The tissue system Questions in English

(B) In a vascular bundle,when the $xylem$ is completely surrounded by $phloem$,the arrangement is known as $amphicribral$ or $leptocentric$ vascular bundle.
This type of arrangement is commonly observed in certain ferns and some monocots.
$Hadrocentric$ $(amphivasal)$ refers to the condition where $phloem$ is surrounded by $xylem$.
$Radial$ refers to the arrangement where $xylem$ and $phloem$ are placed on different radii.
$Conjoint$ refers to the arrangement where $xylem$ and $phloem$ are present on the same radius.

(B) Vessels and tracheids are both components of xylem responsible for water conduction.
Tracheids are elongated,tube-like cells derived from a single cell.
Vessels are long,cylindrical tube-like structures formed by a vertical row of cells (vessel members) where the cross walls (end walls) are dissolved,creating a continuous channel for water transport.
Therefore,the primary structural difference is that vessels consist of multiple cells with dissolved cross walls,whereas tracheids are single-celled.

(C) Laticifers are specialized cells or vessels that contain latex. They are classified into two types: laticiferous cells (non-articulated) and laticiferous vessels (articulated).
Laticiferous cells are found in plants like $Ficus$,$Calotropis$,and $Nerium$.
Laticiferous vessels are formed by the fusion of many cells and are found in plants like $Papaver$ (Poppy) and $Hevea$.

(B) The correct answer is $B$.
Cystoliths are specialized structures found in the epidermal cells of certain plants, such as $Ficus$ \text{ } $bengalensis$ (Banyan tree).
These structures consist of an aggregation of $CaCO_3$ (calcium carbonate) crystals, which often appear in a grape-like cluster attached to the cell wall by a cellulose stalk.

(D) . The vessel elements are characterized by the presence of perforation plates on their end walls,which allow for the efficient transport of water.
Unlike tracheids,which have closed ends,vessel elements are open at both ends due to these perforations,forming a continuous tube-like structure.
While other xylem elements like tracheids and fibers may possess pits,the presence of distinct end-wall perforations is a unique diagnostic feature of vessel elements.

(C) Laticiferous vessels are specialized structures that contain latex,a milky fluid.
These vessels are typically found in the cortex,phloem,and leaves of certain plants such as $Euphorbia$,$Ficus$,and $Papaver$.
Among the given options,the cortex is a primary location where these vessels are commonly observed.
Therefore,the correct answer is $C$.

(D) According to the Histogen theory proposed by Hanstein,the root apex is composed of three distinct meristematic zones:
$1$. Dermatogen: The outermost layer that gives rise to the epidermis or epiblema.
$2$. Periblem: The middle layer that gives rise to the cortex.
$3$. Plerome: The innermost central core that gives rise to the vascular tissue system (xylem and phloem) and the pith.
Therefore,the correct option is $(d)$.

(A) The $Sieve$ $tube$ $elements$ are specialized cells of the phloem tissue that lack a nucleus at maturity.
They possess thin cellulosic walls and remain living despite the absence of a nucleus,as their metabolic functions are regulated by the adjacent companion cells.
In contrast,$Cambium$ cells and $Phloem$ $parenchyma$ cells retain their nuclei throughout their functional life.

(A) The rind of $Citrus$ fruit contains oil glands known as lysigenous glands.
These glands are formed by the degeneration or breakdown of a group of cells,which creates a cavity that fills with essential oils.
Therefore,the correct option is $A$.

(C) Xylem fibres are classified into two types based on their structural characteristics:
$1$. Fibre tracheids: These have relatively thinner walls and possess reduced bordered pits.
$2$. Libriform fibres (often referred to simply as fibres): These have thicker walls and possess simple pits.
Therefore,the correct classification is fibre tracheids and fibres.

(B) Vessels are long,cylindrical tube-like structures made up of many cells called vessel members,each with lignified walls and a large central cavity. They are devoid of protoplasm. Their primary function is the conduction of water and minerals from the roots to the stem and leaves. They also provide mechanical support to the plant body.

