Plant Tissues Questions in English

(N/A) Location: Collenchyma is found in the leaf stalks (petioles) and below the epidermis of dicot stems.
Function: It provides mechanical support and flexibility to the plant,allowing parts like leaf stalks to bend easily without breaking.

(C) The meristem responsible for the increase in the girth (diameter) of the stem and root is known as the $Lateral$ $meristem$ (also called $Cambium$).
It is a secondary meristem that adds to the thickness of the plant body.

(N/A) $(i)$ Aerenchyma: This is a type of parenchyma tissue containing large air cavities that provide buoyancy to aquatic plants,allowing them to float.
$(ii)$ Collenchyma: This is a mechanical tissue that provides structural support and flexibility to the plant,allowing easy bending without breaking.

(N/A) The two types of complex tissues in plants are $Xylem$ and $Phloem$.
$Xylem$ is responsible for the conduction of water and minerals from the roots to the leaves.
$Phloem$ is responsible for the translocation of food (photosynthates) from the leaves to other parts of the plant.

(N/A) $(i)$ In very dry habitats,the epidermis is often thicker to provide protection against water loss. Additionally,the aerial parts of these plants often secrete a waxy,water-resistant layer (cuticle) on the outer surface to protect against water loss,mechanical injury,and invasion by parasitic fungi.
$(ii)$ The primary functions of guard cells are:
$1.$ To regulate the opening and closing of stomata.
$2.$ To facilitate the exchange of gases (like $CO_2$ and $O_2$) between the plant and the atmosphere.
$3.$ To control transpiration by regulating water vapor loss.

(N/A)

Xylem	Phloem
$(i)$ It conducts water and minerals from roots to all parts of the plant.	$(i)$ It conducts organic food synthesized in the leaves and hormones synthesized at the shoot and root tips to other parts of the plant.
$(ii)$ The elements which help in conduction are tracheids and vessels. Both are non-living and have thick walls.	$(ii)$ Sieve-tube cells are responsible for the movement of material through phloem. They are living cells.
$(iii)$ The material in xylem moves only in one direction (unidirectional).	$(iii)$ The material in phloem can move in both directions (bidirectional).
$(iv)$ Except for xylem parenchyma,all other xylem elements are non-living.	$(iv)$ Except for phloem fibres,all other phloem elements are living.

(N/A)

Sclerenchyma	Collenchyma
$1$. It consists of dead cells.	$1$. It consists of living cells.
$2$. Its cell walls are lignified.	$2$. Its cell walls are cellulosic.
$3$. Lumen of the cell is narrow.	$3$. Lumen of the cell is wide.
$4$. It provides mechanical support to the plant.	$4$. It provides mechanical support and elasticity to the plant body.

(N/A) $(i)$ Tracheids and vessels are the main conducting elements that help in the transport of water and minerals.
(ii) Xylem parenchyma is the only living component of xylem that stores food materials in the form of starch or fat.
(iii) Xylem fibres (also known as xylem sclerenchyma) are dead cells with thick walls that provide mechanical support to the plant.

(N/A) $(1)$ Cells divide repeatedly.
$(2)$ Cell walls are thin and made of cellulose.
$(3)$ Vacuoles are either absent or very small.
$(4)$ They are metabolically very active.
$(5)$ They possess dense cytoplasm.
$(6)$ They have a prominent and large nucleus.

(N/A) The chemical substance that makes the cell walls of sclerenchyma hard is $Lignin$. This substance acts as a cement and hardens the cell wall.
Sclerenchyma tissue is typically found in the following locations:
$1$. Around vascular bundles.
$2$. In the veins of leaves.
$3$. In the hard covering of seeds and nuts (e.g.,the shell of a coconut).

(N/A) It provides mechanical support to plants.
$(b)$ It stores food materials like starch,proteins,and fats.
$(c)$ In aquatic plants,parenchyma cells contain large air cavities (aerenchyma) which provide buoyancy and help the plant float.

