Below are 41 practice questions on Anatomy of Flowering Plants, sorted Easy → Hard. Tap “Show answer & explanation” under any question to check yourself. Want the full theory first? Read the Anatomy of Flowering Plants notes.
🔬 Biology · Class 11 · NEET
Anatomy of Flowering Plants — Practice Questions with Answers
41 free MCQs on Anatomy of Flowering Plants with worked answers and explanations. Internal tissue organisation: meristems, permanent tissues (xylem, phloem, parenchyma), and secondary growth. Frequently tested in NEET.
Take the timed Anatomy of Flowering Plants quiz →Easy — 12 questions
Q1.
Which tissue in plants is responsible for growth?
- A Permanent tissue
- B Protective tissue
- C Meristematic tissue
- D Vascular tissue
Show answer & explanation
Answer: C. Meristematic tissue
Why: Meristematic tissue consists of actively dividing cells. Apical meristems are at shoot and root tips (primary growth). Lateral meristems (cambium) increase girth (secondary growth).
Q2.
What is the function of xylem in plants?
- A Transport food sugars from leaves down to roots
- B Transport water and minerals from roots to leaves
- C Provide structural support to the stem alone
- D Store starch reserves within the pith tissue
Show answer & explanation
Answer: B. Transport water and minerals from roots to leaves
Why: Xylem conducts water and dissolved minerals from roots upward to all parts of the plant. It also provides mechanical support. Xylem flow is one-directional (upward).
Q3.
Which plant tissue transports food (sugars) from leaves to other parts?
- A Xylem
- B Phloem
- C Parenchyma
- D Collenchyma
Show answer & explanation
Answer: B. Phloem
Why: Phloem transports organic compounds (mainly sucrose) from leaves (source) to all other parts (sink) like roots, fruits, and growing tips. This is called translocation.
Q4.
What is the primary function of leaves?
- A Water absorption from the surrounding soil
- B Anchorage of the plant within the soil
- C Photosynthesis and gas exchange
- D Reproduction occurring only through flowers
Show answer & explanation
Answer: C. Photosynthesis and gas exchange
Why: Leaves are the primary site of photosynthesis. They also perform gas exchange (CO2 in, O2 out during day) and transpiration through stomata.
Q5.
The outermost layer of a plant root is called
- A Endodermis
- B Cortex
- C Epidermis
- D Pericycle
Show answer & explanation
Answer: C. Epidermis
Why: The epidermis is the outermost single-cell layer covering the root. Root hair cells extend from the root epidermis and greatly increase the surface area for water and mineral absorption.
Q6.
Which of the following is a modification of the root for breathing?
- A Prop root
- B Tap root
- C Pneumatophore
- D Fibrous root
Show answer & explanation
Answer: C. Pneumatophore
Why: Pneumatophores are erect, spongy, breathing roots in plants growing in waterlogged conditions (e.g., mangroves like Avicennia). They protrude above water and have pores (lenticels) for gas exchange.
Q7.
Parenchyma cells are characterized by
- A Thick cell walls with no living cytoplasm
- B Thin walls and living content at maturity
- C Dead cells with heavily lignified secondary walls
- D Tissue found mainly within xylem vessels and tracheids
Show answer & explanation
Answer: B. Thin walls and living content at maturity
Why: Parenchyma cells are living, thin-walled cells that are loosely packed. They perform photosynthesis (when with chloroplasts = chlorenchyma), storage, and packing functions.
Q8.
What are prop roots? Give an example.
- A Swollen underground roots that store starch reserves - carrot
- B Adventitious aerial roots that support the stem - banyan tree
- C Spongy aerial roots that take up oxygen from air - mangrove
- D Thin lateral roots that grip and climb vertical surfaces - ivy
Show answer & explanation
Answer: B. Adventitious aerial roots that support the stem - banyan tree
Why: Prop roots (pillar roots) are adventitious aerial roots that grow from the trunk and branches downward, entering the soil and supporting the wide-spreading canopy. Classic example: banyan tree (Ficus benghalensis).
Q9.
Collenchyma tissue provides what function in plants?
