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2 Tissues "A group of cells...

2 Tissues "A group of cells that are similar in origin and performing a common function is called tissue." Introduction The living organisms are either unicellular like Amoeba or multicellular like human beings. In unicellular organism all the life Division of labour has been made possible by processes are carried out within a single cell. In multicellular specialization where organisms, because of increase in body size, it is difficult for each cells develop to have a cell to efficiently cope with the vast variety of the physiological definite shape, size, needs of the organisms, so cells differentiate into specific tissues to structure and function. perform specific functions. Like in human beings nerve cells carry messages, blood flows to transport oxygen, food, hormones and waste materials. In plants vascular tissues conduct food, water and minerals from one part of the plant to other part. So multicellular organism performs division of labour. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue The term tissue was coined by Bichat. The study of internal structure of any part of an organism with the help of section cutting is called anatomy. The study of tissue with the help of microscope is called histology. Tissue A group of cells that are similar in structure and work together to achieve a particular function is called tissue. Importance of tissues (i) Workload of individual cell decreases. Tissues become organized to form organs and organs into organ systems. Formation of tissues has brought about division of labour in multicellular organisms. NCERT Basics : Class 9 (ii) Multicellular organisms have higher survival due to improved body organization and higher efficiency of functions. Multicellular organisms are made up of more than one cell. Plant tissue Plants are stationary so they require more of supportive tissue for obtaining structural strength. Most of these tissues are dead and hence they provide more mechanical strength and they require less energy for their maintenance. The growth of plants is limited to certain regions. In these certain regions, growing tissues are present, which have capacity to divide throughout life. 1 Why plants consume less energy as compared to animals? Explanation Plants require less energy as they do not move from place to place and possess dead tissues. Classification of Plant Tissues Plant tissues can be classified into two groups on the basis of their dividing capacity, meristematic tissue and permanent tissue. Plant Tissues Meristematic tissue Permanent tissue (Undifferentiated, have capacity of division) (Differentiated, lost the capacity of division) Apical Lateral Intercalary meristem meristem meristem Simple tissue Complex tissues Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue (Composed of single (Composed of more type of cells; protective than one type of & supportive) cells, conductive) Parenchyma Xylem Phloem Chlorenchyma Tracheids Sieve tubes Aerenchyma Vessels Companion cells Collenchyma Sclerenchyma Xylem Phloem parenchyma parenchyma Fibres Xylem Phloem fibres fibres Sclereids  Biology Meristematic tissue These are living tissues which are capable of division Cytoplasm throughout life. These tissues are found in growing Nucleus regions of plants. Cells have thin cell wall and are Cell wall compactly packed with no intercellular space. Cells contain dense cytoplasm and do not have vacuoles. Cells Meristematic Tissue contain prominent and large nucleus. Meristematic tissues are free from virus because meristem has continuously and rapidly dividing cells. These cells have a high rate of metabolism and viruses cannot replicate in such cells. Most of the viruses migrate through vascular elements but at the tip/ meristem region, vascular elements are not formed. Thus, viruses cannot reach the meristem region. Function Meristematic tissue is responsible for the growth in length and width(girth) of plant body. 2 Vacuoles are absent in active tissue or meristematic tissue. Why it is so? Explanation In fast growing cells there is not much stuff to store. Therefore, vacuoles are very small or non- existent. Meristematic cells are metabolically highly active, so stored food is absent. Classification of meristematic tissue On the basis of their location, meristematic tissues are of three types– Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue (i) Apical meristem: It is present at the growing tips of shoot and roots. They are responsible for increase in the length of shoot and root. Root apical meristem is covered by root cap which protects it from getting damaged by the rubbing of soil particles. (ii) Intercalary meristem: These are present at the base of Apical and intercalary meristem are responsible leaf or internode (on either side of the node). They are for primary growth of plant (growth in length). responsible for the growth in length of plant organs. Intercalary