Question
Match the List-I with List – II. [NEET 2021]
Select the correct answer from the options given below.
A B C D
(a) 2 4 1 3
(b) 4 3 2 1
(c) 1 2 3 4
(d) 3 2 4 1
Answer/Explanation
Ans. (a)
(A)-(2), (B)-(4), (C)-(1), (D)-(3)
Meristematic cells are totipotent and are capable of continued cell division. Division of meristematic cells provides new cells for expansion and differentiation of tissues and the initiation of new organs, providing the basic structure of the plant body. Hence, they have cells with active cell division capacity.
Permanent tissues having all cells similar in structure and function are called simple tissue.
Vascular tissues are formed of more than one cell type, found in vascular plants.
The primary components of vascular tissues are the xylem and phloem. These two tissues transport fluid and nutrients internally.
Sclereids are a kind of sclerenchyma cells that are irregular or short. These are dead cells. Their walls are irregular, very thick and their lumen is very narrow. They do not conduct any metabolic activities. They exhibit different types of lignin depositions and also have pits. Sclereids are found in hard parts such as hard seed coats, endocarp of coconut. They are also referred to as stone cells.
Question
Regeneration of damaged growing grass following grazing is largely due to [NEET (Odisha) 2019]
(a) lateral meristem
(b) apical meristem
(c) intercalary meristem
(d) secondary meristem
Answer/Explanation
Ans. (c)
Regeneration of damaged growing grass following grazing is largely due to intercalary meristem. It is the meristem which occurs between mature tissues. It is found in grasses and regenerates parts damaged by the grazing herbivores.
Question
Root hairs develop from the region of [NEET 2017]
(a) maturation
(b) elongation
(c) root cap
(d) meristematic activity
Answer/Explanation
Ans. (d)
The root is covered at the apex by a thimble-like structure called the root cap. It protects the tender apex of the root as it makes its way through the soil. A few millimetres above the root cap is the region of meristematic activity. The cells of this region are very small, thin-walled and with dense protoplasm. They divide repeatedly. The cell proximal to this region undergo rapid elongation and enlargement and are responsible for the growth of the root in length. This region is called the region of elongation. The cells of the elongation zone gradually differentiate and mature. Hence, this zone, proximal. From this region, some of the epidermal cells form very fine and delicate, thread-like structure called root hairs. These root hairs absorb water and minerals from the soil.
Question
Specialised epidermal cells surrounding the guard cells are called [NEET 2016, Phase I]
(a) subsidiary cells
(b) bulliform cells
(c) lenticels
(d) complementary cells
Answer/Explanation
Ans. (a)
Few epidermal cells, in the vicinity of the guard cells become specialised in their shape and size and are known as subsidiary cells. These cells are devoid of chloroplasts.The stomatal aperture, guard cells and the surrounding subsidiary cells are together called stomatal apparatus.
Question
Which of the following is made up of dead cells? [NEET 2017]
(a) Xylem parenchyma
(b) Collenchyma
(c) Phellem
(d) Phloem
Answer/Explanation
Ans. (c)
Phellem or cork is a tissue formed on the outer side of cork cambium. It is composed of dead cells. The cell wall become impermeable due to suberisation.
Question
Tracheids differ from other trachery elements in [CBSE AIPMT 2014]
(a) having casparian strips
(b) being imperforate
(c) lacking nucleus
(d) being lignified
Answer/Explanation
Ans. (b)
Tracheids and vessels both are called tracheary elements because their main function is conduction of sap.
Tracheids differ from other trachaery elements in being imperforate.
Tracheids are the specific cells which have pits to support upwards and lateral conduction of water sap. Tracheid are comparatively short and single cell, while vessels have more than one cell and up to $10 \mathrm{~cm}$ long.
