Permanent Tissue Questions in English

(D) Vessels are specialized conducting elements found primarily in the xylem of angiosperms.
In most pteridophytes and gymnosperms,vessels are absent,and water conduction is carried out by tracheids.
Therefore,both pteridophytes and gymnosperms lack vessels in their xylem,making option $(d)$ the correct answer.

(C) Angiosperms are characterized by the presence of both tracheids and vessels in their xylem tissue.
These elements together form the primary water-conducting tissue in the vascular bundles of angiosperms,facilitating the transport of water and minerals from roots to the rest of the plant.

(C) Xylem parenchyma cells are thin-walled,living cells composed of cellulose. They are the only living components of the xylem tissue and are responsible for storing food materials and assisting in the radial conduction of water.

(D) The correct answer is $D$.
Sieve tubes are specialized cells in the phloem tissue responsible for the translocation of food.
During the winter season or when the plant is injured,the sieve pores become plugged with a carbohydrate polymer known as callose.
This deposition of callose reduces or blocks the transport of food materials through the sieve tubes.

(D) Parenchyma is a simple permanent tissue that serves as the fundamental tissue of plants.
It is highly versatile and can be modified to perform various functions:
$1$. Photosynthesis: When parenchyma cells contain chloroplasts,they are called chlorenchyma,which performs photosynthesis.
$2$. Storage: Parenchyma cells often store food materials like starch,proteins,and fats.
$3$. Secretion and excretion: Parenchyma cells can also be involved in the secretion of substances like resins,tannins,and essential oils.
Therefore,all the mentioned functions are performed by parenchymatous tissue.

(B) Idioblasts are specialized parenchyma cells that differ from the surrounding cells in their structure and function.
These cells are primarily involved in the storage of metabolic byproducts such as tannins,oils,resins,gums,and crystals like calcium oxalate or calcium carbonate.
Sclereids and stone cells are types of sclerenchyma,not parenchyma.
Conjunctive tissue refers to the parenchyma cells present between the xylem and phloem in roots.

(A) $Sclereids$ are a type of sclerenchyma tissue composed of dead cells with highly thickened,lignified walls and narrow cavities $(lumina)$.
Unlike sclerenchyma fibers,which are elongated and needle-like,$sclereids$ are typically isodiametric or irregular in shape.
They can be spherical,oval,cylindrical,$T$-shaped,dumbbell-shaped,or even stellate (star-shaped).

(D) The secondary cell wall is a thick layer formed inside the primary cell wall in certain plant cells,such as tracheids,vessels,and sclerenchyma,to provide structural support.
$Parenchyma$ cells have thin primary walls and lack secondary walls.
$Collenchyma$ cells possess unevenly thickened primary walls (due to cellulose,hemicellulose,and pectin) but do not develop a secondary wall.
$Companion$ cells are specialized parenchyma cells associated with sieve tube elements and also possess only primary cell walls.
Therefore,none of these cell types form a secondary wall.

(B) is the correct answer. Collenchyma is a living mechanical tissue that provides both mechanical support and elasticity to growing organs. Its cells have uneven thickenings of cellulose,hemicellulose,and pectin,which allow the tissue to be extensible and provide tensile strength to young,growing stems and petioles.

(D) The walls of vessels are lignified,which provides mechanical support and rigidity to the plant body.
In contrast,sieve tubes are living cells that possess thin cellulose walls and lack lignification,which allows them to facilitate the translocation of food materials.

(A) In hydrophytic plants,mechanical tissues like $Sclerenchyma$ and $Collenchyma$ are typically absent or poorly developed because the water provides buoyancy and support to the plant body.
Instead,the $Parenchyma$ tissue,specifically $Aerenchyma$ (a type of parenchyma with large air cavities),provides the necessary buoyancy and mechanical support to the plant.