meristem may be present at the internode as in grasses, bamboo and mints or at the base of Pinus leaves. NCERT Basics : Class 9 Apical meristem meristem Intercalary meristem Lateral meristem Location of meristematic tissue in the plant body 1 1. What will happen if the tip of sugarcane plant is Lateral meristem is of two types, vascular removed? cambium and cork cambium. Vascular 2. What will happen if root cap is removed from root tip? cambium produces secondary phloem and secondary xylem. Cork (iii) Lateral meristem (cambium) cambium (phellogen) produces a protective It lies on the lateral sides of stem and root or occurs cork on the outside. along the sides of longitudinal axis of the plant. It helps in increasing the diameter (girth) of plant, hence helps in secondary growth. Difference amongst three types of meristems Characters Apical meristem Intercalary meristem Lateral meristem Position At the apex part of shoot At the base of leaves and Lateral sides of stem and root. internode. and root. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Function Growth in length. Growth in length of leaves and Growth in diameter or internode. girth. 1 1. Sugarcane plant keeps on growing in length because intercalary meristem is present at the base of internode which is responsible for the growth in length of sugarcane. 2. Growth in length of root will be stopped as the root cap protects the root apical meristem from being damaged by the rubbing of soil particles.  Biology 1 Aim To demonstrate that apical meristem causes growth in length of root. Method Take two glass jars. Fill them with water. Place an onion bulb over the (1) (2) mouth of each jar in such a way that stem base of the bulb dips in water. Growth of roots in Observe daily. Roots develop from the base of the bulbs in both the jars. Onion (1) with intact apical meristem. (2), Measure the length of the roots daily. On fourth day, remove 1 cm long with apical meristem apical portion of the roots of bulb (2). Measure the lengths of the roots in removed on fourth day both the bulbs on fifth and sixth day. Observation It is seen that roots of bulb (1) continue to grow on fifth and sixth day. They stop growing in case of bulb (2). The difference between the two jars is that in bulb (1), the root apical meristems are intact while in bulb (2), the root apical meristems have been removed. Differentiation is the development process in Conclusion which cells take up a Apical meristem is responsible for growth in length of the root. permanent shape, size and perform a specific Permanent tissue function. They are formed by division and differentiation of meristematic tissue. They are composed of those cells which have lost the power of division (temporarily or permanent) and attain a permanent shape, size and function. Cells may be living or dead. Permanent tissues are of two types, simple permanent tissue and compound or complex Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue permanent tissue. Simple permanent tissue These tissues are made up of similar types of cells, that perform a common function. They are protective and supportive in nature. Simple tissues are of three types (i) Parenchyma (ii) Parenchyma is the first evolved permanent Collenchyma (iii) Sclerenchyma tissue which is present in all soft parts of plant (i) Parenchyma (therefore called as It is a living and basic packing tissue which consists of universal tissue). relatively unspecialised cells. NCERT Basics : Class 9 Cells of this tissue have thin cell wall which is made up of cellulose. Cells of this tissue have cytoplasm with small nucleus and large vacuole. The cells may either be closely packed or may have intercellular spaces. Functions This tissue provides support to the plant and help in storage of food. Thin primary Intracellular Cell wall space Nucleus Cytoplasm Starch grain Vacuole Cross section Longitudinal section Parenchyma Modification of parenchyma Chlorenchyma Chlorenchyma is the type of parenchyma in which abundant quantity of chloroplasts (containing chlorophyll) are found. They are present in mesophyll of leaves. Functions Synthesis of food (Photosynthesis). Aerenchyma Parenchyma is made up of rounded cells which surrounds the large air cavities. It is found in aquatic plants or hydrophytes. Function Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue It provides buoyancy to the aquatic plants to help them float. 3 What happens to the cells formed by meristematic tissue? Explanation After the division in meristematic cells they become differentiated into permanent tissue and lose the ability to divide. (ii) Collenchyma (Flexible tissue) Cells of this tissue are living, elongated or vary in structure.  