Part 2 — Anatomy of Root: Primary Structure, Endodermis, Pericycle, Lateral Roots (Questions 26–50)

Q26. Root cap cells secrete:

A) Auxin only
B) Mucilage to lubricate soil penetration and protect apical meristem
C) Lignin for strengthening
D) Chlorophyll for photosynthesis
Answer: B
Explanation:

A) Auxin synthesised more widely; root cap does help gravitropism via statoliths.
B) Correct — root cap produces mucilage.
C/D) Not functions.

Q27. Statoliths in root cap are composed of:

A) Starch grains (amyloplasts) that settle under gravity for gravitropic sensing
B) Calcium oxalate crystals exclusively
C) Lignin fragments
D) Lipids only
Answer: A
Explanation:

A) Correct — amyloplasts act as statoliths.
B/C/D) Not gravity-sensing statoliths in roots.

Q28. Which of these best describes exodermis?

A) A layer outside the epidermis only in leaves
B) Modified hypodermis in some roots providing additional barrier (suberized) — present in many monocot roots
C) Inner cell layer of stele
D) Type of stomata
Answer: B
Explanation:

B) Correct — exodermis is suberized hypodermal layer offering protection.
A/C/D) Incorrect.

Q29. Lateral root formation begins from:

A) Epidermis
B) Cortex
C) Pericycle (internal origin)
D) Endodermis only
Answer: C
Explanation:

C) Correct — pericycle cells re-enter cell cycle to form lateral root primordia.
A/B/D) Not typical origin.

Q30. Root hairs are outgrowths of:

A) Epidermal cells (trichoblasts) specialized for absorption, increasing surface area
B) Cortex cells only
C) Endodermis cells
D) Xylem vessels
Answer: A
Explanation:

A) Correct — root hairs are tubular extensions of epidermal cells.
B/C/D) False.

Q31. Presence of prominent aerenchyma is characteristic of:

A) Desert plants
B) Aquatic plants (e.g., rice) to facilitate oxygen diffusion to submerged tissues
C) Alpine plants only
D) None
Answer: B
Explanation:

B) Correct — aerenchyma common in aquatic/swampy species.
A/C/D) Not typical.

Q32. The stele is:

A) Entire cortex of root
B) Central vascular cylinder containing xylem, phloem, pericycle and pith where present
C) Epidermal covering only
D) Leaf lamina
Answer: B
Explanation:

B) Correct — stele = central vascular part.
A/C/D) Wrong.

Q33. Exarch xylem condition means:

A) Protoxylem toward center, metaxylem toward periphery
B) Protoxylem toward periphery, metaxylem toward center — typical in roots (protoxylem outside) — exarch is proto outside
C) No protoxylem present
D) Random arrangement
Answer: B
Explanation:

B) Correct — exarch: protoxylem peripheral (roots).
A) Endarch describes protoxylem inside (typical in stems).
C/D) Incorrect.

Q34. In dicot root, the number of xylem poles is usually:

A) Many scattered bundles
B) Few (e.g., diarch, triarch, tetrarch), depends on species — often radial symmetry with xylem arms
C) Always 10
D) Zero
Answer: B
Explanation:

B) Correct — dicot root xylem often 2–6 arms.
A/C/D) False.

Q35. Which part of root is responsible for conduction from root to shoot?

A) Cortex
B) Epidermis
C) Xylem and phloem in stele; xylem especially for water conduction upward
D) Root cap
Answer: C
Explanation:

C) Correct — vascular tissues in stele conduct water and food.
A/B/D) Not primary conduction tissues.

Q36. Root stele type in monocots commonly is:

A) Polyarch (many xylem strands) and often with central pith absent/present depending on taxa
B) Diarch always
C) No vascular tissues
D) Exposed bundles on surface
Answer: A
Explanation:

A) Correct — monocot roots often polyarch.
B/C/D) Incorrect.

Q37. Which structure controls apoplastic movement at endodermis?

A) Pectin
B) Casparian strip (suberin lamella in radial walls) blocking apoplast and forcing symplastic route via endodermal cells
C) Chloroplast
D) Starch sheath
Answer: B
Explanation:

B) Correct.
A/C/D) Not the barrier.

Q38. Which feature is typically seen in secondary growth of roots?

A) Formation of vascular cambium between primary xylem and phloem leading to secondary vascular tissues and development of periderm replacing epidermis
B) Only primary thickening, no cambium
C) Loss of xylem entirely
D) No secondary tissues formed in any roots
Answer: A
Explanation:

A) Correct — many dicot roots develop cambium and secondary xylem/phloem and periderm.
B/C/D) False.

