Permanent Tissue Questions in English

(A) $Xylem$ is the principal water-conducting tissue of the plant. It consists of four types of cells: tracheids,vessels,xylem fibres,and xylem parenchyma.
$Xylem$ vessels are hollow,elongated cells with open ends and pitted walls. Cell walls are lignified. At maturity,the nucleus is absent in vessels.
The constituent cells of the phloem are sieve elements (sieve cells,sieve tubes),companion cells,phloem fibres,and phloem parenchyma cells.
Sieve tube members are long,slender,tube-like cells joined end-to-end to form long tubular channels called sieve tubes. Sieve tube members possess specialized sieve areas on the end walls called sieve plates. Young sieve tube members have abundant cytoplasm,but there is no nucleus. The nucleus disintegrates during their development.
Therefore,the common feature between mature vessel elements and mature sieve tube elements is the absence of a nucleus (enucleate condition).

(A) The pulp of fruits like guava,pear,and sapota contains stone cells,which are a type of sclereids.
Sclereids are a form of sclerenchyma tissue that provides mechanical support and hardness to plant parts.
These cells are dead at maturity and have thick,lignified cell walls.
Therefore,the correct answer is $A$ (Sclerenchyma).

(A) In dicotyledonous plants,the $Collenchyma$ tissue is typically found in layers just below the epidermis.
It provides mechanical support to the growing parts of the plant such as young stems and petioles of leaves.
$Parenchyma$ is generally found in the ground tissue,while $Sclerenchyma$ fibers are usually associated with vascular bundles or found in mature,non-growing parts.

(A) Xylem parenchyma cells are the only living cells in the xylem tissue.
Their primary function is the storage of food materials.
These cells store food in the form of starch,fats,and other substances like tannins.
Resin,latex,and mucous are typically associated with secretory structures or specialized ducts,not the storage function of xylem parenchyma.
Therefore,the correct substances stored are starch,fat,and tannin.

(C) In plants, tissues are broadly classified into meristematic and permanent tissues.
Meristematic tissues (like $Apical$ and $Intercalary$ meristems) are composed of actively dividing cells and are found in growing regions.
Permanent tissues are composed of cells that have lost the ability to divide and have attained a mature form.
$Xylem$ is a complex permanent tissue that is found in mature plant parts and is responsible for the conduction of water and minerals.
Therefore, $Xylem$ is the tissue found in mature plant parts.

(B) Sclerenchyma is a type of simple permanent tissue in plants.
$1$. Sclerenchyma cells are characterized by thick,lignified secondary cell walls,which provide structural support to the plant.
$2$. At maturity,these cells are typically dead and lack a protoplast.
$3$. Because they are dead at maturity,they do not contain chloroplasts and cannot perform photosynthesis or assimilate food.
$4$. Therefore,statement $B$ is the correct description of Sclerenchyma tissue.

(A) Phloem fibers,also known as bast fibers,are made up of sclerenchymatous cells.
These cells are generally absent in primary phloem but are found in secondary phloem.
They are elongated,unbranched,and have pointed,needle-like apices.
At maturity,these fibers lose their protoplasm and become dead,providing mechanical support to the plant body.

(B) The tissue responsible for the conduction of water and minerals from roots to the stem and leaves is $Xylem$.
$Xylem$ is a complex permanent tissue composed of four types of elements: $Tracheids$,$Vessels$,$Xylem$ $fibres$,and $Xylem$ $parenchyma$.
$Companion$ $cells$ are a component of $Phloem$,which is responsible for the translocation of food (sugars) from leaves to other parts of the plant.
Therefore,$Companion$ $cells$ are not a part of the $Xylem$ tissue.

(C) Sclerenchyma cells are typically dead at maturity and lack a protoplast. Their cell walls are heavily thickened with lignin,which provides significant mechanical strength and support to the plant body. Options $A$,$B$,and $D$ describe characteristics of parenchyma or collenchyma tissues,not sclerenchyma.

