Part 2 — Leaf Morphology & Anatomy (Questions 26–50)
Part 2 — Leaf Morphology & Anatomy (Questions 26–50)
Q26. The main function of stomata is:
A) Water absorption only
B) Gas exchange (CO₂ in, O₂ and water vapor out) and transpiration control
C) Support of leaves
D) Production of chlorophyll
Answer: B
Explanation:
A) Root hairs absorb water.
B) Correct — stomata enable gas exchange and transpiration.
C/D) Not stomatal functions.
Q27. Pinnate venation is characteristic of:
A) Most dicots (reticulate venation with a midrib and lateral veins)
B) Monocots with parallel veins
C) Algae
D) Gymnosperms only
Answer: A
Explanation:
A) Correct — many dicots show pinnate or palmate reticulate venation.
B–D) Incorrect for pinnate.
Q28. Mesophyll is the tissue between upper and lower epidermis, composed of:
A) Palisade parenchyma (columnar chlorenchyma) and spongy parenchyma for photosynthesis and gas exchange
B) Vascular bundles only
C) Epidermis only
D) Root tissue
Answer: A
Explanation:
A) Correct — palisade cells are tightly packed; spongy parenchyma has air spaces.
B/C/D) Incorrect.
Q29. Stomata are typically more numerous on which leaf surface in dicots?
A) Upper (adaxial) surface always
B) Lower (abaxial) surface due to lesser evaporation and protection from direct sunlight
C) Equally distributed always
D) Petiole only
Answer: B
Explanation:
A) Some plants have amphistomatic leaves, but generally stomatal density is higher on lower surface in many dicots.
B) Correct.
C/D) Not general.
Q30. Xerophytic leaves have adaptations like:
A) Thin cuticle and abundant stomata
B) Thick cuticle, sunken stomata, reduced surface area, hairs and succulence to reduce water loss
C) Large broad leaves for high transpiration
D) No vascular tissue
Answer: B
Explanation:
A/C/D) Opposite of xerophytic adaptations.
B) Correct — xerophytes minimize water loss.
Q31. In dorsiventral leaf, palisade parenchyma is found on:
A) Lower side only
B) Upper adaxial side just beneath upper epidermis where light is received for photosynthesis
C) Near vascular bundles only
D) No palisade tissue present
Answer: B
Explanation:
A/C/D) Incorrect.
B) Correct — palisade cells are on upper side for efficient light absorption.
Q32. A leaf which has multiple leaflets attached to a single petiole is called:
A) Simple leaf
B) Compound leaf (e.g., pinnately compound, palmately compound)
C) Scale leaf
D) Bract
Answer: B
Explanation:
A) Simple leaf has a single blade.
B) Correct — compound leaf has several leaflets.
C/D) Different leaf types.
Q33. The midrib of a leaf is mainly formed by:
A) Epidermis only
B) Midrib contains a strong central vascular bundle (primary vein) with xylem and phloem and supporting collenchyma/sclerenchyma
C) Cuticle only
D) Stomata cluster
Answer: B
Explanation:
A/C/D) Not accurate.
B) Correct.
Q34. Which leaf type has entire margin with fine teeth?
A) Lobed margin only
B) Serrated margin (toothed) or dentate — “entire” means smooth; fine teeth = serrate or dentate; question ambiguous — If asked “entire margin” = smooth with no teeth
C) Compound leaves only
D) All leaves have fine teeth
Answer: B (clarification: entire = smooth; fine teeth = serrated/dentate)
Explanation:
Entire margin = smooth. Teeth or serrations = serrate/dentate. Choose based on exact wording.
Q35. Stipules are:
A) Small leaf-like appendages at the base of petiole in some plants (e.g., pea)
B) Root hairs
C) Flower parts only
D) Fruits
Answer: A
Explanation:
A) Correct — stipules may be leaf-like, scale-like, or spiny.
B/C/D) Incorrect.
Q36. Hydrophyte leaves often show:
A) Thick cuticle and sunken stomata
B) Thin or absent cuticle, large air spaces (aerenchyma), stomata mostly on upper surface (floating leaves) and reduced supporting tissues
C) Reduced stomata only on lower surface
D) No venation
Answer: B
Explanation:
A/C/D) Opposite adaptations.
B) Correct — hydrophytes are adapted to aquatic environments.
Q37. A sessile leaf lacks:
A) Lamina
B) Petiole (directly attached to stem)
C) Midrib
D) Stomata
Answer: B
Explanation:
A) Lamina is leaf blade present in sessile leaves too.
B) Correct — sessile leaves have no petiole.
C/D) Not defining features.
