60+ Questions & Answers - NCERT Based (Class 11)
Structured as Part A (1 mark, short answers), Part B (4 marks, ~6 lines answers), Part C (8 marks, detailed). 20 per part, based on chapter content, with answers matching the mark scheme.
Part A: 1 Mark Questions (Short Answers)
1. What is plant anatomy?
1 Mark Answer: Study of internal structure.
2. Basic unit of plants?
1 Mark Answer: Cells.
3. Three tissue systems?
1 Mark Answer: Epidermal, ground, vascular.
4. Epidermis covering?
1 Mark Answer: Cuticle.
5. Stomata regulate?
1 Mark Answer: Transpiration/exchange.
6. Guard cells shape in grasses?
1 Mark Answer: Dumb-bell.
7. Root hairs type?
1 Mark Answer: Unicellular.
8. Trichomes type?
1 Mark Answer: Multicellular.
9. Ground tissue includes?
1 Mark Answer: Parenchyma/collenchyma/sclerenchyma.
10. Mesophyll in leaves?
1 Mark Answer: Ground tissue.
11. Vascular bundles consist of?
1 Mark Answer: Xylem/phloem.
12. Open bundles have?
1 Mark Answer: Cambium.
13. Radial bundles in?
1 Mark Answer: Roots.
14. Conjoint in?
1 Mark Answer: Stems/leaves.
15. Epiblema in?
1 Mark Answer: Roots.
16. Casparian strips in?
1 Mark Answer: Endodermis.
17. Pericycle initiates?
1 Mark Answer: Laterals/cambium.
18. Polyarch in?
1 Mark Answer: Monocot roots.
19. Hypodermis in dicot stem?
1 Mark Answer: Collenchymatous.
20. Bulliform cells in?
1 Mark Answer: Monocot leaves.
Part B: 4 Marks Questions (Answers in ~6 Lines)
1. Define epidermal tissue system.
4 Marks Answer: Outermost covering: Epidermis, stomata, appendages. Epidermis single-layered, cuticle-covered. Stomata regulate exchange with guard cells. Appendages: Root hairs unicellular, trichomes multicellular for protection.
2. Explain stomata structure.
4 Marks Answer: Pore enclosed by guard cells (bean/dumb-bell). Inner walls thick, possess chloroplasts. Subsidiary cells specialize. Apparatus: Aperture, guards, subsidiaries. Regulate opening/closing.
3. Role of trichomes.
4 Marks Answer: Multicellular hairs on shoots; branched/unbranched, soft/stiff, secretory. Prevent water loss, deter herbivores, reflect light. Example: In shoots for transpiration reduction.
4. Describe ground tissue.
4 Marks Answer: Except epidermis/vascular: Parenchyma (storage), collenchyma (support), sclerenchyma (rigidity). In leaves: Mesophyll. Cortex, pericycle, pith in stems/roots.
5. Vascular bundles types.
4 Marks Answer: Open (cambium, secondary growth), closed (no cambium). Radial (roots), conjoint (stems/leaves; phloem outer).
6. Dicot root anatomy.
4 Marks Answer: Epiblema with hairs, parenchyma cortex, endodermis (casparian), pericycle, 2-4 bundles, small pith. Stele inner to endodermis.
