Tissue class 9

Tissue 

A group of cells having similar shape and function and act together to perform a specific function.

Structural Organisation in living organisms:-

Plant Tissues 

A group of cells having a common origin and usually performing a common function in a plant body is called a plant cell.

Concept map of plant tissues:-

Types of Plant Tissue:

Meristematic Tissues 

• They have the capacity to divide.
• Meristematic tissue has cell small in size and isodiametric in shape.
• Vacuoles are usually absent.
• Intercellular spaces are generally absent.
• Cell walls are thin. 

Permanent Tissues 

• They do not have the capacity to divide.
• Permanent tissues  have cells large in size and their shape varies.
• Vacuoles are present in living cells of permanent tissues.
• Visible intercellular spaces are present.
• Cell wall can be thin or thick either.

Protective Tissues 

• The  tissues that are present in the outermost part of the plant that are responsible for protecting the plant body.

Differentiation

The process by which the meristematic tissues develop into different types of permanent tissues based on the location and requirements of the plant.

Meristematic tissues can be further classified into:

Apical Meristem 

• These tissues are found at the tip of the stem and the roots.
• They helps the roots and shoots grow longer.
• This kind of growth is known as primary growth.

Shoot Apical Meristem: present at the tip of the stem.

 Root Apical Meristem:  present at the tip of the roots.

Intercalary Meristem 

• Found at the base of leaves or between the nodes on branches.
• It helps parts like the internode or leaves grow longer.

Lateral Meristem 

• It helps the root or the stem grow thicker.
• Present on the lateral walls of the stem. 
• This thickening is known as secondary growth. 

Permanent tissues can be divided into: 

Simple Permanent Tissues:

A type of tissue that consists of similar cells that have a common origin and perform a specific function. 

Types of simple permanent tissue: 

Parenchyma: 

• Parenchyma tissues support plants and store food in roots and stems. 
• They forms the basic packing tissue in plants. 
• The cells are simple and not very specialised. 
• These cells have thin cell walls and are made up of cellulose. 
• The cells are living. 
• They have large gaps between them because they are loosely packed.

Parenchyma can be divided into: 

Chlorenchyma Tissues 

• Parenchyma tissues which contain chlorophyll and can perform photosynthesis.

Aerenchyma tissues 

• Parenchyma tissues with large air spaces which helps plant float by making them buoyant.

Collenchyma 

• Collenchyma tissues are found in leaf stalks just below the surface. 
• They provide flexibility allowing leaves and stems to bend without breaking. 
• These cells are alive, long and have thick corners.
• Cell wall is made up of cellulose.
• The thickening of the cell walls in the corners is due to the presence of pectin.

Sclerenchyma 

• Sclerenchyma tissues made up the hard and stiff parts of the plant. 
• They are made up of dead, long and narrow cells.
• They have no intercellular spaces. 
• The cell walls are thickened due to the presence of lignin.

Sclerenchyma can be divided into: Fibers:  Fibers are elongated, slender cells that are typically found in bundles within the plant.  They provide tensile strength and flexibility, making them crucial in supporting structures like stems, leaves, and vascular bundles.  Fibers are usually found in areas where the plant needs to withstand mechanical stress and strain, such as in the stem or bark. Sclereids: Sclereids  are shorter, more variable in shape, and often occur singly or in small groups.  They are responsible for providing rigidity and hardness to various plant parts.  Sclereids are commonly found in seed coats, nutshells, and the gritty texture of fruits like pears.  Unlike fibers, sclereids contribute to the plant's overall toughness and protection, rather than flexibility.  Complex Permanent Tissues  A type of tissue that consist of more than one type of cells,  working together to perform a specific function.  This tissues are essential for transport of water, nutrient and food throughout the plant. Complex permanent tissues can be divided into:  Xylem It is also known as wood and is a  vascular and mechanical tissue.  Thick walled cells are found in the form of tubular passage.  It helps in transport of water and minerals in uni-directional form (from roots to shoot apical meristem) in plants.  The four xylem elements are: tracheids, vessels , xylem parenchyma and xylem fibres. Except xylem parenchyma all others is elements are dead . Tracheids   They are tubular structures. They are elongated angular dead cells mainly involved in conduction of water and minerals . Vessels  They are also tubular structures formed from dead cells.  Vessels are cylindrical tube like structures placed one above the other,  end to end which form of continuous channels for efficient conduction of water . Xylem Parenchyma  They are small and thick walled parenchymatous  cells subjected for stories of food . Xylem Fibers  They are not living fibers with thick walls and narrow cavities which provide mechanical support.   Phloem  Phloem is a type of vascular tissue in plant.  It is responsible for transporting food from leaf to other part of the plant bi-directional . There are five phloem elements : sieve tubes, sieve cells, companion cells, phloem parenchyma and phloem fibers. Except phloem fibers all cells are living.