(A) Vessels are specialized conducting elements found in the xylem of angiosperms.
Their primary function is the conduction of water and dissolved mineral salts from the roots to the aerial parts of the plant.
Since 'sap' refers to the fluid consisting of water and dissolved minerals,the conduction of sap is the most accurate description of their chief function.

(A) Phloem parenchyma is a component of the phloem tissue in angiosperms.
It is generally present in dicotyledonous plants like Sunflower,Guava,and Banyan.
However,it is typically absent in most monocotyledonous plants.
Since Maize is a monocot,phloem parenchyma is absent in it.

(B) The correct answer is $B$.
$Schizogenous$ cavities or glands are formed by the separation of cells from each other,which results in the enlargement of the intercellular space.
In contrast,$Lysigenous$ cavities are formed by the dissolution or breakdown of cells.

(A) Latex vessels are formed by the fusion of cells,creating a network-like structure that extends in all directions.
At maturity,they form a highly branched system of channels filled with latex within the plant organ.
Plants possessing such tissues are known as compound or articulated laticifers.
Examples include $Argemone$,$Papaver$,and $Sonchus$.

(C) The correct answer is $C$.
Lignin is a complex polymer that provides structural support and rigidity to plant cells.
In plants,the cells of the $Xylem$ (specifically tracheids and vessels) have thick,lignified secondary cell walls.
This lignification makes the $Xylem$ cells dead at maturity and enables them to conduct water efficiently under high pressure.

(B) Gottlieb Haberlandt,a pioneer in plant anatomy,classified the vascular tissues based on their physiological functions.
He termed the conducting part of the xylem as $Hadrom$ and the conducting part of the phloem as $Leptom$.
Therefore,the correct answer is $Leptom$.

(A) $Protostele$ is the most primitive and simplest type of stele.
It consists of a solid central core of xylem,which is surrounded by a layer of phloem,pericycle,and endodermis.
There is no central pith present in a $Protostele$.
In contrast,$Siphonostele$ contains a central pith,while $Solenostele$ and $Dictyostele$ are more complex types of siphonosteles.

(B) In a $Bicollateral$ vascular bundle,the phloem is present on both the outer and inner sides of the xylem. This type of arrangement is characteristic of the members of the $Cucurbitaceae$ family.

(B) In amphivasal or leptocentric vascular bundles,the phloem is located in the center and is completely surrounded by xylem on all sides.
This type of vascular bundle is characteristic of certain monocotyledonous plants like $Dracaena$ and $Yucca$.

(C) The epidermal cells of the stem often bear hair-like outgrowths known as $Trichomes$.
These structures are usually multicellular and may be branched or unbranched and soft or stiff.
They help in preventing water loss due to transpiration and also provide protection against herbivores.

(A) The cuticle is a waxy,protective layer found on the outermost surface of the plant body,particularly on the leaves and stems.
It is secreted by the epidermal cells (epidermis) to prevent excessive water loss through transpiration and to provide protection against mechanical injury and pathogens.

(B) $Hydathodes$ (water-stomata) are specialized pores present at the margins of leaves.
These pores remain permanently open and are relatively large in size.
Beneath the pore,there is a specialized loose tissue known as $epithem$.
These structures facilitate the process of $guttation$,which is the exudation of water droplets from the leaves.

(C) In a vascular bundle,when xylem and phloem are arranged on the same radius,it is known as a conjoint vascular bundle.
Collateral vascular bundles are a type of conjoint bundle where the phloem is located towards the outer side and the xylem is located towards the inner side.
Radial bundles are those where xylem and phloem are arranged in an alternate manner on different radii.
Concentric bundles are those where one tissue surrounds the other.
Therefore,the correct term for bundles where xylem and phloem are on the same radius is Collateral.

(B) The amphiphloic or bicollateral condition refers to a vascular bundle arrangement where the phloem is present on both the outer and inner sides of the xylem.
This type of arrangement is commonly observed in certain pteridophytes like $Marsilea$ and $Adiantum$.

(C) The plant body is composed of three types of tissue systems based on their structure and location:
$1$. Epidermal tissue system
$2$. Ground or fundamental tissue system
$3$. Vascular or conducting tissue system
$Parenchyma$ and $Sclerenchyma$ are types of simple permanent tissues,not tissue systems. The $Vascular$ tissue system is a type of tissue system consisting of complex tissues like $Xylem$ and $Phloem$.