7. Monocot root difference.
4 Marks Answer: Similar but polyarch bundles (>6), large pith, no secondary growth.
8. Dicot stem cortex.
4 Marks Answer: Hypodermis collenchyma, parenchyma layers, endodermis (starch sheath).
9. Monocot stem bundles.
4 Marks Answer: Scattered, closed, sclerenchymatous sheath, water cavities.
10. Dorsiventral leaf mesophyll.
4 Marks Answer: Palisade (elongated, adaxial), spongy (loose, abaxial with cavities).
11. Isobilateral leaf feature.
4 Marks Answer: Undifferentiated mesophyll, stomata both sides, bulliform cells.
12. Casparian strips role.
4 Marks Answer: Water-impermeable in endodermis; force selective absorption.
13. Endarch vs exarch.
4 Marks Answer: Endarch: Protoxylem inner (stems); exarch: Outer (roots).
14. Bulliform cells function.
4 Marks Answer: Absorb water to expose surface; flaccid curl leaves to reduce loss.
15. Bundle sheath in leaves.
4 Marks Answer: Thick-walled around veins; regulates flow.
16. Starch sheath.
4 Marks Answer: Endodermis in stems with starch grains.
17. Medullary rays.
4 Marks Answer: Parenchyma between bundles in stems; radial transport.
18. Conjunctive tissue.
4 Marks Answer: Between bundles in roots; forms cambium later.
19. Hypodermis in monocot stem.
4 Marks Answer: Sclerenchymatous for support.
20. Venation in dicot leaves.
4 Marks Answer: Reticulate; bundle size varies.
Part C: 8 Marks Questions (Detailed Answers)
1. Discuss epidermal tissue system in detail.
8 Marks Answer: Forms outermost covering of plant body, including epidermal cells, stomata, and appendages like trichomes and hairs. The epidermis is a single layer of elongated, compactly arranged parenchymatous cells with a small amount of cytoplasm and a large vacuole. It is covered by a waxy cuticle that prevents water loss, but the cuticle is absent in roots. Stomata are present in the epidermis of leaves and regulate transpiration and gaseous exchange. Each stoma consists of two bean-shaped guard cells (dumb-bell shaped in grasses) that enclose the stomatal pore. The guard cells have thin outer walls and thick inner walls, possess chloroplasts, and control opening and closing. Subsidiary cells are specialized epidermal cells near the guard cells. The stomatal apparatus includes the pore, guard cells, and subsidiary cells. Root hairs are unicellular elongations of epidermal cells that absorb water and minerals from the soil. Trichomes on stems are multicellular, branched or unbranched, soft or stiff, and may be secretory, helping prevent water loss due to transpiration. This system provides protection, regulates gas exchange, and aids in absorption, with adaptations like thicker cuticles in xerophytes for drought resistance.
2. Explain ground tissue system with examples.
8 Marks Answer: The ground tissue system includes all tissues except the epidermis and vascular bundles, consisting of simple tissues such as parenchyma, collenchyma, and sclerenchyma. Parenchymatous cells are thin-walled and usually present in the cortex, pericycle, pith, and medullary rays in primary stems and roots. In leaves, the ground tissue is called mesophyll and consists of thin-walled cells containing chloroplasts for photosynthesis. Collenchyma provides mechanical support with thickened cell walls at corners, found in hypodermis of young dicot stems for flexibility during growth. Sclerenchyma has lignified thick walls, providing rigidity, and is found in bundle sheaths or pericycle in stems. Examples include the cortex in roots for storage and aeration, pith in stems for lightweight support, and mesophyll in leaves for gas diffusion via air spaces. This system forms the main bulk of the plant, functioning in storage (e.g., starch in parenchyma), mechanical support (collenchyma in growing parts, sclerenchyma in mature), and photosynthesis (chlorenchyma). Adaptations include aerenchyma in aquatic plants with large air cavities for buoyancy and oxygen transport, ensuring survival in waterlogged soils.
3. Describe vascular tissue system and its types.
8 Marks Answer: The vascular tissue system consists of complex tissues, xylem and phloem, which together form vascular bundles for conduction. Xylem transports water and minerals, composed of tracheids, vessels, fibers, and parenchyma. Phloem transports food, including sieve tubes, companion cells, fibers, and parenchyma. In dicot stems, cambium is present between xylem and phloem, making bundles open for secondary growth. Monocots have closed bundles without cambium, preventing secondary tissues. Arrangements include radial (xylem and phloem on different radii, common in roots) and conjoint (on the same radius, in stems and leaves, with phloem usually outer to xylem). Figure 6.2 illustrates radial, conjoint closed, and conjoint open bundles. This system provides mechanical support besides conduction, with xylem being lignified for strength. Adaptations: In roots, exarch xylem (protoxylem outer) aids absorption; in stems, endarch (inner) for upward transport. Open bundles allow woody growth in dicots, while closed suit herbaceous monocots. Overall, vascular bundles translocate essentials, with variations reflecting plant types and environments.
