Connective tissue Questions in English

(B) The provided figure shows Adipose tissue,which is a type of loose connective tissue located mainly beneath the skin.
The cells of this tissue,called adipocytes,are specialised to store fats.
Excess nutrients that are not used immediately are converted into fats and stored in this tissue.
Additionally,it acts as a heat insulator for the body.

(D) The Assertion is incorrect because while bone is a rigid connective tissue,cartilage is a semi-rigid or flexible connective tissue,not a rigid one. The Reason is correct because blood is indeed a specialized fluid connective tissue that transports nutrients,gases,and waste products throughout the body. Since the Assertion is false and the Reason is true,the correct option is $D$.

(B) Chondriocytes are the specialized cells of cartilage.
They are found in small cavities known as lacunae,which are present within the matrix secreted by the cells themselves.
These cells are responsible for the production and maintenance of the cartilaginous matrix.

(N/A)

Dense regular connective tissues	Dense irregular connective tissues
$(1)$ Collagen fibres are present in rows between many parallel bundles of fibres.	$(1)$ Collagen fibres and fibroblasts are arranged irregularly.
$(2)$ They provide great tensile strength in one direction.	$(2)$ They provide structural strength in multiple directions.
$(3)$ Examples include tendons and ligaments.	$(3)$ Examples include the dermis of the skin.

(N/A)

Adipose tissue	Blood tissue
$(1)$ It is composed of collagen fibers,elastin fibers,fibroblasts,macrophages,and adipocytes.	$(1)$ It is composed of $RBCs$,$WBCs$,platelets,and plasma.
$(2)$ It helps in the synthesis,storage,and metabolism of fats.	$(2)$ It helps in the transportation of nutrients,wastes,gases,and hormones.
$(3)$ It is primarily found beneath the skin and around internal organs.	$(3)$ It is found circulating within the blood vessels.

(D) $RBCs$,$WBCs$,and platelets are the three primary cellular components of blood,which is a fluid connective tissue.
Cartilage is a specialized skeletal connective tissue.
Therefore,cartilage is the odd one out as it is not a component of blood.

(D) The terms $Exocrine$, $endocrine$, and $salivary \text{ gland}$ refer to types of glandular epithelium, which is a specialized form of epithelial tissue.
$Ligament$ is a type of dense regular connective tissue that connects bone to bone.
Therefore, $ligament$ is the odd one out.

(N/A) Connective tissues are the most abundant and widely distributed in the body of complex animals. They are named connective tissues because of their special function of linking and supporting other tissues/organs of the body.
Characteristics:
$1$. They consist of a few cells and a large amount of intercellular ground substance.
$2$. The cells secrete structural protein fibres called collagen or elastin,which provide strength,elasticity,and flexibility.
$3$. The cells also secrete modified polysaccharides,which accumulate between cells and fibres and act as a matrix.
Types of Connective Tissue:
Connective tissue is classified into three types:
$(i)$ Loose connective tissue
(ii) Dense connective tissue
(iii) Specialised connective tissue
$(i)$ Loose Connective Tissue: Cells and fibres are loosely arranged in a semi-fluid ground substance. Examples include:
$(a)$ Areolar tissue: Present beneath the skin. It serves as a support framework for epithelium.
$(b)$ Adipose tissue: Located mainly beneath the skin. The cells are specialised to store fats.
(ii) Dense Connective Tissue: Fibres and fibroblasts are compactly packed. It is of two types:
$(a)$ Dense regular: Collagen fibres are present in rows between many parallel bundles of fibres (e.g.,tendons and ligaments).
$(b)$ Dense irregular: Fibroblasts and many fibres (mostly collagen) are oriented differently.
(iii) Specialised Connective Tissue:
$(a)$ Cartilage: The intercellular material is solid and pliable and resists compression. Cells are called chondrocytes.
$(b)$ Bone: It has a hard and non-pliable ground substance rich in calcium salts and collagen fibres which give bone its strength. Cells are called osteocytes.
$(c)$ Blood: $A$ fluid connective tissue containing plasma,red blood cells (RBCs),white blood cells (WBCs),and platelets.

(N/A) The matrix of bones contains a protein called ossein,which provides structural support. Additionally,the matrix is heavily mineralized with calcium ions $(Ca^{++})$,making it hard and rigid.
In contrast,the matrix of cartilage contains a protein called chondrin,which gives it flexibility. The presence of calcium ions $(Ca^{++})$ in the cartilage matrix is either absent or present in very small amounts,making cartilage pliable and less rigid than bone.

