Q3671. Match the List-I with List-II.
A. Lenticels
B. Cork cambium
C. Secondary cortex
D. Cork
✅ Correct Answer: A-3, B-1, C-4, D-2
🧠 Solution:
(A)-(3) Lenticels – Exchange of gases
(B)-(1) Cork cambium – Phellogen
(C)-(4) Secondary cortex – Phelloderm
(D)-(2) Cork – Suberin deposition
Q3670. Select the correct pair.
✅ Correct Answer: Cells of medullary rays that form part of cambial ring − Interfascicular cambium
🧠 Solution:
Medullary ray cells adjacent to intrafascicular cambium become meristematic and form interfascicular cambium, completing the cambial ring.
Q3616.
Match the List-I with List-II.
List-I:
A. Cells with active cell division capacity
B. Tissue having all cells similar in structure and function
C. Tissue having different types of cells
D. Dead cells with highly thickened walls and narrow lumen
List-II:
1. Vascular tissues
2. Meristematic tissue
3. Sclereids
4. Simple tissue Select the correct answer from the options given below.
✅ Correct Answer:
2 4 1 3
🧠 Solution:
(A)-(2), (B)-(4), (C)-(1), (D)-(3) Meristematic cells are totipotent and actively divide. Simple tissues have all cells similar in structure and function. Vascular tissues have different cell types (xylem and phloem). Sclereids are dead cells with thickened walls and narrow lumen.
Q3676. Secondary xylem and phloem in dicot stem are produced by
✅ Correct Answer: vascular cambium
🧠 Solution:
Secondary vascular tissues, i.e., secondary xylem and phloem are formed by the vascular cambium. It is produced by fascicular (intrafascicular) and interfascicular cambium. Intrafascicular cambium is a primary meristem which occurs as strips in vascular bundles. It divides to form secondary phloem on the outer side and secondary xylem on the inner side. Interfascicular cambium arises secondarily from the cells of medullary rays.
Q3674. Plants having little or no secondary growth are
✅ Correct Answer: grasses
🧠 Solution:
Grasses are monocots and lack vascular cambium, hence they do not exhibit secondary growth. Deciduous angiosperms, conifers, and cycads show secondary growth.
Q3660. Casparian strips occur in
✅ Correct Answer: endodermis
🧠 Solution:
Casparian strips are found in the endodermis of roots. They are bands of suberin and lignin thickening on the radial and tangential walls of endodermal cells, preventing plasmolysis and controlling solute flow.
Q3678. The vascular cambium normally gives rise to
✅ Correct Answer: secondary xylem
🧠 Solution:
Vascular cambium located between xylem and phloem in stems and roots produces secondary xylem towards the pith and secondary phloem towards the bark. Phellogen produces cork (phellem) and phelloderm, collectively called periderm.
Q3675. Identify the wrong statement in context of heartwood.
✅ Correct Answer: It is responsible for the formation of lenticels
🧠 Solution:
Heartwood is the dark, non-functional central region of secondary xylem. It provides mechanical support but does not form lenticels. Hence, option (b) is incorrect.
Q3619. Which of the following is made up of dead cells?
✅ Correct Answer: Phellem
🧠 Solution:
Phellem or cork is made of dead cells. These cells have suberized walls, making them impermeable to water and protective for underlying tissues.
Q3618. Root hairs develop from the region of
✅ Correct Answer: meristematic activity
🧠 Solution:
Root hairs develop from the region of meristematic activity, just above the root cap. The cells here divide repeatedly and form new tissues for root growth.
Q3662.
Cortex is the region found between
✅ Correct Answer:
epidermis and stele
🧠 Solution:
Cortex tissue lies between the epidermis and stele. It is multilayered and made of parenchymatous cells with large intercellular spaces for aeration.
Q3661.
The balloon-shaped structures called tyloses
✅ Correct Answer:
are extensions of xylem parenchyma cells into vessels
🧠 Solution:
Tyloses are extensions of xylem parenchyma cells into the vessels of woody tissue. They block the vessels and prevent the spread of pathogens, often found in the heartwood of dicot stems.
Q3620. Specialised epidermal cells surrounding the guard cells are called
✅ Correct Answer: subsidiary cells
🧠 Solution:
Subsidiary cells are specialised epidermal cells surrounding the guard cells. They assist in stomatal movement and are part of the stomatal apparatus.
