Epithelial tissue Questions in English

(D) Cell junctions are most frequently found in epithelial tissues,such as the ciliated epithelium.
Cell junctions are specialized structures that provide contact between neighboring cells or between a cell and the extracellular matrix.
They are essential for the structural integrity of epithelial tissues,as they help form the paracellular barrier and regulate paracellular transport.
In contrast,connective tissues like ligaments,tendons,and cartilage have fewer cell junctions because their cells are widely separated by an abundant extracellular matrix.

(C) The columnar epithelium is composed of a single layer of tall and slender cells.
The free surface of these cells often contains microvilli, which are found in the lining of the stomach and intestine.
These structures significantly increase the surface area, thereby facilitating the processes of secretion and absorption.

(B) Columnar epithelium consists of a single layer of tall and slender cells.
These cells have oval nuclei located at the base.
They are found in the lining of the stomach and intestine,where they perform the functions of secretion and absorption.
The presence of microvilli on the free surface further increases the surface area for absorption.
Therefore,the described characteristics correspond to Columnar epithelium.

(A) Tissue $1$ represents ciliated columnar epithelium,characterized by tall,slender cells with cilia on their free surfaces.
Tissue $2$ represents a goblet cell,which is a unicellular gland. Unicellular glands consist of isolated glandular cells (e.g.,goblet cells of the alimentary canal).
Therefore,the correct identification is $1$: Columnar cells bearing cilia; $2$: Unicellular glandular epithelium.

(D) Squamous epithelium is composed of thin,discoidal,and polygonal cells that fit together like tiles on a floor,which is why it is also known as pavement epithelium.
It is found lining the walls of blood vessels,in the alveoli of the lungs for gas exchange,and in the Bowman's capsule of the nephron for ultrafiltration.

(B) Ciliated columnar epithelial cells are characterized by the presence of cilia on their free surface.
These cells are primarily found in the inner surface of hollow organs like the bronchioles and the fallopian tubes (oviducts).
The movement of cilia helps in the transport of mucus or particles in the respiratory tract and the movement of the ovum in the fallopian tubes.

(D) The basement membrane is a thin,extracellular,non-cellular supporting layer that separates a layer of epithelial cells from the underlying connective tissue (lamina propria). It is composed of two layers: the basal lamina and the reticular lamina. This structure is unique to epithelial tissue and is not found in muscular,nervous,or connective tissues.

(D) Compound epithelium is made up of more than one layer of cells and thus has a limited role in secretion and absorption. Its main function is to provide protection against chemical and mechanical stresses. It covers the dry surface of the skin,the moist surface of the buccal cavity,the pharynx,the inner lining of the ducts of salivary glands,and the pancreatic ducts.

$(A)$ The correct matching is as follows:
$1$. Cuboidal epithelium $(A)$ is found in the lining of pancreatic ducts $(V)$.
$2$. Ciliated epithelium $(B)$ is found in the inner lining of the fallopian tube $(IV)$.
$3$. Columnar epithelium $(C)$ is found in the inner surface of the gall bladder $(III)$.
$4$. Squamous epithelium $(D)$ is found in the inner lining of blood vessels $(II)$.
$5$. Keratinized squamous epithelium $(E)$ is found in the epidermis of the skin $(I)$.
Therefore, the correct sequence is $A-V, B-IV, C-III, D-II, E-I$.

$(A)$ The correct matches are as follows:
$A$. Squamous epithelium: It is made up of a single thin layer of flattened cells with irregular boundaries. $(A-IV)$
$B$. Cuboidal epithelium: It is composed of a single layer of cube-like cells. $(B-I)$
$C$. Columnar epithelium: It is composed of a single layer of tall and slender cells. $(C-III)$
$D$. Ciliated epithelium: These cells have cilia on their free surface. $(D-II)$
Therefore, the correct sequence is $A-IV, B-I, C-III, D-II$.