(D) The cortex is a region of ground tissue in plants composed primarily of parenchyma cells. While most parenchyma cells are living and contain all typical organelles,some specialized parenchyma cells in the cortex may lack chloroplasts (chlorophyll) depending on their location and function,such as those in deep root tissues or storage organs. However,the question refers to a general characteristic where certain cortical cells do not perform photosynthesis and thus lack chlorophyll.

(A) Some of the cells in the leaves of grasses are comparatively very large,called bulliform or motor cells.
These cells are hygroscopic in nature.
They are thin-walled and contain large central vacuoles filled with water.
When water is lost due to stress,these cells become flaccid,causing the leaves to curl or fold to minimize water loss.
When water is available,they become turgid,causing the leaves to unfold.
$e.g.$,$Ammophila$.

(A) In a vascular bundle,when xylem and phloem are arranged on the same radius with phloem towards the outer side and xylem towards the inner side,it is called a collateral vascular bundle.
If a strip of cambium is present between the xylem and phloem,it allows for secondary growth,and the bundle is termed as 'open'.
If cambium is absent,the bundle is termed as 'closed'.
Therefore,a collateral bundle with a strip of cambium is known as 'Collateral and open'.

(C) The $Protostele$ is considered the most primitive type of stele.
In a $Protostele$,the central core of the stem consists of a solid column of vascular tissue (xylem) surrounded by phloem,without a central pith.
This type is commonly found in primitive vascular plants like $Psilotum$ and in the roots of many higher plants.

(B) vascular bundle is described as $closed$ when the $cambium$ is absent between the $xylem$ and $phloem$. In such bundles,secondary growth does not occur.

(C) The correct answer is $C$.
$Vascular$ tissue (xylem and phloem) is well developed in $Xerophytes$.
$Xerophytes$ are plants that grow in environments with limited water availability.
To survive in such arid conditions, they require an efficient transport system to move water from deep soil layers to the aerial parts of the plant.
Therefore, they possess a well-developed root system and highly developed vascular tissue to maximize water uptake and conduction.

(C) vascular bundle in which the phloem is present on both the outer and inner sides of the xylem is called a bicollateral vascular bundle.
In this arrangement,the xylem is located in the center,flanked by two strips of cambium on either side,which are further followed by outer and inner phloem layers.
The sequence is: Outer phloem $\rightarrow$ Outer cambium $\rightarrow$ Middle xylem $\rightarrow$ Inner cambium $\rightarrow$ Inner phloem.
This type of vascular bundle is characteristic of the family Cucurbitaceae.

(C) Phloem parenchyma is a component of the phloem tissue. It is generally present in pteridophytes,gymnosperms,and most dicotyledonous angiosperms. However,it is typically absent in the phloem of monocotyledonous plants,such as the monocot stem.

(A) The pith is the central part of the stem or root in flowering plants.
It is primarily composed of thin-walled $Parenchyma$ cells.
These cells are responsible for the storage of food and water.
Therefore,the correct option is $A$.

(B) According to the Tunica-Corpus theory,the tunica layers undergo only anticlinal divisions,which increase the surface area of the shoot apex.
Since the tunica layers are responsible for surface growth,only the outermost layer of the tunica differentiates into the epidermis of the stem.
The inner layers of the tunica and the corpus contribute to the formation of the internal tissues,such as the cortex and vascular tissues.

(B) $Cystolith$ is a botanical term referring to a concretion of mineral matter, typically $Calcium \text{ } carbonate$, formed within the cells of certain plants.
These structures are commonly found in the leaves of plants belonging to families like $Urticaceae$, $Moraceae$, and $Acanthaceae$.
They are usually deposited in specialized cells called $Lithocysts$.
Therefore, the correct composition of a $Cystolith$ is $Calcium \text{ } carbonate$ $(CaCO_3)$.