Sieve Elements

• Sieve tubes are slender tubes like structure made up of a elongated, thin walled  cells place end to end.
•  nucleus of sieve cell degenerates at maturity.
•  The end wall of sieve tubes are perforated by numerous pores called sieve plates.
•  Sieve cells possess simple protein or protein which is concerned with growth and repair of sieve cells.

Companion cell

•  Function of companion cell is to support sieve element by carrying out cell metabolism and regulation .

Phloem Fibre 

• They give mechanical support to sieve tube .

 Phloem Parenchyma

•  They store food and help in radical conduction of food.

Protective tissues can be classified into: 

Epidermis 

• The outermost layer of the cell is called epidermis. 
• The epidermis is usually made of a single layer of cells.
• In desert plants , the thick cuticle of the epidermis reduces loss by lowering the rate of transpiration. 
• Epidermis cells of the aerial parts of the plant often secrete a waxy, water resistant layer on their surface which aids in protection from loss of water mechanical injury and invasion by the parasitic fungi.
• Epidermal tissues form a continuous layer without intercellular spaces. 
• Most epidermal tissues are relatively flat. 

Stomata 

• Small pores present in epidermis of a leaf are called stomata. 
• Stomata are enclosed by two kidney shaped cells called guard cells.
•  They are necessary for exchanging of gases and transpiration.

Cork

• The outermost protective court of a tree is called cork.
• As the plant grow older , the outer protective tissue undergoes certain changes. A strip of secondary Meristem located in the cortex forms layers of cells which constitutes the cork.
• It is one of the components of a tree bark.
• It is made up of dead cells and has no intercellular spaces.
• It's cell wall has a substance called suberin that makes it impervious to gases and water.
• It protects the tree from bacterial or fungal infection.
• It also prevents water loss from the bark.

NCERT QUESTIONS/SOLUTION 

1. What is a tissue ?

Answer : 

Tissue can be defined as a group of cells having similar shape and function , act together to perform a specific function .

2. What is the utility of tissues in multicellular organisms ?

Answer : 

Tissues in multicellular organisms allow for the specialization of cells, enabling different functions to be performed efficiently. This division of labor enhances the organism's overall functioning. Tissues also provide structural support, helping to maintain the shape and integrity of organs and systems, contributing to the organism's stability and strength.

3. Name the types of simple tissues.

Answer : 

The types of simple tissues are as follows:

➢ Parenchyma

➢ Collenchyma

➢ Sclerenchyma

4. Where is apical meristem found?

Answer : 

In plants, apical meristem is typically found at the tip of the shoot and root of the plant. 

5. Which tissue makes up the husk of the coconut ?

Answer :

 The husk of a coconut is made up of sclerenchyma tissue. This tissue is composed of thick-walled, lignified cells that provide mechanical support and protection to the fruit. The fibers in the coconut husk are a type of sclerenchyma that is particularly strong and durable.

6. What are the constituents of phloem ?

Answer :

The phloem constitutes of the following five elements, they are:

➢Sieve cells

➢ Sieve tube

➢ Companion cells

➢ Phloem parenchyma

➢ Phloem fibers

7.How many types of elements together make up the xylem tissue? Name them.

Answer : 

The xylem tissue is made up of four main elements, namely:

➢ Vessels

➢ Tracheids

➢ Xylem fibers

➢ Xylem parenchyma

8. How are simple tissues different from complex tissues in plants ?

Answer : 

Simple tissues:-

• A type of tissue that consist of similar cells that have a common origin and perform a common function.

Complex tissues:-

• A type of tissue that consist of more than one types of cells , working together to perform a specific function.

9. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell walls .

Answer : 

Parenchyma:-

• Cell walls are thin and made up of cellulose .

Collenchyma :-

• Cell walls are thick at the edges due to the deposition of pectin .

Sclerenchyma:-

• Cell walls are thick due to the deposition of lignin.

10. What are the functions of stomata? 

Answer :

Stomata are small pores present in epidermis of a leaf. They are necessary for exchange of gases and transpiration. 

11. Name the regions in which parenchyma tissues is present.

Answer :

The parenchyma is found in:

• The pith of stems and roots.
• When parenchyma contains chlorophyll it is called a chlorenchyma. It is found in green leaves.
• Parenchyma found in aquatic plants has large air cavities which enables them to float, and are hence called aerenchyma.