$(A)$. Exocrine glands secrete products like mucus,saliva,earwax,oil,milk,and digestive enzymes through ducts $(A-IV)$.
$B$. Endocrine glands are ductless and secrete hormones directly into the fluid bathing the gland $(B-II)$.
$C$. Tight junctions help to stop substances from leaking across a tissue $(C-I)$.
$D$. Adhering junctions perform cementing to keep neighbouring cells together $(D-III)$.
Therefore,the correct matching is $A-IV, B-II, C-I, D-III$.

$(A)$ The correct matching is as follows:
$A$. Exocrine gland: These glands secrete products like mucus,saliva,earwax,oil,milk,and digestive enzymes through ducts $(IV)$.
$B$. Endocrine gland: These are ductless glands that secrete hormones directly into the fluid bathing the gland $(II)$.
$C$. Tight junctions: These junctions help to stop substances from leaking across a tissue $(I)$.
$D$. Adhering junctions: These junctions perform cementing to keep neighbouring cells together $(III)$.
Thus,the correct sequence is $A-IV, B-II, C-I, D-III$.

(C) Cuboidal epithelium is composed of a single layer of cube-like cells and is commonly found in the ducts of glands and the tubular parts of nephrons in kidneys. Its main functions are secretion and absorption. The walls of blood vessels and the air sacs of lungs are lined by squamous epithelium,not cuboidal epithelium. Therefore,statement $C$ is incorrect.

(D) Compound epithelium consists of more than one layer of cells (multi-layered).
Only the cells of the deepest layer rest on the basement membrane.
Due to being multi-layered,compound epithelia have a limited role in secretion and absorption.
Their primary function is to provide protection against chemical,mechanical,thermal,or osmotic stresses.
They are found covering the dry surface of the skin,the moist surface of the buccal cavity,the pharynx,and the inner lining of the ducts of salivary glands and pancreatic ducts.

(D) cell junction is a specialized structure that provides contact between neighbouring cells or between a cell and the extracellular matrix in animal tissues.
$1$. Tight junctions: These junctions help to stop substances from leaking across a tissue.
$2$. Adhering junctions: These perform cementing to keep neighbouring cells together.
$3$. Gap junctions: These facilitate communication between cells by connecting the cytoplasm of adjoining cells,allowing for the rapid transfer of ions,small molecules,and sometimes big molecules.
Since all the given statements are correct,the correct option is $D$.

(A) The statements describe the characteristics of simple squamous epithelium.
$1$. It consists of a single thin layer of flattened cells with irregular boundaries,which gives them a tile-like appearance.
$2$. These cells are found in the walls of blood vessels (endothelium) and air sacs (alveoli) of the lungs,where they facilitate the exchange of gases and nutrients.
$3$. Due to their thin structure,they are primarily involved in forming a diffusion boundary,allowing substances to pass through easily.
Therefore,the correct answer is $A$ (Squamous epithelium).

(B) The correct option is $B$.
$1$. Brush bordered cuboidal epithelium is found in the Proximal Convoluted Tubule $(PCT)$ of the nephron,where it significantly increases the surface area for the reabsorption of essential nutrients and water.
$2$. Reticular tissue in the spleen functions primarily in filtration and immune response,not secretion.
$3$. The cornea is composed of stratified squamous epithelium,not neurosensory epithelium.
$4$. The lining of blood vessels is composed of simple squamous epithelium (endothelium),not glandular epithelium.

(B) Tissue is a group of similar cells along with intercellular substances,which are specialized to perform a specific function.
Each tissue performs one or more functions of the body.
Thus,the body of a multicellular organism exhibits division of labour and contributes to the survival of the body as a whole.

(A) group of cells that are similar in structure,perform a common function,and have a common embryonic origin is defined as a tissue. Tissues are the fundamental building blocks of organs in multicellular organisms.

(D) Epithelial tissue consists of a sheet of cells that covers the external surface of the body and lines the internal organs and cavities within the body. It acts as a protective barrier and is involved in absorption,secretion,and sensation.