(D) Chlorenchyma: These are specialized parenchyma cells that contain chlorophyll and are primarily responsible for performing photosynthesis.
Aerenchyma: These are specialized parenchyma cells found in aquatic plants that contain large air cavities. These cavities help the plants to float (buoyancy) and facilitate gas exchange.

(N/A) The two basic structural differences are as follows:
$1$. Cell Wall: Parenchyma cells have thin cell walls made of cellulose,whereas collenchyma cells have unevenly thickened cell walls due to the deposition of cellulose,hemicellulose,and pectin at the corners.
$2$. Intercellular Spaces: Parenchyma cells are loosely packed with large intercellular spaces,whereas collenchyma cells are closely packed with very little or no intercellular space.

(N/A) The type of parenchyma tissue present in aquatic plants is known as $Aerenchyma$.
Role: $Aerenchyma$ contains large air cavities that provide buoyancy to the aquatic plants,which helps them to float in water.

(N/A) Epidermal cells on the aerial parts of the plant often secrete a waxy,water-resistant layer on their outer surface. This layer,known as the cuticle,aids in protection against water loss,mechanical injury,and invasion by parasitic fungi.
$(b)$ The epidermis of the leaf contains small pores called stomata,which are essential for gaseous exchange (oxygen and carbon dioxide) and the process of transpiration.
$(c)$ The epidermal cells of roots possess long,hair-like extensions called root hairs. These structures significantly increase the total surface area available for the absorption of water and dissolved minerals from the soil.

(N/A) $(1)$ Composition: Whether the tissue is made up of one type of cell (simple) or more than one type of cells (complex).
$(2)$ Function: Whether the tissue is supportive (parenchyma),protective (epidermis),or conducting (xylem and phloem).
$(3)$ Cell wall structure: Whether the cell wall is thick or thin.
$(4)$ Viability: Whether the cells are living or dead at maturity.

(N/A) $(i)$ Epidermis is the outermost single layer of cells that covers all parts of the plant externally.
$(ii)$ Functions of epidermis:
$(a)$ Protection: It protects the plant against water loss,mechanical injury,and invasion by parasitic fungi.
$(b)$ Secretion: Epidermal cells on the aerial parts of the plant often secrete a waxy,water-resistant layer (cuticle) which further helps in protection from mechanical injury and water loss.
$(c)$ Absorption: Root hairs present on the epidermis of roots help in the absorption of water and minerals from the soil.

(N/A) Stomata are small,microscopic pores found primarily in the epidermis of plant leaves.
Functions of Stomata:
$(i)$ Gaseous Exchange: Stomata serve as the primary sites for the exchange of gases,such as carbon dioxide $(CO_2)$ and oxygen $(O_2)$,between the plant's internal tissues and the external environment.
$(ii)$ Transpiration: $A$ significant portion of transpiration,the process of water loss in the form of water vapor,occurs through stomata. This process helps in the upward movement of water and minerals from the roots and keeps the plant surface cool.

(N/A) $(i)$ Sclerenchyma cells have extremely thick cell walls due to the deposition of lignin,which significantly reduces the internal space or lumen of the cell.
$(ii)$ Branches of a tree contain collenchyma tissue,which provides mechanical support and flexibility,allowing them to bend without breaking in high wind.
$(iii)$ The husk of a coconut is made of sclerenchyma tissue,which consists of dead,thick-walled,and tightly packed fibres that provide great strength and rigidity,making it difficult to pull apart.

(N/A) $(i)$ Cells of the bark are dead and compactly arranged without intercellular spaces. They contain a chemical substance called suberin in their cell walls,which makes them impervious to gases and water.
$(ii)$ The thick waxy coating on the epidermis is composed of cutin,a chemical substance with waterproof properties. This coating helps in protecting the plant against water loss and parasitic fungi.
$(iii)$ The primary function of epidermal cells in roots is water absorption. The hair-like extensions,known as root hairs,significantly increase the total surface area available for absorption.

