Plant Tissues Questions in English

(N/A) The three main types of simple tissues are:
$1.$ Parenchyma: These are living cells with thin cell walls and are responsible for storage and photosynthesis.
$2.$ Collenchyma: These are living cells with thickened corners,providing mechanical support and flexibility to the plant.
$3.$ Sclerenchyma: These are dead cells with thick,lignified walls,providing structural strength and rigidity to the plant.

(B) Apical meristem is found at the growing tips of stems and roots of plants. It is responsible for the primary growth of the plant,which involves increasing the length of the stem and the root.

(C) The husk of coconut is made up of sclerenchymatous tissue. Sclerenchyma is a type of permanent tissue in plants that provides mechanical strength and rigidity. These cells are dead at maturity and have thick,lignified cell walls.

(N/A) The constituents of phloem tissue are:
$1.$ Sieve tubes (tubular living cells with perforated end walls)
$2.$ Companion cells (living cells)
$3.$ Phloem parenchyma (living cells)
$4.$ Phloem fibres (non-living and sclerenchyma cells)

(N/A) A group of cells that are similar in structure and are organized together to perform a specific function is called a tissue.

(N/A) The xylem tissue is composed of four different types of elements:
$1.$ Xylem tracheids.
$2.$ Xylem vessels.
$3.$ Xylem parenchyma.
$4.$ Xylem fibres.

(N/A) Simple tissues are composed of only one type of cells that perform a common function. They are mainly responsible for mechanical support and storage. Examples include parenchyma,collenchyma,and sclerenchyma.
Complex tissues are composed of more than one type of cells that work together as a unit. They are mainly responsible for the transport of water,minerals,sugars,and other metabolites throughout the plant. Examples include xylem and phloem.

(N/A) The differences between parenchyma,collenchyma,and sclerenchyma based on their cell walls are as follows:
$1$. $\text{Parenchyma}$: These are living cells with thin cell walls composed of cellulose. The cell walls are uniformly thin,and the cells are loosely packed with large intercellular spaces.
$2$. $\text{Collenchyma}$: These are living cells with unevenly thickened cell walls. The thickening is primarily due to the deposition of pectin and cellulose,specifically at the corners of the cells. They have very little intercellular space.
$3$. $\text{Sclerenchyma}$: These are dead cells with extremely thick,lignified cell walls. The deposition of lignin makes the walls rigid and impermeable to water. Due to this heavy thickening,the internal lumen (cell cavity) is often absent or significantly reduced.

(B) Stomata are small pores present on the surface of leaves.
Their primary functions are:
$1$. Gas exchange: They allow the exchange of gases like $CO_2$ and $O_2$ between the plant and the atmosphere for processes like photosynthesis and respiration.
$2$. Transpiration: They facilitate the loss of water in the form of water vapour from the aerial parts of the plant,which helps in the upward movement of water and minerals.

(N/A) Parenchyma is a type of simple permanent tissue that serves as the packing tissue in plants. It is found in the following regions:
$1$. It is present in the soft parts of the plant such as the cortex of stems and roots.
$2$. It is found in the ground tissue of stems and roots.
$3$. It forms the bulk of the leaves (mesophyll tissue).
$4$. It is also present in the pith of stems and roots.
$5$. In some cases,it contains chlorophyll and is called chlorenchyma,which performs photosynthesis.

(A) The epidermis is the outermost layer of cells in plants. Its primary roles include:
$1$. Protection: It protects all parts of the plant from external environmental factors.
$2$. Water Conservation: In aerial parts,the epidermal cells often secrete a waxy,water-resistant layer on their outer surface,which helps in protection against loss of water,mechanical injury,and invasion by parasitic fungi.
$3$. Gas Exchange: Small pores called stomata present in the epidermis allow for gaseous exchange and transpiration.

(N/A) Cork is a protective tissue composed of dead cells rich in $Suberin$,which forms a thick and waterproof covering on older stems and roots.
$Suberin$ is a waxy,waterproof substance that restricts the movement of water.
The presence of $Suberin$ in the dead cells of the cork and the absence of intercellular spaces make these cells impermeable to water and gases.
This structure protects the underlying tissues from desiccation,mechanical injury,and pathogenic infection.

(N/A) Permanent tissues in plants are classified into two main types: Simple and Complex.
$1$. Simple permanent tissues are composed of only one type of cell. They are further divided into:
- Parenchyma
- Collenchyma
- Sclerenchyma
$2$. Complex permanent tissues are composed of more than one type of cell that work together as a unit. They are divided into:
- Xylem
- Phloem
Therefore,the completed chart should have 'Parenchyma' and 'Sclerenchyma' under 'Simple' tissues,and 'Phloem' under 'Complex' tissues.

