Worksheet with Solutions: Anatomy of Flowering Plants | Biology Class 11 - NEET PDF Download

Ans: Epidermis

Ans: Cuticle

Ans: Endodermis

Ans: Conjunctive

Ans: Bulliform

Ans: a-ii, b-i, c-iii, d-iv, e-v

Ans: (c) Epidermal tissue system

Ans: (b) Presence of cambium

Ans: (b) Casparian strips on radial walls

Ans: (b) Monocot root

Ans: (b) Undifferentiated parenchyma

Ans: (a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
The assertion is true because vascular bundles in dicot stems are indeed arranged in a ring. The reason is also true, as the arrangement of vascular bundles with cambium between them allows for secondary growth. The reason directly explains the assertion because the presence of cambium in the vascular bundles is the mechanism that enables secondary growth. Thus, the correct answer is (a): "Both assertion and reason are true, and the reason is the correct explanation of the assertion."

Ans: (c) Assertion is false, but the reason is true.
The assertion is false because monocot roots do not undergo secondary growth due to the absence of cambium. However, the reason is true because monocot roots lack cambium, which is a prerequisite for secondary growth. Therefore, the correct answer is (c): "Assertion is false, but the reason is true."

Ans:
The epidermal tissue system includes:

• Epidermis: A single layer of compactly arranged parenchymatous cells (e.g., in sunflower stem). It protects against physical damage and pathogens.

• Cuticle: A waxy layer on the epidermis (absent in roots) that prevents water loss (e.g., in dicot leaves).

• Stomata: Structures with guard cells (bean-shaped in dicots, dumb-bell shaped in grasses) regulating transpiration and gas exchange. Subsidiary cells surround the stomatal pore, forming the stomatal apparatus.

• Trichomes: Multicellular hairs on stems (e.g., in dicot stems) that reduce transpiration and deter herbivores. Root hairs (unicellular, e.g., in sunflower roots) aid in water and mineral absorption. These components collectively ensure protection, water conservation, and environmental interaction.

Ans: The vascular tissue system comprises xylem and phloem, forming vascular bundles:

• Radial: Xylem and phloem alternate along different radii, common in roots (e.g., sunflower root).

• Conjoint: Xylem and phloem are on the same radius, typical in stems and leaves.

  • Open: Contains cambium for secondary growth, found in dicot stems (e.g., sunflower stem).

  • Closed: Lacks cambium, found in monocot stems (e.g., maize stem).
    Differences:

• Dicots: Vascular bundles are arranged in a ring, conjoint, open, with endarch protoxylem (e.g., sunflower stem). Cambium enables secondary growth.

• Monocots: Vascular bundles are scattered, conjoint, closed, with sclerenchymatous bundle sheaths (e.g., maize stem). No secondary growth occurs. These arrangements reflect adaptations for transport and structural needs.

 Various types of vascular bundles : (a) radial (b) conjoint closed (c) conjoint open

Ans: Guard cells, found in pairs around the stomatal pore, regulate the opening and closing of stomata. They contain chloroplasts and have thickened inner walls (e.g., bean-shaped in dicots). Changes in turgor pressure cause them to open (turgid) or close (flaccid), controlling transpiration and gas exchange.

Ans:

• Collenchyma: Living cells with unevenly thickened cellulose walls, providing flexible mechanical support (e.g., in hypodermis of dicot stem).

• Sclerenchyma: Dead cells with uniformly thickened lignified walls, offering rigid support (e.g., in pericycle of dicot stem).

Ans: The pericycle, a layer of thick-walled parenchymatous cells next to the endodermis in dicot roots (e.g., sunflower), initiates lateral root formation and contributes to the vascular cambium during secondary growth.

Ans: The bundle sheath, a layer of thick-walled cells surrounding vascular bundles in leaves (e.g., in dicot leaves), provides structural support and regulates the flow of materials between vascular tissues and mesophyll, aiding in efficient transport.

Ans: Medullary rays, radially placed parenchymatous cells between vascular bundles in dicot stems (e.g., sunflower), facilitate radial transport of water, nutrients, and gases between the pith and cortex, supporting metabolic activities.

Ans: The sclerenchymatous hypodermis in monocot stems (e.g., maize) provides mechanical strength, supporting the stem against bending and external pressures.

Ans: The stele is the central part of the root, comprising all tissues inside the endodermis, including the pericycle, vascular bundles, pith, and conjunctive tissue (e.g., in sunflower root).