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

(C) Vessels are one of the components of $xylem$ in angiosperms.
They are long,cylindrical,tube-like structures made up of many cells called vessel members.
Each vessel member has lignified walls and a large central cavity.
These cells are devoid of protoplasm at maturity,meaning they are dead cells.
Therefore,the statement 'Presence of protoplasm' is incorrect for vessels.

(D) The correct pair is $D$.
$A$: Parenchyma is a simple permanent tissue found in the soft parts of plants,not in the hard seed coats of legumes (which contain sclereids).
$B$: Collenchyma tissue is characterized by the absence of intercellular spaces due to localized thickening of cell walls.
$C$: Xylem parenchyma is the only living component of xylem; other elements like tracheids,vessels,and xylem fibers are dead.
$D$: Sclerenchyma tissue consists of long,narrow cells with thick,lignified cell walls,which provide mechanical support to the plant.

(C) Collenchyma is a type of simple permanent tissue found in the dicotyledonous plants.
It occurs in layers below the epidermis in most dicotyledonous stems and petioles.
Its cells are much thickened at the corners due to the deposition of cellulose,hemicellulose,and pectin.
Collenchyma provides mechanical support to the growing parts of the plant,such as the young stem and the petiole of a leaf,while also allowing for growth and elongation.

(D) Parenchyma is a type of simple permanent tissue that forms the basic packing tissue of plants.
Its cells are generally isodiametric,thin-walled,and living.
The cell walls are primarily composed of cellulose.
Unlike collenchyma (which shows pectin thickening) or sclerenchyma (which shows lignin thickening),parenchyma cells do not exhibit secondary wall thickening.
Therefore,they do not show thickening.

(C) The $Parenchyma$ tissue consists of relatively unspecialized cells with thin cell walls made of cellulose.
These cells are generally isodiametric and are either closely packed or have small intercellular spaces.
In contrast,$Collenchyma$ cells have thickened corners due to cellulose,hemicellulose,and pectin deposition,leaving little to no intercellular space.
$Sclerenchyma$ cells are dead at maturity and have thick,lignified cell walls that provide structural support,with no intercellular spaces.
Therefore,compared to the other two,$Parenchyma$ cells have the most significant intercellular space.

(B) The correct answer is $B$.
$Parenchyma$,$Sclerenchyma$,and $Collenchyma$ are types of simple permanent tissues,which are composed of only one type of cell.
$Xylem$ is a complex permanent tissue,which is composed of different types of cells (tracheids,vessels,xylem parenchyma,and xylem fibers) working together as a unit to conduct water and minerals.

(C) Xylem is a complex permanent tissue that functions as a conducting tissue for water and minerals from roots to the stem and leaves.
It is composed of four different kinds of elements:
$1$. Tracheids: Elongated tube-like cells with thick,lignified walls and tapering ends.
$2$. Vessels: Long cylindrical tube-like structures made up of many cells called vessel members,each with lignified walls and a large central cavity.
$3$. Xylem parenchyma: These are the only living cells in the xylem,responsible for the storage of food materials (starch or fat) and radial conduction of water.
$4$. Xylem fibers: Highly thickened walls and obliterated central lumens,providing mechanical support.
Since these four elements have different structures and functions,xylem is considered a complex tissue.

(D) In plants,primary phloem is formed during the development of the plant body.
$1$. The first formed primary phloem elements are narrow and are called $A$-protophloem.
$2$. The later formed primary phloem elements are larger and are called $B$-metaphloem.
Therefore,the correct combination is $A$-protophloem and $B$-metaphloem.

(B) The provided figure shows a $tracheid$.
Tracheids are elongated or tube-like cells with thick and lignified walls and tapering ends.
These are dead cells and are devoid of protoplasm.
They are the main water-conducting elements in gymnosperms and pteridophytes.
Therefore,the correct option is $B$.