Question
The common bottle cork is a product of [CBSE AIPMT 2012]
(a) dermatogen
(b) phellogen
(c) xylem
(d) vascular cambium
Answer/Explanation
Ans. (b)
The cork cambium or phellogen cells divide periclinally cutting off cells towards the outside and inside. The cells cut off towards the out side becomes suberised and dead. These are compactly packed in radial rows without intercellular spaces and form cork or phellem. Cork is impervious to water due to the suberin and provides protection to underlying tissues. The cells cut off from cork cambium towards inside add to the cortex and are called secondary cortex cells or phelloderm cells.
Question
Companion cells are closely associated with [CBSE AIPMT 2012]
(a) sieve elements
(b) vessel elements
(c) trichomes
(d) guard cells
Answer/Explanation
Ans. (a)
Companion cells are characteristic elements of phloem tissue associated with the sieve tubes (sieve elements) in the angiosperms. The sieve tubes and companion cells are related ontogenically as they develop from the same mother cell. The companion cells and sieve tubes maintain close cytoplasmic connections through plasmodesmata.
Question
Closed vascular bundles lack [CBSE AIPMT 2012]
(a) ground tissue
(b) conjunctive tissue
(c) cambium
(d) pith
Answer/Explanation
Ans. (c)
Closed vascular bundles lack cambium. In dicot stems, cambium is present between phloem and xylem. Such vascular bundles because of the presence of cambium, possess the ability to form secondary xylem and phloem tissues and hence, are called open vascular bundles. On the contrary, vascular bundles in monocots have no cambium. Hence, they do not form secondary tissues, and are referred to as closed.
Question
Ground tissue includes[CBSE AIPMT 2011]
(a) all tissues except epidermis and vascular bundles
(b) epidermis and cortex
(c) all tissues internal to endodermis
(d) all tissues external to endodermis
Answer/Explanation
Ans. (a)
All tissues except epidermis and vascular bundles constitute the ground tissue or fundamental tissue. It consists of simple tissues such as parenchyma, collenchyma and sclerenchyma. It includes cortex, pericycle, medullary rays, in leaves the ground tissue consists of mesophyll.
Question
The chief water conducting elements of xylem in gymnosperms are [CBSE AIPMT 2010]
(a) vessels
(b) fibres
(c) transfusion tissue
(d) tracheids
Answer/Explanation
Ans. (d)
The tracheids are elongated, angular dead cells with hard lignified wide lumen and narrow end walls. The walls of tracheids possess different types of thickenings and the unthickened areas of its wall allow the rapid movement of water from one tracheid to another. Tracheids are the characteristic cell types of xylem tissues in gymnosperms and pteridophytes, where they are the chief elements of water conduction.
Question
Which one of the following is not a lateral meristem? [CBSE AIPMT 2010]
(a) Intrafascicular cambium
(b) Interfascicular cambium
(c) Phellogen
(d) Intercalary meristem
Answer/Explanation
Ans. (d)
Intercalary meristems are the portions of apical meristems which are separated from the apex during the growth of axis and formation of permanent tissues. It is present mostly at the base of node, (e.g. Mentha viridis), base of internode, (e.g. stem of many monocots viz, wheat, paddy, grasses; pteridophytes like Equisetum) or at the base of leaf, (e.g. Pinus).
Question
Palisade parenchyma is absent in leaves of [CBSE AIPMT 2009]
(a) Sorghum
(b) mustard
(c) soyabean
(d) gram
Answer/Explanation
Ans. (a)
Sorghum (family-Poaceae) is a monocot plant. The leaves of monocot do not contain palisade parenchyma because the mesophyll of monocot leaf is not differentiated into palisade and spongy parenchyma, all being thin walled, chlorophyllous and irregularly compactly arranged with fewer intercellular spaces.
Palisade cells occur in dicotyledonous plants and also in the net-veined monocots, the Araceae and Dioscoreaceae.