- A Storage of water in vacuolated parenchyma
- B Structural support in young growing organs
- C Transport of food through sieve elements
- D Reproduction via spore-forming tissue
Show answer & explanation
Answer: B. Structural support in young growing organs
Why: Collenchyma is a supporting tissue in young, growing plant parts (stems, petioles). Its cells have unevenly thickened cell walls (at corners) and are living. Provides flexibility and support simultaneously.
Q10.
Sclerenchyma cells are
- A Living, thin-walled cells used for storage
- B Dead, thick-walled cells that provide rigid support
- C Chloroplast-containing cells for photosynthesis
- D Elongated cells specialized for conducting water
Show answer & explanation
Answer: B. Dead, thick-walled cells that provide rigid support
Why: Sclerenchyma cells are dead at maturity with uniformly thick, lignified walls. They provide rigid mechanical support. Types: fibres (long, narrow) and sclereids (isodiametric, stone cells in pear grit).
Q11.
Which zone of the root is responsible for water absorption?
- A Root cap zone, which protects the apical meristem
- B Meristematic zone, where active cell division occurs
- C Elongation zone, where cells increase in length
- D Maturation zone (root hair zone)
Show answer & explanation
Answer: D. Maturation zone (root hair zone)
Why: The maturation (root hair) zone has differentiated cells including root hairs that massively increase surface area for water and mineral absorption. The root hair is an extension of a single epidermal cell.
Q12.
What is the function of the root cap?
- A Absorb water and minerals through specialized root hair cells
- B Protect the root meristem as it pushes through soil
- C Conduct water and dissolved minerals upward through xylem vessels
- D Perform photosynthesis using chlorophyll in root plastids
Show answer & explanation
Answer: B. Protect the root meristem as it pushes through soil
Why: The root cap is a thimble-like structure at the root tip that protects the delicate meristematic cells as the root pushes through soil. It also secretes mucilage to reduce friction.
Medium — 14 questions
Q13.
What is the difference between open and closed vascular bundles in plants?
- A Open bundles have xylem facing outward; closed bundles have phloem facing outward instead
- B Open bundles have cambium (allow secondary growth); closed bundles have no cambium
- C Open bundles occur mainly in monocots; closed bundles occur mainly in dicots
- D Open bundles contain vessels; closed bundles contain mainly tracheids instead
Show answer & explanation
Answer: B. Open bundles have cambium (allow secondary growth); closed bundles have no cambium
Why: Open vascular bundles contain cambium between xylem and phloem, allowing secondary (lateral) growth - found in dicot stems. Closed bundles have no cambium - found in monocot stems (no secondary growth).
Q14.
What is the Casparian strip and what is its function?
- A A loosely packed waxy band found scattered throughout the entire cortex region of the root in most textbook accounts
- B A waxy band of suberin in the endodermal cell walls that forces water through the symplast pathway
- C A protective lignified layer that encloses and hardens the mature seed coat tissue during normal conditions
- D A corky structure embedded deep within the secondary bark of older woody stems as generally observed
Show answer & explanation
Answer: B. A waxy band of suberin in the endodermal cell walls that forces water through the symplast pathway
Why: The Casparian strip is a band of suberin (waxy material) in the radial and transverse walls of endodermal cells. It blocks apoplastic (cell wall) water flow, forcing all water through the symplast (via cell membranes), allowing selective mineral absorption.
Q15.
In dicot stems, vascular bundles are arranged in a ring and are conjoint, collateral, and open. What does 'conjoint' mean?
- A Xylem and phloem occur as largely separate bundles
- B Xylem and phloem are in the same vascular bundle
- C The bundle contains two distinct xylem groups facing outward
- D The bundle consists mainly of undifferentiated cambium cells
Show answer & explanation
Answer: B. Xylem and phloem are in the same vascular bundle
Why: Conjoint means xylem and phloem occur together in the same vascular bundle. Collateral means phloem is on the outside and xylem on the inside of the same bundle. This is the typical arrangement in dicot stems.
Q16.
What is anomalous secondary growth?