(A) The germinal epithelium found in the ovary and seminiferous tubules is composed of cuboidal epithelial cells. These cells are responsible for the production of gametes.

(D) Epithelial cells are held together by specialized intercellular junctions,which serve as structural and functional links between adjacent cells.
These junctions are characteristic of epithelial tissues,providing mechanical strength,preventing leakage of substances,and facilitating communication between cells.

(A) Simple squamous epithelium consists of a single thin layer of flattened cells with irregular boundaries. The cells are closely fitted like tiles in a floor. Therefore,these are also known as pavement epithelium.

(B) The correct matches are as follows:
$1$. Squamous epithelium: Found in the walls of blood vessels and air sacs of lungs $(a-iii)$.
$2$. Cuboidal epithelium: Found in the ducts of glands and tubular parts of nephrons in kidneys, as well as the germinal epithelium of the ovary $(b-ii)$.
$3$. Columnar epithelium: Found in the lining of the stomach and intestine $(c-i)$.
$4$. Ciliated epithelium: Found in the inner surface of hollow organs like bronchioles and fallopian tubes $(d-iv)$.
Therefore, the correct sequence is $a(iii), b(ii), c(i), d(iv)$.

(D) The intestinal epithelium possesses microvilli to increase the surface area for absorption.
This gives a brush-bordered appearance to the epithelium.
Hence,it is called brush-bordered columnar epithelium.

(A) Tight junctions are specialized structures that prevent the leakage of substances across a tissue. They are formed by the fusion of plasma membranes in the apical parts of adjacent epithelial cells. Therefore,the statement that tight junctions promote leaking is incorrect.

(A) The Assertion is true because in non-keratinised stratified squamous epithelium,the superficial layers (stratum corneum) are devoid of the insoluble protein called keratin.
The Reason is also true because,due to the absence of keratin,this epithelium is found covering moist surfaces such as the buccal cavity,pharynx,and oesophagus,which are not exposed to drying but are frequently subjected to mechanical abrasions.
Therefore,both Assertion and Reason are true,and the Reason is the correct explanation of the Assertion.

(A) Assertion is correct because gap junctions are specialized structures that connect the cytoplasm of adjoining cells,allowing for the passage of ions,small molecules,and sometimes big molecules.
Reason is also correct because these junctions facilitate communication between cells by enabling the rapid transfer of chemical and electrical signals.
However,the primary function of gap junctions is the facilitation of communication,and the structural connection is the mechanism by which this is achieved. In standard biological assessment contexts,the structural connection is considered the definition,and the communication is the functional outcome. Therefore,Reason is the correct explanation for Assertion.

(C) Assertion is true because epithelial tissue consists of cells that are compactly packed with very little intercellular matrix.
Reason is false because epithelial cells are often secretory in nature. They are responsible for secreting various substances,including the basal lamina (basement membrane) and various enzymes or hormones in glandular epithelium.
Therefore,the Assertion is true,but the Reason is false.

(D) The Assertion is false because the inner lining of hollow organs like the trachea,bronchi,and fallopian tubes consists of ciliated columnar epithelium,which possesses motile cilia,not non-motile cilia.
The Reason is also false because the brush-border epithelium is formed by microvilli,which are cytoplasmic extensions found on the surface of cells in the intestinal mucosa,not by cilia.
Therefore,both the Assertion and the Reason are incorrect.

(B) The walls of capillaries are composed of a single layer of cells known as simple squamous epithelium or endothelium. This thin structure is essential as it facilitates the rapid exchange of gases,nutrients,and waste products between the blood and the surrounding tissues.

(D) Transitional epithelium is found in organs that undergo a great degree of distension or expansion,such as the urinary bladder and ureters.
It appears stratified with $4$ to $6$ layers of cells.
This epithelium prevents the rupture of the urinary bladder by allowing it to stretch and accommodate varying volumes of urine.
It is a specialized type of epithelium also known as urothelium.