Question
The annular and spirally thickened conducting elements generally develop in the protoxylem when the root or stem is [CBSE AIPMT 2009]
(a) maturing
(b) elongating
(c) widening
(d) differentiating
Answer/Explanation
Ans. (c)
Vessels or tracheae are made up of a row of cells, placed one above the other, with their intervening walls absent or variously pored. The walls of vessels are lignified and hard but not very thick. The cell cavity or the lumen is wide. The thickening may be annular, spiral, scalariform, reticulate and pitted.
Question
In barley stem, vascular bundles are [CBSE AIPMT 2009]
(a) open and scattered
(b) closed and scattered
(c) open and in a ring
(d) closed and radial
Answer/Explanation
Ans. (b)
The vascular bundles in Hordeum vulgare(barley) plant are scattered in ground tissues, many in number and vary in size-smaller towards periphery and bigger towards centre of the ground tissue, oval or rounded in outline, conjoint, collateral and closed.
Question
Reduction in vascular tissue, mechanical tissue and cuticle is characteristic of [CBSE AIPMT 2009]
(a) xerophytes
(b)mesophytes
(c) epiphytes
(d) hydrophytes
Answer/Explanation
Ans. (d)
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.
Question
The length of different internodes in a culm of sugarcane is variable because of [CBSE AIPMT 2008]
(a) shoot apical meristem
(b) position of axillary buds
(c) size of leaf lamina at the node below each internode
(d) intercalary meristem
Answer/Explanation
Ans. (d)
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.
The shoot apical meristem present at the apices of shoot, is self determining and autonomous organising centre. The primary growth and differentiation of primary tissues is entirely due to this meristem as it continuously divides giving rise to new cells. These are the apical meristems that increase the length of plant but not internodes variability.
Question
Vascular tissues in flowering plants develop from [CBSE AIPMT 2008]
(a) phellogen
(b) plerome
(c) periblem
(d) dermatogen
Answer/Explanation
Ans. (b)
Histogen theory for shoot apical meristem has been proposed by Hanstein (1870). It advocates that there are three distinct meristematic zones (layers) called dermatogen, periblem and plerome. The dermatogen is the outermost histogen giving rise to epidermis, periblem is the middle one producing the cortex and plerome is the innermost resulting in central cylinder, (i.e. vascular tissue).
Cork cambium (phellogen) is the secondary lateral meristem found in outer cortical region. Its cells divide periclinally cutting off cells towards the out side (forming cork or phellem) and inside (forming secondary cortex or phelloderm).
Question
Passage cells are thin walled cells found in [CBSE AIPMT 2007]
(a) endodermis of roots facilitating rapid transport of water from cortex to pericycle
(b) phloem elements that serve as entry points for substances for transport to other plant parts
(c) testa of seeds to enable emergence of growing embryonic axis during seed germination
(d) central region of style through which the pollen tube grows towards the ovary
Answer/Explanation
Ans. (a)
In roots, endodermis is the innermost layer of cortex. Some of the endodermal cells present opposite to the xylem patches are thin walled and are called passage cells or transfusion cells.
Passage cells help in transfer of water and dissolved salts from cortex directly into the xylem and ultimately to the pericycle.
Question
A common structural feature of vessel elements and sieve tube elements are [CBSE AIPMT 2006]
(a) pores on lateral walls
(b) presence of $p$-protein
(c) enucleate condition
(d) thick secondary walls
Answer/Explanation
Ans. (a)
The vessels are nucleated and the sieve tube elements are enucleated.
The wall of both the vessel and sieve tube elements are perforated by large openings. Due to these adaptation the cell to cell contact is possible.
Question
Chlorenchyma is known to develop in the [CBSE AIPMT 2003]
(a) pollen tube of Pinus
(b) cytoplasm of Chlorella
(c) mycelium of a green mould such as Aspergillus
(d) spore capsule of a moss
Answer/Explanation
Ans. (d)
The apophysis of moss capsule contains chloroplast bearing parenchymatous cells, called as chlorenchyma. Due to the presence of chloroplasts, chlorenchyma cells have the ability to prepare food by the process of photosynthesis.