Q3683. Age of a tree can be estimated by
✅ Correct Answer: number of annual rings
🧠 Solution:
The age of a tree can be estimated by counting the number of annual rings (dendrochronology). Each annual ring represents one year's growth.
Q3682. Interfascicular cambium develops from the cells of
✅ Correct Answer: medullary rays
🧠 Solution:
In dicot stems, cambium present between primary xylem and primary phloem is intrafascicular cambium. The cells of medullary rays adjoining it become meristematic to form interfascicular cambium.
Q3698. The transverse section of a plant shows the following anatomical features: (I) Large number of scattered vascular bundles surrounded by bundle sheath, (II) Large conspicuous parenchymatous ground tissue, (III) Vascular bundles conjoint and closed, (IV) Phloem parenchyma absent. Identify the category of plant and its part.
✅ Correct Answer: Monocotyledonous stem
🧠 Solution:
The transverse section of a monocotyledonous stem shows scattered conjoint and closed vascular bundles surrounded by sclerenchymatous bundle sheath. The ground tissue is large and parenchymatous. Phloem parenchyma and medullary rays are absent, confirming the part as a monocot stem.
Q3659. In dicot root, the vascular cambium originates from
✅ Correct Answer: tissue located below the phloem bundles and a portion of pericycle tissue above protoxylem
🧠 Solution:
In dicot root, the vascular cambium originates from tissues located below the phloem bundles and a portion of pericycle tissue above protoxylem. Vascular cambium is the meristematic layer that cuts off vascular tissues (xylem and phloem). In young stem, it is present in patches between xylem and phloem.
Q3617. Regeneration of damaged growing grass following grazing is largely due to
✅ Correct Answer: intercalary meristem
🧠 Solution:
Regeneration of damaged grass is largely due to intercalary meristem, which occurs between mature tissues. It helps regenerate parts damaged by grazing and is found at the base of nodes and internodes of grasses.
Q3672. Which of the following statements about cork cambium is incorrect?
✅ Correct Answer: It forms secondary cortex on its outer side
🧠 Solution:
Cork cambium (phellogen) is a meristematic tissue that produces cork (phellem) on the outer side and secondary cortex (phelloderm) on the inner side. Hence, option (a) is incorrect.
Q3673. Which of the statements given below is not true about formation of annual rings in trees?
✅ Correct Answer: Annual rings are not prominent in trees of temperate region
🧠 Solution:
The statement 'annual rings are not prominent in trees of temperate region' is incorrect. In temperate climates, seasonal variations in cambium activity produce distinct annual rings.
Q3679. Read the different components (I–IV) and tell the correct order from outer side to inner side in a woody dicot stem: I. Secondary cortex, II. Wood, III. Secondary phloem, IV. Phellem
✅ Correct Answer: IV, I, III, II
🧠 Solution:
The correct order from outside to inside in a woody dicot stem is: Phellem → Secondary cortex → Secondary phloem → Wood.
Q3681. You are given a fairly old piece of dicot stem and a dicot root. Which anatomical structure will you use to distinguish between the two?
✅ Correct Answer: Protoxylem
🧠 Solution:
In dicot stem, the protoxylem is endarch (towards the center), while in dicot root, it is exarch (towards the periphery). Thus, protoxylem position distinguishes between them.
Q3621. Tracheids differ from other tracheary elements in
✅ Correct Answer: being imperforate
🧠 Solution:
Tracheids differ from other tracheary elements by being imperforate. They have pits to allow lateral conduction of water and are dead lignified cells.
Q3699. Water containing cavities in vascular bundles are found in
✅ Correct Answer: maize
🧠 Solution:
In the monocot stem of Zea mays (maize), the vascular bundles are conjoint, collateral, and closed. The lower protoxylem elements and xylem parenchyma cells disintegrate to form a water-containing lysigenous cavity called the protoxylem cavity or lacuna.
Q3623. Companion cells are closely associated with
✅ Correct Answer: sieve elements
🧠 Solution:
Companion cells are closely associated with sieve elements of phloem. They are connected by plasmodesmata and develop from the same mother cell.
Q3622. The common bottle cork is a product of
✅ Correct Answer: phellogen
🧠 Solution:
Cork cambium or phellogen divides periclinally, cutting off suberized dead cells towards the outside. These cells form cork (phellem).