4. Compare dicot and monocot root anatomy.
8 Marks Answer: Both have similar basic structure: Epidermis (epiblema with root hairs for absorption), cortex (parenchyma with intercellular spaces for storage), endodermis (barrel-shaped cells with casparian strips for regulation), pericycle (initiates laterals and cambium), vascular bundles, and pith. However, dicot roots have 2-4 xylem and phloem patches (diarch to tetrarch), small or inconspicuous pith, and undergo secondary growth via cambium ring between bundles. Conjunctive tissue (parenchyma between bundles) later forms cambium. The stele includes pericycle inward. In contrast, monocot roots have more than 6 xylem bundles (polyarch), large and well-developed pith for storage, and no secondary growth due to absence of cambium. Figure 6.3 shows T.S. of sunflower (dicot) and typical monocot root. Differences reflect lifestyles: Dicots often perennial with thickening roots; monocots fibrous, herbaceous. Both exarch (protoxylem outer, metaxylem inner). These variations aid classification and understanding functions like efficient conduction in monocots' multiple bundles.
5. Explain dicot stem anatomy in detail.
8 Marks Answer: The transverse section of a young dicot stem shows epidermis as the outermost protective layer, covered with cuticle, bearing trichomes and stomata for protection and gas exchange. The cortex consists of hypodermis (few layers of collenchyma just below epidermis for mechanical strength in growing stems), rounded parenchymatous cells with intercellular spaces for storage and aeration, and innermost endodermis (starch sheath rich in grains). Pericycle is inner to endodermis, as semi-lunar sclerenchyma patches above phloem for support. Medullary rays are radially placed parenchyma between vascular bundles for lateral transport. Vascular bundles are arranged in a ring, each conjoint, open (with cambium), and endarch (protoxylem inner). This arrangement is characteristic of dicots, allowing secondary growth. Central pith is large, parenchymatous with intercellular spaces for storage and lightness. Figure 6.4(a) illustrates this. The structure provides support (hypodermis, pericycle), conduction (bundles), and storage (pith, rays), with adaptations like open bundles for woody perennial growth.
6. Describe monocot stem anatomy.
8 Marks Answer: The monocot stem has a sclerenchymatous hypodermis for rigid support, lacking collenchyma. Vascular bundles are numerous and scattered throughout the stem, each surrounded by a sclerenchymatous bundle sheath for protection and strength. Bundles are conjoint and closed (no cambium, no secondary growth), with peripheral bundles generally smaller than central ones. Phloem parenchyma is absent, and water-containing cavities are present within bundles for storage in dry conditions. The ground tissue is large, conspicuous, and parenchymatous, filling the space between bundles. Figure 6.4(b) shows this structure. This anatomy suits herbaceous, flexible grasses that bend without breaking, with scattered bundles providing even distribution of strength and conduction. No medullary rays or distinct pith like dicots. Adaptations include cavities for water retention in monocots like maize, and closed bundles limiting size but enabling quick growth in annuals.
7. Discuss dorsiventral leaf anatomy.
8 Marks Answer: The vertical section of a dorsiventral (dicot) leaf shows epidermis, mesophyll, and vascular system. Epidermis covers both adaxial (upper) and abaxial (lower) surfaces with cuticle; abaxial has more stomata for transpiration. Mesophyll between epidermises possesses chloroplasts for photosynthesis, differentiated into palisade parenchyma (adaxially placed, elongated vertical cells for maximum light absorption) and spongy parenchyma (below, oval/round, loosely arranged with large air spaces for gas diffusion and cavities). Vascular system includes bundles in veins and midrib, size dependent on vein thickness in reticulate venation. Bundles surrounded by thick-walled bundle sheath cells for regulation. Figure 6.5(a) shows xylem position (adaxial). This structure optimizes photosynthesis (palisade) and exchange (spongy), with adaptations like fewer adaxial stomata to reduce water loss in sun-exposed leaves.
8. Explain isobilateral leaf anatomy.
8 Marks Answer: The isobilateral (monocot) leaf anatomy is similar to dorsiventral but with characteristic differences: Stomata present on both surfaces for balanced exchange; mesophyll not differentiated into palisade and spongy, consisting of uniform parenchyma with chloroplasts. In grasses, certain adaxial epidermal cells modify into large, empty, colorless bulliform cells that absorb water to expose the leaf surface when turgid; when flaccid due to stress, they curl leaves inward to minimize water loss. Parallel venation reflects near-similar vascular bundle sizes (except main veins) in vertical sections. Figure 6.5(b) illustrates this. The symmetric structure suits vertical, narrow leaves like in grasses, optimizing light capture on both sides. Bulliform cells are key adaptations for drought tolerance, reducing transpiration by curling. Undifferentiated mesophyll ensures efficient photosynthesis in uniform layers.