- A The typical, predictable secondary growth pattern that most dicot stems generally follow
- B Secondary growth that does not follow the typical pattern, found in some climbers and monocots
- C Secondary growth that occurs mainly within the root system rather than the stem
- D Vegetative growth occurring within non-vascular mosses and liverworts over time
Show answer & explanation
Answer: B. Secondary growth that does not follow the typical pattern, found in some climbers and monocots
Why: Anomalous (atypical) secondary growth deviates from the normal pattern. It occurs in some dicot climbers (Bignonia, Dracaena) and some monocots (Agave, Yucca). It involves additional cambium rings or development outside typical positions.
Q17.
What is the difference between collenchyma and sclerenchyma?
- A Collenchyma cells are dead at maturity; sclerenchyma cells remain living throughout their lifespan in typical laboratory settings
- B Collenchyma has unevenly thickened walls and is living; sclerenchyma has uniformly thickened lignified walls and is dead
- C Both tissue types are dead at maturity, differing mainly in their cell wall thickness and shape under usual circumstances
- D They are functionally and structurally identical tissues, given two different historical names according to most researchers
Show answer & explanation
Answer: B. Collenchyma has unevenly thickened walls and is living; sclerenchyma has uniformly thickened lignified walls and is dead
Why: Collenchyma: living cells, unevenly thickened (cellulose) walls, flexible support in young plants. Sclerenchyma: dead cells, uniformly thick, lignified walls, rigid support. Both are supporting tissues but differ in flexibility and life status.
Q18.
Phloem tissue consists of which cells? (NEET important)
- A Mainly vessels and tracheids, with very few living cells present
- B Sieve tubes, companion cells, phloem fibres, and phloem parenchyma
- C Mainly sieve tubes, with relatively few associated companion cells
- D Vessels, companion cells, and sclerenchyma fibres combined together
Show answer & explanation
Answer: B. Sieve tubes, companion cells, phloem fibres, and phloem parenchyma
Why: Phloem has four components: (1) Sieve tube elements - main conducting cells with sieve plates; (2) Companion cells - regulate sieve tubes; (3) Phloem fibres - support; (4) Phloem parenchyma - storage.
Q19.
What are the components of xylem? (NEET important)
- A Sieve tubes and companion cells, both metabolically active
- B Vessels, tracheids, xylem fibres, and xylem parenchyma
- C Only vessels, with no tracheids or fibres present
- D Vessels and sieve tubes combined within one tissue type
Show answer & explanation
Answer: B. Vessels, tracheids, xylem fibres, and xylem parenchyma
Why: Xylem has four components: (1) Vessels - wide tubes for water conduction; (2) Tracheids - narrow cells for water conduction and support; (3) Xylem fibres - mechanical support; (4) Xylem parenchyma - storage and lateral transport.
Q20.
What is the endodermis and where is it found?
- A Outermost protective layer covering the young root
- B Innermost layer of root cortex surrounding the vascular bundle
- C Middle photosynthetic layer found within the leaf mesophyll
- D Outer corky layer forming part of the stem bark
Show answer & explanation
Answer: B. Innermost layer of root cortex surrounding the vascular bundle
Why: The endodermis is the innermost layer of the root cortex that surrounds the vascular cylinder (stele). Its cells have the Casparian strip. It controls what enters the vascular tissue.
Q21.
A leaf with leaflets arranged on both sides of a common axis like a feather is called
- A Palmate compound leaf
- B Pinnate compound leaf
- C Trifoliate
- D Bifoliate
Show answer & explanation
Answer: B. Pinnate compound leaf
Why: Pinnate compound leaves have leaflets arranged on both sides of a rachis (midrib extension), like neem, pea, and rose. Palmate compound leaves have all leaflets arising from a common point, like Cannabis and Bombax.
Q22.
What is stomata and how do guard cells regulate it?
- A Pores embedded deep within the corky bark of mature woody perennial stems
- B Pores in leaf epidermis regulated by guard cell turgor - open when guard cells are turgid
- C A thin tubular extension of the epidermis that forms a single absorptive root hair
- D A specialized sugar-conducting cell type found within the phloem sieve tube
Show answer & explanation
Answer: B. Pores in leaf epidermis regulated by guard cell turgor - open when guard cells are turgid
Why: Stomata are pores in leaf epidermis for gas exchange and transpiration. Guard cells surround each stoma. When guard cells absorb K+ (in light), water enters by osmosis, making them turgid and opening the stomata.