Question
The apical meristem of the root is present [CBSE AIPMT 2003]
(a) in all the roots
(b) only in radicals
(c) only in tap roots
(d) only in adventitious roots
Answer/Explanation
Ans. (a)
Apical meristems are primary meristems which are located in the growing points (roots and shoot apices), as well as buds in the axils of leaves. The various organs increase in length due to the activity of apical meristem.
Question
The cells of the quiescent centre are characterised by [CBSE AIPMT 2003]
(a) dividing regularly to add to tunica
(b) having dense cytoplasm and prominent nuclei
(c) having light cytoplasm and small nuclei
(d) dividing regularly to add to the corpus
Answer/Explanation
Ans. (c)
The region of quiescent centre was discovered by Clowes (1958). The cells of quiescent centre have lower concentration of DNA, RNA and protein as compared to other cells in the root apex. These cells also have fewer mitochondria, little endoplasmic reticulum and very small nuclei and nucleoli.
Question
Vessels are found in [CBSE AIPMT 2002]
(a) all angiosperms and some gymnosperms
(b) most of angiosperms and few gymnosperms
(c) all angiosperms and few gymnosperms and some pteridophytes
(d) all pteridophytes
Answer/Explanation
Ans. (b)
Most angiosperms have vessels except a few, (e.g. Drimys, Tetracentron, Trochodendron). The gymnosperms, as a rule, lack vessels but these are found in the order-Gnetales. Vessels are the constituent of xylem. They are composed of row of cells placed one above the other. Transverse wall of these cells is absent due to the dissolution.
Question
Four radial vascular bundles are found in [CBSE AIPMT 2002]
(a) dicot root
(b) monocot root
(c) dicot stem
(d) monocot stem
Answer/Explanation
Ans. (a)
Roots have radial vascular bundles while stems have conjoint vascular bundles. Dicot roots have 3-6 vascular bundles while monocot roots have more than 6 vascular bundles.
Question
Axillary bud and terminal bud are derived from the activity of [CBSE AIPMT 2002]
(a) lateral meristem
(b) intercalary meristem
(c) apical meristem
(d) parenchyma
Answer/Explanation
Ans. (c)
It is the shoot apical meristem which gives rise to lateral buds. The lateral buds however remain suppressed due to the apical dominance.
Question
Which of the following statements is true? [CBSE AIPMT 2002]
(a) Vessels are multicellular with narrow lumen
(b) Tracheids are multicellular with narrow lumen
(c) Vessels are unicellular with wide lumen
(d) Tracheids are unicellular with wide lumen
Answer/Explanation
Ans. (a)
Each vessel is made up of a number of components called ‘vessel members’ arranged end-to-end running parallel to the long axis of the organ in which it lies.
Question
What happens during vascularisation in plants? [CBSE AIPMT 2000]
(a) Differentiation of procambium is immediately followed by the development of secondary xylem and phloem
(b) Differentiation of procambium followed by the development of xylem and phloem
(c) Differentiation of procambium, xylem and phloem is simultaneous
(d) Differentiation of procambium followed by the development of primary phloem and then by primary xylem
Answer/Explanation
Ans. (c)
From the procambium, primary xylem and phloem arise simultaneously.
Question
Which of the following meristems is responsible for extrastelar secondary growth in dicotyledonous stem? [CBSE AIPMT 1998]
(a) Intrafascicular cambium
(b) Interfascicular cambium
(c) Intercalary meristem
(d) Phellogen
Answer/Explanation
Ans. (d)
Phellogen or cork cambium is a part of periderm. It presents between phellem or cork towards outerside and phelloderm or secondary cortex towards inner side. Phellogen appearing in the cortical regions cuts off new cells for extrastelar secondary growth-cork on the outer side and secondary cortex on the inner side.