(B) $1$. Tight junctions: These junctions help to stop the leakage of substances across a tissue by forming a seal between adjacent cells.
$2$. Adhering junctions: These perform cementing to keep neighbouring cells together.
$3$. Gap junctions: These facilitate communication between neighbouring cells by connecting the cytoplasm of adjoining cells,allowing for the rapid transfer of ions,small molecules,and sometimes big molecules.
Therefore,the correct sequence is Tight junctions and Gap junctions.

(A) In biological organization,a group of cells that are similar in structure and perform a common function is known as a tissue.
Cells are the fundamental unit of life.
When similar cells aggregate to perform a specific function,they form a tissue.
Multiple tissues organize to form an organ,and multiple organs work together to form an organ system.

(D) Epithelial tissue is characterized by cells that are very compactly packed with little intercellular matrix. Option $D$ states that it has loosely packed cells with a large amount of intercellular space,which is a characteristic of connective tissue,not epithelial tissue. Therefore,statement $D$ is incorrect.

(A) In the given figure,$P$ represents a single layer of cells resting on a basement membrane,which is characteristic of a Simple epithelium.
$Q$ represents multiple layers of cells,which is characteristic of a Compound epithelium.
Therefore,$P$ is a Simple epithelium and $Q$ is a Compound epithelium.

(A) The epithelial tissue is classified into two types based on the number of cell layers: $1$. Simple epithelium and $2$. Compound epithelium.
Simple epithelium is composed of a single layer of cells and functions as a lining for body cavities,ducts,and tubes.
Compound epithelium consists of two or more cell layers and has a protective function against chemical and mechanical stresses.
Therefore,the lining of body cavities,ducts,and tubes is made up of simple epithelium.

(B) The skin is covered by a compound epithelium,specifically a stratified squamous epithelium.
Unlike simple epithelium,which consists of a single layer of cells,the compound epithelium is made up of two or more layers of cells.
Its primary function is to provide protection against chemical and mechanical stresses,making it ideal for the skin surface.

(D) The image shows Simple Squamous Epithelium.
$I$ - It consists of a single thin layer of flattened cells with irregular boundaries. This is correct.
$II$ - It is not primarily a secretory tissue; glandular epithelium is secretory. This is incorrect.
$III$ - It is a single-layered tissue. This is correct.
$IV$ - It is found in the walls of blood vessels and air sacs of lungs (alveoli). This is correct.
$V$ - It functions as a diffusion boundary,facilitating the exchange of gases and nutrients. This is correct.
Therefore,statements $I, III, IV,$ and $V$ are correct.

(B) The tissue described is cuboidal epithelium.
Statement $I$ is correct: It consists of a single layer of cube-like cells.
Statement $II$ is correct: It is commonly found in the ducts of glands and the tubular parts of nephrons in the kidneys.
Statement $III$ is correct: The primary functions of cuboidal epithelium are secretion and absorption.
Statement $IV$ is incorrect: The epithelium of the proximal convoluted tubule $(PCT)$ in the nephron has microvilli,not cilia. Cilia are found in ciliated epithelium,whereas microvilli are characteristic of the $PCT$ to increase the surface area for absorption.
Therefore,statements $I, II,$ and $III$ are correct.

(A) Columnar epithelial tissue is composed of a single layer of tall and slender cells. Their nuclei are located at the base. This tissue is primarily found in the inner lining of the stomach and intestine,where it helps in secretion and absorption. Therefore,the correct option is $A$.

(D) Ciliated epithelium consists of cells that have cilia on their free surface.
These cilia are hair-like projections that beat to move particles or mucus in a specific direction over the epithelial surface.
They are primarily located in the inner lining of hollow organs such as the bronchioles (in the respiratory tract) and the fallopian tubes (in the female reproductive tract).
Since all the statements $A$,$B$,and $C$ are correct descriptions of ciliated epithelium,the correct answer is $D$.