Q38. In leaf anatomy, vascular bundle is surrounded by bundle sheath cells. In C4 plants, bundle sheath cells:
A) Are not important
B) Contain chloroplasts and are site of Calvin cycle (Kranz anatomy), concentrating CO₂ to reduce photorespiration
C) Never contain chloroplasts
D) Store starch only
Answer: B
Explanation:
A/C/D) Incorrect for C4 plants.
B) Correct — Kranz anatomy.
Q39. The arrangement of veins in monocot leaves is typically:
A) Reticulate (net-like)
B) Parallel venation (longitudinal veins running parallel)
C) Dichotomous
D) Random spots
Answer: B
Explanation:
A) Reticulate is typical of dicots.
B) Correct — monocots like grasses exhibit parallel venation.
C/D) Not typical.
Q40. Which tissue stores food in leaves?
A) Spongy mesophyll (can store some) and palisade parenchyma are mainly photosynthetic; specialized leaves (succulents) store water and food in parenchyma tissues like chlorenchyma
B) Xylem only
C) Phloem only
D) Epidermis only
Answer: A
Explanation:
B/C/D) Not main storage tissue.
A) Correct with nuance: parenchyma stores reserves; palisade mainly photosynthetic.
Q41. The leaf base that clasps the stem forming a sheath in grasses is called:
A) Petiole
B) Pulvinus
C) Sheathing base (leaf sheath) — typical of monocots like grasses (Poaceae) where the base wraps the stem
D) Tendril
Answer: C
Explanation:
A) Petiole is stalk.
B) Pulvinus is a swelling at petiole base enabling movement.
C) Correct.
D) Not applicable.
Q42. Pulvinus is associated with:
A) Leaf movement (nyctinastic or seismonastic movements) due to turgor changes (e.g., Mimosa pudica, touch-me-not)
B) Water absorption only
C) Seed formation
D) Root growth
Answer: A
Explanation:
A) Correct — pulvini act as motor organs.
B/C/D) Incorrect.
Q43. Leaves modified into pitchers for carnivory (e.g., Nepenthes) mainly function to:
A) Photosynthesis only
B) Trap insects and digest them to supplement nutrients (especially nitrogen) in poor soils
C) Support climbing only
D) Seed dispersal
Answer: B
Explanation:
A) While photosynthesis still occurs, primary specialized function is carnivory.
B) Correct.
C/D) Not primary.
Q44. In compound leaf, leaflets are attached to:
A) Petiole or rachis (the continuation of petiole in pinnate leaves) and each leaflet has no axillary bud at its base (axillary buds present at base of whole leaf only)
B) Stem node always (leaflets have axillary bud)
C) Root tip
D) Flower stalk
Answer: A
Explanation:
A) Correct — a key distinction: leaflet lacks axillary bud.
B/C/D) Incorrect.
Q45. Xerophyte leaves may have all the following except:
A) Thick cuticle
B) Reduced stomatal density or sunken stomata
C) Large, thin, broad lamina with many stomata
D) Hairs/trichomes and rolled leaves
Answer: C
Explanation:
A/B/D) Xerophytic adaptations.
C) Incorrect for xerophytes — that increases transpiration.
Q46. Kranz anatomy is typical of which plants?
A) C3 plants only
B) C4 plants where mesophyll and bundle sheath cells are anatomically distinct and arranged concentrically (Kranz)
C) CAM plants only
D) Non-photosynthetic plants
Answer: B
Explanation:
A/C/D) Not describing Kranz.
B) Correct.
Q47. The cuticle of leaf is primarily composed of:
A) Cellulose only
B) Waxes (cutin and cuticular waxes) forming a hydrophobic layer to reduce water loss
C) Lignin only
D) Starch only
Answer: B
Explanation:
A/C/D) False.
B) Correct.
Q48. Which leaf type is seen in onion?
A) Dorsiventral leaf
B) Succulent leaf
C) Fleshy, modified into scales forming bulb; leaves are storage type (onion bulb composed of fleshy leaf bases)
D) Needle leaf
Answer: C
Explanation:
A/B/D) Onion is not typical of those.
C) Correct — onion leaves are modified for storage.
Q49. The stomatal apparatus consists of:
A) Guard cells and subsidiary cells forming a pore (stoma) for regulated gas exchange
B) Only epidermal cells with no specialization
C) Vascular bundle only
D) Mesophyll cells only
Answer: A
Explanation:
A) Correct.
B/C/D) Incorrect.
Q50. Heterophylly refers to:
A) Leaves of only one shape on a plant
B) Presence of different types of leaves on the same plant often due to environment or developmental stage (e.g., buttercup, aquatic plants)
C) Presence of only needles and scales
D) Root modification
Answer: B
Explanation:
A) Opposite.
B) Correct.
C/D) Not definition.