Secondary xylem
Q24. Which tissue in stems contains sieve tubes and companion cells?
- Xylem
- Phloem
- Periderm
- Pith
Correct Answer: Phloem
Q25. A dicot stem with prominent fiber caps associated with phloem likely has which cell type providing mechanical support?
- Sclerenchyma fibers
- Collenchyma
- Parenchyma
- Tracheids
Correct Answer: Sclerenchyma fibers
Q26. Which of the following stele types is most commonly associated with typical dicot stems?
- Protostele
- Siphonostele
- Eustele
- Atactostele
Correct Answer: Eustele
Q27. In transverse section of a dicot stem, what lies immediately internal to the phloem?
- Periderm
- Secondary xylem (wood)
- Pith rays
- Epidermis
Correct Answer: Secondary xylem (wood)
Q28. Which of the following explains anomalous secondary growth in some dicots and monocots?
- Uniform activity of vascular cambium only
- Activity of additional cambia or parenchymatous proliferation leading to unusual vascular arrangements
- Absence of any meristematic activity after primary growth
- Only epidermal thickening
Correct Answer: Activity of additional cambia or parenchymatous proliferation leading to unusual vascular arrangements
Q29. The term ‘conjoint vascular bundle’ refers to a bundle having:
- Only xylem elements
- Xylem and phloem together
- Interspersed cortex cells
- Only phloem elements
Correct Answer: Xylem and phloem together
Q30. Which structure in the stem is most directly involved in lateral transport of water and solutes between vascular bundles?
- Medullary rays
- Cortex cells only
- Cuticle
- Stomata
Correct Answer: Medullary rays
Q31. In wood anatomy, the presence of large vessel elements arranged in distinct radial files is characteristic of:
- Softwood (gymnosperm)
- Diffuse-porous hardwood
- Ring-porous hardwood
- Monocot stem
Correct Answer: Ring-porous hardwood
Q32. Which feature of stem anatomy is commonly used to distinguish crude drug bark samples in pharmacognosy?
- Number of stomata on epidermis
- Structure and arrangement of cork, cortex, phloem and stone cells
- Leaf venation pattern
- Root hair presence
Correct Answer: Structure and arrangement of cork, cortex, phloem and stone cells
Q33. What is the role of pericycle in dicot stems when present?
- Generates lateral roots
- May give rise to cork cambium or contribute to vascular cambium
- Forms epidermis
- Stores chlorophyll
Correct Answer: May give rise to cork cambium or contribute to vascular cambium
Q34. Which cells in phloem are responsible for loading and unloading of photosynthates in angiosperm stems?
- Vessel elements
- Sieve tube elements and companion cells
- Tracheids
- Sclereids
Correct Answer: Sieve tube elements and companion cells
Q35. The presence of calcium oxalate crystals in stem tissues is significant for:
- Strengthening xylem vessels only
- Taxonomic identification and authentication of medicinal plants
- Photosynthesis enhancement
- Transpiration control
Correct Answer: Taxonomic identification and authentication of medicinal plants
Q36. In a transverse section of a dicot stem, the ray cells connecting pith and cortex are derived from:
- Vascular cambium
- Epidermis
- Periderm
- Cortex parenchyma
Correct Answer: Vascular cambium
Q37. Which type of secondary growth is commonly absent in monocot stems?
- Primary thickening growth
- Anomalous secondary growth via accessory cambia
- Typical cambial secondary growth producing wood and bark
- Cambial activity in root
Correct Answer: Typical cambial secondary growth producing wood and bark
Q38. Which of the following best describes the phyllotaxy term ‘alternate’?
- Two leaves per node opposite each other
- Several leaves encircling the node
- One leaf per node on alternating sides along the stem
- Leaves fused to form a sheath
Correct Answer: One leaf per node on alternating sides along the stem
Q39. In stems of climbers and some succulent medicinal plants, what adaptation is common to reduce water loss?