Q23.
What is the pericycle and what does it give rise to?
- A The outermost cortex layer, which gradually differentiates into the corky outer bark over time
- B Outermost layer of vascular cylinder - gives rise to lateral roots and part of vascular cambium
- C An innermost epidermal layer that directly protects the central vascular cylinder structure
- D Undifferentiated storage parenchyma tissue scattered throughout the entire root cortex region
Show answer & explanation
Answer: B. Outermost layer of vascular cylinder - gives rise to lateral roots and part of vascular cambium
Why: The pericycle is the outermost layer of the vascular cylinder (stele), just inside the endodermis. In roots, lateral roots arise from pericycle cells (endogenous origin). In secondary growth, vascular cambium is partly derived from pericycle.
Q24.
What is the difference between primary and secondary growth in plants?
- A Primary growth occurs mainly in roots; secondary growth occurs mainly in stems in the majority of cases studied
- B Primary = increase in length (apical meristems); secondary = increase in girth (lateral meristems)
- C Primary growth is seen mainly in angiosperms; secondary growth mainly in gymnosperms as widely reported
- D Primary growth is mostly vegetative; secondary growth is mostly reproductive in nature in standard practice
Show answer & explanation
Answer: B. Primary = increase in length (apical meristems); secondary = increase in girth (lateral meristems)
Why: Primary growth occurs at apical meristems (shoot and root tips), causing elongation. Secondary growth occurs at lateral meristems (vascular cambium and cork cambium), causing increase in girth. Only dicots and gymnosperms show significant secondary growth.
Q25.
Which type of venation is found in Calophyllum (a dicot) that appears similar to parallel venation?
- A Pinnate venation
- B Unicostate reticulate venation
- C Multicostate parallel venation
- D Palmate reticulate venation
Show answer & explanation
Answer: B. Unicostate reticulate venation
Why: Calophyllum shows unicostate reticulate venation with a prominent midrib and numerous lateral veins running parallel to each other but connected by smaller veinlets. It looks superficially parallel but has reticulate connections.
Q26.
What is chlorenchyma?
- A A continuously dividing meristematic tissue located at the tip of the shoot apex
- B Parenchyma cells containing chloroplasts; the main site of photosynthesis in leaves
- C Thick-walled, lignified supporting tissue found in mature woody stem regions
- D Vacuolated storage parenchyma specialized for holding large reserves of water
Show answer & explanation
Answer: B. Parenchyma cells containing chloroplasts; the main site of photosynthesis in leaves
Why: Chlorenchyma is parenchyma tissue containing chloroplasts. It forms the mesophyll of leaves (palisade and spongy mesophyll) and is responsible for photosynthesis. Green stems also contain chlorenchyma.
Hard — 15 questions
Q27.
What is the significance of the endogenous origin of lateral roots?
- A Lateral roots are sometimes mistakenly thought to arise from the outer epidermis, growing outward without disturbing internal tissue
- B Lateral roots arise from deep pericycle cells, allowing them to push through cortex and epidermis, ensuring strong anchoring
- C Lateral roots are sometimes mistakenly thought to arise spontaneously, carrying no real developmental or anchoring significance
- D Lateral roots are sometimes mistakenly thought to arise mainly from endodermal cells without much pericycle involvement
Show answer & explanation
Answer: B. Lateral roots arise from deep pericycle cells, allowing them to push through cortex and epidermis, ensuring strong anchoring
Why: Lateral roots originate from pericycle cells (inside the endodermis) - endogenous origin. They push through cortex and epidermis to emerge. This contrasts with lateral stem branches which are exogenous (arise from surface meristems). Endogenous origin ensures strong vascular connection.
Q28.
In secondary growth of dicot stem, what is the role of the vascular cambium?