(A) Fibrous connective tissue is a type of dense connective tissue characterized by an abundance of fibers,primarily collagen,which provide strength and support.
$1$. Structure: It consists of fibroblasts (cells that produce fibers) and a matrix containing densely packed fibers. Based on the orientation of these fibers,it is classified into two types:
- Dense Regular: Fibers are arranged in a regular,parallel pattern (e.g.,tendons and ligaments).
- Dense Irregular: Fibers are oriented in various directions,providing resistance to stress from multiple angles (e.g.,dermis of the skin).
$2$. Function: Its primary function is to provide structural integrity,mechanical strength,and attachment points for muscles and bones. It connects different tissues and organs,maintaining the body's structural framework.

(N/A) Adipose tissue is a type of loose connective tissue primarily located beneath the skin.
Its cells,known as adipocytes,are specialized to store fats.
Excess nutrients that are not utilized immediately by the body are converted into fats and stored within these cells.
This tissue also acts as an insulator and provides cushioning to internal organs.

(N/A)

Cartilaginous tissue	Bone tissue
$(1)$ It is pliable and flexible.	$(1)$ It is hard and non-pliable.
$(2)$ The cells,chondrocytes,are enclosed in small spaces within the matrix.	$(2)$ The bone cells,osteocytes,are present in spaces called lacunae.
$(3)$ Its matrix is solid,pliable,and resists compression.	$(3)$ Its matrix is very hard and non-pliable due to the presence of calcium salts.
$(4)$ It provides support and flexibility to body parts.	$(4)$ It provides structural frame and support to the body.

(N/A) $(i)$ Ligaments: These are specialized connective tissues that connect one bone to another bone. They are highly elastic and provide stability to joints.
(ii) Tendon: These are dense regular connective tissues that attach skeletal muscles to bones. They are characterized by great strength and limited flexibility.

(N/A) $(i)$ Perichondrium: It is a layer of dense irregular connective tissue that surrounds the cartilage of developing bone.
$(ii)$ Serum: It is the clear,yellowish fluid part of blood that remains after the coagulation factors (like fibrinogen) have been removed from the blood plasma.

(N/A) $(i)$ Mast cells:
Location: Found in the matrix of areolar connective tissue.
Function: They secrete substances like Heparin (anticoagulant),Histamine (vasodilator),and Serotonin (vasoconstrictor) involved in inflammatory responses.
$(ii)$ Hyaline cartilage:
Location: Found in the embryonic skeleton,trachea,larynx,and at the ends of long bones.
Function: It provides structural support,flexibility,and a smooth surface for joint movement.

(N/A) $\Rightarrow$ Connective tissue provides a structural framework,forms tissues,and offers support to other organs.
$\Rightarrow$ Blood is a fluid or vascular connective tissue that connects various organs and transports materials from one place to another.
$\Rightarrow$ Bone is a dense,hard,and strong skeletal connective tissue that provides structural support to the body and aids in locomotion.
$\Rightarrow$ Cartilage is also a skeletal connective tissue. However,it is not as rigid as bone; it is flexible and can withstand pressure. It functions in support and protection and is found in areas such as the joints,nose,and outer ear.

(N/A) $ \Rightarrow $ General characteristics of connective tissue:
$(i)$ Connective tissues are the most abundant and widely distributed in the body of complex animals.
$(ii)$ They link and support other tissues or organs of the body.
$(iii)$ Connective tissue arises from the mesoderm.
$(iv)$ Mainly three components are present: matrix, cells, and fibres.
$(v)$ The matrix is an extracellular material composed of glycoproteins and polysaccharides, which can be fluid, gel-like, or solid.
$(vi)$ These tissues have a good capacity for regeneration.
$(vii)$ Functions include structural support, protection of organs, and maintenance of body integrity.
$ \Rightarrow $ Difference between Bone and Cartilage:

Bone	Cartilage
Type: Dense or spongy. Can be long, short, flat, or irregular.	Type: Hyaline, fibrous, and elastic cartilage.
Function: Provides structural framework, locomotion, protection, and mineral storage; site of blood cell formation.	Function: Prevents wear and tear in joints, supports trachea, absorbs shocks, and provides flexibility.
Structure: Contains osteocytes in a hard, calcified matrix. Highly vascularized.	Structure: Contains chondrocytes in a semi-solid, flexible matrix. Generally avascular.
Location: Forms the main axial and appendicular skeleton.	Location: Found in joints, tip of the nose, outer ear, and trachea.
Fibrous coating: Surrounded by periosteum, which is rich in sensory nerve fibers.	Fibrous coating: Surrounded by a fibrous membrane known as perichondrium.