Q3680. The cork cambium, cork and secondary cortex are collectively called
✅ Correct Answer: periderm
🧠 Solution:
The periderm is a secondary protective tissue made up of cork cambium (phellogen), cork (phellem), and secondary cortex (phelloderm).
Q3625. Closed vascular bundles lack
✅ Correct Answer: phellogen
🧠 Solution:
Closed vascular bundles lack cambium. They are typical of monocot stems and cannot form secondary tissues.
Q3624. Ground tissue includes
✅ Correct Answer: all tissues except epidermis and vascular bundles
🧠 Solution:
All tissues except epidermis and vascular bundles constitute the ground tissue. It includes cortex, pericycle, medullary rays, and mesophyll in leaves.
Q3677. Heartwood differs from sapwood in
✅ Correct Answer: It conducts water and minerals efficiently
🧠 Solution:
Heartwood (duramen) is the central dead wood of trees. It comprises dead, lignified cells containing organic compounds like tannins, resins, and oils, which make it dark and durable. It does not conduct water and minerals because of dead elements. Water conduction occurs in sapwood, which contains living cells.
Q3627. Which one of the following is not a lateral meristem?
✅ Correct Answer: intercalary meristem
🧠 Solution:
Intercalary meristem is not a lateral meristem. It is derived from apical meristem and helps in the elongation of plant parts.
Q3626. The chief water-conducting elements of xylem in gymnosperms are
✅ Correct Answer: tracheids
🧠 Solution:
Tracheids are the main water-conducting elements in gymnosperms. They are elongated, dead cells with lignified walls and bordered pits.
Q3663. Anatomically fairly old dicotyledonous root is distinguished from the dicotyledonous stem by
✅ Correct Answer: position of protoxylem
🧠 Solution:
In dicot root, xylem is exarch (protoxylem away from the center and metaxylem towards the center), whereas in dicot stem xylem is endarch (protoxylem towards the center).
Q3631. Reduction in vascular tissue, mechanical tissue and cuticle is characteristic of
✅ Correct Answer: hydrophytes
🧠 Solution:
In hydrophytes, vascular tissue and mechanical tissue are reduced. Cuticle is either completely absent or, if present, it is thin and poorly developed. In xerophytes, cuticle is heavy and well developed. Vascular tissue and mechanical tissue are well developed and differentiated. In mesophytes, cuticle in aerial part is moderately developed. Vascular and mechanical tissues are fairly developed and well differentiated.
Q3630. In barley stem, vascular bundles are
✅ Correct Answer: closed and scattered
🧠 Solution:
In barley (a monocot), vascular bundles are numerous, scattered in the ground tissue, conjoint, collateral, and closed (without cambium).
Q3629. The annular and spirally thickened conducting elements generally develop in the protoxylem when the root or stem is
✅ Correct Answer: elongating
🧠 Solution:
Annular and spiral thickenings develop in protoxylem during elongation of the organ, allowing flexibility during growth.
Q3628. Palisade parenchyma is absent in leaves of
✅ Correct Answer: Sorghum
🧠 Solution:
Palisade parenchyma is absent in monocot leaves like Sorghum. Monocots have undifferentiated mesophyll tissue.
Q3633. Vascular tissues in flowering plants develop from
✅ Correct Answer: plerome
🧠 Solution:
According to histogen theory proposed by Hanstein (1870), there are three distinct meristematic zones: dermatogen, periblem and plerome. Dermatogen gives rise to epidermis, periblem produces the cortex and plerome forms the central cylinder (vascular tissue).
Q3632. The length of different internodes in a culm of sugarcane is variable because of
✅ Correct Answer: intercalary meristem
🧠 Solution:
Intercalary meristem is present away from apical meristem in primary permanent tissue. It is present at the base of internodes, e.g., in family Gramineae or at the base of leaves, e.g., Pinus or at the base of node, e.g., Mentha. Intercalary meristem is responsible for increase in length.
Q3685. For a critical study of secondary growth in plants, which one of the following pairs is suitable?
✅ Correct Answer: Teak and pine
🧠 Solution:
Secondary growth is studied in dicot stems and gymnosperms. Teak (dicot) and pine (gymnosperm) exhibit typical secondary growth.