- A It is sometimes mistakenly thought to produce mainly secondary phloem outwardly, with little inward xylem production
- B It produces secondary xylem (wood) inwardly and secondary phloem outwardly, increasing girth
- C It is sometimes mistakenly thought to produce mainly cork cells outward, replacing the epidermis each season
- D It is sometimes mistakenly thought to produce a largely new layer of epidermis to replace the damaged outer surface
Show answer & explanation
Answer: B. It produces secondary xylem (wood) inwardly and secondary phloem outwardly, increasing girth
Why: The vascular cambium is a lateral meristem that produces secondary xylem (wood) toward the interior and secondary phloem toward the exterior. Annual rings in wood represent seasonal variation in secondary xylem production.
Q29.
What is the difference between heartwood (duramen) and sapwood (alburnum)?
- A Heartwood is sometimes mistakenly thought to be the newer wood formed each season; sapwood the older wood near the bark
- B Heartwood is older, darker, non-conducting, impregnated with tannins; sapwood is younger, lighter, still conducts water
- C Both heartwood and sapwood are sometimes mistakenly thought to be functionally identical in conduction and support
- D Heartwood is sometimes mistakenly thought to be located within the outer bark layer; sapwood occupying the central stem region
Show answer & explanation
Answer: B. Heartwood is older, darker, non-conducting, impregnated with tannins; sapwood is younger, lighter, still conducts water
Why: Heartwood (duramen): older, inner secondary xylem, dark due to tannins/resins/oils, dead, non-conducting, provides mechanical support. Sapwood (alburnum): outer secondary xylem, lighter, still conducts water. Heartwood is more durable for timber.
Q30.
What is the apoplast pathway and symplast pathway in roots?
- A Apoplast is sometimes mistakenly thought to move water mainly through cell membranes; symplast mainly through cell walls
- B Apoplast = through cell walls and intercellular spaces (no membranes crossed); symplast = through connected cytoplasm via plasmodesmata
- C Apoplast and symplast are sometimes mistakenly thought to describe the exact same single continuous transport pathway in plant roots
- D Apoplast is sometimes mistakenly thought to transport mainly dissolved mineral ions; symplast mainly free water molecules
Show answer & explanation
Answer: B. Apoplast = through cell walls and intercellular spaces (no membranes crossed); symplast = through connected cytoplasm via plasmodesmata
Why: Apoplast: water moves through cell walls and intercellular spaces without crossing membranes. Symplast: water moves through the cytoplasm connected by plasmodesmata. The Casparian strip forces water from apoplast to symplast at endodermis, controlling mineral entry.
Q31.
What is the significance of companion cells in phloem?
- A They are sometimes mistakenly thought to carry water upward from the root system to the leaves through lignified xylem vessels in general practice
- B They are metabolically active cells that regulate sieve tube elements, loading and unloading sugars, and maintaining sieve tube function
- C They are sometimes mistakenly thought to form mainly the rigid, lignified structural cell wall surrounding the phloem bundle as frequently described
- D They are sometimes mistakenly thought to function mainly as inert storage cells that passively hold starch reserves in phloem in most textbook accounts
Show answer & explanation
Answer: B. They are metabolically active cells that regulate sieve tube elements, loading and unloading sugars, and maintaining sieve tube function
Why: Companion cells are metabolically active, have dense cytoplasm and many mitochondria. They are connected to sieve tube elements by plasmodesmata and regulate their function (sieve tubes lack nuclei at maturity). They actively load and unload sugars.
Q32.
How does the annual ring pattern in wood record climate history (dendrochronology)?
- A Ring width is sometimes reported to remain essentially constant and largely unchanging regardless of yearly climate or rainfall conditions year to year
- B Wide rings indicate favorable growth (warm, moist); narrow rings indicate stress (drought, cold). Counting rings gives age; patterns record climate history
- C Every single annual growth ring observed within a tree trunk is sometimes thought to be identical in width across all growth years measured precisely
- D Annual growth rings are sometimes said to form mainly within tropical trees and to be largely absent from temperate climate trees overall
Show answer & explanation
Answer: B. Wide rings indicate favorable growth (warm, moist); narrow rings indicate stress (drought, cold). Counting rings gives age; patterns record climate history
Why: Early wood (spring wood) is lighter and has wide, thin-walled vessels; late wood (autumn wood) is darker with narrow, thick-walled vessels. Ring width varies with growing conditions. Dendrochronology uses ring patterns to date wood and reconstruct past climate.