(N/A) $(i)$ The diagram should show a layer of tightly packed epidermal cells with stomatal openings surrounded by two bean-shaped guard cells.
$(ii)$ $(a)$ Plants living in very dry habitats have a thick,waxy,and water-resistant layer of cutin on their epidermis. This adaptation helps in preventing excessive water loss through transpiration,protecting the plant from mechanical injury,and preventing parasitic invasion.
$(b)$ The primary function of guard cells is to regulate the opening and closing of the stomatal pore. When water enters the guard cells,they become turgid and swell,causing the stomatal pore to open. Conversely,when water leaves the guard cells,they become flaccid and shrink,causing the stomatal pore to close.

(N/A)

Simple permanent tissue	Complex permanent tissue
$1$. These tissues are made up of only one type of cells that perform a common function.	$1$. These tissues are made up of more than one type of cells that work together as a unit to perform a common function.
$2$. They are primarily involved in support,storage,and photosynthesis.	$2$. They are primarily involved in the transport of water,minerals,and food.
$3$. Examples include parenchyma,collenchyma,and sclerenchyma.	$3$. Examples include xylem and phloem.

(N/A) $(X)$ is a tracheid,and $(Y)$ is a vessel.
$(b)$ Both are tubular structures. They consist of dead cells with thick,lignified walls.
$(c)$ Both tracheids and vessels are components of the xylem tissue and are primarily responsible for the vertical transport of water and dissolved minerals from the roots to the rest of the plant.

(N/A) The constituents of phloem are:
$(i)$ Sieve tubes
$(ii)$ Companion cells
$(iii)$ Phloem fibres
$(iv)$ Phloem parenchyma
$(b)$ Cork acts as a protective tissue because its cells are dead and compactly arranged without intercellular spaces,which prevents the entry of pathogens. Furthermore,the cell walls of cork contain a chemical substance called suberin,which makes them impervious to gases and water,thereby protecting the plant from mechanical injury and desiccation.

(N/A) $M$ - Chloroplast
$N$ - Nucleus
$O$ - Cytoplasm
$P$ - Intercellular space

(N/A) These pores are called Stomata.
$(i)$ They facilitate the exchange of gases like $CO_2$ and $O_2$ between the plant and the atmosphere.
$(ii)$ They facilitate the process of transpiration,which is the loss of water in the form of water vapor from the aerial parts of the plant.

(A) The statement is $True$. $A$ seed is the reproductive unit of a flowering plant. It contains the embryo,which is the young plant in a dormant state,and stored food (in the form of cotyledons or endosperm). This stored food provides the necessary energy and nutrients for the embryo to grow during the early stages of germination until it can perform photosynthesis.

(A) The statement is $True$.
Cotyledons are embryonic leaves found within the seed. They contain stored food reserves that provide nourishment to the developing embryo during germination. Because they are part of the embryo structure,they are considered a fundamental component of the pre-designed plant structure within the seed.

(N/A) Parenchyma is called a permanent tissue because its cells have differentiated and lost the ability to divide,taking up a specific role in the plant body.
The two special types of parenchyma are:
$1$. Chlorenchyma
$2$. Aerenchyma
Their specific roles are:
- Chlorenchyma contains chlorophyll and performs photosynthesis.
- Aerenchyma contains large air cavities and provides buoyancy to aquatic plants,helping them to float.

(N/A) Lateral meristem: It is responsible for the increase in the girth (thickness) of the stem and root.
$(b)$ Intercalary meristem: It is responsible for the growth of internodes and the formation of leaves and branches.
$(c)$ Apical meristem: It is responsible for the increase in the length of the stem and the root.

(N/A) Collenchyma: These cells have irregular thickenings of pectin and cellulose at the corners. Location: Found in the leaf stalks below the epidermis.
$(b)$ Aerenchyma: $A$ type of parenchyma tissue with large intercellular spaces and air cavities to provide buoyancy. Location: Found in the stems and leaves of aquatic plants.
$(c)$ Sclerenchyma: These cells are long,narrow,and dead at maturity due to lignin deposition. Location: Found in the hard parts of the plant such as seed coats,fruit walls,and vascular bundles.