9. Role of endodermis in roots and stems.
8 Marks Answer: In roots, endodermis is the innermost cortex layer, consisting of a single layer of barrel-shaped cells without intercellular spaces. Tangential and radial walls have water-impermeable suberin deposits as casparian strips, forcing selective absorption via symplast path for ion control. It regulates flow from cortex to stele, preventing backflow. In stems, endodermis is also innermost cortex, rich in starch grains (starch sheath), functioning in storage rather than regulation. Example: In dicot roots, next to pericycle; in stems, below hypodermis. Significance: In roots, ensures nutrient selectivity, aids root pressure; in stems, stores reserves for growth. Adaptations: Thicker strips in xerophytes for conservation; absent or modified in aquatics.
10. Compare dicot and monocot stem anatomy.
8 Marks Answer: Dicot stems have epidermis with cuticle/trichomes/stomata, cortex with collenchymatous hypodermis for flexible support, parenchymatous layers, and starch sheath endodermis. Pericycle sclerenchymatous, bundles in ring (conjoint open, endarch), medullary rays between, large pith. Allows secondary growth. Monocot stems have sclerenchymatous hypodermis for rigidity, scattered closed bundles with sclerenchymatous sheaths and water cavities, no phloem parenchyma, large parenchymatous ground tissue without distinct rays/pith division. No secondary growth. Figure 6.4 compares. Dicots suit woody perennials (thickening), monocots herbaceous flexibility (scatter for even strength). Adaptations: Dicots ring for stability; monocots cavities for hydration in grasses.
11. Discuss adaptations in plant anatomy to environments.
8 Marks Answer: Plant anatomy shows adaptations to diverse environments. In xerophytes, thick cuticle and sunken stomata reduce transpiration; trichomes reflect light. Casparian strips in endodermis ensure water conservation. In hydrophytes, aerenchyma (air cavities in parenchyma) aids buoyancy and oxygen transport in waterlogged soils; reduced vascular tissues. In mesophytes, balanced structures like differentiated mesophyll optimize photosynthesis. Bulliform cells in monocot leaves curl to minimize loss in dry conditions. Open bundles in dicots allow secondary growth for tall woody plants in forests. Radial bundles in roots efficient for soil absorption. These adaptations enhance survival, like polyarch in monocot roots for fibrous systems in grasses, or large pith in monocots for storage in variable climates.
12. Explain stomatal apparatus with diagram reference.
8 Marks Answer: The stomatal apparatus includes the stomatal aperture (pore), two guard cells, and surrounding subsidiary cells. Guard cells are bean-shaped in dicots (thin outer, thick inner walls) and dumb-bell in monocots (grasses), possessing chloroplasts for photosynthesis-dependent opening. Inner walls thicken toward pore; outer thin for flexibility. Subsidiary cells specialize in shape/size near guards. Figure 6.1 shows bean and dumb-bell types. Apparatus regulates transpiration and CO2 intake; opens when guard cells turgid (K+ influx, water entry), closes when flaccid. Significance: Balances water loss and gas exchange; more on abaxial leaf surface to reduce evaporation. Adaptations: In xerophytes, fewer/sunken; in aquatics, on upper surface (epistomatic).
13. Describe secondary growth in dicots.
8 Marks Answer: Secondary growth occurs in dicot roots and stems due to open vascular bundles with cambium. In stems, cambium between xylem/phloem divides to form secondary xylem inward (wood) and phloem outward (bark). Pericycle contributes to cork cambium for periderm. In roots, conjunctive tissue and pericycle form cambium ring between bundles. Results in thickening, annual rings from seasonal activity. No such in monocots (closed bundles). Significance: Enables perennial life, tall trees; provides mechanical strength. Adaptations: In tropical areas, continuous growth; temperate, seasonal rings for age determination. Figure references: Bundles in 6.2, 6.3, 6.4 show open types.