(B) Soil is the primary source of nutrients for plants.
Plants absorb dissolved mineral nutrients from the soil through their root systems.
This water and the dissolved nutrients are then transported to different parts of the plant body through the $xylem$ tissue.

(A) Sclerenchyma is a permanent tissue that is entirely composed of dead cells with thick,lignified walls.
In contrast,Parenchyma and Collenchyma are simple permanent tissues composed of living cells.
Epithelial tissue is an animal tissue composed of living cells.

(B) Meristematic tissues are actively dividing cells and are not permanent tissues. They are characterized by dense cytoplasm,thin cell walls,and the absence of vacuoles. Permanent tissues are derived from meristematic tissues after they lose the ability to divide. Therefore,the statement that apical and intercalary meristems are permanent tissues is incorrect.

(C) The apical meristem is responsible for the increase in the length of the stem and root.
Intercalary meristem is found at the internodes and helps in the growth of leaves and internodes.
Lateral meristem (also known as cambium) is responsible for the increase in the girth or diameter of the stem and root in plants.

(D) perforated cell wall is a characteristic feature of conducting elements in plants that facilitate the transport of materials.
$1$. Tracheids and Vessels are xylem elements involved in water transport and possess perforated or pitted walls.
$2$. Sieve tubes are phloem elements involved in food transport and have perforated end walls called sieve plates.
$3$. Companion cells are specialized parenchyma cells associated with sieve tubes. They are living cells with a dense cytoplasm and a nucleus,and they do not possess perforated cell walls.

(A) Meristematic tissues consist of actively dividing cells that are restricted to specific regions of the plant,such as the tips of roots and shoots.
These tissues are responsible for the growth of the plant body.
Unlike permanent tissues,meristematic cells retain the ability to divide throughout their life.

(B) The epidermis is the outermost protective layer of the plant body. Its primary functions include protection against mechanical injury,prevention of water loss,and regulation of gaseous exchange through stomata. Conduction of water is the primary function of the $Xylem$ tissue,not the epidermis.

(B) Phloem is a complex permanent tissue responsible for the translocation of food in plants. It consists of four types of elements: sieve tubes,companion cells,phloem parenchyma,and phloem fibres. Among these,phloem fibres (also known as bast fibres) are the only dead elements,as they possess thick lignified cell walls and lack protoplasm at maturity. The other three elements are living at maturity.

(C) Companion cells are specialized parenchyma cells found in the phloem of angiosperms. Unlike sieve tube elements,which lose their nucleus and other organelles at maturity to facilitate the transport of food,companion cells retain their nucleus and dense cytoplasm to regulate the metabolic activities of the sieve tube elements.

(D) The $cuticle$ is a waxy, water-repellent protective layer covering the epidermis of leaves and stems. In desert plants, this layer is often thick to minimize transpiration and protect the plant from excessive heat, thereby reducing the rate of water loss.

(B) Xylem parenchyma is the only living component of the xylem tissue. It is responsible for the lateral conduction of water and the storage of food materials in plants. Xylem vessels are primarily involved in the vertical conduction of water. Parenchyma and collenchyma are simple permanent tissues that do not participate in the conduction of water.

(B) Intercalary meristem is located at the base of leaves or internodes (the region between two nodes).
It facilitates the longitudinal growth of the internodes in monocots like sugarcane.
Therefore,even if the apical meristem (responsible for primary growth at the tip) is removed,the plant continues to grow in length due to the activity of the intercalary meristem.

(C) The longitudinal growth (increase in height) in a tree stem occurs primarily at the apical meristem located at the tips of the branches and the main trunk.
Since the nail is inserted into the mature,differentiated tissue below the apical meristem,this region does not undergo further vertical elongation.
Therefore,the nail will remain at the same height of $1$ metre from the ground level even after $3$ years of growth.

(D) Parenchyma is the simplest among simple permanent tissues.
The cells of parenchyma are generally isodiametric,thin-walled,and relatively unspecified,meaning they retain the ability to divide and perform various functions like storage,photosynthesis,and secretion.

(A) Collenchyma is a type of permanent tissue that provides both mechanical support and flexibility to plant parts like young stems and petioles.
This flexibility is possible because of the uneven thickening of cell walls at the corners due to the deposition of cellulose,hemicellulose,and pectin.

(B) Cork cells are the outer protective tissues of older stems and roots.
As these cells mature,they develop a waxy substance in their cell walls known as suberin.
Suberin makes these cells impervious to water and gases,thereby preventing water loss and protecting the plant from mechanical injury and pathogens.