(N/A) $(i)$ Multicellular organisms are composed of millions of different types of cells which form specific tissues to perform specific functions more efficiently. There is a division of labour amongst cells,making these organisms more efficient.
$(ii)$ Sclerenchyma cells have a narrow lumen due to the heavy deposition of lignin on their cell walls. These walls become so thick that there is hardly any internal space left inside the cell.
$(iii)$ The epidermis is thicker in desert plants to prevent water loss through transpiration. This is achieved by the presence of a thick,waxy,water-resistant coating of cutin.
$(b)$ $(i)$ Meristematic tissue
$(ii)$ Apical meristem
$(iii)$ Intercalary meristem
$(iv)$ Parenchyma

(N/A)

Meristematic tissue	Permanent tissue
$1.$ Cells of this tissue divide throughout their life.	$1.$ They lose the ability to divide to take up specific functions.

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

(N/A) These structures,known as root hairs,increase the total surface area for the absorption of water and minerals from the soil.
$(b)$ Cutin is a waterproof,waxy substance. In desert plants,it prevents excessive water loss through transpiration and protects the plant from intense heat by reflecting sunlight.
$(c)$ These pores,known as stomata,facilitate gaseous exchange (oxygen and carbon dioxide) and the process of transpiration.
$(d)$ Multiple layers of epidermis in cactus act as a protective barrier to prevent excessive water loss in arid environments.
$(e)$ Suberin is a chemical that makes the cell walls of cork cells impervious to gases and water,providing protection and preventing desiccation.

(N/A) Permanent tissues in plants are classified into two main categories based on the types of cells they contain:
$1$. Simple Permanent Tissues: These are made up of only one type of cell that performs a similar function. They are further divided into:
- Supportive tissues: Includes $Parenchyma$,$Collenchyma$,and $Sclerenchyma$.
- Protective tissues: Includes $Cork$ and $Epidermis$.
$2$. Complex Permanent Tissues: These are made up of more than one type of cell working together to perform a common function. These are also known as conducting tissues and include:
- $Xylem$
- $Phloem$

(N/A) Sclerenchyma cells have a narrow lumen because of the excessive deposition of lignin on their cell walls,which makes the walls extremely thick and reduces the internal space.
$(b)$ Sclerenchyma tissues are present in stems,around vascular bundles,in the veins of leaves,and in the hard covering of seeds and nuts. They are present in these locations to provide mechanical strength,rigidity,and structural support to the plant parts.

(N/A) In desert plants,the epidermis is thicker due to the presence of a thick waxy coating of cutin to prevent water loss.
$(b)$ The waxy layer of cutin present on the outer surface of plants is water-resistant and protects the plant against excessive loss of water through transpiration.
$(c)$ Vacuoles provide turgidity and rigidity to mature plant cells. Since the primary role of meristematic tissue cells is to divide continuously to facilitate growth,they do not require large vacuoles,which would otherwise hinder the rapid process of cell division.

(N/A) Meristematic tissues are found in the regions of the plant that undergo active cell division and growth.
Based on their position in the plant body, meristems are classified into three types: Apical, Lateral, and Intercalary.

Name of the Meristem	Position and Function
$Apical$	Found at the growing tips of stems (shoot apex) and roots (root apex). They are responsible for the elongation of the root and stem, known as primary growth.
$Lateral$	Found beneath the bark (cork cambium) and in vascular bundles of dicot roots and stems (vascular cambium). They are responsible for increasing the diameter of the root and stem, known as secondary growth.
$Intercalary$	Found at the base of leaves or internodes (e.g., in the stems of grasses). They are responsible for the increase in the length of the organ.

(N/A) $(i)$ Cambium is the region responsible for secondary growth,which leads to an increase in the thickness or girth of the plant stem and root.
$(ii)$ Lignin is a complex organic polymer that acts as a cementing material,providing structural support and hardening the cell wall. It is primarily present in the cell walls of sclerenchyma tissue,making them lignified and dead at maturity.
$(iii)$ The cells of the epidermis are typically elongated,flattened,and arranged in a single layer without any intercellular spaces. They are living cells that often secrete a waxy,water-resistant layer on their outer surface to protect the plant.