14. Compare leaf anatomy in dicots and monocots.
8 Marks Answer: Dicot leaves are dorsiventral: Adaxial/abaxial epidermis differ (more stomata abaxial), mesophyll differentiated into palisade (vertical, compact for light capture) and spongy (loose with cavities for diffusion), reticulate venation with varying bundle sizes, bundle sheaths. Monocot leaves isobilateral: Stomata both sides, undifferentiated mesophyll, parallel venation with similar bundles, bulliform cells on adaxial for curling in stress. Figure 6.5 compares. Dicots optimize for broad leaves in varied light; monocots for narrow vertical leaves in grasses. Adaptations: Dicots more palisade in sun leaves; monocots bulliform for arid grasslands.
15. Role of pericycle in plant growth.
8 Marks Answer: Pericycle is a few layers of thick-walled parenchymatous cells inner to endodermis in roots and stems. In roots, initiates lateral roots (from primordia) and vascular cambium for secondary growth. In stems, forms semi-lunar sclerenchyma patches above phloem for support. Example: In dicot roots, opposite protoxylem. Significance: Key for branching (increases absorption area) and thickening (secondary tissues). In monocots, similar but no cambium initiation. Adaptations: In fibrous roots, prolific laterals; in taproots, deeper penetration. Without pericycle activity, plants limited in spread and strength.
16. Explain bundle arrangements and their significance.
8 Marks Answer: Vascular bundles arranged as radial (alternate on different radii in roots for separate conduction paths, efficient absorption) or conjoint (same radius in stems/leaves for coordinated transport). Conjoint open (cambium, dicot stems/roots for secondary growth) or closed (no cambium, monocots). Ring in dicot stems for stability, scattered in monocots for flexibility. Figure 6.2 shows types. Significance: Radial suits root penetration; conjoint endarch in stems for upward flow. Open allows woody growth; closed herbaceous. Adaptations: Scattered in wind-prone grasses; ring in trees for height.
17. Discuss mesophyll types and functions.
8 Marks Answer: Mesophyll is leaf ground tissue with chloroplasts for photosynthesis. In dicots (dorsiventral), palisade (adaxial, elongated parallel cells for high light absorption, dense chloroplasts) and spongy (abaxial, loose round cells with air cavities for CO2 diffusion/O2 exit). In monocots (isobilateral), undifferentiated uniform parenchyma. Figure 6.5. Functions: Palisade maximizes capture; spongy facilitates exchange/transpiration. Significance: 80% photosynthesis here; air spaces store gases. Adaptations: Thicker palisade in sun leaves; more spongy in shade for diffusion.
18. Importance of cuticle and its variations.
8 Marks Answer: Cuticle is waxy layer on epidermis preventing water loss, pathogen entry, UV damage. Thick in xerophytes (cacti) for conservation; thin/absent in hydrophytes for absorption. Absent in roots for uptake. Example: In leaves/stems. Significance: Reduces transpiration (90% cuticular in some), maintains turgor. Variations: Thicker in arid (epicuticular wax crystals reflect light); glossy in tropics for runoff. Without cuticle, plants dehydrate quickly; key adaptation for terrestrial life.
19. Explain pith and its role.
8 Marks Answer: Pith is central parenchymatous tissue with large intercellular spaces for storage and lightness. Small/inconspicuous in dicot roots, large/well-developed in monocots for water/food reserves. In stems, occupies center, may degenerate in maturity. Example: In sunflower root small; in maize large. Role: Stores starch/water; provides buoyancy in some; rays connect to cortex. Significance: In drought, supplies moisture; in herbs, reduces weight. Adaptations: Large in succulents; aerenchymatous in aquatics.
20. Summarize chapter key points.
8 Marks Answer: Anatomy studies plant internal structure: Cells to tissues to organs. Tissue systems: Epidermal (protection, exchange via stomata), ground (bulk, support/storage/photosynthesis), vascular (conduction via bundles). Dicots/monocots differ: Dicots open bundles, secondary growth, ring stems, dorsiventral leaves; monocots closed, scattered, isobilateral. Roots exarch, stems endarch. Adaptations to environments: Cuticle/trichomes for dry, aerenchyma for wet. Functions: Transport, support, assimilation. Importance: Classification, agriculture (e.g., breeding), ecology.
Practice Tip: Draw labeled diagrams; focus on comparisons.