(B) $(i)$ Bone growth is bidirectional because it occurs through the activity of osteoblasts and osteoclasts,allowing for remodeling and growth in multiple directions.
$(ii)$ Ligaments are dense regular connective tissues primarily composed of yellow elastic fibers,which provide the necessary elasticity for joint movement.

(N/A) Structure: The matrix of this tissue is relatively fluid and contains a network of fibers.
$\Rightarrow$ Fibers are of two types: White fibers and Yellow fibers.
$\Rightarrow$ White fibers: These are made up of collagen protein. They are wavy,unbranched,and arranged in bundles. They provide tensile strength and can tolerate stretch and pressure.
$\Rightarrow$ Yellow fibers: These are made up of elastin protein. They are single,branched,and provide elasticity to the tissue.
$\Rightarrow$ Cells: It contains three main types of cells: fibroblasts (which produce fibers),macrophages (which act as phagocytes),and mast cells (which secrete histamine,heparin,and serotonin).
Function: It acts as a supporting framework for epithelium and serves as a packing material between organs,filling the space inside the organs and attaching skin to underlying muscles.

(A) The given diagram represents the structure of compact bone tissue.
$(A)$ points to the central Haversian canal,which contains blood vessels and nerves.
$(B)$ points to the lacuna,which is a small space containing an osteocyte.
$(C)$ points to the concentric layers of bone matrix called Lamellae.
$(D)$ represents the entire structural unit known as the Haversian system or Osteon.

(B) Cartilage is an avascular tissue,meaning it lacks a direct blood supply. Nutrients and oxygen must diffuse through the matrix to reach the chondrocytes. Because of this limited access to the circulatory system,cartilage grows and repairs much more slowly than other tissues following an injury.

(D) Collagen is the most abundant protein in the animal kingdom. In dense regular connective tissues,collagen fibers are present in rows between many parallel bundles of fibers. Tendons,which attach skeletal muscles to bones,are a prime example of this tissue and are composed primarily of collagen.

(D) Loose connective tissue is a category of connective tissue that includes areolar tissue,reticular tissue,and adipose tissue.
It serves several critical functions in the body:
$1$. It occupies the spaces between organs and provides support to epithelial tissues.
$2$. It supports and surrounds blood vessels and nerves,providing structural integrity.
$3$. It helps in cushioning organs,storing lipids (in adipose tissue),and facilitating the diffusion of nutrients and waste products between blood and tissues.
Therefore,all the listed functions are correct.

(C) Connective tissue fills the spaces between organs and tissues and provides structural and metabolic support for other tissues and organs.
The three basic components of connective tissue are:
$1$. Cells (such as fibroblasts,mast cells,and macrophages).
$2$. Protein fibers (such as collagen,elastin,and reticular fibers).
$3$. Ground substance (a gel-like material that fills the space between cells and fibers).

(D) The given figure represents loose connective tissue (areolar tissue).
Loose connective tissue has cells and fibres loosely arranged in a semi-fluid ground substance,for example,areolar tissue present beneath the skin.
It serves as a support framework for epithelium.
Based on the standard $NCERT$ diagram of areolar tissue:
$A$ represents a Macrophage (phagocytic cell).
$B$ represents a Fibroblast (cell that produces and secretes fibres).
$C$ represents Collagen fibres (structural protein fibres).
$D$ represents a Mast cell (involved in inflammatory responses).
Therefore,the correct matching is $A$-Macrophage,$B$-Fibroblast,$C$-Collagen fibres,$D$-Mast cells.

(A) Figure $I$ represents dense regular connective tissue,where collagen fibres are present in rows between many parallel bundles of fibres. Tendons and ligaments are examples of this tissue.
Figure $II$ represents dense irregular connective tissue,which has fibroblasts and many fibres (mostly collagen) that are oriented differently. This tissue is present in the skin.