Biology Cells of this tissue are irregularly thickened at the corners due to the deposition of pectin. It is present below the epidermis in stem of some plants and also present at leaf stalk and leaf margin. Intercellular spaces are usually very little between cells of this tissue. Nucleus Vacuole Vacuole Thickening at the corners Nucleus Cross section Longitudinal section Fig. Collenchyma Collenchyma Functions It provides mechanical support (tensile strength) and elasticity. It allows easy bending in various parts of plant (tendrils and stems of climbers) without breaking. It provides flexibility to plant. (iii) Sclerenchyma Sclerenchyma cells are dead, narrow and long cells and they are devoid of protoplasm. The walls of cells of Lignin is a complex sclerenchyma are greatly thickened with deposition of polymer which acts as a cement and hardens lignin. Such cell walls are called lignified. The cells of cell wall. Lignin makes sclerenchyma are closely packed without intercellular the cell wall impermeable spaces. so important substances are unable to pass They are found in stems of some plants (around the vascular through it. bundle), orchid roots, veins of leaves, husk of coconut, hard coverings of seed and nuts. Functions Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue It is the main mechanical tissue which provides mechanical support. It makes the plant hard and stiff. Thick lignified Simple pit walls Narrow lumen Lignified thick wall Transverse section Longitudinal section Sclerenchyma Sclerenchyma fibres NCERT Basics : Class 9 Sclerenchymatous cells are of two types in structure: 1. Fibres 2. Sclereids Sclerenchyma fibres: They constitute the major Sclereids mechanical tissue of the plants and are abundantly found in plants. Commercial fibres obtained from plants (e.g. jute, flax, hemp) usually are sclerenchymatous fibres. Husk of coconut is made up of sclerenchymatous tissue. Sclereids: They are highly thickened and irregularly shaped dead cells. They are found in various parts of the plant such as cortex, pith, phloem, hard seed coats. Sclereids provide strength to seed covering and grittiness to the pulp of many fruits, such as guava, apple and pear. 2 1. Why do leaf margin in plants are not cracked due to action of wind? 2. Why do sclerenchymatous cells become dead after deposition of lignin? 3. What will happen when we bite a fruit of pear? Comparison between Parenchyma, Collenchyma and Sclerenchyma Parenchyma Collenchyma Sclerenchyma It consists of living cells. It consists of living cells. It consists of dead cells. Intercellular spaces are usually Intercellular spaces are usually Intercellular spaces are present or may be absent. absent or very little. absent. Cell wall is thin without having Cell wall is thick as it has pectin Cell wall is thick as it has secondary deposition. deposition. lignin deposition. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Cells contain cytoplasm. Cells contain cytoplasm. Cells are devoid of cytoplasm. They have vital functions like They have both vital as well as It is chiefly a mechanical synthesis and storage of food. mechanical functions, providing tissue. support and elasticity to plant body. Compound or Complex Permanent Tissue The complex tissues consist of more than one type of cells. All these cells coordinate to perform a common function. Complex tissues are of the following two types: (i) Xylem or wood (ii) Phloem or bast  Biology (i) Xylem or wood: Xylem is made up of four types of cells (a) Tracheids (b) Tracheae or vessels Dead elements (c) Xylem fibres (d) Xylem parenchyma – Living element Vascular bundles consist of xylem and phloem and both are known as conducting tissue. They transport water, mineral and food materials respectively from one part to another part of the plant body. (a) Tracheids: Tracheids are elongated cells with tapering ends. Since tracheids do not have open ends like the vessels, so the water has to pass from cell to cell via the pits. Tracheids are the chief water conducting elements in non-flowering plants. i.e. gymnosperms. (b) Vessels or tracheae: Very long tube-like structures formed by a row of cells placed end to end. Vessels are present in flowering plants i.e. angiosperms only. The transverse walls between the vessels are completely dissolved to form continuous channels or water-pipes. Tracheids and vessels help in long distance conduction of water and minerals vertically upward from the root system to various parts of plant. Tracheids and vessels also provide mechanical support. (c) Xylem fibre: These are dead and lignified sclerenchymatous cells which are mainly supportive in function. (d) Xylem parenchyma: It is formed of living parenchymatous cells which helps in storage of food and radial conduction of water and minerals. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Pit Nucleus Cortex is the region between epidermis and endodermis. Endodermis is a single layer of compactly arranged Pits parenchy-matous cells Cytoplasm between the cortex and pericycle. (a) Tracheid (b) Vessel (c) Xylem parenchyma NCERT Basics : Class 9 Trichome Cuticle Epidermis Cortex Epidermis Endodermis Cortex Pericycle Endodermis Phloem Pericycle Xylem Phloem Cambium Cambium Pith Xylem T.S. of stem Pith Section of stem (ii) Phloem It is also made up of four types of cells The central portions (a) Sieve tubes of root and stem are (b) Companion cells Living elements occupied by pith. It is usually made up of (c) Phloem parenchyma parenchymatous cells (d) Phloem fibres – Dead element with intercellular spaces. (a) Sieve tubes: Sieve tubes are slender, tube like structures composed of elongated thin-walled cells, placed end to end. Their end walls are perforated by numerous pores and are called sieve plates. Wall of sieve tube is perforated. The nucleus of each sieve tube degenerates at maturity, however cytoplasm persists in the mature sieve tube. Thus, nuclei are absent in mature sieve tube elements. (b) Companion cells: These are associated with sieve tubes. These are smaller cells having dense cytoplasm Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue and prominent nucleus. The companion cells help the Pericycle is a single layered or multilayered sieve tubes in the conduction of food material. cylinder of thin walled or thick walled cells present (c) Phloem parenchyma: These are living and thin between endodermis and vascular tissue. walled cells which helps in sideways conduction of food. It stores various materials like resin, latex and mucilage. (d) Phloem fibre: Phloem fibres are dead sclerenchymatous cells. Phloem or bast fibres of some plants are source of commercial fibres e.g. Jute, Hemp, Flax.  Biology Sieve Plate Sieve Tube Companion Cell Phloem Parenchyma Phloem tissue Function of phloem Phloem transports photosynthetically prepared food materials in both direction from the leaves to the storage organs and later when required from storage organs to the growing regions of the plant body. 2 1. In leaves, collenchymatous tissue is present below the epidermis of the leaf margin which protects the leaf margin from injury. 2. Lignin makes the cell wall impermeable so important substances are unable to pass through it as a result, cells become dead. 3. A special sound is produced due to the presence of sclereid cells in pulp of pear fruit. Differences between Xylem and Phloem Xylem Phloem It is composed of vessels, tracheids, xylem It is composed of sieve tubes, companion cells, parenchyma and xylem fibres. phloem parenchyma and phloem fibres. It conducts water and minerals from roots to It translocates food from leaves to different parts of leaves. the plant. Xylem parenchyma are the only living cell in Sieve tubes, companion cell and phloem parenchyma xylem. are the living cells in phloem. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue No end walls between cells Cells have end Water and walls with minerals Dedifferentiation perforations takes place only in One-way Two-way permanent cells. In this flow only flow process the specialized Thick walls cells regain the division Water of power and become stiffened and food with lignin meristematic e.g. cork cambium. Xylem and Phloem NCERT Basics : Class 9 4 Although sieve tube elements do not have nuclei, but they still remain living. Explain. Explanation It is so because they are dependent on adjacent companion cells which develop from the same original meristematic cell. The two cells together form a functional unit. Differences between Meristematic tissue and Permanent tissue Meristematic Tissue Permanent Tissue The cells of meristematic tissue are The cells of permanent tissue are large, small, isodiametric and differentiated with different shapes. undifferentiated. These are generally found at the These are found in different parts of the tips of root and stem. plant. They do not have intercellular Inter cellular spaces are often present. space. In such type of tissue cell wall is Cell wall is thin or thick. thin. These cells undergo regular The cells do not normally divide. divisions. Meristematic tissue is a simple Permanent tissue may be simple or tissue. complex. Metabolic rate is high. Metabolic rate is comparatively slower. The cells lack vacuoles. Large central vacuole is found in living permanent cells. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue The cells are living. Cells may be living or dead. Meristem takes part in growth. Permanent tissue takes part in protection, photosynthesis, transportation, storage etc. Protective tissue These tissues are primarily protective in function. They are of two types: (i) Epidermis (ii) Cork (i) Epidermis It is the outermost layer of all organs of plant body which is formed from parenchymal cells. In epidermal cell outer walls are thicker than inner wall. It is mostly single layer but in desert plant it is multilayered for protection against water loss. It protects the internal tissue from mechanical injuries and entry of germs.  