Q33.
What is periderm and how is it formed?
- A It replaces epidermis as plants grow older through activity of cork cambium (phellogen)
- B It is the original protective tissue covering young plants before any secondary growth begins
- C Periderm forms mainly within roots and is largely absent from stems
- D Periderm is generally another name used interchangeably for the original epidermis
Show answer & explanation
Answer: A. It replaces epidermis as plants grow older through activity of cork cambium (phellogen)
Why: Periderm replaces the epidermis in mature woody stems and roots. It is produced by cork cambium (phellogen): outward divisions produce cork (phellem, dead cells with suberin), inward divisions produce phelloderm. Together: periderm = phellem + phellogen + phelloderm.
Q34.
What is the conjunctive tissue in a root?
- A Parenchyma between xylem and phloem bundles in the vascular cylinder of roots
- B Vascular tissue specifically connecting the root system to the stem at the collar region
- C Specialized companion cells embedded within the phloem sieve tube network
- D Endodermal tissue forming the innermost layer of the root cortex
Show answer & explanation
Answer: A. Parenchyma between xylem and phloem bundles in the vascular cylinder of roots
Why: In dicot roots, the vascular bundles are separate (xylem and phloem alternate). The parenchymatous tissue between them is called conjunctive tissue. It plays a role in the formation of vascular cambium during secondary growth.
Q35.
What is the difference between palisade mesophyll and spongy mesophyll in leaves?
- A Palisade and spongy mesophyll are sometimes mistakenly thought to be structurally and functionally identical leaf tissue layers with little real distinction
- B Palisade = columnar cells, densely packed, upper layer, more chloroplasts (primary photosynthesis); spongy = irregular cells, loose with air spaces (gas exchange)
- C Palisade mesophyll is sometimes mistakenly thought to be positioned directly beneath the lower epidermis; spongy mesophyll beneath the upper epidermis
- D Spongy mesophyll is sometimes mistakenly thought to contain substantially more chloroplasts than the palisade layer positioned directly above it
Show answer & explanation
Answer: B. Palisade = columnar cells, densely packed, upper layer, more chloroplasts (primary photosynthesis); spongy = irregular cells, loose with air spaces (gas exchange)
Why: Palisade mesophyll: columnar cells, densely packed, many chloroplasts, upper layer - primary site of photosynthesis. Spongy mesophyll: irregular cells, loose arrangement with large air spaces - facilitates CO2 diffusion and gas exchange. Both found between upper and lower epidermis.
Q36.
What are plasmodesmata and what is their significance?
- A Simple pores embedded within the cell wall that permit mainly passive, largely unregulated diffusion of small dissolved solutes during normal conditions
- B Cytoplasmic channels connecting adjacent plant cells through cell walls, enabling direct cell-to-cell communication and transport (symplast pathway)
- C A specialized membrane structure that surrounds and encloses the large central vacuole found within a typical mature plant cell as generally observed
- D Channels found mainly embedded within the plasma membrane itself, rarely spanning across the rigid surrounding cell wall structure in typical laboratory settings
Show answer & explanation
Answer: B. Cytoplasmic channels connecting adjacent plant cells through cell walls, enabling direct cell-to-cell communication and transport (symplast pathway)
Why: Plasmodesmata are narrow cytoplasmic channels that pass through the cell walls connecting the cytoplasm of adjacent cells. They form the symplast pathway for transport of water, solutes, and signaling molecules. They also allow viral spread between cells.
Q37.
What is the significance of the waxy cuticle on leaves?
- A It is sometimes mistakenly thought to actively perform photosynthesis using embedded chloroplasts within its waxy layer
- B It reduces water loss by transpiration, protects against pathogens, and reflects excess light
- C It is sometimes mistakenly thought to absorb atmospheric water vapor directly into the leaf mesophyll tissue
- D It is sometimes mistakenly thought to provide rigid structural support comparable to lignified sclerenchyma fibres
Show answer & explanation
Answer: B. It reduces water loss by transpiration, protects against pathogens, and reflects excess light
Why: The cuticle is a layer of cutin (waxy polymer) secreted by epidermal cells. It dramatically reduces cuticular transpiration (water loss through leaf surface), protects against pathogen entry, and reduces UV damage. Desert plants have thicker cuticles.