(C) The survival of plants in terrestrial environments is primarily due to the presence of conducting tissues,specifically $Xylem$ and $Phloem$.
$Xylem$ is responsible for the conduction of water and minerals from the soil to the aerial parts of the plant,which is essential for survival in environments where water is not directly available to all plant parts.
$Phloem$ transports food synthesized in the leaves to other parts of the plant.
Therefore,conducting tissues allow plants to overcome the challenge of water scarcity and nutrient distribution in terrestrial habitats.

(B) The primary water-conducting elements in gymnosperms are tracheids.
$1$. Sieve tubes are components of the phloem and are involved in the transport of food,not water.
$2$. Xylem fibres provide mechanical support and structural rigidity to the plant but do not participate in water conduction.
$3$. Vessels are specialized water-conducting structures that are typically absent in most gymnosperms (except for the Gnetales order).
$4$. Therefore,tracheids are the main water-conducting tissue in gymnosperms.

(N/A) The xylem tissue is composed of four main types of elements:
$1$. Tracheids
$2$. Vessels
$3$. Xylem parenchyma
$4$. Xylem fibres
Among these,xylem parenchyma is the only living component of the xylem tissue,while the others (tracheids,vessels,and xylem fibres) are dead at maturity. The diagram of xylem parenchyma is provided below.

(N/A) Water hyacinth contains a specialized type of parenchyma tissue known as $Aerenchyma$.
This tissue is characterized by the presence of large air-filled cavities or intercellular spaces.
These air spaces provide buoyancy to the plant,which allows the water hyacinth to float on the surface of the water.

(B) The $Epidermis$ is the outermost protective layer of the plant body.
It is often covered by a thick, waxy, and water-resistant layer called the $Cuticle$.
This $Cuticle$ acts as a physical barrier that prevents the entry of pathogens, parasites, and excessive water loss, thereby protecting the plant.

(A) Suberin: It is a waxy substance deposited in the cell walls of cork cells,making them impermeable to water and gases.
$(b)$ Sieve tubes: These are components of the phloem tissue,consisting of living tubular cells with perforated end walls (sieve plates).
$(c)$ Calcium and phosphorus: The matrix of bone is rich in calcium and phosphorus salts,which provide strength and rigidity to the skeletal system.

(C) The epidermis is important for plants due to the following reasons:
$(i)$ It provides protection to the underlying tissues against mechanical injury and pathogen invasion.
$(ii)$ It helps in gaseous exchange through specialized structures called stomata.
$(iii)$ It checks excessive water loss through the process of transpiration by forming a waxy cuticle layer.
$(iv)$ Root hairs arising from the epidermal cells increase the surface area for the absorption of water and minerals from the soil.

(N/A) Xylem and phloem are complex tissues.
$(b)$ Stomata have guard cells.
$(c)$ Cells of cork contain a chemical called Suberin.
$(d)$ Husk of coconut is made of Sclerenchyma tissue.
$(e)$ Collenchyma gives flexibility in plants.
$(f)$ Xylem and phloem are both conducting tissues.
$(g)$ Xylem transports water and minerals from soil.
$(h)$ Phloem transports food from leaves to other parts of the plant.

(N/A) The differences between parenchyma and sclerenchyma tissues are as follows:

Parenchyma	Sclerenchyma
$(1)$ Cells are thin-walled and unspecialized.	$(1)$ Cells are thick-walled and lignified.
$(2)$ These are living cells.	$(2)$ These are dead cells.
$(3)$ Cells are usually loosely packed with large intercellular spaces.	$(3)$ No intercellular spaces are found between the cells.
$(4)$ Stores nutrients and water in stems and roots.	$(4)$ Provides mechanical strength to plant parts.
$(5)$ Some cells contain chlorophyll (chlorenchyma) and perform photosynthesis. Others have large air cavities (aerenchyma) providing buoyancy to aquatic plants.	$(5)$ Cells are long and narrow,making the plant hard and stiff. Found in stems,around vascular bundles,in leaf veins,and the hard covering of seeds and nuts.

[Diagrams: Refer to the provided images showing $T$.$S$. and $L$.$S$. of both tissues.]