Q3634. Passage cells are thin-walled cells found in
✅ Correct Answer: endodermis of roots facilitating rapid transport of water from cortex to pericycle
🧠 Solution:
In roots, endodermis is the innermost layer of cortex. Some endodermal cells present opposite to the xylem patches are thin walled and called passage cells. They help in transfer of water and dissolved salts from cortex directly into the xylem and ultimately to the pericycle.
Q3635. A common structural feature of vessel elements and sieve tube elements is
✅ Correct Answer: pores on lateral walls
🧠 Solution:
The wall of both vessel elements and sieve tube elements are perforated by large openings, allowing cell-to-cell contact. Vessels are nucleated, while sieve tube elements are enucleated.
Q3665.
Ectophloic siphonostele is found in
✅ Correct Answer:
Osmunda and Equisetum
🧠 Solution:
In ectophloic siphonostele, the xylem surrounds the pith and is itself surrounded by phloem, pericycle, and endodermis, e.g., Osmunda and Equisetum.
Q3664. In a woody dicotyledonous tree, which of the following parts will mainly consist of primary tissues?
✅ Correct Answer: Shoot tips and root tips
🧠 Solution:
Primary tissues are derived directly from embryonic meristematic tissues and are found in growing regions such as shoot tips and root tips.
Q3666. In a longitudinal section of root, starting from the tip upward, the four zones occur in the following order
✅ Correct Answer: root cap, cell division, cell enlargement, cell maturation
🧠 Solution:
From root tip upward: Root cap → Zone of cell division → Zone of cell elongation → Zone of cell maturation.
Q3638. The cells of the quiescent centre are characterised by
✅ Correct Answer: having light cytoplasm and small nuclei
🧠 Solution:
The quiescent centre, discovered by Clowes (1958), has cells with lower DNA, RNA, and protein concentration, fewer mitochondria, and small nuclei and nucleoli.
Q3637. The apical meristem of the root is present
✅ Correct Answer: in all the roots
🧠 Solution:
Apical meristems are primary meristems located in the growing points (roots and shoot apices). Growth in length of roots and shoots is due to their activity.
Q3636. Chlorenchyma is known to develop in the
✅ Correct Answer: spore capsule of a moss
🧠 Solution:
The apophysis of moss capsule contains chloroplast-bearing parenchymatous cells called chlorenchyma. Due to chloroplasts, they can perform photosynthesis.
Q3686. Main function of lenticel is
✅ Correct Answer: gaseous exchange
🧠 Solution:
Lenticels are openings in the bark that allow gaseous exchange between internal tissues and the external atmosphere.
Q3642. Which of the following meristems is responsible for extrastelar secondary growth in dicotyledonous stem?
✅ Correct Answer: Phellogen
🧠 Solution:
Phellogen (cork cambium) is a secondary lateral meristem found in the cortical region. It cuts off new cells for extrastelar secondary growth—cork on the outside and secondary cortex inside.
Q3641. Axillary bud and terminal bud are derived from the activity of
✅ Correct Answer: apical meristem
🧠 Solution:
The shoot apical meristem gives rise to lateral (axillary) buds, which remain suppressed due to apical dominance.
Q3640.
Four radial vascular bundles are found in
✅ Correct Answer:
dicot root
🧠 Solution:
Roots have radial vascular bundles while stems have conjoint bundles. Dicot roots have 3–6 vascular bundles; monocot roots have more than 6.
Q3639. Vessels are found in
✅ Correct Answer: most of angiosperms and few gymnosperms
🧠 Solution:
Most angiosperms have vessels except a few (e.g., Drimys, Tetracentron, Trochodendron). Gymnosperms generally lack vessels except in the order Gnetales.
Q3643. What happens during vascularisation in plants?
✅ Correct Answer: Differentiation of procambium, xylem and phloem is simultaneous
🧠 Solution:
From the procambium, primary xylem and phloem arise simultaneously during vascularisation.
Q3644. A leaf primordium grows into the adult leaf lamina by means of
✅ Correct Answer: at first by apical meristem and later largely by marginal meristem
🧠 Solution:
Apical meristem initiates leaf growth; later, marginal meristem (plate meristem) helps in the expansion of leaf lamina by anticlinal divisions.
Q3645. At maturity which of the following is enucleate?