Biology Cuticle: The outer wall of epidermis of aerial parts of plant secretes and deposits a waxy substance, called cutin which form a waterproof layer called cuticle. Cuticle Epidermis Epidermis It checks the loss of water by transpiration, mechanical injuries and invasion by parasitic fungi. Stomata: Epidermis of leaves has large number of microscopic apertures called stomata. Each stomata is an elliptical aperture bounded by two kidney shaped guard cells which regulate opening and closing of stomata. Guard cells contains chloroplast unlike other epidermal cells hence they can perform photosynthesis. Transpiration (loss of water in the form of water vapours) takes place through stomata. Stomata helps in exchange of gases. Epidermal cell Guard cells Stoma Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Guard cell Epidermis showing stomata. (1) lateral view. (2) surface view Root hairs: Epidermis of roots (epiblema) have root hairs which greatly increase their surface area for absorption of water and minerals. Function of epidermis (i) It gives mechanical support and strength to plants parts. (ii) It protects the internal tissues from injuries and invasion by pathogens. (iii) It reduces the rate of transpiration by developing cuticle. (iv) Exchange of gases and transpiration take place through stomata. NCERT Basics : Class 9 (v) It bears unicellular or multicellular appendages in the form of root hairs, stem hairs, glands etc. (ii) Cork or Phellem Cork is the peripheral tissue of old stems and roots of woody trees and is formed due to activity of cork cambium or phellogen (secondary lateral meristem). Cork cambium (phellogen) produces new cells on its both sides, thus, forming cork (phellem) on the outer side and the secondary cortex or phelloderm on the inner side. It is made up of dead cells with thick walls but no intercellular spaces. Epidermis Phellem [cork] Phellogen [cork cambium] Phelloderm [secondary cortex] Cortex Cork Commercial importance of Cork Commercial cork is obtained from the stem surface of cork oak (Quercus suber). Cork is light and highly compressible which does not catch fire easily. Cork is used in the making of a variety of sport goods such as cricket balls, table tennis, shuttlecocks, wooden paddles etc. Functions of Cork Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue (i) Cork checks the entry of harmful microorganisms into plant parts. (ii) Multilayered, impervious cork prevent loss of water by evaporation. (iii) Cork provides protection against mechanical injury, extreme temperature and fire. Note: The walls of cork cells are heavily thickened by the deposition of an organic substance (a fatty substance), called suberin. Suberin makes these cells impermeable to water and gases and it also helps in conservation of water in the trees. Animal Tissue Every animal, whether it is unicellular or multicellular, is capable of performing all vital functions such as respiration, ingestion, excretion and reproduction.  Biology Stomach Smooth muscle fibres Smooth muscle Nucleus fibre Cell Location of muscle fibres Types of animal tissue: Based on the location and function, the animal tissues are classified into four types – Animal Tissues Epithelial Muscular Connective Nervous Tissue Tissue Tissue Tissue Squamous Cuboidal Columnar Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Skeletal/Striated Smooth/Non striated Cardiac Areolar Adipose Fluid connective Dense Regular Skeletal or loose connective Tissue connective connective connective tissue (Vascular Tissue) tissue tissue tissue Blood Lymph Tendon Ligament Cartilage Bone Epithelial Tissue Word epithelium is composed of two words Epi-upon, Thelio-grows. (Means - A tissue which grows upon another tissue is called epithelium). NCERT Basics : Class 9 Nature It is the simplest tissue. It is the protective tissue of animal's body. It covers most organs and cavities within the body. It also forms a barrier to keep different body systems separate. Epithelial cells are closely packed and have small amount of cementing material, so there are very little inter-cellular spaces present between the cells. Due to absence or less of intercellular spaces; blood vessels, lymph vessels and capillaries are unable to pierce this tissue, so blood circulation is absent in epithelium. Hence cells depend for their nutrients on the underlying connective tissue. It always rests upon underlying connective tissue. At the junction of the epithelial tissue and connective tissue a layer is present which is called basement membrane (extra cellular fibrous), which is formed of mucopolysaccharides and collagen fibrils. 