(A) The given figure represents the image of cartilage.
Cartilage is an important structural component of the body.
It is a firm tissue but is softer and much more flexible than bone.
It is a connective tissue found in joints between bones (e.g.,the elbows,knees,and ankles),ends of the ribs,between the vertebrae in the spine,ears,nose,and bronchial tubes.
Cartilage is made up of specialized cells called chondrocytes $(B)$.
These chondrocytes produce large amounts of extracellular matrix composed of collagen $(A)$ fibres,proteoglycan,and elastin fibres.
There are no blood vessels in cartilage to supply the chondrocytes with nutrients.

(A) The given figure represents areolar tissue,which is a type of loose connective tissue.
Statement $(i)$ is correct: Areolar tissue is a type of loose connective tissue.
Statement $(ii)$ is correct: It contains cells like fibroblasts,macrophages,and mast cells,along with collagen fibres.
Statement $(iii)$ is incorrect: Adipose tissue is the specialized connective tissue responsible for the storage of fats,not areolar tissue.
Statement $(iv)$ is incorrect: Epithelial tissue forms the inner lining of blood vessels,stomach,and intestine,whereas areolar tissue acts as a support framework for epithelium and attaches it to underlying tissues.
Therefore,the correct features are $(i)$ and $(ii)$.

(C) Mast cells are specialized cells found in the connective tissue,particularly in the areolar connective tissue.
These cells contain numerous basophilic granules.
They play a crucial role in the immune response by releasing substances such as heparin,histamine,and serotonin in response to injury,infection,or inflammation of tissues.

(D) tendon is a dense regular connective tissue primarily composed of collagen fibres arranged in rows. The cells present in this tissue are known as fibroblasts,which are responsible for the synthesis and secretion of the collagen fibres. Since these cells produce the collagenous matrix,they are often referred to as collagenous cells in the context of their function. Therefore,both $b$ and $c$ are correct descriptions of the cells found in a tendon.

(C) Chondrocytes are the specialized cells found in cartilage.
They are responsible for the production and maintenance of the cartilaginous matrix,which is composed primarily of collagen and proteoglycans.
These cells are located within small spaces called lacunae inside the matrix.
Cartilage is a type of specialized connective tissue found in areas such as the epiglottis,the pinnae (external ear),and at the ends of long bones.

(C) Elastic cartilage,also known as yellow cartilage,is a specialized type of cartilage found in the pinna (outer ear),Eustachian tube,and epiglottis.
It is characterized by the presence of a dense network of elastic fibers and collagen fibers within the matrix.
The primary protein responsible for its flexibility and shape-retaining property is elastin.
Therefore,the shape of the human ear is maintained by elastic cartilage.

(C) Tendons,which attach skeletal muscles to bones,and ligaments,which attach one bone to another,are examples of dense regular connective tissues.
In these tissues,collagen fibers are present in rows between many parallel bundles of fibers.

(D) In all connective tissues,except for blood (which is a fluid connective tissue),the cells secrete fibres of structural proteins known as collagen or elastin. These fibres provide strength,elasticity,and flexibility to the tissue matrix.

(A) The correct matching is as follows:
$A.$ Loose connective tissue contains cells like fibroblasts,macrophages,and mast cells $(A-IV)$.
$B.$ Dense regular connective tissue includes tendons and ligaments $(B-I)$.
$C.$ Dense irregular connective tissue is found in the skin $(C-II)$.
$D.$ Specialized connective tissue includes cartilage,bones,and blood $(D-III)$.
Therefore,the correct sequence is $A-IV, B-I, C-II, D-III$.

(D) Cartilage is a specialized connective tissue,not an areolar tissue. Areolar tissue is a type of loose connective tissue found beneath the skin. Therefore,the pair 'Cartilage - Areolar tissue' is incorrectly matched.
- Goblet cells are unicellular glandular cells.
- Saliva is secreted by salivary glands,which are exocrine glands.
- Smooth muscle cells are fusiform (spindle-shaped) in structure.

(C) The correct answer is $C$.
Cartilage is a specialized connective tissue that has a solid and pliable matrix,which resists compression.
Crucially,cartilage is avascular,meaning it lacks blood vessels.
In contrast,Areolar tissue has a loosely organized matrix with protein fibers,Bone has a hard,non-pliable,mineralized matrix rich in calcium salts,and Blood is a fluid connective tissue with a liquid matrix called plasma.