12. What is the role of epidermis in plants ?

Answer :

Role of epidermis in plants are: 

• The epidermis in plants forms an uninterrupted and continuous layer that has no intercellular spaces.
•  It provides protection.
•  In roots , epidermal cells increase the surface area aiding in better absorption.
•  In desert plants, the thick cuticle of the epidermis reduces loss by lowering down the rate of transpiration.
•  Epidermis cells on the aerial parts of the plant often secrete a waxy, water resistant layer on the outer surface . This aids in protection from the loss of water, mechanical injury and invasion by parasitic fungi.

13. How does the cork act as a protective tissue ?

Answer :

Cork cells are dead. The arrangement of cells is so dense, that there is no intercellular space. Deposition of suberin is observed on the walls of the cells that make them impervious to water and gases. It protect the tree from bacterial or fungal infection. It also prevent water loss from the bark.

14. Complete the following chart :

Answer:

Animal Tissue 

• Animal tissues are made up of animal cells. 
• These tissues are usually not rigid since the cells do not have cell walls.

Concept map of animal tissue:- 

Types of Animal Tissue:

Epithelial Tissue 

• Tissues that are seen on the outer layer of a body or organ surface.
• Consist of a single layer of cells.
• Always grows on some other types of tissue. 
• It's primary protective in function. 

They can be classified into:

Squamous Epithelium 

• Squamous epithelium forms and extremely thin and flat layer of tissues.
• They are semi permeable and thus, perfect for gaseous exchange. 
• Present in the lining of oesophagus and the mouth. 

Stratified Squamous Epithelium 

• This kind of tissue is formed when multiple layer of squamous epithelium are arranged in a pattern.
• Present on outer layer of skin.

Cuboidal Epithelium 

• They are cuboidal in shape.
•  They form the lining of salivary gland and kidney tubules.
•  They provide mechanical support .

Glandular Epithelium 

• Sometimes a portion of   epithelium tissue folds inward and multicellular gland is formed this is glandular epithelium.

Columnar Epithelium 

• These are made up of elongated cells.
• These tissues lying the organ which helps in absorption and secretion, such as the lining of intestine.
• When cilia are present in the cells they form Ciliated columnar epithelium like those present in respiratory tract.

Muscular Tissues 

•  These tissues consist of elongated cells called muscle fibres.
• This tissue is responsible for the movement in our body .
• Muscles contain special protein called contractile proteins, which contract and relax to cause movement. 

They can be classified into :

Straited Muscles

•  These are also called as voluntary muscles because these are under the control of one's will.
• Muscle fibres or cells are long, cylindrical, unbranched and multi nucleated.
• These are also called as skeletal muscles as they are mostly attached to the bones and help in body movement. 
• These muscles get tired and need rest.
• Each fibre is enclosed by a thin membrane which is called as sarcolemma.

Non - Straited Muscles 

• They are involuntary muscles also called as smooth muscles.
• These muscle fibres are uni nucleated and spindle in shape.
• They are not enclosed by membrane but many fibres are join together in bundles. 
• Mood muscles are found in the walls of stomach,  urinary bladder, bronchi , iris of the eye ,etc. 
• Peristaltic  movement in elementary canal are bought  by smooth muscles. 
• These muscles also get tired and need rest. 

Cardiac Muscles Fibres

• They are also involuntary muscles. 
• They can be found in the walls of the heart. 
• They are uni nucleated and branched. Branches are United by intercalated disc. 
• In this muscles rhythmic contraction and relaxation occur throughout the life. 
• They do not take rest. 
• These cells are cylindrical , branched and uni nucleated.

Connective Tissue

• The tissues help in connecting different parts of the body.
• It provides structural frame work.
• It stores fats.
• It offers protection against infections. 
• It occupies and fills spaces.

Different types of connective tissues are:

Blood

• It is a fluid connective tissue.
• Bloods flows and transports gases, digested food hormones, and waste materials to different parts of the body.
• It also provides protection.

It comprises of :

Plasma: 

• It forms 55% parts of blood.
•  It consists of 90-91% of water, 7% of protein, 0.9% of inorganic salt, etc.

Corpuscles:

•  It Forms 45% part of blood.

 It comprises of:

Red Blood Corpuscles:

• They are also colled as erythrocytes, containing red colored respiratory pigment called  haemoglobin  that helps in transportation of oxygen.

White Blood Corpuscles: 

• They are also called as 'soldiers of the body'. 
• They are irregular, amoeboid, phagocyte cells that protects our body by engulfing bacterial & other foreign particles.

Blood platelets or thrombocytes:

• They are spindle shaped cells which are involved in cotting of blood.