(A) The provided image shows unicellular glandular epithelium,which consists of isolated glandular cells. These cells are specialized for the secretion of mucus. $A$ classic example of unicellular glandular epithelium is the goblet cells found in the lining of the alimentary canal. In contrast,salivary,mammary,and sweat glands are examples of multicellular glandular epithelium.

(D) The provided image shows a cluster of cells forming a gland.
Since it consists of a group of cells (multicellular) rather than a single isolated cell,it represents a multicellular glandular epithelium.
Unicellular glands,such as goblet cells of the alimentary canal,consist of isolated glandular cells.
Multicellular glands,such as the salivary gland,consist of a cluster of cells.
Therefore,the correct option is multicellular glandular epithelium found in the salivary gland.

(A) The figure shows a stratified squamous epithelium.
This tissue is characterized by multiple layers of cells,where the cells of the basal layer are cuboidal or columnar and become flattened towards the surface.
It is primarily protective in function.
It is found in the dry surface of the skin (keratinized) and the moist surface of the buccal cavity and pharynx (non-keratinized).
Option $C$ refers to simple cuboidal epithelium,which is different from the tissue shown.
Therefore,both $A$ and $B$ are correct locations for stratified squamous epithelium,but since $C$ is incorrect,the question implies identifying the tissue type correctly. However,given the options,the most appropriate answer is that the tissue shown is stratified squamous epithelium,which is found in both $A$ and $B$.

(A) The correct matching is as follows:
$1$. Tight junctions $(P-I)$: These junctions help to stop substances from leaking across a tissue.
$2$. Adhering junctions $(Q-II)$: These perform cementing to keep neighbouring cells together.
$3$. Gap junctions $(R-III)$: These facilitate the cells to communicate with each other by connecting the cytoplasm of adjoining cells,for rapid transfer of ions,small molecules and sometimes big molecules.
Therefore,the correct sequence is $(P-I), (Q-II), (R-III)$.

(C) melanocyte is a specialized cell found in the skin,eyes,and hair follicles. Its primary function is to produce melanin,a pigment that provides color to these tissues and protects them from ultraviolet $(UV)$ radiation. Therefore,it is classified as a cell.

(C) The epithelium present in the bronchioles and Fallopian tubes is the ciliated epithelium.
Ciliated epithelium consists of cells that have hair-like projections called cilia on their free surface.
These cilia move particles or mucus in a specific direction over the epithelial surface.
In the Fallopian tubes,the cilia help in the movement of the ovum towards the uterus.
In the bronchioles,the cilia help in moving mucus and trapped dust particles out of the respiratory tract.

(D) The correct answer is $D$ $(A-II, B-I, C-IV, D-III)$.
- Mast cells are found in the areolar connective tissue,which also contains fibroblasts and macrophages.
- The inner surface of bronchioles is lined by ciliated epithelium,which helps in moving mucus and particles.
- Blood is classified as a specialised connective tissue because it consists of a fluid matrix (plasma) and formed elements.
- The tubular parts of the nephron (such as the proximal convoluted tubule) are lined by cuboidal epithelium,which is involved in absorption and secretion.

(B) The correct matching is as follows:
$A$. Unicellular glandular epithelium: These consist of isolated glandular cells, such as the $III$. Goblet cells of the alimentary canal.
$B$. Compound epithelium: This is made of more than one layer of cells and has a limited role in secretion and absorption. It provides protection against chemical and mechanical stresses, such as the $IV$. Moist surface of the buccal cavity.
$C$. Multicellular glandular epithelium: These consist of a cluster of cells, such as the $I$. Salivary glands.
$D$. Endocrine glandular epithelium: These are ductless glands that secrete hormones directly into the fluid bathing the gland, such as the $II$. Pancreas (which has both exocrine and endocrine functions).
Therefore, the correct sequence is $A-III, B-IV, C-I, D-II$, which corresponds to option $B$.