Question
A leaf primordium grows into the adult leaf lamina by means of [CBSE AIPMT 1998]
(a) apical meristem
(b) lateral meristem
(c) marginal meristem
(d) at first by apical meristem and later largely by marginal meristem
Answer/Explanation
Ans. (d)
Apical meristem is present at the tips of stems, roots and leaves, it takes part in initial growth or elongation of roots, stems and leaves. Marginal meristem or plate meristem has parallel layers of cells which divide anticlinally in two planes as in growing flat organs like-leaves.
Question
At maturity which of the following is enucleate? [CBSE AIPMT 1997]
(a) Sieve cell
(b) Companion cell
(c) Palisade cell
(d)Cortical cell
Answer/Explanation
Ans. (a)
Phloem (complex tissue) is composed of companion cells, phloem parenchyma, phloem fibre and sieve tube cells. Sieve tube cells are cylindrical and tube-like structure which are involved in transport of organic solute. In sieve cells nucleus is evident in the younger stage but disappears in mature stage.
Question
What is not true about sclereids? [CBSE AIPMT 1996]
(a) These are parenchyma cells with thickened lignified walls
(b) These are elongated and flexible with tapered ends
(c) These are commonly found in the shells of nuts and in the pulp of guava, pear, etc
(d) These are also called the stone cells
Answer/Explanation
Ans. (a)
Sclereids are broad sclerenchyma cells which may be oval, spherical, cylindrical, or stellate in structure. Sclereids develop from sclerenchyma cells, occur singly or in groups to provide stiffness.
These may be of different types, such as brachysclereids (stone cells) found in grit of pear, apple, macrosclereids (columnar), e.g. legume seeds, astrosclereids (star shaped), e.g. tea leaves, etc.
Question
Bordered pits are found in [CBSE AIPMT 1993]
(a) sieve cells
(b) vessel wall
(c) companion cells
(d) sieve tube wall
Answer/Explanation
Ans. (b)
Pits are the depressions or cavity formed in the cell wall that are found in the sclerenchyma, thick walled parenchyma cells and the tracheary elements, (i.e. vessels and tracheids).
Simple pits are uniform while bordered pits are the flask shaped depressions.
Question
Which is correct about transport or conduction of substances? [CBSE AIPMT 1991, 97]
(a) Organic food moves up through phloem
(b) Organic food moves up through xylem
(c) Inorganic food moves upwardly and downwardly through xylem
(d) Organic food moves upwardly and downwardly through phloem
Answer/Explanation
Ans. (d)
Sieve tubes are the conducting elements of phloem that carry the organic nutrients upwardly and downwardly. Organic nutrients absorbed through roots reaches the shoot apex and other parts through phloem cells. Moreover, nutrients are also translocated downwardly through phloem as demonstrated by girdling experiment (Malpighi; 1671) in which removal of ring of bark (including phloem) prevents downward translocation of food and causing starvation and death of roots.
Question
Angular collenchyma occurs in [CBSE AIPMT 1991]
(a) Cucrbita
(b) Tagetes
(c) Althaea
(d) Salvia
Answer/Explanation
Ans. (b)
Depending upon the thickening, collenchyma is of three types-(a) Angular-thickening at the angles, e.g. stem of tomato, Datura, Tagetes (marigold), (b) Lamellar-thickening on tangential walls, e.g. stem of sunflower, (c) Lacunate-thickening on the walls bordering intercellular spaces, e.g. stem of Cucurbita.
Question
An organised and differentiated cellular structure having cytoplasm but no nucleus is [CBSE AIPMT 1991]
(a)vessels
(b) xylem parenchyma
(c) sieve tubes
(d) tracheids
Answer/Explanation
Ans. (c)
Sieve tubes are food conducting elements of phloem. They possess nucleus in the young stage but disappears in mature ones. The central part of sieve tube has an organised and differentiated cellular structure with a network of cytoplasmic strands, though the peripheral cytoplasm is thin and tonoplast is absent.