(N/A) Meristematic cells are actively dividing cells. $A$ prominent nucleus and dense cytoplasm are required to support rapid metabolic activity and cell division. Vacuoles are absent because these cells do not need to store food or maintain turgidity for structural support.
$(b)$ Sclerenchymatous cells have thick,lignified cell walls that are tightly packed together,leaving no intercellular spaces.
$(c)$ Pear fruit contains specialized sclerenchyma cells known as stone cells or sclereids,which provide a gritty and granular texture.
$(d)$ Collenchyma tissue is present in the stalks and branches of plants. It provides both structural support and flexibility,allowing branches to bend without breaking in high wind.
$(e)$ The husk of a coconut is made of sclerenchyma tissue,which is dead and heavily lignified,making it extremely hard and tough to remove.

(N/A) Characteristics:
- The cells of cork are dead at maturity.
- These cells are compactly arranged without any intercellular spaces.
- The cell walls possess a chemical substance called $suberin$, which makes them impervious to gases and water.
- They are several layers thick.
Formation:
- As plants grow older, the epidermis of the stem is replaced by a strip of secondary meristem known as the $phellogen$ or cork cambium.
- The cells cut off on the outer side by this meristem differentiate into cork cells.
Role:
- Cork acts as a protective tissue for older stems, twigs, and branches.
- It prevents water loss and protects the plant from mechanical injury and microbial infection.

(N/A) Xylem and phloem are called complex tissues because they are made up of more than one type of cells that work together as a unit to perform a common function.

Xylem	Phloem
Consists of tracheids,vessels,xylem parenchyma,and xylem fibres.	Consists of sieve tubes,companion cells,phloem parenchyma,and phloem fibres.
Transports water and minerals vertically from the soil to the aerial parts of the plant.	Transports food (photosynthates) from the leaves to other parts of the plant.
Most of the cells,except xylem parenchyma,are dead at maturity.	Most of the cells,except phloem fibres,are living at maturity.

(N/A)

Meristematic Tissue	Permanent Tissue
Cells of this tissue divide throughout their life.	They lose the ability to divide to take up specific functions.
They are located at specific regions of the plant,viz.,apical,lateral,and intercalary.	They are distributed throughout the plant body.
Cells are very active,have dense cytoplasm,thin walls,and prominent nuclei. They lack vacuoles.	They are vacuolated,vary in shape and size. Their cell wall may be thick.
Cell wall is cellulosic.	Cell wall is made up of cellulose,lignin,or suberin.

$(b)$ The process by which cells derived from meristematic tissue take up a permanent shape,size,and function and lose the ability to divide is called differentiation.
$(c)$ Simple permanent tissues: Parenchyma,Collenchyma (any two).
Complex permanent tissues: Xylem,Phloem.

(N/A) The cells that make up meristematic tissue have dense cytoplasm,thin cellulose cell walls,and prominent nuclei. Additionally,they lack vacuoles.

(C) Lateral meristem is the type of meristematic tissue that is responsible for the secondary growth in plants.
It increases the girth or diameter of the stem and root.
This tissue is commonly referred to as cambium.

(D) The veins of leaves contain vascular tissues known as $Xylem$ and $Phloem$. $Xylem$ is responsible for the conduction of water and minerals,while $Phloem$ is responsible for the translocation of food. Additionally,$Sclerenchyma$ fibers are often present around the vascular bundles to provide mechanical support.

(B) The cells present at the growing tips of roots and stems are called meristematic cells (or meristem).
These cells have the ability to divide continuously,which leads to the growth of the plant in length.
This specific type of meristem is known as apical meristem.

(A) The tissue in which food is stored in plants is known as $Parenchyma$.
$Parenchyma$ is a type of simple permanent tissue that acts as a packing tissue and provides support to plants.
Specifically,when $Parenchyma$ contains chlorophyll and performs photosynthesis,it is called $Chlorenchyma$,and when it stores food and water,it serves as a storage tissue.

(N/A) Vascular bundles are complex tissues found in plants that consist of two primary conducting tissues: xylem and phloem.
Xylem is responsible for the transport of water and dissolved minerals from the roots to the rest of the plant.
Phloem is responsible for the transport of food (sugars) synthesized during photosynthesis from the leaves to other parts of the plant.
Together,these tissues form a structural unit known as a vascular bundle,which is essential for the transport system in vascular plants.

(N/A) Stomata are microscopic apertures or pores primarily found on the epidermis of leaves. They are surrounded by two specialized cells known as guard cells. Their main functions include the exchange of gases ($CO_2$ and $O_2$) between the plant and the atmosphere and the process of transpiration,which is the loss of water vapor from the plant surface.

(N/A) Tracheids and vessels are the main conducting elements of the xylem tissue in plants.
Their tubular structure provides a low-resistance pathway for the bulk flow of water and dissolved minerals from the roots to the leaves.
This vertical,pipe-like arrangement allows for efficient long-distance transport against gravity,which is essential for the survival of vascular plants.