NCERT Solutions Class 9th Science Chapter – 6 Tissues
| Textbook | NCERT |
| Class | 9th |
| Subject | Science |
| Chapter | 6th |
| Chapter Name | Tissues |
| Category | Class 9th Science |
| Medium | English |
| Source | Last Doubt |
| NCERT Solutions Class 9th Science Chapter – 6 Tissues Notes were prepared based on the latest exam pattern. We have Provided Is Matter Around Us Class 9 Science MCQs Questions with Answers to help students understand the concept very well. What is importance of tissue? What is tissue called? What is the structure of tissue? Where is human tissue? What is tissue made of? Who is the father of tissue in biology? What are tissue cells? Who used tissue word first? What is study of tissue called?When was the first tissue made?What is a tissue short answer? Who called the term tissue? |
NCERT Solutions Class 9th Science Chapter – 6 Tissues
Chapter – 6
Tissues
Notes
Tissue
| A group of cell that are similar in structure and work together to achieve a particular function is called Tissue. |
Histology
| The microscopic study of tissue is called Histology. |
Plant tissue
| Meristematic & Permanent Tissues Meristematic Tissue (growth tissue) These are simple living tissues having thin walled, compactly arranged immature cells. which are capable of division and formation of new cells. Main features of Meristematic tissues are: • Thin primary cell wall (cellulosic). • Intercellular spaces are absent (compact tissue). • Generally vacuoles are absent, dense cytoplasm & prominent nuclei are present. • Actively dividing cells are present in growing regions of plants e.g., root & shoot tips. |
Classification on the Basis of Origin
| (A) Primary Meristem (Promeristem) • Derived directly from the meristems of embryo. • They consist of cells derived from primary meristem. • They add to primary growth of plants. (B) Secondary meristem • These are having cells derived from primary permanent tissue. • They usually add to the diameter of plants. |
Classification on the Basis of location
 (A) Apical Meristem • It is present at the growing tips of stems and roots. • Cell division in this tissue leads to the elongation of stem & root, thus it is involved in primary growth of the plant. (B) Intercalary Meristem • It is present behind the apex. It helps in longitudinal growth. • It is the part of apical meristem which is left behind during growth period. • These are present at the base of leaf and internode region. • These lead to the increase in the length of leaf (Primary) eg., in grass stem, bamboo stem, mint stem etc. (c) Lateral Meristem (Cambium) • It is also called as secondary meristem. • It occurs along the side of longitudinal axis of the plant. • It gives rise to the vascular tissues. • Responsible for growth in girth of stem and root. • They are responsible for secondary growth by increasing the girth. |
Permanent tissue
| • The permanent tissues are formed from those meristematic cells which are left behind and have lost their capability to divide. • The division and differentiation of the cells of meristematic tissues give rise to permanent tissues. • They have definite shape, size and thickness. The permanent tissue may be dead or living. • As a result of cell differentiation the meristematic tissues tend to form different type of permanent tissues. • In cell differentiation, developing tissues changes from simple to more complex forms to perform various specialized functions. Depending upon the stucture and composition the permanent tissue are classfied into two types: (A) Simple Permanent Tissues (Supporting tissue and protective tissue) (B) Complex Permanent Tissue (A) Simple Permanent Tissues: (a) Protective (b) Supportive Protective Tissues- These dermal tissues are primarily protective in function. They Consist of: (i) Epidermis • Epidermis forms one cell thick outermost layer of various body organs of plants such as leaves, flowers, stems and roots. • Epidermis is covered outside by cuticle. Cuticle is a water proof layer of waxy substance called as cutin which is secreted by the epidermal cells and provide protection against loss of water and also invasion by microbes. • Cells of epidermis of leaves are not continuous at some places due to the presence of small pores called as stomata. • Each stomata is guarded by a pair of bean-shaped cells called as guard cells. These are the only epidermal cells which possess chloroplasts, the rest being colourless.  |
Functions of Epidermis
| • The main function of epidermis is to protect the plant from desiccation and infection. • Cuticle of epidermis cuts the rate of transpiration and evaporation of water and prevents wilting. Function of Stomata – It allows gaseous exchange to occur during photosynthesis, respiration and also helps in transpiration. (ii) Cork or Phellem • In older roots and stems, tissues at the periphery become cork cells or phellem cells. • Cork is made up of dead cells with thick walls and without any intercellular spaces. • The cell wall in cork deposit waxy substance called as suberin. • The cells of cork become impermeable to water and gases due to the deposition of suberin. • The cork cells are without any protoplasm but are filled with resins or tannins.  Functions of Cork: • Cork is protective in function. Cork cells prevent plants from desiccation, infection and mechanical injury. • Imperviousness, lightness, toughness, compressibility and elasticity make the cork commercially valuable. |