5 "Skin forms the outer covering of our body" Give reason why skin is considered as an organ instead of tissue? Explanation It is because skin is made up of different tissues which collectively perform a specialized function (protection). The two main layers of skin – (1) epidermis (epithelial tissue) (2) dermis (connective tissue). Skin epithelial cells are arranged in many layers to prevent wear and tear so it is called stratified squamous epithelium. The epithelial tissue can be simple (single layered) or stratified (multilayered). Simple squamous epithelium forms the lining of blood vessels and alveoli of lungs. Stratified squamous epithelium is found in skin, buccal cavity and esophagus. Types of epithelial tissue on the basis of shapes and functions Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Type: Squamous epithelium (scale like) Description: Flattened cells, extremely thin. Common locations: Walls of blood vessel, air sacs of lungs, oesophagus, lining of mouth. Squamous epithelium (scale like) Function: Diffusion Type: Stratified epithelium Description: When cells of epithelium are arranged in layers, it is called Stratified epithelium. Common locations: Skin, Vagina etc. Stratified epithelium  Biology Function: Protection Type: Cuboidal epithelium Description: Cube like cells, may have microvilli at its free surface. Common locatsions: Lining of kidney tubules, ducts of salivary Cuboidal epithelium glands. It also forms germinal epithelium of gonads. Function: Secretion, absorption, mechanical support, excretion. Type: Columnar (Pillar like) Description: Tall slender cells; may have microvilli at its free surface. Common locations: Inner lining of intestine, part of respiratory tract Columnar(pillar like) lining. Function: Secretion, absorption. Squamous epithelial tissue is also known as Modification of columnar epithelium pavement epithelium, as a compact structure (i) Glandular epithelium gives an impression like tile on a floor. Description: Tall, slender cells, some cells from the free surface invaginate inside to form secretory cells - goblet cells. Common location: Lining of intestine & glands, trachea, bronchi. Function: Secretion of mucus and other secretions. (ii) Ciliated columnar epithelium Description: Tall, slender cells which possess cilia. Common location: Lines the nasal passages, oviducts, terminal bronchioles. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Function: Protection, movement of substances in a particular direction for e.g. of mucus in nasal passages, egg in oviduct. Glandular epithelium Ciliated columnar epithelium NCERT Basics : Class 9 6 What are the functions of cilia and microvilli present on the surface of epithelial tissue? The most abundant tissue in our body is Explanation connective tissue. The simplest and most widely Cilia show rhythmic beating movements in the respiratory distributed connective tract. Thus, this beating of cilia help to keep unwanted particle tissue is Areolar Loose connective tissue. from entering the lungs. The microvilli are finger like projections on the epithelial cells of intestine & kidney tubules where they help in increasing the surface area for absorption. Connective Tissue The cells of connective tissue are loosely spaced and embedded into a noncellular matrix. The matrix may be solid (as in bone), soft (as in loose connective tissue), or liquid (as in blood). On the basis of nature of matrix, major types of connective tissue are: (i) Loose/ areolar connective tissue (ii) Adipose tissue (iii) Fluid / vascular connective tissue (iv) Fibrous / Dense regular connective tissue (v) Skeletal connective tissue (i) Loose connective tissue Loose connective tissue is a mass of widely scattered cells whose matrix is a loose weave of fibres. Many of the fibres are strong protein fibres called collagen. Loose connective tissue is found beneath the skin and between organs. It is a binding and packing material whose main purpose is to provide support, to hold other tissues and Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue organs in place. Macrophage Fibroblast The layer of adipose tissue found in whale is known as blubber. The hump of camel is also rich in adipose tissue. Plasma cell Collagen fibre Reticular Fibre Areolar connective tissue  Biology (ii) Adipose Tissue It consists of adipose cells (Adipocytes) filled with fat globules in loose connective tissue. Each adipose cell stores a large droplet of fat that swells when fat is stored and shrinks when fat is used to provide energy. Adipose tissue pads and insulates the animal body. Fat droplet Nucleus Adipose tissue (iii) Fluid/Vascular Connective Tissue It is a special type of connective tissue which maintains link among different parts of the body. It receives materials from certain parts of the body and transports them to the other parts. It constitutes the transport Heparin, is a natural system of animals. It consists of two basic components anti-coagulant in our – blood and lymph. blood that prevents Blood the blood from clotting inside the Blood is a connective tissue of cells separated by liquid blood vessels. matrix called plasma. It lacks fibres in its matrix. Blood constitutes 55 percent of plasma and 45 percent blood corpuscles. Plasma contains water, salts, sugars, lipids, amino acids etc. Blood corpuscles are of 3 types : (i) Red blood cells or erythrocytes. (ii) White blood cells or leucocytes (iii) Platelets or thrombocytes. