Part 7 — Applied & NEET-Level Complex Questions: Comparative Anatomy Growth (Questions 151–175)

Part 7 — Applied & NEET-Level Complex Questions: Comparative Anatomy, Anomalous Growth (Questions 151–175)

Q151. Which feature distinguishes dicot and monocot roots?

A) Number of cotyledons only
B) Dicot roots often have xylem in an X-shape (fewer poles), monocot roots are polyarch with many xylem poles; cortex & pith arrangement may differ
C) Monocot roots always lack epidermis
D) Dicots never form lateral roots
Answer: B
Explanation:

B) Correct — root vascular patterns differ by number of xylem poles.
A/C/D) Incorrect.

Q152. In stems showing anomalous secondary growth like Dracaena, the thickening is due to:

A) Vascular cambium only as in dicots
B) Activity of a secondary thickening meristem (STM) producing parenchyma and new vascular bundles leading to concentric growth — differs from typical ring-forming cambium
C) Epidermis multiplication only
D) Root formation exclusively
Answer: B
Explanation:

B) Correct — monocot secondary thickening is anomalous.
A/C/D) Not applicable.

Q153. Which criterion is most reliable for distinguishing a stem from a root in cross section?

A) Presence of trichomes only
B) Presence of node and internode, axillary buds, and leaf traces indicate stem; roots lack nodes/axillary buds and have root hairs and endodermis/casparian strips
C) Color only
D) Smell only
Answer: B
Explanation:

B) Correct — morphological markers (nodes/buds) differentiate stems from roots.
A/C/D) Not reliable.

Q154. Which of the following best explains why monocot stems rarely show secondary growth?

A) Monocots lack vascular cambium between primary xylem and phloem in bundles; their bundles are usually closed and scattered, preventing formation of continuous cambial ring needed for normal secondary growth
B) Monocots have giant cambium rings always
C) Monocots do secondary growth via pericycle only
D) Monocots are not vascular plants
Answer: A
Explanation:

A) Correct.
B/C/D) False.

Q155. In wood anatomy, vessel element perforations and pit structure most directly influence:

A) Mechanical strength only
B) Hydraulic conductivity and vulnerability to cavitation; vessel size and pit membrane properties affect flow and safety trade-offs
C) Photosynthesis in wood
D) Root hair formation
Answer: B
Explanation:

B) Correct.
A/C/D) Not primary effects.

Q156. Which statement about cambial growth is accurate?

A) Cambium always produces equal amounts of xylem and phloem
B) Cambium typically produces more secondary xylem than secondary phloem leading to larger wood volume compared to bark; phloem tissue often thinner
C) Cambium forms only phloem
D) Cambium is present only in roots of monocots
Answer: B
Explanation:

B) Correct — more xylem produced than phloem.
A/C/D) Incorrect.

Q157. Which anatomical trait is a hallmark of secondary phloem?

A) Presence of vessel elements only
B) Sieve tubes with companion cells, phloem fibres and phloem parenchyma arranged externally to cambium; active in translocation but less voluminous than xylem
C) Lignified vessels only
D) Epidermis replacement only
Answer: B
Explanation:

B) Correct.
A/C/D) Not characteristic.

Q158. In a cross section of a woody stem, how do you recognize secondary phloem?

A) Outside vascular cambium with sieve elements and phloem parenchyma; often crushed and less conspicuous than xylem, forms inner bark with rays contiguous with xylem rays
B) Inside xylem region only
C) At the pith center only
D) In epidermis only
Answer: A
Explanation:

A) Correct.
B/C/D) Wrong.

Q159. In anatomy, a “steler” condition refers to:

A) Arrangement of vascular tissues — protostele, siphonostele, dictyostele, etc., classification of stele types in axes and roots
B) Only epidermal structures
C) Photosynthetic efficiency only
D) A type of stomata
Answer: A
Explanation:

A) Correct — stele diversity important in evolution of vascular plants.
B/C/D) Not related.

Q160. Which of these indicates a leaf trace in cross-section of stem?

A) A strand of vascular tissue diverging from central stele toward a leaf; leaf traces break continuity and form leaf gap above they leave the stele
B) A stomatal pore only
C) A root hair only
D) Epidermal gland
Answer: A
Explanation:

A) Correct.
B/C/D) Not leaf traces.

Q161. Which is true about tyloses formation and their role?

A) Tyloses form from adjacent parenchyma protruding into vessel lumina to block them — beneficial for blocking pathogens and contribute to heartwood formation, but reduce conductivity
B) Tyloses increase conductivity always
C) Only formed in phloem
D) Prevent cambium formation
Answer: A
Explanation:

A) Correct.
B/C/D) False.

Q162. A student finds concentric rings of vascular bundles in a stem cross-section. It likely indicates:

A) Typical monocot primary anatomy only
B) A stem with secondary cambial activity or monocot with secondary thickening forming concentric vascular cylinders (e.g., Dracaena) — anomalous growth leads to concentric rings
C) No vascular tissue present
D) Root section only
Answer: B
Explanation:

B) Correct — concentric rings may indicate secondary thickening or anomalous bundles.
A/C/D) Incorrect.

Q163. Which property distinguishes periderm from primary epidermis?