(A) Fibers are a type of sclerenchyma tissue that provide mechanical support to plants.
In the case of $Cocos$ $nucifera$ (coconut),the husk is composed of abundant sclerenchymatous fibers,which are commercially known as coir.
These fibers are highly lignified and provide strength to the fruit covering.

(C) 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.
It is characteristically absent in monocot stems and roots.
It is primarily found in the hypodermis of dicot stems and the petioles of dicot leaves.
Therefore,collenchyma is found in the stem and petiole of dicot plants.

(C) Sieve tube elements are specialized cells in the phloem of angiosperms.
During their maturation,they lose their nucleus,ribosomes,and vacuoles to facilitate the transport of food materials.
However,they retain a thin layer of cytoplasm and are associated with companion cells that regulate their metabolic activities.

(A) Collenchyma is a type of simple permanent tissue that provides mechanical support to the plant. Based on the deposition of pectin and cellulose,collenchyma is classified into three types:
$1$. Angular collenchyma: Thickening is present at the corners where cells meet. It is found in $Cucurbita$ (pumpkin/gourd family).
$2$. Lamellar collenchyma: Thickening is present on the tangential walls. It is found in $Althaea$.
$3$. Lacunar collenchyma: Thickening is present near the intercellular spaces. It is found in $Salvia$ or $Malva$.

(B) Bordered pits are specialized structures found in the cell walls of xylem elements,particularly in tracheids and vessel elements. These pits facilitate the lateral transport of water and minerals between adjacent cells. Sieve cells,companion cells,and sieve tube elements are components of the phloem and do not possess bordered pits.

(A) Sclereids are a type of sclerenchyma cells that are typically short,irregular in shape,and possess extremely thick,lignified cell walls with narrow lumens.
Option $A$ is incorrect because elongated,elastic cells with pointed ends are characteristic of sclerenchyma fibers,not sclereids.
Option $B$ is correct as sclereids possess highly thickened,lignified walls.
Option $C$ is correct as sclereids provide grit to the pulp of fruits like guavas and pears.
Option $D$ is correct as they are commonly referred to as stone cells due to their hardness.

(A) In angiosperms,the $Sieve$ $tube$ $elements$ are the main conducting cells of the phloem. During their development and maturation,they lose their nucleus,ribosomes,and vacuoles to facilitate the efficient transport of food materials. This process makes them enucleated at maturity,while they remain associated with companion cells that regulate their metabolic activities.

(A) Vessels $(tracheae)$ are long,cylindrical,tube-like structures made up of many cells,each called a vessel member. These members possess lignified walls and a large central cavity (lumen). In contrast,tracheids are individual,elongated cells with tapering ends and relatively narrower lumens compared to vessels. Therefore,vessels are multicellular structures with wide lumens,while tracheids are unicellular structures.

(B) Vessels are a characteristic feature of angiosperms.
Almost all angiosperms possess vessels,while they are generally absent in gymnosperms and pteridophytes.
However,there are exceptions; for example,some gymnosperms like $Gnetum$ possess vessels.
Therefore,the most accurate description is that they are found in almost all angiosperms and some gymnosperms.

(A) Both xylem tracheary elements (vessels and tracheids) and sieve tube elements are specialized for long-distance transport of substances.
$1$. Xylem vessels and tracheids are dead at maturity and lack a nucleus.
$2$. Sieve tube elements,although living,lose their nucleus at maturity to facilitate the flow of sap.
$3$. Both cell types possess pits on their lateral walls,which allow for the lateral movement of water and solutes between adjacent cells.

(A) Companion cells are specialized parenchyma cells associated with sieve tube elements in the phloem of angiosperms. They are involved in the loading and unloading of sugars into the sieve tubes for translocation to various parts of the plant. Therefore,they are found in phloem tissue.