Ans: Mesophyll in dicot leaves (e.g., sunflower) consists of palisade parenchyma (elongated, chloroplast-rich cells for photosynthesis) and spongy parenchyma (loosely arranged cells with air spaces for gas exchange), enabling efficient photosynthesis and respiration.

Ans: The ground tissue system, comprising all tissues except epidermis and vascular bundles, forms the bulk of the plant body and includes:

• Parenchyma: Thin-walled, living cells for storage, photosynthesis, and secretion (e.g., cortex and pith in sunflower stem, mesophyll in leaves).

• Collenchyma: Living cells with thickened cellulose walls for flexible support (e.g., hypodermis in dicot stem).

• Sclerenchyma: Dead, lignified cells for rigid support (e.g., pericycle patches in dicot stem).
  Functions:

• Storage: Parenchyma stores nutrients (e.g., in cortex of roots).

• Photosynthesis: Chloroplast-containing mesophyll in leaves (e.g., sunflower).

• Support: Collenchyma and sclerenchyma provide mechanical strength (e.g., in stems). These tissues support diverse physiological roles, adapting plants to various environments.

Ans: Dicot and monocot roots differ in their internal structure:

• Dicot Root (e.g., sunflower):

  • Epiblema: Outermost layer with root hairs.

  • Cortex: Parenchymatous with intercellular spaces.

  • Endodermis: Single layer with casparian strips.

  • Vascular Bundles: 2–4 xylem and phloem patches, radial, with cambium forming later for secondary growth.

  • Pith: Small or inconspicuous.

• Monocot Root (e.g., maize):

  • Epiblema: Similar, with root hairs.

  • Cortex: Parenchymatous, similar to dicot.

  • Endodermis: With casparian strips.

  • Vascular Bundles: Polyarch (>6 xylem patches), radial, closed (no cambium), no secondary growth.

  • Pith: Large and well-developed. These differences reflect adaptations for water absorption and structural support, with dicots suited for secondary growth.

(a) Dicot root (Primary) (b) Monocot root

Ans: The dicotyledonous stem (e.g., sunflower) has:

• Epidermis: Outermost layer with cuticle, stomata, and trichomes for protection and gas exchange.

• Cortex: Includes collenchymatous hypodermis (mechanical support), parenchymatous cortical layers (storage), and endodermis (starch sheath).

• Vascular Bundles: Arranged in a ring, conjoint, open, with endarch protoxylem, enabling secondary growth via cambium.

• Pericycle: Sclerenchymatous patches above phloem for support.

• Medullary Rays: Parenchyma for radial transport.

• Pith: Central parenchymatous tissue for storage.

• Functional Significance: The ring arrangement and cambium support secondary growth, increasing girth. The cortex and pith store nutrients, while the hypodermis and pericycle provide mechanical strength, ensuring structural integrity and resource distribution.

Ans: Monocotyledonous leaves (e.g., maize, grasses) have anatomical adaptations:

• Isobilateral Structure: Stomata on both epidermal surfaces (adaxial and abaxial) maximize gas exchange.

• Undifferentiated Mesophyll: Uniform parenchymatous cells with chloroplasts ensure efficient photosynthesis across the leaf (unlike dicot’s palisade/spongy differentiation).

• Bulliform Cells: Large, empty adaxial epidermal cells that curl leaves inward when flaccid, reducing water loss during stress (e.g., in grasses).

• Parallel Venation: Uniform vascular bundles (except main veins) ensure consistent water and nutrient supply for photosynthesis. Significance: These adaptations allow monocots to thrive in open, sunny habitats, balancing high photosynthetic rates with water conservation, critical for survival in variable climates.

Ans: Dorsiventral (Dicot) Leaf (e.g., sunflower):

• Epidermis: More stomata on abaxial surface, cuticle on both.

• Mesophyll: Differentiated into palisade (adaxial, elongated cells) and spongy parenchyma (abaxial, loose with air spaces).

• Vascular Bundles: Vary in size, surrounded by bundle sheath, reflecting reticulate venation.

• Bulliform Cells: Absent.

• Isobilateral (Monocot) Leaf (e.g., maize):

  • Epidermis: Stomata on both surfaces, cuticle present.

  • Mesophyll: Undifferentiated, uniform parenchymatous cells with chloroplasts.

  • Vascular Bundles: Similar in size (except main veins), with sclerenchymatous bundle sheath, reflecting parallel venation.

  • Bulliform Cells: Present, aid in leaf curling to reduce water loss. Key Difference: Dorsiventral leaves optimize photosynthesis via specialized mesophyll, while isobilateral leaves balance photosynthesis and water conservation with uniform mesophyll and bulliform cells.