Biology For Class IX - Chapter No.4 - Cells And Tissues - Continue Questions and Answers - Animals and Plant Tissues

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CHAPTER 4
CELLS AND TISSUES

ANIMAL AND PLANTS TISSUES

Q.36: Define tissue? and mention the types of tissue?
Ans: TISSUES:
A group of cells which are similar in shape and functions is called tissue.

OR

A group of similar cells that work together to perform a common function is known as a tissue.
For example: The cells in the small intestine that absorb nutrients look very different from the muscle cells needed for body movement.

Q.37: Name the types of animal tissues?
Ans: ANIMAL TISSUES:
Humans and other large multicellular animals are made up of four basic types tissues:

1. Epithelial tissue
2. Connective tissue
3. Muscular tissue and
4. Nervous tissue

Q.38: Define epithelial tissues? Describe types of epithelial tissues in detail with diagrams (where necessary)?
Ans: EPITHELIAL TISSUES:

• Epithelial tissue covers the surface of the body, lines the spaces inside the body (i.e organs and cavities) and forms glands.
• For instance, the outer layer of our skin is an epithelial tissue and the lining of small intestine are made up of epithelial tissues.
• Epithelial cells are polarized, means that they have a top and a bottom side.

Types Of Epithelial Tissues

There are different types of epithelial tissue depending on their function in a particular location. The simplest classification of these tissues is based on the number of cell layers.

1. Simple Epithelial Tissue
2. Stratified Epithelial Tissue

1. Simple epithelial tissue:
   When the epithelium is composed of a single layer of cells, it is called simple epithelial tissue.
   
   
Types Of Simple Epithelial Tissue:
On the basis of function, these tissues are classified as:

1. Simple squamous epithelium:
   Location: are found in the alveoli of lungs.
   Function: its structure is important for the exchange of gases between the blood and lungs.
   
   
2. Simple Cuboidal Epithelia:
   Location: line the lumen of collecting ducts in the kidney and are present in the thyroid gland around the follicles.
   Function: secrete thyroid hormones.
   
   
3. Simple Columnar Epithelia:
   Location: are found in the female reproductive system and in the digestive tract.
   Function: secretion.


2. Stratified epithelial tissues:
   When the epithelium is containing two or more layers of cells are called stratified epithelial tissues.
   
   Types Of Stratified Epithelial Tissues:
Stratified epithelia consist of more than one layer of cells and only one layer is in direct contact with the basement membrane.


1. Stratified Squamous Epithelia:
   Location: are found in skin, with many dead, keratinized cells.
   Function: provide protection against water and nutrient loss.
   
   
2. Stratified Cuboidal Epithelia:
   Location: are found surrounding the ducts of many glands, including mammary glands in the breast and salivary glands in the mouth.
   Function: helps in secretion and protection.
   
   
3. Stratified Columnar Epithelia:
   Location: are rare, found predominantly in some organs of the reproductive system.
   Function: protection.
   
   
4. Transitional epithelia:
   Location: They are a special subset of stratified epithelia. They are exclusively found in the excretory system.
   Function: Protection and transit shape of cells.

Q.39: Define the connective tissues and its type?
Ans: CONNECTIVE TISSUES:
Those tissue which connects or bind the different types of cells called connective tissues. They also bind other tissues of the body with each other. Connective tissue holds structures in the body together, such as tendons.

Types Of Connective Tissues:
There are two type of connective tissues:

1. Supporting connective tissues
2. Fluid connective tissue

a) Supporting Connective Tissues:
There are three types of supporting connective tissues.

• Cartilage:
  * It is a type of supporting connective tissue.
  * It is a dense connective tissue.
  * Cartilage has limited ground substance and can range from semisolid to a flexible matrix.
  * e.g: Cartilage present in pina of ear
  
  
• Bone:
  * It is another type of supporting connective tissue.
  * Bone can either be compact (dense) or spongy (cancellous), and contains the osteoblasts or osteocytes cells.
  
  
• Adipose:
  * It is another type of supporting connective tissue that provides cushions and stores excess energy and fat.

b) Fluid Connective Tissue:

• Blood:
  Blood referred to as fluid connective tissue. It transports materials in the body.

Q.40: What do you know about muscles tissues and its types?
Ans: MUSCLES TISSUES:

• Muscle tissue are most abundant tissues in animal.
• They contain bundles of long cells.
• Function: contains the cells that are responsible for the contraction and relaxation of muscles.