(B) In angiosperms,the xylem is the principal water-conducting tissue.
It consists of tracheids and vessels,which are the main elements responsible for the long-distance transport of water and minerals from roots to other parts of the plant.
Sieve tubes are part of the phloem,which is responsible for the translocation of food (organic solutes).
Since both tracheids and vessels are involved in water conduction in angiosperms,the most accurate answer is that water conduction occurs through these xylem elements. However,in the context of multiple-choice questions where 'all of the above' is provided,it is important to note that sieve tubes do not conduct water. Therefore,the question implies the primary xylem elements. Given the options,'Vessels' are the most specialized and efficient water-conducting structures in angiosperms.

(D) Sclerenchyma consists of long,narrow cells with thick and lignified cell walls having a few or numerous pits.
They are usually dead and without protoplasts.

(D) Collenchyma consists of living cells with unevenly thickened cell walls.
The cell walls are composed of cellulose,hemicellulose,and pectin.
Since collenchyma cells are living,the assertion that they are 'dead tissue' is incorrect.
However,the reason stating that collenchymatous cells show thickenings of pectin is correct.
Therefore,the Assertion is incorrect,but the Reason is correct.

(C) The Assertion is correct because the presence of vessels in the xylem of angiosperms provides a more efficient pathway for water transport compared to tracheids alone.
However,the Reason is incorrect. The conduction of water through xylem vessels is a passive process driven by transpiration pull (cohesion-tension theory),not an active process requiring energy from xylem parenchyma.

(A) Vessels are more efficient for water conduction compared to tracheids because they form long,continuous,tube-like structures with perforated end walls,which offer less resistance to water flow.
Tracheids are individual,elongated cells with tapered ends,whereas vessels are composed of a vertical row of cylindrical cells with dissolved end walls.
Both vessels and tracheids are dead and lignified at maturity,which provides structural support and facilitates water transport.
Since the Reason correctly describes a characteristic of vessels that contributes to their function,it is a correct explanation of the Assertion.

(D) Xerophytic plants conserve water by storing it in parenchymatous cells specialized for this purpose.
These plants are specially adapted to survive in arid climates.
They are typically able to withstand long periods of drought and the drying effects of desert winds.
Some plants have adapted to arid lands by developing specialized water-storage tissues,which are modified parenchymatous cells.

(A) Xylem and phloem are known as complex tissues because they are made up of more than one type of cells. These cells work in a coordinated manner,as a unit,to perform the various functions of the xylem and phloem.
Xylem helps in conducting water and minerals. It also provides mechanical support to plants. It is made up of the following components:
$1$. Tracheids (xylem vessels and xylem tracheids)
$2$. Xylem parenchyma
$3$. Xylem fibres
Tracheids are elongated,thick-walled dead cells with tapering ends. Vessels are long,tubular,and cylindrical structures formed from the vessel members,with each having lignified walls and large central cavities. Both tracheids and vessels lack protoplasm. Xylem fibres consist of thick walls with an almost insignificant lumen. They help in providing mechanical support to the plant. Xylem parenchyma is made up of thin-walled parenchymatous cells that help in the storage of food materials and in the radial conduction of water.
Phloem helps in conducting food materials. It is composed of:
$1$. Sieve tube elements
$2$. Companion cells
$3$. Phloem parenchyma
$4$. Phloem fibres
Sieve tube elements are tube-like elongated structures associated with companion cells. The end walls of sieve tube elements are perforated to form the sieve plate. Sieve tube elements are living cells containing cytoplasm and nucleus. Companion cells are parenchymatous in nature. They help in maintaining the pressure gradient in the sieve tube elements. Phloem parenchyma helps in the storage of food and is made up of long tapering cells with a dense cytoplasm. Phloem fibres are made up of elongated sclerenchymatous cells with thick cell walls.

