Part 1 — Root & Stem Morphology (Questions 1–25)

Part 1 — Root & Stem Morphology (Questions 1–25)

Q1. The primary function of root hairs is:

A) Photosynthesis
B) Absorption of water and minerals
C) Mechanical support only
D) Production of flowers
Answer: B
Explanation:
A) Incorrect — root hairs lack chloroplasts.
B) Correct — root hairs increase surface area for water/mineral absorption.
C) Partly true (roots anchor) but root hairs mainly absorb.
D) Incorrect — flowering is reproductive.

Q2. A tap root system is characteristic of:

A) Grasses (Poaceae)
B) Many dicots like sunflower, pea
C) Ferns
D) Bryophytes
Answer: B
Explanation:
A) Grasses have fibrous root systems.
B) Correct — many dicots develop a primary taproot.
C/D) Non-seed plants; different root-like structures.

Q3. Adventitious roots arise from:

A) Radical of embryo only
B) Any part other than radicle (stem, leaf)
C) Seed coat
D) Root cap
Answer: B
Explanation:
A) Radicle forms primary root, not adventitious.
B) Correct — adventitious roots develop from stems, leaves or nodes.
C/D) Not origin sites for adventitious roots.

Q4. Pneumatophores are:

A) Support roots of vines
B) Aerial roots of mangroves for gaseous exchange
C) Roots for photosynthesis
D) Typical storage roots of carrot
Answer: B
Explanation:
A) Support roots = prop roots.
B) Correct — pneumatophores (e.g., Avicennia) aid aeration in waterlogged soils.
C/D) Incorrect functions.

Q5. Prop roots are found in:

A) Banyan (Ficus benghalensis) and some maize varieties (adventitious brace roots)
B) All aquatic plants only
C) Root nodules for nitrogen fixation
D) Conifers only
Answer: A
Explanation:
A) Correct — banyan forms aerial prop roots that become supportive trunks.
B/C/D) Not accurate.

Q6. The root cap functions to:

A) Protect the root apical meristem and help in gravity perception
B) Absorb most water
C) Produce flowers
D) Conduct photosynthesis
Answer: A
Explanation:
A) Correct — root cap secretes mucilage, protects meristem, statoliths aid gravitropism.
B) Absorption mainly by root hairs.
C/D) Incorrect.

Q7. In a dicot stem, vascular bundles are:

A) Scattered and closed
B) Arranged in a ring and usually open (with cambium)
C) Radial in arrangement like root
D) Absent
Answer: B
Explanation:
A) Scattered and closed is monocot stem.
B) Correct — dicot stems typically have ring-arranged collateral bundles with cambium enabling secondary growth.
C) Radial is typical of roots.
D) False.

Q8. Monocot stems lack:

A) Vascular bundles
B) Pith
C) Secondary growth due to absence of vascular cambium
D) Epidermis
Answer: C
Explanation:
A) False — they have vascular bundles.
B) Many monocots do have a central ground tissue but pith concept is variable.
C) Correct — monocot stems generally lack a continuous vascular cambium and so do not undergo normal secondary thickening.
D) Epidermis is present.

Q9. Lenticels are:

A) Small pores on leaves for transpiration
B) Pores on stems and roots that allow gas exchange in periderm
C) Root hairs in seedlings
D) Flower buds
Answer: B
Explanation:
A) Stomata are leaf pores.
B) Correct — lenticels occur on bark/periderm for gas exchange.
C/D) Incorrect.

Q10. Secondary growth in plants results from activity of:

A) Apical meristem only
B) Lateral meristems (vascular cambium and cork cambium)
C) Root hairs
D) Guard cells
Answer: B
Explanation:
A) Apical meristem causes primary growth (length).
B) Correct — vascular cambium produces secondary xylem/phloem; cork cambium produces periderm.
C/D) Not meristem sources.

Q11. In woody dicots, wood toward the inner side of vascular cambium is called:

A) Secondary phloem
B) Secondary xylem (wood)
C) Primary xylem
D) Cortex
Answer: B
Explanation:
A) Secondary phloem is produced to the outer side.
B) Correct — secondary xylem accumulates as wood.
C/D) Not correct in this context.

Q12. Which feature distinguishes monocot stem anatomy from dicot?

A) Vascular bundles in ring
B) Scattered vascular bundles and absence of cambium
C) Presence of secondary xylem
D) Pith absent always
Answer: B
Explanation:
A) Dicot stems.
B) Correct — monocot stems have scattered collateral bundles and usually lack cambium.
C) Secondary xylem = wood, uncommon in monocots.
D) Pith may or may not be distinct in monocots.