(B) Connective tissue is the most abundant and widely distributed tissue in the body of complex animals.
They are named connective tissues because of their special function of linking and supporting other tissues/organs of the body.
They range from soft connective tissues to specialized types,which include cartilage,bone,adipose,and blood.
These tissues provide strength,elasticity,and flexibility to the body.
In all connective tissues,except blood,the cells secrete fibres of structural proteins called collagen or elastin.
The cells also secrete modified polysaccharides,which accumulate between cells and fibres and act as matrix (ground substance).

(D) Statement $(i)$ is correct: Loose connective tissue contains cells like fibroblasts,macrophages,and mast cells.
Statement $(ii)$ is incorrect: Adipose tissue is a type of loose connective tissue,not dense connective tissue.
Statement $(iii)$ is correct: Tendons and ligaments are examples of dense connective tissue (dense regular connective tissue).
Statement $(iv)$ is correct: Cartilage and bones are types of specialized connective tissue,often referred to as skeletal or hard connective tissue.
Therefore,statements $(i)$,$(iii)$,and $(iv)$ are correct.

(B) All the given statements are associated with bone tissue.
$(i)$ Bone has a hard and non-pliable ground substance (matrix) rich in calcium salts and collagen fibres,which provides strength.
$(ii)$ Bones provide a structural framework that supports and protects softer tissues and organs of the body.
$(iii)$ Bone cells,known as osteocytes,are located in small spaces within the matrix called lacunae.
$(iv)$ Bones interact with skeletal muscles attached to them via tendons to facilitate body movements.
Therefore,the correct answer is Bone.

(B) Connective tissue contains various cell types such as mast cells,plasma cells,macrophages,and fibroblasts.
$1$. Mast cells are involved in inflammatory responses and release histamine,heparin,and serotonin.
$2$. Plasma cells are specialized $B$-lymphocytes that are responsible for the synthesis and secretion of antibodies (immunoglobulins).
$3$. Macrophages are phagocytic cells that engulf cell debris and pathogens.
$4$. Fibroblasts are responsible for the production of fibers and the ground substance of the matrix.
Therefore,the correct answer is plasma cells.

(A) Dense irregular connective tissue contains fibroblasts and many fibers (mostly collagen) that are oriented in different directions.
This tissue is primarily found in the skin.
In contrast,tendons and ligaments are examples of dense regular connective tissue,where fibers are oriented in a regular pattern.

(C) The cytoplasm of mast cells contains granules of Heparin and Histamine.
Histamine is a chemical mediator that induces inflammation and increases the permeability of blood vessels.

(B) Adipose tissue is an aggregation of fat cells or adipocytes.
Each adipocyte is rounded or oval,containing a large droplet of fat that almost fills the entire cell.
Adipose tissue is found in the blubber of whales and elephants,which serves as an insulating layer to regulate body temperature and store energy.

(A) The Haversian canal is a characteristic feature of mammalian bones,found within the bone matrix.
Each Haversian canal contains an artery,a vein,a lymph vessel,a nerve,and bone cells,all embedded within connective tissue.
These canals are essential for the transport of nutrients and waste products to and from the osteocytes.

(A) The matrix of bone is composed of an organic substance called ossein protein,which provides flexibility and tensile strength to the bone tissue.
Chondrin is found in cartilage,keratin is found in skin,hair,and nails,and globulin is a type of blood protein.

(C) The correct statement is that lacunae contain bone cells called $osteocytes$. $Chondrocytes$ are the cells found in cartilage,not bone. Therefore,the statement in option $C$ is incorrect. Bone cells $(osteocytes)$ lie in lacunae singly.

(A) Areolar tissue is the most widely distributed connective tissue in the animal body.
It serves as a support framework for the epithelium.
It is present beneath the skin.
Areolar tissue joins the skin to muscles and fills the space inside organs.

(B) Adipose tissue is a specialised loose connective tissue which possesses abundant fat-storing cells called adipocytes.
Adipose tissue acts as a fat reservoir and functions as an insulator.
Because it is a poor conductor of heat,it effectively reduces heat loss from the body.

(D) Macrophages are also known as Histiocytes,which occur in connective tissue.
Macrophages engulf and digest microbes,foreign particles,and degenerating cells.
Therefore,both Macrophages and Histiocytes are phagocytic in nature.