Q38.
What is the key difference between monocot and dicot root anatomy?
- A Monocot roots are sometimes reported to develop a true vascular cambium layer; dicot roots are said to largely lack one altogether under usual circumstances
- B Dicot roots have limited vascular bundles (2-4 protoxylem poles); monocot roots have numerous vascular bundles (polyarch) arranged in a ring
- C Monocot and dicot root anatomy are sometimes thought to be essentially identical to one another when viewed in cross-section closely according to most researchers
- D Dicot roots are sometimes said to largely lack an endodermal layer surrounding their central vascular cylinder structure altogether in the majority of cases studied
Show answer & explanation
Answer: B. Dicot roots have limited vascular bundles (2-4 protoxylem poles); monocot roots have numerous vascular bundles (polyarch) arranged in a ring
Why: Dicot roots: diarch to tetrarch (2-4 xylem poles); pith absent or small; secondary growth possible. Monocot roots: polyarch (many xylem poles arranged in a ring); large pith; no secondary growth; Casparian strip may have suberin lamellae.
Q39.
What is transfusion tissue in gymnosperm leaves?
- A Specialized xylem vessel elements that are sometimes thought to enable unusually rapid, long-distance lateral water transport throughout
- B Tissue of tracheids and parenchyma surrounding the vascular bundle in gymnosperm leaves, facilitating lateral transport
- C A modified type of guard cell found mainly along the outer leaf margins of conifer species specifically
- D The dense, chlorophyll-bearing mesophyll layer that fills most of the bulk of a typical gymnosperm leaf
Show answer & explanation
Answer: B. Tissue of tracheids and parenchyma surrounding the vascular bundle in gymnosperm leaves, facilitating lateral transport
Why: Transfusion tissue is unique to gymnosperm leaves, found surrounding the vascular bundle. It consists of tracheids (for water distribution) and parenchyma cells (for lateral transport of organic materials between mesophyll and vascular bundle).
Q40.
What is the sunken stomata found in xerophytes and what is its adaptive significance?
- A Stomata that are sometimes thought to be structurally oriented to open mainly in a downward direction toward the soil
- B Stomata in pits or crypts in the leaf surface, creating a humid microenvironment that reduces transpiration in dry habitats
- C Stomata that are sometimes thought to be located mainly on root tissue rather than on the leaf surface itself
- D Stomata that are sometimes thought to have permanently lost most function and remain closed under nearly every condition
Show answer & explanation
Answer: B. Stomata in pits or crypts in the leaf surface, creating a humid microenvironment that reduces transpiration in dry habitats
Why: Xerophytic plants (desert plants like Pinus, Nerium) have sunken stomata in pits/crypts below the leaf surface. Trapped humid air in the pit reduces the water vapor concentration gradient between the leaf and atmosphere, reducing transpiration rate.
Q41.
What is the difference between protoderm, ground meristem, and procambium?
- A All three of these tissues are sometimes mistakenly thought to be lateral meristems responsible mainly for increasing the overall girth of the stem region as widely reported
- B They are the three primary meristems derived from apical meristem: protoderm becomes epidermis, ground meristem becomes cortex/pith, procambium becomes vascular tissue
- C All three of these meristems are sometimes said to arise mainly as secondary meristems after primary growth of the plant has largely finished in standard practice
- D All three meristem types are sometimes thought to be found mainly confined within the root system of the plant, rarely occurring within the shoot under most conditions encountered
Show answer & explanation
Answer: B. They are the three primary meristems derived from apical meristem: protoderm becomes epidermis, ground meristem becomes cortex/pith, procambium becomes vascular tissue
Why: As the apical meristem divides, it gives rise to three primary meristems: (1) Protoderm - outer layer, becomes epidermis; (2) Ground meristem - middle, becomes cortex, pith, and other ground tissue; (3) Procambium - central, becomes primary vascular tissue (xylem and phloem).