✅ Correct Answer: Sieve cell
🧠 Solution:
Phloem is composed of companion cells, phloem parenchyma, phloem fibre, and sieve tube cells. Sieve tube cells are cylindrical and involved in transport of organic solutes. In sieve cells, the nucleus is present at the younger stage but disappears in mature stage.
Q3646. What is not true about sclereids?
✅ Correct Answer: These are parenchyma cells with thickened lignified walls
🧠 Solution:
Sclereids are broad sclerenchyma cells which may be oval, spherical, cylindrical, or stellate. They occur singly or in groups to provide stiffness and are found in pear grit and nutshells.
Q3688. Procambium forms
✅ Correct Answer: primary vascular bundles and vascular cambium
🧠 Solution:
Procambium is a meristematic tissue that gives rise to primary vascular bundles and later contributes to vascular cambium formation.
Q3687. As secondary growth proceeds in a tree, thickness of
✅ Correct Answer: heartwood increases
🧠 Solution:
As secondary growth continues, older sapwood rings become heartwood. Thus, heartwood increases while sapwood remains about the same thickness.
Q3684. Heartwood differs from sapwood in
✅ Correct Answer: having dead and non-conducting elements
🧠 Solution:
Heartwood is the non-functional, lignified, dead portion of secondary xylem. It is filled with resins and tannins, making it hard and non-conducting. Sapwood conducts water and minerals.
Q3692. Which exposed wood will decay faster?
✅ Correct Answer: Sapwood
🧠 Solution:
Sapwood contains living cells and moisture, making it more prone to decay than heartwood, which is durable and resistant.
Q3691. Periderm is produced by
✅ Correct Answer: phellogen
🧠 Solution:
Phellogen (cork cambium) divides to form cork (phellem) externally and secondary cortex (phelloderm) internally. Together they form the periderm.
Q3690. A narrow layer of thin-walled cells found between phloem/bark and wood of a dicot is
✅ Correct Answer: vascular cambium
🧠 Solution:
Vascular cambium is a narrow layer of meristematic cells located between phloem and xylem; it forms secondary vascular tissues.
Q3689. Abnormal/anomalous secondary growth occurs in
✅ Correct Answer: Dracaena
🧠 Solution:
Woody monocots like Dracaena and Yucca show anomalous secondary growth through the activity of secondary thickening meristem.
Q3647. Bordered pits are found in
✅ Correct Answer: Vessel wall
🧠 Solution:
Pits are depressions in the cell wall found in sclerenchyma, parenchyma, vessels, and tracheids. Bordered pits are flask-shaped depressions found in vessel walls.
Q3669. A bicollateral vascular bundle is characterised by
✅ Correct Answer: xylem being sandwiched between phloem
🧠 Solution:
In bicollateral vascular bundles, xylem is sandwiched between two phloem patches (external and internal), e.g., in Cucurbita and Solanaceae.
Q3648. Which is correct about transport or conduction of substances?
✅ Correct Answer: Organic food moves upwardly and downwardly through phloem
🧠 Solution:
Sieve tubes are conducting elements of phloem that carry organic nutrients upwardly and downwardly. This was demonstrated by Malpighi's girdling experiment (1671).
Q3693. Commercial cork is obtained from
✅ Correct Answer: Quercus (Oak)
🧠 Solution:
Commercial cork is obtained from the bark of Quercus suber (cork oak). The cork is formed from phellem cells produced by phellogen.
Q3650. An organised and differentiated cellular structure having cytoplasm but no nucleus is
✅ Correct Answer: Sieve tubes
🧠 Solution:
Sieve tubes are food-conducting elements of phloem. They lose their nuclei at maturity but retain cytoplasmic strands for transport.
Q3649. Angular collenchyma occurs in
✅ Correct Answer: Tagetes
🧠 Solution:
Collenchyma is of three types: (a) Angular (at angles, e.g. Tagetes), (b) Lamellar (on tangential walls, e.g. sunflower), and (c) Lacunate (bordering spaces, e.g. Cucurbita).
Q3668. Where do the Casparian bands occur?
✅ Correct Answer: Endodermis
🧠 Solution:
Casparian bands (strips) are ligno-suberin thickenings found on the radial and tangential walls of endodermal cells in roots.