Types Of Muscle tissues:
There are three types of muscular tissues i.e.

1. Skeletal
2. Cardiac
3. Smooth

Skeletal Muscle:

• Skeletal muscle, which is also called striated (striped) muscle, is what we refer to as muscle in everyday life.
• Skeletal muscle is attached to bones by tendons.
• For instance, the muscles in our legs and our arms are skeletal muscle.
• Function: responsible for the movement of bones.

Cardiac Muscle:

• Cardiac muscle is found only in the walls of the heart.
• Like skeletal muscle, cardiac muscle is striated, or striped. But it's not under voluntary control.
• Function: responsible to produce heart beat involuntary. It means we don't need to think about making our heart beat.

Smooth Muscle:

• Smooth muscle is found in the walls of blood vessels, as well as in the walls of the digestive tract, the uterus, the urinary bladder, and various other internal structures.
• Smooth muscle is un-striped, (unstriated), it is involuntary, not under conscious control.
• Function: responsible to produce movement of food through our digestive tract and we don't need to think about it (involuntary).

Q.41: Write a short note on nervous tissue? Draw a labelled diagram of neurons?
Ans: NERVOUS TISSUES:

• It is composed of neurons.
• It is found in the brain, spinal cord, and nerves.

Function Or Role Of Nervous Tissues In Body:

• Neurons transmit information to other cells.
• It is responsible for coordinating and controlling many body activities.
• It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning.
• To do all these things, cells in nervous tissue need to be able to communicate with each other by way of electrical nerve impulses.

Q.42: What are plant tissue? Describe its type?
Ans: PLANT TISSUES:
As same in animals, plant cells are grouped into tissues with characteristic functions such as photosynthesis, transport etc.

Major Types Of Plant Tissues:
There are two major categories of tissues in plants i.e.

1. Meristematic tissues and
2. Permanent tissues

1. MERISTEMATIC TISSUES:

• These tissues are composed of cells, which have the ability to divide.
• The cells are thin walled, have large nucleus and number of small vacuoles.
• Usually they do not have inter-cellular spaces, so the cells are arranged compactly.

Types Of Meristematic Tissues:
Two main types of meristematic tissues recognized in plants are:

• Apical meristems
• Lateral meristems

(A) Apical meristems:

• Thy are present at the apex of roots and stems.
• According to their position they are Apical meristems.
• Function: Stem and root increase in length by the division of cells of these tissues. This type of growth is called primary growth.

(B) Lateral meristems:

• They are located on the lateral sides of roots and shoot.
• Function: When they divide, they are responsible for increase in growth of plant parts. This growth is called secondary growth.

2. PERMANENT TISSUES:

• Permanent tissues originate from meristematic tissue.
• The cells of these tissues do not have the ability to divide and may have intercellular spaces in between cells.

Types Of Permanent Tissues:
Permanent tissues are further classified into following two types either on the basis of position or composition:

• Simple permanent tissue
• Compound or complex tissue

(A) Simple Permanent Tissue:
Simple permanent tissues are made up of only one type of cell. They are further divide as:

• Epidermal Tissues
• Ground Tissues
• Supporting Tissues

(i) Epidermal Tissues:

• They are composed of a single layer of cells and they cover plant body.
• Function:
  i) They act as a barrier between environment and internal plant tissues.
  ii) In roots, they are also responsible for the absorption of water and minerals.
  iii) On stem and leaves they secrete cutin (the coating of cutin is called cuticle) which prevents evaporation.
  iv) They also have some specialized structure that perform specific functions.
  For example root hairs and stomata.

(ii) Ground tissues:

• They are simple tissues made up of parenchyma cells.
• Parenchyma cells are the most abundant cells in plants.
• Overall they are spherical but flat at point of contact.
• They have thin primary cell walls and have large vacuoles for storage of food.
• Function:
  i) In leaves, they are called mesophyll and are the sites of photosynthesis.
  ii) In other parts, they are the sites of respiration and protein synthesis.
  iii) They also store food in their vacuole.
  iv) Most parenchyma cells can develop the ability to divide and differentiate into other types of cells and they do so during the process of repairing an injury.