Q13. Haustoria are specialized roots of:

A) Parasitic plants to penetrate host tissues and absorb nutrients (e.g., Cuscuta, Orobanche)
B) Aquatic plants for buoyancy
C) Legumes for nodulation
D) Grasses for photosynthesis
Answer: A
Explanation:
A) Correct — haustoria are invasive organs that connect parasite to host vascular tissues.
B/C/D) Incorrect.

Q14. Mycorrhiza is a symbiotic association between:

A) Root nodules and bacteria
B) Fungal hyphae and roots that enhances mineral uptake, particularly phosphorus
C) Leaves and algae
D) Stem and nematodes
Answer: B
Explanation:
A) Root nodules associate with rhizobia (bacteria) for N fixation, different symbiosis.
B) Correct — mycorrhizae improve nutrient/water uptake and confer stress tolerance.
C/D) Irrelevant.

Q15. In roots, Casparian strip is located in:

A) Epidermis cell walls
B) Endodermis cell walls (suberinized band) — controls apoplastic flow into stele
C) Pericycle only
D) Root cap
Answer: B
Explanation:
A/C/D) Incorrect.
B) Correct — Casparian strip forces selective entry via symplast.

Q16. Pericycle in root gives rise to:

A) Root cap
B) Lateral roots and contributes to vascular cambium in dicots
C) Epidermis
D) Stomata
Answer: B
Explanation:
A/C/D) Not produced by pericycle.
B) Correct — pericycle cells re-enter cell cycle to form lateral root primordia; in secondary growth they may contribute to cambium.

Q17. Which stem modification stores water and shows thickened fleshy tissues?

A) Rhizome
B) Bulb
C) Succulent stems (e.g., Opuntia — cactus pads)
D) Stolon
Answer: C
Explanation:
A) Rhizome = underground stem for perennation (ginger).
B) Bulb = leaf base storage (onion).
C) Correct — succulent stems store water.
D) Stolon = above-ground runner.

Q18. Tendrils are modified:

A) Roots only
B) Stems or leaves that coil and provide climbing support (e.g., pea tendrils are modified leaflets; Bignonia tendrils are modified stems)
C) Flowers
D) Seeds
Answer: B
Explanation:
A/C/D) Not general.
B) Correct — tendrils may be modified leaves, leaflets, or stems depending on species.

Q19. The term “decussate” refers to leaf arrangement where:

A) Leaves are alternate on one plane only
B) Opposite pairs are at right angles to the pairs above and below (e.g., many Lamiaceae)
C) Leaves are whorled with many per node
D) Leaves are spiral with no pattern
Answer: B
Explanation:
A/C/D) Incorrect patterns.
B) Correct — decussate opposite leaves at right angles.

Q20. The arrangement of xylem and phloem in a typical dicot root is:

A) Vascular bundles scattered
B) Central xylem in X or star shape with phloem between arms (radial arrangement)
C) Concentric with xylem surrounding phloem
D) None of the above
Answer: B
Explanation:
A) Stems of monocots.
B) Correct — dicot root shows centrally located xylem forming radiating arms.
C) Concentric types (e.g., amphicribral) are rare.

Q21. The region of stem where leaves and buds are attached is called:

A) Node
B) Internode
C) Apex
D) Petiole
Answer: A
Explanation:
A) Correct — node bears leaves and axillary buds.
B) Internode is the region between nodes.
C/D) Not nodes.

Q22. Cladodes are:

A) Photosynthetic flattened stems that resemble leaves (e.g., Asparagus, Ruscus)
B) Modified roots for storage
C) Seed appendages
D) Flower parts
Answer: A
Explanation:
A) Correct — cladodes perform photosynthesis in place of leaves.
B/C/D) Incorrect.

Q23. In vascular bundles of dicot stem, the phloem is located:

A) Towards inner side of bundle only
B) Towards the outer side of bundle (external to xylem)
C) Completely surrounding xylem in concentric manner always
D) Absent
Answer: B
Explanation:
A) Wrong orientation.
B) Correct — typical collateral vascular bundle has phloem outer to xylem.
C/D) Not general.

Q24. Aerial roots that help in fixation and gas exchange in epiphytic orchids are called:

A) Prop roots
B) Haustoria
C) Velamen roots (with spongy multilayered epidermis)
D) Rhizoids
Answer: C
Explanation:
A) Prop roots support ground-based plants.
B) Haustoria are parasitic.
C) Correct — velamen helps water retention and gas exchange in epiphytic orchids.
D) Rhizoids belong to bryophytes/fungi.

Q25. What is phyllotaxy?

A) Arrangement of flowers on an inflorescence
B) Arrangement of leaves on the stem (alternate, opposite, whorled)
C) Root branching pattern
D) Seed dispersal mechanism
Answer: B
Explanation:
A) Inflorescence arrangement = inflorescence type.
B) Correct — phyllotaxy describes leaf arrangement on stem.
C/D) Different concepts.

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