(N/A) $\rightarrow$ Following divisions of cells in both primary and secondary meristems, the newly formed cells become structurally and functionally specialised and lose the ability to divide. Such cells are termed permanent or mature cells and constitute the permanent tissues.
$\rightarrow$ There are two types of permanent tissues: $(A)$ Simple Tissues $(B)$ Complex Tissues.
$(A)$ Simple Tissues: The cells of the permanent tissues do not generally divide further. Permanent tissues having all cells similar in structure and function are called simple tissues. There are $3$ types of simple tissues: $(a)$ Parenchyma $(b)$ Collenchyma $(c)$ Sclerenchyma.
$(a)$ Parenchyma Tissues: Parenchyma forms the major component within organs.
$\rightarrow$ The cells of the parenchyma are generally isodiametric.
$\rightarrow$ They may be spherical, oval, round, polygonal or elongated in shape.
$\rightarrow$ Their walls are thin and made up of cellulose.
$\rightarrow$ They may either be closely packed or have small intercellular spaces.
$\rightarrow$ Importance: The parenchyma performs various functions like photosynthesis, storage, and secretion.
$(b)$ Collenchyma Tissues: The collenchyma occurs in layers below the epidermis in dicotyledonous plants. It is absent in monocotyledonous and underground parts of the plant.
$\rightarrow$ It is found either as a homogeneous layer or in patches.
$\rightarrow$ It consists of cells which are much thickened at the corners due to a deposition of cellulose, hemicellulose and pectin.
$\rightarrow$ Collenchymatous cells may be oval, spherical or polygonal and often contain chloroplasts.
$\rightarrow$ These cells assimilate food when they contain chloroplasts.
$(c)$ Sclerenchyma Tissues: These consist of long, narrow cells with thick and lignified cell walls having a few or numerous pits. They are usually dead and without protoplasts.

(N/A) Companion cells are specialized parenchyma cells associated with sieve tube elements in the phloem of angiosperms.
Their importance includes:
$1$. Maintenance of Pressure Gradient: They help in maintaining the pressure gradient in the sieve tubes,which is essential for the translocation of food.
$2$. Metabolic Support: Since mature sieve tube elements lack a nucleus and other organelles,companion cells provide metabolic support by supplying proteins and $ATP$.
$3$. Loading and Unloading: They play a crucial role in the active loading of sugars into the sieve tubes at the source and unloading at the sink.

(N/A) $\rightarrow$ Complex tissues are made of more than one type of cells, and these cells work together as a single unit.
$\rightarrow$ These tissues are primarily associated with the transport of water, mineral substances, nutrients, and organic substances; therefore, they are also known as vascular tissues.
$\rightarrow$ In plants, the two main types of complex tissues are xylem and phloem.
$\rightarrow$ Xylem is responsible for the conduction of water and minerals from roots to the stem and leaves.
$\rightarrow$ Phloem is responsible for the translocation of food (organic substances) from leaves to other parts of the plant.

(N/A) $\rightarrow$ Sclerenchyma consists of long, narrow cells with thick and lignified cell walls having a few or numerous pits.
$\rightarrow$ They are usually dead and without protoplasts.
$\rightarrow$ Due to the deposition of lignin, the cell wall is strong, hard, and impermeable to water.
$\rightarrow$ Cells do not have intercellular spaces.

(N/A) Complex tissues are made up of more than one type of cells that work together as a unit to perform a common function. In plants,the two main types of complex tissues are $Xylem$ and $Phloem$.
$1$. $Xylem$: It functions primarily as a conducting tissue for water and minerals from roots to the stem and leaves. It also provides mechanical strength to the plant parts. $Xylem$ is composed of four different kinds of elements: $Tracheids$,$Vessels$,$Xylem$ $fibres$,and $Xylem$ $parenchyma$.
$2$. $Phloem$: It transports food materials,usually from leaves to other parts of the plant. $Phloem$ in angiosperms is composed of $Sieve$ $tube$ $elements$,$Companion$ $cells$,$Phloem$ $parenchyma$,and $Phloem$ $fibres$.