Tendons & Ligaments

Tendons

• Connective tissue that attaches muscles to bone.
• They are non-elastic and tough.
• They help in the movement of bones.
• Each muscles contains one tendon.
• White in color due to less blood supply.

Ligaments

• Connective tissue that attaches bone to bone.
• They are elastic and strong.
• They help in stability and holding of bones together.
• Each joint contains many ligaments.
• Yellow in color due to presence of elastin fibers.

Bones and Cartilages

Bone

• It is hard, tough and inflexible.
• It does not have a rich blood supply.
• Growth is unidirectional.
• Bone cells are embedded in a hard matix composed of Calcium phosphate.
• It forms the frame work that supports our body.

Cartilage

• It is soft, elastic and flexible.
• It has widely spaced cells.
• It has a rich blood supply.
• Growth is bidirectional.
• The solid matrix is composed of proteins and Sugar.

Areolar Tissue

• It is the most distributed connective tissue in the body.
• This tissue fills spaces inside organs.
• It supports internal organs and helps in repair of tissues.
• It is found between the skin and the muscles , around blood vessels, nerves and in bone marrow.

Adipose Tissue

• Adipose tissue is made up of many round and oval adipocytes filled with fat  globules.
•  Excess nutrients tissue are stored as fat in this tissue.
• It helps in temperature regulation.
• It is commonly found beneath the skin around internal organs like the Kidney.

Nervous Tissue

• Nervous tissue makes up the entire brain, spinal cord and nerves of the body.
• They are responsible for sensations, consciousness, memory and emotion.
• They are highly specialized tissue due to which the animals are able to perceive and respond to stimuli.
• Their functional  and structural uint is called as nerve cell or neuron.

Many nerve fibers bound together by connective tissue make up a nerve.

Nerve impulse: The signal that passes along the nerve fiber.

Nerve impulse allow up to move our muscles when we want to.

Neuron

• Functional and structural unit of nervous system.
• Longest cell in body.
• Cell  body is called cyton which is covered  by plasma membrane.

Parts of a Neuron are : 

Dendrite: 

• Many Short, branched parts/structure that collect information from the previous neuron and pass it to the cell body.

Cell body : 

• Contains the nucleus and other cell organelles.

Axon : 

• Tube like structure that  carries information from the cell body to the nerve ending.

Nerve ending: 

• The end of the  axon where the nerve signal is transmitted to the next neuron or target cell. 

Nucleus: 

• Contains genetic material of the cell.

Difference between plant and animal tissue

Animal and plant tissues differ in structure, function, and the types of cells they contain due to the distinct needs of animals and plants. Here are the primary differences:

1. Types of Tissue

Animal Tissue: Primarily divided into four types – epithelial, connective, muscular, and nervous tissues.

Plant Tissue: Divided into two main types – meristematic (actively dividing) and permanent (non-dividing). Permanent tissues further include dermal, vascular, and ground tissues.

2. Growth

Animal Tissue: Growth is generally limited to certain stages in life and is spread throughout the body.

Plant Tissue: Growth occurs in specific regions, mainly in meristematic tissues, allowing plants to grow continuously throughout their lives.

3. Cell Structure

Animal Cells: Lack cell walls, but have a flexible cell membrane. They may have specialized structures such as centrioles and lysosomes.

Plant Cells: Have a rigid cell wall made of cellulose, along with a cell membrane. They contain chloroplasts for photosynthesis and large central vacuoles for storage.

4. Function and Adaptation

Animal Tissue: Specialized for movement, sensory response, and complex bodily functions such as circulation, respiration, and digestion.

Plant Tissue: Specialized for photosynthesis, support, water and nutrient transport, and storage, as plants are typically sessile (immobile).

5. Energy Storage

Animal Tissue: Stores energy in the form of glycogen.

Plant Tissue: Stores energy in the form of starch.

6. Vascular System

Animal Tissue: Has a circulatory system (blood vessels) to transport nutrients, gases, and wastes.

Plant Tissue: Uses vascular tissues (xylem and phloem) for transporting water, nutrients, and food.

7. Regeneration and Repair

Animal Tissue: Regeneration ability varies; some tissues, like skin and liver, can regenerate, while others (such as nervous tissue) have limited repair capacity.

Plant Tissue: Generally has a high capacity for regeneration, especially through meristematic tissues.

8. Photosynthesis Capability

Animal Tissue: Does not perform photosynthesis as animals lack chlorophyll.

Plant Tissue: Contains chloroplasts in certain cells (like mesophyll) that enable photosynthesis for energy production.