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Components Erythrocytes (RBCs) Leucocytes (WBCs) Platelets Monocyte Lymphocyt e Basophil Neutrophi Eosinophi l l Number per mm 3 5-6 million 5,000-10,000 2,50,000- of blood 4,00,000 Function Transport oxygen and Destroy foreign cells, produce Blood clotting carbon dioxide antibodies, roles in allergic responses Blood Cells NCERT Basics : Class 9 Functions of blood (i) It transports nutrients, hormones and vitamins to the tissues and carries excretory products from the tissues to the excretory organs. (ii) The RBC’s of blood helps in the transport of respiratory gases, oxygen & CO2. (iii) The WBCs fight with diseases by producing antibodies and engulfing the germs (antigens). Neutrophils are polynuclear leucocytes. (iv) Blood platelets helps in the clotting of blood. (v) Blood helps in thermoregulation, water balance and maintenance of pH of body. 7 What will happen if the epithelial lining of the capillaries is multilayered? Explanation If this happens, then permeability of capillaries will be affected so that exchange of substances by diffusion will not take place. Lymph Lymph is actually filtered blood which is similar to blood in In human, RBCs are small, circular, composition except that it is devoid of RBC, platelets and some biconcave & disc shaped and lack blood protein. WBCs are present in abundance in lymph. Due nuclei when mature. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue to the absence of haemoglobin, lymph is colourless. Functions of lymph (i) Helps in the transport of nutrients. Nutrients that filter out from blood capillaries into lymph are transported back by lymph into blood through heart. (ii) Helps in the transportation of fat absorbed from intestine to the blood. (iii) Keeps the tissues and organs of the body moist. (iv) Lymphatic organs (lymph nodes, spleen) produce lymphocytes which in turn produce antibodies to strengthen the immune system of the body.  Biology 3 1. Which tissue forms the outer covering of various organs of the body? 2. Name the blood cells which deal with immune reaction. 3. Which is the most abundant tissue of our body? 4. Which tissue act as fat depot of our body? (iv) Fibrous/dense regular connective tissue This tissue consists mainly of fibres. The fibres are of 2 types: (1) Collagen white fibres The dominance of the (white inelastic) collagen fibres contributes to the considerable mechanical strength of white fibrous tissue. (2) Elastin yellow fibres It can stretch upto one and a half times their length then snaps back to its original length when relaxed. Dense regular connective tissue occurs in two forms- (a) Tendons These are cords of dense (white fibres) connective tissue that attach skeletal muscles to bones. They have great strength, but its flexibility is limited. (b) Ligaments These are cords of yellow fibrous connective tissue containing elastin and collagen fibres having little matrix that connect one bone to the another. Shoulder bone Tendon (joining bone Ligament to muscle) Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue (Joining Muscle bone to Excessive pulling or bone) overstretching of ligaments produces Bone sprain. Ligaments Tendon Tendons and ligaments (v) Skeletal Connective Tissue It mainly consists of bones and cartilage, that provide a strong supportive framework for the body. In these connective tissues, the matrix contains numerous fibres and, in some cases, deposits of insoluble calcium salts. NCERT Basics : Class 9 Bone: It is a rigid connective tissue that has a matrix of collagen fibres and salt of calcium and phosphorous compounds, giving it greater rigidity and strength. Most of the Bone is the hardest tissue of our body but skeletal system is comprised of bone. Haversian system are the hardest substance in our body is enamel, the structural units of mammalian bone. It consists of found as outer Haversian canals, Haversian lamellae and osteocyte. covering on teeth. Functions of bones (i) It provides support for muscle attachment. (ii) It protects the internal organs from mechanical injury. (iii) It serves as a reservoir for calcium. Immature bone cells (Osteoblast), mature bone cells (Osteocytes), Immature cartilage cells (Chondroblast), mature cartilage cells (Chondrocytes). Bone destroying cells (Osteoclast), cartilage destroying cells (chondroclast) Osteocytes Hyaline Haversian canal matrix Haversian (Contains blood System vessel and nerve fibres) Chondrocyte Interstitial Lamellae Cartilage T. S. of bone Cartilage: It is a connective tissue with an abundant number of collagen fibres in a rubbery matrix. The matrix is made up of proteins and sugars. It is both strong and flexible but softer than bone. It forms the embryonic skeleton of vertebrates and the adult skeleton of sharks and rays. It also occurs in the human body in the ear pinna, tip of the nose, trachea, larynx and surrounding ends of joints such as knees. Muscle that contracts Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue 3 without conscious control and found in walls of organs like 1. Epithelial tissue stomach, intestine, etc are called involuntary 2. White blood cells/leucocytes. muscles. 