Q3696. Vascular cambium produces
✅ Correct Answer: secondary xylem and secondary phloem
🧠 Solution:
Vascular cambium, formed by fascicular and interfascicular cambium, leads to secondary growth in dicot stems and roots. It produces secondary phloem on the outer side and secondary xylem on the inner side. The youngest xylem layer occurs just inside the vascular cambium, while the oldest lies near the pith. The reverse is true for phloem.
Q3700. What is true about a monocot leaf?
✅ Correct Answer: Mesophyll not differentiated into palisade and spongy tissues
🧠 Solution:
Monocot leaves are isobilateral, having parallel venation and amphistomatic structure. The upper epidermis contains bulliform (motor) cells. The mesophyll is undifferentiated and made up of isodiametric parenchyma cells with intercellular spaces. It is not divided into palisade and spongy tissues.
Q3695. For union between stock and scion in grafting which one is the first to occur?
✅ Correct Answer: Formation of callus
🧠 Solution:
In grafting, the cambium-bearing shoot (scion) of one plant is joined to the cambium-bearing stump (stock) of a related plant. The first event in the union between stock and scion is the formation of callus — an irregular, unorganised and undifferentiated mass of actively dividing cells. Later, new vascular tissues differentiate through the callus bridge to complete the union.
Q3694. Cork cambium and vascular cambium are
✅ Correct Answer: lateral meristems
🧠 Solution:
Cork cambium and vascular cambium are lateral meristems responsible for secondary growth, increasing girth in dicots and gymnosperms.
Q3667. Pericycle of roots produces
✅ Correct Answer: lateral roots
🧠 Solution:
The pericycle in roots is a parenchymatous layer beneath the endodermis that gives rise to lateral roots, vascular cambium, and cork cambium.
Q3652. Monocot leaves possess
✅ Correct Answer: Intercalary meristem
🧠 Solution:
Intercalary meristems occur at leaf bases and nodes in grasses. They help in leaf elongation and allow prostrate stems to become erect.
Q3651. Collenchyma occurs in the stem and petioles of
✅ Correct Answer: Dicot herbs
🧠 Solution:
Collenchyma is a living mechanical tissue that provides strength and flexibility. It is found in the stems and petioles of dicot herbs.
Q3656. Out of diffuse porous and ring porous woods, which is correct?
✅ Correct Answer: Ring porous wood carries more water when need is higher
🧠 Solution:
Ring porous woods (e.g., Quercus) have large vessels in early wood and conduct more water when demand is high.
Q3655. Death of protoplasm is a prerequisite for a vital function like
✅ Correct Answer: Transport of sap
🧠 Solution:
Xylem vessels are dead cells that conduct water (sap) through the plant. Their lignified walls allow water conduction after protoplasm death.
Q3654. Sieve tubes are suited for translocation of food because they possess
✅ Correct Answer: Broader lumen and perforated cross walls
🧠 Solution:
Sieve tubes have broader lumens and perforated sieve plates which enable efficient food translocation.
Q3653. Organisation of stem apex into corpus and tunica is determined mainly by
✅ Correct Answer: Planes of cell division
🧠 Solution:
Tunica divides anticlinally to form epidermis, while corpus divides in various planes to form procambium and ground meristem.
Q3701. Pith and cortex do not differentiate in
✅ Correct Answer: monocot stem
🧠 Solution:
In monocot stems, the ground tissue is undifferentiated; hence, cortex, pericycle, endodermis, and pith cannot be distinctly recognized. It consists mostly of parenchyma cells that store food.
Q3697. Cork is formed from
✅ Correct Answer: cork cambium (phellogen)
🧠 Solution:
Cells of cork cambium (phellogen) divide on both sides — outwardly forming cork or phellem and inwardly forming secondary cortex or phelloderm. Cork (phellem) consists of dead, suberised, rectangular cells filled with air and tannins, making it protective in nature.
Q3658. Tunica-corpus theory is connected with
✅ Correct Answer: Shoot apex
🧠 Solution:
Given by Schmidt (1927), the tunica-corpus theory explains shoot apex organisation — tunica forms epidermis and corpus forms procambium and ground meristem.
Q3657. Which meristem helps in increasing girth?
✅ Correct Answer: Lateral meristem
🧠 Solution:
Lateral meristems such as vascular cambium and cork cambium help in increasing girth during secondary growth.