Question
Collenchyma occurs in the stem and petioles of [CBSE AIPMT 1990]
(a) xerophytes
(b) monocots
(c) dicot herbs
(d) hydrophytes
Answer/Explanation
Ans. (c)
Collenchyma is a simple permanent tissue, made of elongated living cells having thickened pectocellulosic walls. It is a living mechanical tissue which provides both mechanical strength and elasticity and allow them to grow in size. Collenchyma is found in epidermis of dicot stem and petioles and abundant in climbing stems.
Question
Monocot leaves possess [CBSE AIPMT 1990]
(a) intercalary meristem
(b) lateral meristem
(c) apical meristem
(d) mass meristem
Answer/Explanation
Ans. (a)
Intercalary meristems are derived from the apical meristems and separated from the same by permanent cells. These meristems occur at leaf bases and above or below the nodes (e.g. grass, mint). They help in elongation of leaves and internodes besides allowing the prostrate stems to become erect.
Question
Organisation of stem apex into corpus and tunica is determined mainly by [CBSE AIPMT 1989]
(a) planes of cell division
(b) regions of meristematic activity
(c) rate of cell growth
(d) rate of shoot tip growth
Answer/Explanation
Ans. (a)
Tunica (outer zone of shoot apex) forms protoderm which through anticlinal divisions gives rise to epidermis of stem and leaves. Corpus is inner mass of meristem where cells undergo divisions in different planes to form procambium and ground meristem.
Question
Sieve tubes are suited for translocation of food because they possess [CBSE AIPMT 1989]
(a) bordered pits
(b) no ends walls
(c) broader lumen and perforated cross walls
(d) no protoplasm
Answer/Explanation
Ans. (c)
Sieve tubes function as the food conducting elements of phloem which are elongated tubular channels formed by end to end union of numerous cells. Sieve tubes have broader lumen, thin walls. Septa present between sieve tube cells are called sieve plates, they possess a number of perforations called sieve pores or sieve pits.
Question
Death of protoplasm is a prerequisite for a vital function like [CBSE AIPMT 1989]
(a) transport of sap
(b) transport of food
(c) absorption of water
(d) gaseous exchange
Answer/Explanation
Ans. (a)
Certain cells get lignified, leading to death of protoplasm such as xylem cells. Xylem cells are dead, i.e. devoid of protoplasm, and performs the function of conducting water or sap inside the plant.
Question
Out of diffuse porous and ring porous woods, which is correct? [CBSE AIPMT 1989]
(a) Ring porous wood, carries more water for short period
(b) Diffuse porous wood carries more water
(c) Ring porous wood carries more water when need is higher
(d) Diffuse porous wood is less specialised but conducts water rapidly through out
Answer/Explanation
Ans. (c)
In dicots, large sized vessels are arranged in two ways-ring porous (large sized vessels in early wood, e.g. Quercus) and diffuse porous (large sized vessels distributed throughout, e.g. Azadirachta). Ring porous vessels are more efficient and advanced as they provide quicker translocation when water requirement is maximum.
Question
Which meristem helps in increasing girth? [CBSE AIPMT 1988]
(a) Lateral meristem
(b) Intercalary meristem
(c) Primary meristem
(d) Apical meristem
Answer/Explanation
Ans. (a)
Lateral meristem occurs on the sides and helpful in increasing girth of stem and root, e.g. vascular cambium, phellogen (cork cambium).
Question
Tunica corpus theory is connected with [CBSE AIPMT 1988]
(a) root apex
(b) root cap
(c) shoot apex
(d) secondary growth
Answer/Explanation
Ans. (c)
Tunica corpus theory, given by Schmidt (1927) is related with shoot apex or stem apical meristem. According to it, tunica is the outer zone of shoot apex while corpus is inner zone. Tunica forms protoderm that give rise to epidermis of stem and leaves. Corpus is the inner mass which undergoes divisions to form procambium and ground meristem.