(A) The outer walls of the epidermal cells in plants are often covered with a waxy,thick layer called the cuticle.
This cuticle is composed of a waxy substance known as cutin.
Cutin is a fatty acid derivative that helps in preventing water loss through transpiration and provides protection against mechanical injury and pathogen invasion.
Therefore,the correct answer is $A$ (Cutin).

(C) Girdling is a process where a ring of bark is removed from the circumference of a tree trunk.
This ring includes all tissues from the epidermis through the cortex and the phloem,down to the xylem.
Since the phloem is responsible for the translocation of food (sugars) from leaves to other parts of the plant,its removal disrupts the downward movement of nutrients.
The xylem remains intact,allowing water transport to continue for a short period.

(A) Lenticels are small pores found on the bark of woody stems that facilitate gas exchange. Hydathodes are specialized pores found at the tips or margins of leaves that facilitate guttation (the exudation of water droplets). Both structures are characterized by the fact that they lack a regulatory mechanism for opening and closing,unlike stomata which are regulated by guard cells. Therefore,they remain permanently open.

(B) Safranin is a water-soluble dye used to stain plant tissues.
When the cut end of a shoot is placed in a safranin solution,the dye is absorbed along with water through the xylem vessels.
Since xylem is responsible for the conduction of water and minerals from the roots to the aerial parts of the plant,the dye will be transported upward through the xylem.
Tracheids and vessels are the primary conducting elements of the xylem.
Therefore,the presence of the dye will be observed in the tracheid elements.

(A) Epithem is a specialized tissue found in hydathodes,which are structures involved in guttation.
It consists of a mass of small,thin-walled,and loosely arranged parenchyma cells.
These cells are located at the terminal ends of the vascular bundles (xylem) within the leaf,facilitating the movement of water from the xylem to the water pores (stomata) of the hydathode.

(D) Phloem is composed of four main elements: sieve tube elements, companion cells, phloem parenchyma, and phloem fibers (sclerenchyma).
$Vessels$ (tracheae) are a characteristic component of the xylem tissue, not the phloem.
Therefore, the correct option is $(d)$.

(C) In woody stems and certain fruits like apples,as well as in tubers like potatoes,the outer protective layer is often composed of cork or periderm.
These structures contain small pores known as $Lenticels$.
$Lenticels$ are lens-shaped openings that allow for the exchange of gases ($O_2$ and $CO_2$) between the internal tissues of the plant and the external atmosphere.
Therefore,apples and potatoes obtain $O_2$ through $Lenticels$.

(C) Cystoliths are specialized plant structures found in the cells of certain plant species,such as those in the family $Urticaceae$ and $Moraceae$.
They consist of a mass of calcium carbonate crystals deposited on a cellulose stalk that projects into the cell lumen.
These structures are typically found in specialized cells called lithocysts.

(C) The stems and leaves of many grasses feel rough to the touch because their epidermal cells contain deposits of $Silica$ $(SiO_2)$.
These silica deposits form phytoliths,which provide structural support and act as a defense mechanism against herbivores by making the plant tissue abrasive and difficult to digest.

(A) Cystoliths are calcium carbonate crystals that are typically found in the epidermal cells of certain plants. They are commonly observed in the leaves of the rubber plant $(Ficus \text{ } elastica)$. These structures are formed within specialized cells called lithocysts.

(B) Amphivasal or leptocentric vascular bundles are a type of concentric vascular bundle where the phloem is located in the center and is completely surrounded by xylem.
These are characteristic features of certain monocotyledonous stems,such as $Dracaena$ and $Yucca$.
In contrast,amphicribral (hadrocentric) bundles have xylem in the center surrounded by phloem,which is common in ferns like $Dryopteris$.

(A) The epidermis is the outermost layer of the primary plant body.
It is covered by a waxy,thick layer called the cuticle,which prevents the loss of water.
The cuticle is made up of a fatty substance known as cutin.
Therefore,the correct answer is $A$.

(A) Xylem fibers are sclerenchymatous cells associated with the xylem. They are highly thickened and provide mechanical support to the conducting elements of the xylem, specifically the $Xylem$ $\text{vessels}$ and $Tracheids$, which are responsible for the transport of water and minerals. Among the given options, xylem fibers primarily provide structural strength to the conducting elements of the xylem.