(B) $Collenchyma$ is a type of simple permanent tissue that provides mechanical support to the growing parts of the plant, such as young stems and petioles of leaves.
These cells are living at maturity and possess characteristic thickening at the corners due to the deposition of cellulose, hemicellulose, and pectin.
In contrast, $Sclerenchyma$ cells are dead at maturity, while $Parenchyma$ and $Chlorenchyma$ are primarily involved in storage and photosynthesis, respectively, and provide minimal mechanical support.

(D) $Aerenchyma$ is a specialized type of parenchyma tissue found in aquatic plants $(hydrophytes)$.
It contains large air cavities or air spaces that store gases.
These air cavities provide buoyancy to the plants,allowing them to float on the surface of the water.
Therefore,the correct option is $D$.

(B) $Collenchyma$ is a simple permanent tissue found in the primary plant body.
It consists of cells that are often oval,spherical,or polygonal (isodiametric).
The characteristic feature of $Collenchyma$ is the uneven thickening of the cell walls.
These thickenings are primarily composed of cellulose,hemicellulose,and pectin,and they are specifically deposited at the corners where the cells meet.
Therefore,option $B$ is the correct description.

(D) The correct answer is $D$.
In mature angiosperms,sieve tube elements are specialized conducting cells that lose their nuclei at maturity to facilitate the efficient transport of food materials (phloem sap).
While they possess a nucleus during their early developmental stage,it degenerates as they mature,leaving them with only a thin layer of cytoplasm and a large central vacuole.

(A) Collenchyma cells are living and retain their protoplasm at maturity. They provide mechanical support to the growing parts of the plant.
In contrast,sclerenchyma cells are dead at maturity and lack protoplasm. Their cell walls are heavily thickened due to the deposition of $lignin$,which makes them hard and rigid.

(B) The correct answer is $B$.
Sclerenchyma cells possess hard and extremely thick secondary cell walls due to the uniform deposition of lignin.
Lignin is a complex polymer that provides structural support and mechanical strength to the plant.

(D) Companion cells are specialized parenchymatous cells that are closely associated with sieve tube elements in the phloem of angiosperms.
They are connected to the sieve tubes by pit fields present between their common longitudinal walls.
Companion cells help in maintaining the pressure gradient in the sieve tubes,which is essential for the translocation of food.

(A) Sieve tubes are specialized cells in the phloem tissue of angiosperms that are responsible for the translocation of food (sugars).
They are better suited for this function because they possess a broader lumen,which reduces resistance to the flow of sap,and perforated cross walls known as sieve plates,which facilitate the movement of materials between adjacent sieve tube elements.

(D) Collenchyma is a type of simple permanent tissue that provides mechanical support to young stems and petioles.
Unlike parenchyma,which has uniformly thin cell walls made of cellulose,collenchyma cells are characterized by localized thickenings of the cell wall at the corners.
These thickenings are primarily composed of pectin,hemicellulose,and cellulose.
Therefore,the presence of pectin deposits at the corners is the distinguishing feature of collenchyma compared to parenchyma.

(A) The term xylem was introduced by Nageli $(1858)$. Xylem is a complex conducting tissue.
It consists of four types of elements: Tracheids,Trachea (vessels),Xylem fibres (wood fibres),and Xylem parenchyma.

(B) Tyloses are balloon-like outgrowths of parenchyma cells that protrude into the lumen of xylem vessels through the pits.
They are formed when the plant is under stress or injured,effectively blocking the vessel lumen and preventing the spread of pathogens or air bubbles (embolism).
Therefore,they are responsible for plugging the lumen of vessels.

(D) Tracheids are elongated cells with tapering ends and are dead at maturity.
In Gymnosperms,tracheids are the primary water-conducting elements and are characterized by the presence of bordered pits.
In Angiosperms,the primary water-conducting elements are vessels,while tracheids are also present but are not the primary conducting elements.
Since bordered pits are a characteristic feature of Gymnosperm tracheids and are not the defining feature used to recognize Angiosperm tracheids,the correct answer is $D$.