(N/A) $(i)$ Cutin: Cutin is a waterproof layer of a waxy substance. The epidermis is one cell thick and is covered with a cuticle. This cuticle has a variable thickness and is thicker in xerophytic plants to prevent water loss.
$(ii)$ Suberin: It is a complex polymer present in the walls of cork cells. It makes the cell wall impervious to gases and water,providing protection and preventing desiccation.
$(iii)$ Sclereids: These are sclerenchymatous cells that are short and possess extremely thick,lignified walls with long,tubular simple pits. They are irregular in shape and provide mechanical support and rigidity to plant parts.

(D) The tissue responsible for the sideways (lateral) conduction of water and minerals in plants is $Xylem \text{ } parenchyma$.
While $Xylem \text{ } vessels$ and $tracheids$ are primarily responsible for the vertical conduction of water, $Xylem \text{ } parenchyma$ stores food and helps in the lateral conduction of water through the rays of the $Xylem$.

(C) The growth in length of the sugarcane plant,even after the removal of the apical tip,is due to the presence of $Intercalary \ meristem$.
$Intercalary \ meristem$ is found at the internodes or at the base of the leaves in monocotyledonous plants like sugarcane and grasses.
It allows these plants to regrow parts removed by grazing herbivores or other mechanical damage,as it is responsible for the elongation of the internodes.

(FALSE) The statement is False.
Sclerenchyma is a permanent tissue that provides mechanical strength and rigidity to the plant body.
It consists of dead cells with thick,lignified walls,which makes the plant hard and stiff,not soft or flexible.
Collenchyma is the tissue responsible for providing flexibility to plants.

(TRUE) The statement is $True$.
$Collenchyma$ is a type of simple permanent tissue found in plants. Its cells are living,elongated,and possess uneven thickenings of cellulose,hemicellulose,and pectin at the corners,which provide mechanical support and flexibility to the plant body.

(TRUE) The statement is True.
In aquatic plants,a specialized type of parenchyma tissue known as aerenchyma is present.
These cells contain large air cavities or air spaces that store gases,which provide buoyancy to the plants.
This buoyancy allows the aquatic plants to float on the surface of the water.

(D) Parenchyma is a type of simple permanent tissue in plants.
These cells are living and possess thin cell walls made of cellulose.
They are considered relatively unspecialized because they perform various functions like storage,photosynthesis,and secretion,and they retain the ability to divide.
Unlike sclerenchyma,they are not lignified,and unlike collenchyma,they do not have unevenly thickened walls.

(B) Flexibility in plants is provided by the tissue known as $Collenchyma$.
$Collenchyma$ allows for easy bending in various parts of a plant (like young stems and leaf stalks) without breaking.
It provides both mechanical support and elasticity to the plant body.
$Parenchyma$ is involved in food storage and photosynthesis.
$Sclerenchyma$ provides hardness and stiffness to the plant.
$Chlorenchyma$ is a type of $Parenchyma$ containing chlorophyll,involved in photosynthesis.

(B) Cork cells are the outer protective tissues of older stems and roots.
As these cells mature,they deposit a waxy substance called $Suberin$ in their cell walls.
$Suberin$ is a complex fatty substance that makes the cell walls impervious to water and gases,thereby preventing water loss and protecting the plant from mechanical injury and microbial infection.

(C) The survival of plants in a terrestrial environment is primarily dependent on their ability to transport water,minerals,and food over long distances against gravity.
This is made possible by the presence of complex permanent tissues known as conducting tissues,which include xylem and phloem.
Xylem is responsible for the conduction of water and dissolved minerals from the roots to the aerial parts of the plant,while phloem transports synthesized food from the leaves to other parts of the plant.
These tissues provide the necessary structural support and efficient transport system required for life on land.

(B) Permanent tissues are formed from meristematic tissues.
Meristematic tissues consist of actively dividing cells that have the capacity to divide.
When these cells lose their ability to divide,they undergo differentiation and mature into permanent tissues.
These permanent tissues perform specific functions in the plant body and do not divide further.