(iii) Supporting Tissues:

• These tissues provide strength and flexibility to plants.
• They are further of two types.
  a) Collenchyma Tissues
  b) Sclerenchyma Tissues
  
  
• a) Collenchyma Tissues: 
  i) They are found in cortex (beneath epidermis) of young stems and in the midribs of leaves and in petals of flowers.
  ii) They are made of elongated cells with unevenly thickened primary cell walls.
  Function:
  iii) They are flexible and function to support the organs in which they are found.
  
  
• b) Sclerenchyma Tissues:
  i) They are composed of cells with rigid secondary cell walls.
  ii) Their cell walls are hardened with lignin, which is the main chemical component of wood.
  iii) Mature sclerenchyma cells cannot elongate and most of them are dead.

(B) Compound (Complex) Tissues:

• A plant tissue composed of more than one type of cell is called a compound or complex tissue.
• They are found only in vascular plants.
• Examples of compound tissues are:
  Xylem tissues and
  Phloem tissues

(i) Xylem Tissue:
Xylem tissue consists of dead cells.
Due to the presence of lignin, the secondary walls of its cells are thick and rigid.

Types of cells Found in Xylem:
Two main types of cell are found in xylem tissue i.e:

1. Vessel: Vessels have thick secondary cell walls. Their cells lack end walls and join together to form long tubes.
2. Tracheids: Tracheids are made up of slender cells with overlapping ends.

Function:

• Xylem tissue is responsible for the transport of water and dissolved substances from roots to the aerial parts.
• Xylem tissue also provides support to plant body, due to presence of lignin

(ii) Phloem Tissue:
Phloem tissue consists of living cells and mainly contains:

• Sieve tube cells and
• Companion cells

1. Sieve tube:
   Sieve tube cells are long and their end walls have small pores.
   Many sieve tube cells join to form long sieve tubes.
   
   
2. Companion cells:
   Companion cells are parenchymatous, narrow, elongated cells, and are closely associated with the sieve tube.

Function:

• Phloem tissue is responsible for the conduction of dissolved organic matter (food) between different parts of plant body.
• Conduction with the sieve tube is done through the pores present on the walls of these cells.
• They help the sieve tubes in conduction of food materials and make proteins for sieve tube cells.

Q.43: Draw the outline or the chart of the plant tissues?

OR

Q.44: Differentiate between xylem and phloem?
Ans: Difference Between Xylem and Phloem:

S.NO.	Xylem	Phloem
1.	Xylem tissue is responsible for the transport of water and dissolved substances from roots to the aerial parts.	Phloem tissue is responsible for the conduction of dissolved organic matter (food) between different parts of plant body.
2.	Xylem tissue consists of dead cells.	Phloem tissue consists of living cells.
3.	Transport is unidirectional i.e. from roots to apical parts of the plants.	Transport is bidirectional i.e. from leaves and storage organs to different parts of plants.
4.	Xylem tissues consists of vessels and tracheids	Phloem tissues consists of Sieve tube cells and Companion cells
5.	Xylem cells are star shaped.	Phloem cells are not star shaped.

Q.45: Comparison between parenrenchyma, Sclerenchyma and Collenchyma.
Ans: Between Parenrenchyma, Sclerenchyma and Collenchyma

S.NO.	Parenchyma	Collenchyma	Sclerenchyma
1.	They are simple, living storage tissues.	They are simple, living mechanical tissues.	They are simple, dead mechanical tissues.
2.	They formed ground tissues and epidermis and are the most abundant cells in plants.	They formed supporting tissues and are found in cortex (beneath epidermis) of young stems and in the midribs of leaves and in petals of flowers. Absent in roots.	They formed supporting tissues and are found in all the region of plant body, particullarly in the fruit wall and seed coat.
3.	They are spherical or oval in shape but flat at point of contact.	They are flexible and made of elongated cells or irregular in shape.	They are also enlongate or iregular in shape. But mature sclerenchyma cells cannot elongate
4.	They have thin primary cell walls.	They have unevenly thickened primary cell walls.	They are composed of cells with rigid secondary cell walls. Their cell walls are hardened with lignin, which is the main chemical component of wood.
5.	They have large vacuoles for storage of food.	They have small or no vacuoles.	Vacuoles are absent
6.	They are loosely arranged with intercellular spaces.	They are compactly arranged with few, small or no intercellular spaces.	They are very compactly arranged with no intercellular spaces.
7.	they are the sites of respiration and protein synthesis.	They give flexible support to the organs in which they are found.	They provide rigidity support and protection to the plants.