Textbook - TISSUES Questions in English

(B) group of cells that are similar in structure and are organized together to achieve a particular function is called a tissue.
In multicellular organisms,tissues are specialized to perform specific tasks efficiently.

(N/A) In multicellular organisms,the body system is based on the division of labour (e.g.,muscle cells form muscular tissue,which helps in movement).
This means that cells performing a specific function are grouped together to form a particular tissue.
The different tissues are organized in a way to provide the highest efficiency in the functioning of the body.

(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)

(C) Muscular tissue is responsible for movement in our body. It consists of specialized cells called muscle fibers that have the ability to contract and relax,which facilitates body movement and locomotion.

(A) neuron consists of a cell body (cyton) containing a nucleus and cytoplasm.
It has two types of extensions: axons and dendrites.
Each neuron has a single long process called the axon and many short,branched processes called dendrites.
Many nerve fibers are bound together by connective tissue to form a nerve.

(N/A) The features of cardiac muscles are as follows:
$1.$ These are involuntary muscles that exhibit rhythmic contraction and relaxation throughout life.
$2.$ The cells are cylindrical,branched,and uninucleate,possessing faint cross-striations.
$3.$ These muscles do not get fatigued under normal physiological conditions.

(N/A) Functions of areolar tissue :
$1.$ It fills the space inside the organs,thus acts as a packing tissue between the organs.
$2.$ It supports many delicate organs in the body.
$3.$ It plays a role in the repair of tissues.

(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) The three types of muscle fibres are:
$1.$ Striated muscle: These are cylindrical,unbranched,and multinucleated cells with alternating light and dark bands (striations).
$2.$ Smooth muscle: These are spindle-shaped,uninucleated cells that lack striations and are found in the walls of internal organs.
$3.$ Cardiac muscle: These are cylindrical,branched,and uninucleated cells with faint striations,found exclusively in the heart.

(B) The uninucleated,striated,tubular,and branched muscles that form the wall of the heart are known as cardiac muscles.
They serve to bring about rhythmic contraction and relaxation of the heart to allow the pumping of blood throughout life.
Since these muscles contract without any nerve stimulation or conscious control,they are involuntary in nature.

(N/A) The differences between the three types of muscles are as follows:
$1$. Striated (Skeletal) Muscles: These are cylindrical,unbranched,and multinucleated cells with light and dark bands (striations). They are attached to bones and are responsible for voluntary movements.
$2$. Unstriated (Smooth) Muscles: These are spindle-shaped,uninucleated,and lack striations. They are found in the walls of internal organs like the stomach,intestines,and blood vessels,and are responsible for involuntary movements.
$3$. Cardiac Muscles: These are cylindrical,branched,and uninucleated cells with faint striations. They are found exclusively in the walls of the heart and are responsible for the rhythmic contraction and relaxation of the heart throughout life.

(N/A) neuron (nerve cell) consists of three main parts: the cell body (cyton),dendrites,and the axon.
$1$. Cell body (Cyton): It contains the nucleus and cytoplasm. It is the metabolic center of the neuron.
$2$. Dendrites: These are short,branched extensions that receive signals from other neurons or sensory receptors.
$3$. Axon: It is a long,slender projection that conducts electrical impulses away from the cell body.
Key structures include the myelin sheath (insulating layer),nodes of Ranvier (gaps in the myelin sheath),and the motor end plate (synaptic terminal) which transmits signals to the next cell.

(N/A) The inner lining of the mouth is formed by Squamous Epithelium.
$(b)$ Tendons are the fibrous connective tissues that connect muscle to bone.
$(c)$ Phloem is the vascular tissue responsible for the transport of food in plants.
$(d)$ Adipose tissue is the specialized connective tissue that stores fat in our body.
$(e)$ Blood is a connective tissue that has a fluid matrix called plasma.
$(f)$ Nervous tissue is the primary tissue present in the brain,composed of neurons.

(N/A) The classification of the given tissues is as follows:
$1$. Skin: Epithelial tissue (specifically stratified squamous epithelium).
$2$. Bark of tree: Cork (protective tissue).
$3$. Bone: Connective tissue.
$4$. Lining of kidney tubule: Cuboidal epithelial tissue.
$5$. Vascular bundle: Complex permanent tissue (xylem and phloem).
Parenchyma tissue is present in the following regions:
- It is found in the soft parts of plants such as the cortex of roots,ground tissue of stems,and mesophyll of leaves.
- It is also present in the pith and the pericycle of stems and roots.

(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.