(A-D) The differences between Parenchyma and Sclerenchyma are as follows:
$1$. Nature: Parenchyma cells are living at maturity,whereas Sclerenchyma cells are dead at maturity.
$2$. Cell Wall: Parenchyma has thin cell walls composed of cellulose. Sclerenchyma has thick,lignified secondary cell walls.
$3$. Function: Parenchyma performs storage,photosynthesis,and secretion. Sclerenchyma provides mechanical strength and rigidity to the plant.
$4$. Intercellular Spaces: Parenchyma cells usually have intercellular spaces. Sclerenchyma cells are closely packed and lack intercellular spaces.

(N/A)

Sieve cell	Sieve tubes
$(1)$ In Gymnosperms,it is a unicellular element.	$(1)$ It is a multicellular element found in Angiosperms.
$(2)$ It possesses a nucleus.	$(2)$ It lacks a nucleus at maturity.
$(3)$ Sieve areas are less specialized and scattered.	$(3)$ The end walls are modified into sieve plates with large pores.
$(4)$ Food transport capacity is relatively low.	$(4)$ Food transport capacity is significantly higher.

(N/A)

Tracheids	Vessels
$1$. These are unicellular components found in gymnosperms.	$1$. These are multicellular components found in angiosperms.
$2$. Their transverse walls are perforated.	$2$. Their transverse walls are completely dissolved.
$3$. They are elongated,tube-like cells with tapering ends.	$3$. They are long,cylindrical,tube-like structures.
$4$. They have lower water conduction efficiency.	$4$. They have higher water conduction efficiency.

(N/A)

Parenchyma	Sclerenchyma
$(1)$ Universally present in plants, found in roots, stems, leaves, fruits, etc.	$(1)$ Found in the pericycle of dicot stems, and hypodermis of monocot stems and petioles.
$(2)$ Cells are living with thin cell walls made of cellulose.	$(2)$ Cells are generally dead and lack protoplasm.
$(3)$ Intercellular spaces are present.	$(3)$ Intercellular spaces are absent.
$(4)$ Performs functions like photosynthesis, storage, and secretion.	$(4)$ Provides mechanical strength to organs due to lignin deposition.

(N/A) $\Rightarrow$ Vascular tissues are composed of more than one type of cell that work together as a unit to perform a common function. Because they consist of diverse cell types,they are termed complex tissues.
$\Rightarrow$ Xylem tissue is composed of tracheids,vessels,xylem parenchyma,and xylem sclerenchyma (fibres).
$\Rightarrow$ Phloem tissue is composed of sieve tube elements,companion cells,phloem parenchyma,and phloem sclerenchyma (fibres).
$\Rightarrow$ Since these tissues are made up of different types of cells working in coordination,they are classified as complex tissues.

(A) The stone-like structures found in the fleshy pulp of fruits like peach and pear are called sclereids.
Sclereids are a type of sclerenchyma cell,which are dead cells at maturity with highly thickened,lignified cell walls.
Their primary function is to provide mechanical support and rigidity to the soft tissues of the plant.

(B) $\Rightarrow$ The shedding of leaves by plants during hot summer or autumn is known as abscission.
$\Rightarrow$ Anatomically,a specialized region called the abscission zone forms at the base of the petiole.
$\Rightarrow$ The cells in this zone are thin-walled and lack secondary wall thickenings like suberin or lignin.
$\Rightarrow$ During abscission,enzymes (such as cellulases and pectinases) dissolve the middle lamella and the primary cell walls between the cells of the abscission layer.
$\Rightarrow$ As these cell walls break down,the structural connection between the leaf and the stem is lost,allowing the leaf to fall off easily due to wind or gravity.

(N/A) $1$. Companion cells are specialized parenchymatous cells that are closely associated with sieve tube elements.
$2$. They maintain the pressure gradient in the sieve tube elements,which is essential for the translocation of food (sugars) through the phloem.
$3$. They provide metabolic support to the sieve tube elements,as sieve tube elements lack a nucleus and other organelles at maturity.
$4$. The sieve tube elements and companion cells are connected by pit fields present between their common longitudinal walls,facilitating the exchange of materials.