A) Periderm is living and photosynthetic while epidermis dead always
B) Periderm (cork) contains suberized dead cells impermeable to water and gas, serving protective function and replacing epidermis during secondary growth; epidermis is living in herbaceous plants and contains stomata
C) Periderm conducts sugars only
D) Periderm has stomata only
Answer: B
Explanation:

B) Correct.
A/C/D) False.

Q164. Which of following is true about secondary xylem rays?

A) They are formed only in roots but not in stems
B) Formed by ray initial cells in cambium; oriented radially and consist of parenchyma for radial transport and storage; present in both roots and stems of woody plants
C) Composed of sieve tube elements only
D) Only present in monocots
Answer: B
Explanation:

B) Correct.
A/C/D) Not correct.

Q165. In woody dicot trees, phloem skeleton is often crushed; what remains functional?

A) Outer bark only
B) Inner phloem active in conduction for a short time; older phloem is crushed and forms part of bark; cambium continuously produces new phloem and xylem
C) Xylem stops functioning entirely
D) Leaves transform into cambium
Answer: B
Explanation:

B) Correct — old phloem crushed.
A/C/D) False.

Q166. Which of following best explains why monocots seldom form true wood?

A) Monocots lack true xylem
B) Because they usually lack vascular cambium necessary for producing large amounts of secondary xylem; some monocots form anomalous secondary thickening via different meristems but not true wood as in dicots
C) Monocots have too many leaves only
D) Monocots are not vascular plants
Answer: B
Explanation:

B) Correct.
A/C/D) False.

Q167. During secondary growth, phloem forms:

A) Thick wood only
B) Thin layer external to cambium, often crushed and not accumulating like xylem; newest phloem is functional in conduction but old phloem becomes part of bark
C) No tissues at all
D) Epidermis layers
Answer: B
Explanation:

B) Correct.
A/C/D) Wrong.

Q168. Which is true about “cambial zone” under microscope?

A) Cambial initials small and densely cytoplasmic; zone includes fusiform and ray initials; divides anticlinally and periclinally to produce derivatives that differentiate into secondary xylem/phloem
B) Cambial zone comprises large dead cells only
C) Cambium is only present in leaves
D) Cambium is epidermal tissue
Answer: A
Explanation:

A) Correct.
B/C/D) False.

Q169. Which statement regarding formation of wood (secondary xylem) is correct?

A) Secondary xylem is composed of vessels, tracheids, fibers and xylem parenchyma produced by vascular cambium toward inside; heartwood and sapwood distinctions based on functionality and extractives
B) Secondary xylem forms the outer bark
C) Secondary xylem is only parenchyma no vessels
D) Only phloem forms wood
Answer: A
Explanation:

A) Correct.
B/C/D) Incorrect.

Q170. Which phenomenon explains why bark is thicker on one side of a leaning tree?

A) Symmetrical growth only
B) Reaction wood formation and differential cambial activity producing eccentric growth rings to compensate mechanical stresses causing asymmetric wood and bark development
C) Bark forms only in roots on one side
D) Leaves direct bark growth only on one side
Answer: B
Explanation:

B) Correct — eccentric wood and reaction wood (compression/ tension) cause asymmetry.
A/C/D) Not accurate.

Q171. Bark includes periderm; secondary phloem; which of the following is NOT part of bark?

A) Cork (phellem) and phelloderm
B) Secondary phloem and cortex remnants
C) Secondary xylem (wood) internal to cambium
D) Phellogen (cork cambium)
Answer: C
Explanation:

C) Correct — wood is internal to cambium, not part of bark.
A/B/D) Are bark components.

Q172. Formation of lenticels during periderm development is due to:

A) Localized activity of cork cambium producing loosely arranged cells that rupture outer phelloderm creating pore — facilitates gas exchange
B) Formation of stomata only
C) Vascular bundle formation only
D) Root cap detachment only
Answer: A
Explanation:

A) Correct.
B/C/D) Wrong.

Q173. Which of following statements about cambial activity under drought is true?

A) Cambial activity increases linearly with drought
B) Drought reduces cambial activity reducing width of growth rings; stress periods show narrow late wood or absent rings in severe droughts
C) Cambium unaffected by moisture
D) Cambium stops only in summer always
Answer: B
Explanation:

B) Correct — cambial growth sensitive to water availability.
A/C/D) Not universally true.

Q174. In which situation would you expect more parenchyma in xylem?

A) Species adapted to rapid radial storage (e.g., tropical trees) often exhibit abundant xylem parenchyma compared to temperate woods — parenchyma proportions vary with ecology and life strategy
B) Parenchyma never present
C) Parenchyma only in epidermis
D) Parenchyma only in roots always
Answer: A
Explanation:

A) Correct nuance.
B/C/D) False.

Q175. The difference between primary and secondary phloem is:

A) Primary phloem originates from procambium during primary growth and is part of primary plant body; secondary phloem is formed by vascular cambium during secondary growth and contributes to inner bark
B) No difference at all
C) Primary phloem is lignified like wood
D) Secondary phloem forms before primary tissues
Answer: A
Explanation:

A) Correct.
B/C/D) Incorrect.

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