(B) Plant fibres are elongated,lignified,and dead cells that provide mechanical support to the plant.
They are found in various parts of the plant body.
Specifically,fibres are present in the $Xylem$ (as xylem fibres),$Phloem$ (as phloem fibres or bast fibres),and they are a primary component of $Sclerenchyma$ tissue.
Therefore,plant fibres can originate from phloem,xylem,and sclerenchyma tissues.

(D) The correct answer is $D$.
$Xylem$ is a complex permanent tissue that acts as a conducting tissue for water and minerals from roots to the stem and leaves.
The primary components of $Xylem$ are tracheids, vessels, $Xylem$ fibers, and $Xylem$ parenchyma.
Tracheids and vessels are dead cells at maturity and possess hard, thick, and lignified cell walls to provide mechanical support and facilitate water transport.

(A) Permanent tissues are composed of mature cells that have lost the capacity to divide. These cells have attained a permanent shape,size,and specific function as a result of division and differentiation occurring in meristematic tissues.

(B) Safranine is a biological stain used in histology and cytology. It is a basic dye that has a high affinity for lignified cell walls. Therefore,it is commonly used to stain lignified elements of the tissue,such as xylem vessels and tracheids,appearing red under a microscope.

(A) The sieve tubes are specialized conducting cells of the phloem tissue.
Their primary function is the translocation of organic nutrients,specifically sucrose,from the source (leaves) to the sink (roots,fruits,or growing regions).
They are living cells that lack a nucleus at maturity and are associated with companion cells to facilitate the transport process.

(A) . Parenchyma is a simple permanent tissue that primarily functions in the storage of food materials,photosynthesis,and secretion. Examples include the storage of starch in roots like carrots and beetroots.

(A) $Collenchyma$ is a living mechanical tissue that provides both mechanical support and flexibility to the growing parts of plants,such as young stems and petioles of leaves.
In climbing plants,$collenchyma$ is particularly abundant because these plants require significant flexibility and tensile strength to grow and support themselves while climbing on other structures without breaking.

(C) Parenchyma is a simple permanent tissue consisting of cells that are generally isodiametric in shape.
These cells have thin cell walls made up of cellulose.
Because the cells are loosely packed,there is a significant presence of intercellular spaces between them.
In contrast,collenchyma is characterized by thickening in the corners,and sclerenchyma is characterized by lignified walls.

(C) Lignin is a complex polymer that provides structural support,rigidity,and water-proofing to plant cell walls.
It is a characteristic feature of $Xylem$ (specifically tracheids and vessels) and $Sclerenchyma$ cells.
Among the given options,$Xylem$ (woody tissue) is the correct answer because its cells are heavily lignified to facilitate water transport and provide mechanical strength to the plant body.

(B) Simple tissues are composed of only one type of cells which are structurally and functionally similar.
In plants,simple permanent tissues include $Parenchyma$,$Collenchyma$,and $Sclerenchyma$.
$Xylem$ and $Phloem$ are complex tissues because they are made up of more than one type of cells.

(C) Bordered pits are specialized structures found in the cell walls of tracheids and vessels. In the context of xylem development,metaxylem vessels are larger and more mature compared to protoxylem. These vessels,along with tracheids,frequently exhibit bordered pits to facilitate the lateral movement of water between adjacent cells. Therefore,bordered pits are characteristically found in metaxylem.

(C) Sieve tubes are specialized conducting cells of the phloem in angiosperms.
They are arranged in a longitudinal series to form a tube-like structure.
The end walls of these cells are called sieve plates,which are perforated to allow the passage of materials.
These end walls are typically oblique in orientation,facilitating efficient transport.

(B) Totipotency is the ability of a single cell to divide and produce all the differentiated cells in an organism.
$A$ cell must possess a nucleus and the necessary genetic information to express all traits to be totipotent.
$Sieve$ cells are specialized components of the phloem tissue that lose their nucleus at maturity to facilitate the transport of food.
Since they lack a nucleus,they cannot undergo division or express the full genome,and therefore,they are not totipotent.