3. Connective tissue 4. Adipose tissue Muscular tissue : Muscular tissue is distinguished from other tissues by its unique ability to contract & relax and thereby perform mechanical work. It is responsible for movement of body organs and locomotion of body. The presence of intercalated discs and oblique bridges are unique features of cardiac muscles. These help the muscles in faster conduction of wave of contraction.  Biology General structure The structural unit of muscular tissue is the muscle cells which because of its elongated shape is also called muscle fibre. The contractility is due to the presence of contractile proteins (actin & myosin) in the muscle fibre. General functions of muscular tissue (i) It supports the bones and other organs of the body. Muscles present in (ii) Muscles cause peristalsis of gut, heart beat, production our limbs move when we want them to and of sound, etc. stop when we so (iii) Muscles cause movements of body parts and decide. Such muscles are called voluntary locomotion of the animals. muscles. (iv) Facial expression also depends on muscles. (v) Contraction of muscles causes delivery of a baby. Light Nucleus Plasma band Intercalated disc Branch membrane Dark band Dark band Light band Nucleus Cardiac muscle fibres Straited muscle fibres Smooth muscle fibres Types of muscle fibres Differences between Skeletal muscle tissue, Cardiac muscle tissue, Smooth muscle tissue Types of Muscle Cardiac Skeletal Muscle Tissue Smooth Muscle Tissue Tissue Muscle Tissue Location in body Wall of the Attached to bones of the skeleton. In Walls of hollow internal structures, heart only the case of facial muscles, attached to including – Blood Vessels, Stomach, other tissues including skin-hence Intestines, Gall Bladder, Urinary “ Bladder, Airways to the lungs, Iris of Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue x ”. the eye. Voluntary or Involuntary Voluntary Involuntary involuntary Striations Present, Present, Striated muscle Absent, Nonstriated muscle (alternate light Striated and dark bands) muscle Cell Nuclei One (centrally Many nuclei (located at periphery of One (centrally located) nucleus located) long cylindrical muscles fibre) nucleus Cell Shape Cylindrical and Elongated cylindrical and Spindle shaped and unbranched branched unbranched NCERT Basics : Class 9 4 1. Name the connective tissue that lacks fibres in its matrix. 2. Give reason why cartilage is softer than bones. 3. Name the structural proteins found in the muscular tissue. Nervous tissue : The nervous tissue, contains densely packed cells called nerve cells or neurons, is present in the brain, spinal cord and nerves. The neurons are specialised for conduction of nerve impulses. They receive stimuli from within or outside the body and Nodes of Ranvier are gaps in the myelin conduct impulses (signals) which travel from one neuron sheath coating on the to another neuron. Nerve impulse allow us to move our axon. muscles when we want to. The functional combination of nerve and muscle tissue is fundamental to most animals. This combination enables animals to move rapidly in response to stimulus. Each neuron has following 2 parts : (i) Cyton or cell body: Contains a central nucleus and cytoplasm with characteristic deeply stained particles called Nissl's granules (i.e. clumps of ribosomes and rough endoplasmic reticulum). (ii) Cell Processes (a) Dendrites: These may be one to many, generally short and branched cytoplasmic processes. Dendrites are afferent processes because they receive impulse from receptor or other Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue neuron and bring it to cyton. (b) Axon: It is single generally long efferent process which Stimulus: An agent conducts impulse away from cyton to other neuron. or a change in the external or internal Longest cell in body is neuron because axon can be environment that induces reaction in more than one metre long. Axon has uniform thickness, the body. but it has terminal thin branches called telodendria. Terminal end buttons or synaptic knobs occur at the end of telodendria.  Biology Dendrites N ’ Neurons are the longest cells of our Cell Body body (upto 1m). They have least power of Nucleus regeneration. Schwann Cell Axon Myelin Sheath Nodes of Ranvier Axon terminal Synaptic knob Structure of Neuron 4 3 4 1. Blood. 2. In cartilage, the matrix is made up of protein and sugars but in bones, the matrix contains 70% inorganic salts which contributes to their hardness and rigidity. 3. Contractile proteins namely actin and myosin. Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue NCERT Basics : Class 9 Biology Diagrams made Easy Intercellular space Nucleus Parenchyma Wall thickenings Nucelus Vacuole Cell wall Collenchyma Thick lignified walls Sclerenchyma (transverse section) Publishing$\PNCF\2024-25\Print Module\SET-1\NCERT\Biology\9th\02. Tissue Narrow lumen Lignified thick wall Sclerenchyma (Longitudinal section)