Q39. In roots, tyloses formation occurs primarily in:

A) Phloem sieve tubes
B) Xylem vessels as outgrowths of adjacent parenchyma into vessels to block them (in heartwood formation)
C) Epidermis for absorption
D) Root hairs
Answer: B
Explanation:

B) Correct — tyloses block vessels in heartwood.
A/C/D) Incorrect.

Q40. Which is true about root epidermis in mature woody roots?

A) Remains intact throughout life
B) Replaced by periderm (cork) during secondary growth
C) Becomes xylem
D) Transforms into phloem
Answer: B
Explanation:

B) Correct — epidermis is sloughed off and replaced by cork during secondary growth.
A/C/D) Wrong.

Q41. Mycorrhiza refers to:

A) Symbiotic association between roots and fungi aiding in mineral/water absorption and sometimes protection against pathogens
B) Symbiosis between leaves and bacteria
C) Parasitic fungus killing roots only
D) Root hair disease only
Answer: A
Explanation:

A) Correct — mutualistic association increases absorption area.
B/C/D) Incorrect.

Q42. Root nodules in legumes are formed by:

A) Fungi
B) N₂-fixing bacteria (Rhizobium), induced by plant for nitrogen fixation
C) Earthworms
D) Protozoans
Answer: B
Explanation:

B) Correct — Rhizobium forms nodules for symbiotic N fixation.
A/C/D) Not correct.

Q43. Which root type is characteristic of monocots like grasses?

A) Tap root only
B) Adventitious fibrous root system (many roots arising from stem base)
C) Only aerial roots
D) No roots at all
Answer: B
Explanation:

B) Correct — monocots generally produce fibrous/adventitious root systems.
A/C/D) False.

Q44. Endodermal cells often contain suberin lamella in:

A) Primary roots always absent
B) Older roots as additional suberization (suberin lamella) forming exodermis/endodermal lamella for impermeability
C) Leaves only
D) Flowers only
Answer: B
Explanation:

B) Correct — suberization increases in older roots.
A/C/D) Not correct.

Q45. Which tissue is present between vascular bundles in dicot root?

A) Pith always present
B) Pericycle and often no large pith in typical dicot roots; vascular bundles form central xylem and phloem in radial fashion
C) Epidermis
D) Lenticels
Answer: B
Explanation:

B) Correct nuance — dicot roots typically lack central pith; stele is occupied by xylem & phloem; pericycle is inner boundary.
A/C/D) Incorrect.

Q46. Which of the following is true for root cortex?

A) Composed mainly of sclerenchyma
B) Parenchymatous region functioning in storage and transport from epidermis to stele (esp. food storage)
C) Contains stomata for gas exchange
D) It’s vascular tissue
Answer: B
Explanation:

B) Correct — cortex stores starch and aids movement to stele.
A/C/D) Wrong.

Q47. In which root zone do root hairs appear?

A) Root cap
B) Elongation zone (maturation zone where epidermal cells differentiate into root hairs)
C) Meristematic zone only
D) Secondary growth zone only
Answer: B
Explanation:

B) Correct — root hairs form in maturation zone.
A/C/D) False.

Q48. Secondary growth in roots causes formation of:

A) Secondary xylem only in dicots and gymnosperms; cork cambium (phellogen) forms cork; periderm replaces epidermis
B) No secondary tissues in dicots
C) Only primary tissues persist
D) Leaves to form on roots
Answer: A
Explanation:

A) Correct — typical dicot root undergoes secondary growth.
B/C/D) False.

Q49. The stele arrangement in young monocot stem is:

A) Single central vascular bundle only
B) Scattered vascular bundles with no clear ring; ground tissue undifferentiated into cortex/pith in many monocots
C) Concentric zones as in roots only
D) No vascular tissue at all
Answer: B
Explanation:

B) Correct — monocot stems have scattered bundles embedded in ground tissue.
A/C/D) Incorrect.

Q50. Which is the major difference between root and stem epidermis?

A) Roots lack root hairs
B) Root epidermis often lacks cuticle and stomata and has root hairs for absorption, whereas stem epidermis often has thick cuticle and stomata for transpiration control
C) Stem epidermis contains pericycle
D) Root epidermis contains phloem
Answer: B
Explanation:

B) Correct — root epidermis adapted for absorption; no stomata; thin/no cuticle.
A/C/D) Incorrect.

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Part 2 — Anatomy of Root: Primary Structure, Endodermis, Pericycle, Lateral Roots (Questions 26–50)