(A) Hydrophytes are aquatic plants that possess a specialized type of parenchyma tissue known as $Aerenchyma$.
$Aerenchyma$ contains large air cavities or air spaces within the tissue.
These air spaces provide buoyancy to the plant,allowing it to float on the surface of the water.
Therefore,the correct option is $A$.

(D) The conductive function in plants is performed by the vascular tissues,which include $Xylem$ and $Phloem$.
$Xylem$ is responsible for the conduction of water and minerals from the roots to the aerial parts of the plant.
$Phloem$ is responsible for the translocation of food (organic nutrients) from the leaves to other parts of the plant.
Therefore,both $Xylem$ and $Phloem$ perform conductive functions.

(A) Idioblasts are specialized parenchymatous cells that differ from the surrounding tissue and are involved in the storage of ergastic substances such as gums,resins,tannins,calcium oxalate crystals,or starch grains.

(A) In a young seedling,the hypocotyl requires both structural strength and turgor pressure to remain upright. The epidermis provides a protective outer layer and maintains turgor pressure within the cells,while collenchyma is a living mechanical tissue that provides flexible structural support to growing plant organs. Together,they provide the necessary support for the hypocotyl.

(D) Vessels are a characteristic feature of the xylem in angiosperms. While most gymnosperms lack vessels,members of the order Gnetales (such as $Gnetum$,$Ephedra$,and $Welwitschia$) possess vessels in their xylem. Pteridophytes generally lack vessels. Therefore,vessels are found in all angiosperms and some gymnosperms.

(A) In mature phloem tissue,the sieve tube elements lose their nucleus to facilitate the efficient transport of food materials.
While sieve cells (in gymnosperms) and sieve tube elements (in angiosperms) are non-nucleated at maturity,companion cells remain nucleated to regulate the metabolic activities of the sieve elements.
Palisade cells and cortical cells are parenchyma cells that retain their nucleus throughout their life.

(A) Lignin is a complex organic polymer that is deposited in the cell walls of many plants,making them rigid and woody.
It is the primary component of secondary cell walls in xylem vessels and tracheids,which provide structural support to woody tissues.
Therefore,lignin is the main constituent of woody tissues.

(D) $P$-protein is found in the sieve tube elements of the phloem.
$A$ network of fibres composed of $P_1$ and $P_2$ proteins is present in the central part of the lumen of the sieve tube.
This protein network helps in controlling the movement of materials and,along with callose,assists in the sealing of sieve pores after injury to prevent the loss of sap.

(B) In the hierarchy of biological organization,cells are the fundamental structural and functional units of life.
When a group of cells having a common origin and usually performing a common function are organized together,they form a tissue.
Therefore,cells represent the first level of organization,and tissues represent the second level of organization in plants.

(B) $Macrosclereids$ or rod cells are rod-shaped elongated sclereids.
They are typically found in the seed coats of pulses (legumes),the cortex of stems,and leaves.
These cells provide mechanical support and protection to the seed.

(C) Plant tissues are primarily classified into simple and complex tissues.
Simple tissues are composed of only one type of cells,such as parenchyma,collenchyma,and sclerenchyma (including sclereids).
Complex tissues are composed of more than one type of cells that work together as a unit to perform a specific function.
Xylem and phloem are the two main complex tissues in plants.
Therefore,the correct option is $C$.

(C) Chlorenchyma is a specialized type of parenchyma tissue that contains chloroplasts and is capable of performing photosynthesis. Therefore,chlorenchyma cells are modified parenchyma cells.

(B) Aerenchyma is a type of parenchyma tissue characterized by large air-filled intercellular spaces.
It is primarily found in $Hydrophytes$ (aquatic plants).
The presence of these air cavities provides buoyancy,which helps the plants to float on the water surface and facilitates the exchange of gases in submerged conditions.

(B) Lacunate collenchyma is a type of collenchyma where the cell wall thickenings are present on the walls bordering the intercellular spaces.
This type of collenchyma is typically found in the hypodermis of the stems of plants belonging to the family Cucurbitaceae,such as $Cucurbita$.