- Thin cuticle and many stomata
- Thick cuticle and sunken stomata with abundant water-storage parenchyma
- Absence of pith
- Increased number of vessels only
Correct Answer: Thick cuticle and sunken stomata with abundant water-storage parenchyma
Q40. What anatomical change marks the transition from primary to secondary growth in dicot stems?
- Formation of epidermis
- Initiation of vascular cambium and production of secondary xylem and phloem
- Loss of cortex entirely
- Development of leaf traces
Correct Answer: Initiation of vascular cambium and production of secondary xylem and phloem
Q41. Which staining/observation feature is commonly used to identify lignified sclerenchyma in stem T.S. during pharmacognostic studies?
- Cells stain blue with iodine
- Lignified walls stain red with phloroglucinol-HCl (or show autofluorescence under UV)
- Cells show green color with Sudan III
- Cells collapse when treated with water
Correct Answer: Lignified walls stain red with phloroglucinol-HCl (or show autofluorescence under UV)
Q42. Which type of vascular bundle is typical of herbaceous monocot stems like maize?
- Open conjoint collateral bundles in ring
- Closed, scattered conjoint bundles (atactostele)
- Protostele at center
- Conspicuous fascicular cambium in each bundle
Correct Answer: Closed, scattered conjoint bundles (atactostele)
Q43. The prominence of phloem fibers in the bark is useful pharmacognostically because:
- Fibers dissolve in alkaloid tests
- Fiber morphology helps in identification and quality assessment of bark drugs
- Fibers indicate presence of essential oils only
- Fibers determine stomatal density
Correct Answer: Fiber morphology helps in identification and quality assessment of bark drugs
Q44. Which statement best describes the origin of leaf traces in stems?
- They originate from root meristem
- They are vascular bundles that diverge from the main stem vascular cylinder to supply leaves
- They are epidermal appendages
- They form the cork cambium
Correct Answer: They are vascular bundles that diverge from the main stem vascular cylinder to supply leaves
Q45. In transverse section, which feature indicates a succulent stem specialized for water storage?
- Thin parenchyma and many stomata
- Large water-storage parenchyma cells in cortex and/or pith
- Highly lignified xylem predominating
- Scattered vascular bundles with no parenchyma
Correct Answer: Large water-storage parenchyma cells in cortex and/or pith
Q46. Which anatomical element is primarily responsible for water conduction in angiosperm stems?
- Sieve tube elements
- Vessel elements and tracheary elements of xylem
- Phloem parenchyma
- Epidermal hairs
Correct Answer: Vessel elements and tracheary elements of xylem
Q47. The presence of starch grains in stem parenchyma is typically detected with which reagent in microscopic examination?
- Phloroglucinol
- Sudan III
- Iodine-potassium iodide (I2-KI)
- Safranin
Correct Answer: Iodine-potassium iodide (I2-KI)
Q48. Which of the following is a consequence of extensive secondary growth in dicot stems?
- Reduced diameter of stem
- Formation of wood (secondary xylem) and bark (secondary phloem + periderm) leading to increased girth
- Loss of vascular bundles
- Conversion of xylem into epidermis
Correct Answer: Formation of wood (secondary xylem) and bark (secondary phloem + periderm) leading to increased girth
Q49. Which anatomical character is most helpful to distinguish between root and stem transverse sections?
- Presence of stomata
- Arrangement of vascular tissues: ring of vascular bundles and presence of pith in stem vs central vascular cylinder in root
- Thickness of cuticle only
- Leaf traces in root
Correct Answer: Arrangement of vascular tissues: ring of vascular bundles and presence of pith in stem vs central vascular cylinder in root
Q50. Why is knowledge of stem anatomy important for B. Pharm students in the context of herbal drug standardization?
- Stem anatomy is irrelevant to drug standardization
- Microscopic stem features help authenticate medicinal plant material, detect adulteration, and localize drug-bearing tissues
- Only chemical tests are used for authentication
- Stem anatomy only matters for agricultural practices
Correct Answer: Microscopic stem features help authenticate medicinal plant material, detect adulteration, and localize drug-bearing tissues
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