Supportive tissues
These are supportive in function and are of three types: • Loosely packed thin walled cells, oval or spherical in structure with large space between them • Cell wall mainly composed of cellulose & pectin. • Large central vacuole for food & water storage. • Primary function is food storage and packing.  Idioblast – Some parenchyma involved in storage of excretory substances such as resin, tannin, gum and oils called as idioblast. • In typical parenchyma chlorophyll is absent. Chlorenchyma : Chloroplast containing parenchyma tissues are called as chlorenchyma which perform photosynthesis e.g., mesophyll cells of leaves. Aerenchyma : In hydrophytic plants aerenchyma (a type of parenchyma containing air spaces) provides buoyancy. (ii) Collenchyma – It is the living mechanical tissue.  • Elongated cells with thick corners. • Localized cellulose and pectin thickening. • Provides flexibility & easy bending of various parts of plant. • Few chloroplasts may be present. • Give mechanical strength and elasticity to te growing stems. • They have no or very little intercellular spaces.  (iii) Selerenchyma Cells of sclerenchyma are of two types: Sclereids: • These are also called grit cells or stone cells. • These are small cells, where lumen is so small due to higher thickening of cell wall, as present in drupe fruit (mango, coconut, walnut) legume seeds (Macrosclereid)  |
Fibres
| • They are very long, narrow, thick, lignified cells. Lumen is large as compared to sclereids. Generally 1-3 mm long. • In the thick walls of both the fibres and sclereids thin areas called as pits, are present. |
Uses of Sclerenchyma Fibres
| • These are used in the manufacture of ropes, mats & certain textile fibres. • Jute and coir are obtained from the thick bundle of fibres.  |
Complex permanent Tissues
| • It consists of more than one type of cells which work together as a unit. • It helps in transportation of organic materials, water and minerals. • It is also known as conducting or vascular tissue. • Xylem and phloem together form vascular bundles. |
Phloem
It transport (translocation) food from leaves to other parts of the plant. All phloem cells are living except phloem fibres. (i) Sieve tubes: • Sieve tubes are tubular structures made up of elongated, thin walled cells placed end to end. • The end walls of sieve tube cells are perforated by numerous pores, called as sieve plates. • Nucleus of sieve cell degenerates at maturity. However, cytoplasm persists, because of protoplasmic continuation of sieve tube with companion cell through plasmodesmata. (ii) Companion cells : • Companion cells have dense cytoplasm and prominent nuclei. • Sieve tubes & companion cells are also called sister cells because they originate from single mother cell. (iii) Phloem fibre/Phloem Sclerenchyma : • They give mechanical support to sieve tubes and are dead. (iv) Phloem parenchyma : • They store food and help in radial conduction of food. |
Epithelial tissue
| • Cells of epithelium are set very close to each other tightly packed and the tissue rests on a non-cellular basement membrane & consists of single layer of cells. • It covers all the organs and line the cavities of hollow organs like stomach. • It is primarily protective in function.  |
Epithelium tissues are classified as
| (a) Squamous epithelium: Also called pavement epithelium. • Cells arranged end to end like tiles on a floor. • Cells are polygonal in surface view. • It forms the delicate lining of cavities (mouth, oesophagus, nose, pericardium, alveoli etc.) blood vessels and covering of the tongue and skin. • Epithelial cells are arranged in many layers (stratum) to prevent wear and tear in skin. This pattern is stratified squamous epithelium. (b) Cuboidal epithelium: • They are cube like cells that fit closely, cells look like squares in section, but free surfarce appears hexagonal. • It is found in kidney tubules, thyroid vesicles and in glands (salivary glands, sweat glands). • It forms germinal epithelium of gonads (testes and ovaries). • It is involved in absorption, excretion and secretion. It also provides mechanical support . (c) Colummar epithelium: • Columnar means ‘pillar-like’ epithelium. It forms lining of stomach. • Small intestine and colon, forming mucous membranes. • Border of micro villi is present at the free surface end of each cell which increases absorption efficiency in small intestine. (d) Ciliated epithelium: • Cells may be cuboidal or columnar. • Found in respiratory tract, lining of spermduct, oviduct & kidney tubules etc. • On its free surface are present protoplasmic outgrowths called cilia. • It helps in the movement of ova in the fallopian tube. (e) Glandular epithelium: • Gland cells secretes substances at the epithelial surface. • Sometimes position of epithelial tissue folds inward and form multicellular gland so called Glandular epithelial. |
Tissues
| Group of cells having a common origin and similar function are termed as tissues. A. Plant tissues – On the basis of the dividing capacity, Plant tissues are of two types 1.Meristematic tissues 2.Permanent tissues |
1. Meristematic tissues
| Consist of actively-dividing cells. Meristematic tissues are of three types: Apical meristem – Present at the growing tips of stems and roots. Important function: To increase the length of stems and roots. Intercalary meristem – Present at the base of leaves or internodes. Important function: For the longitudinal growth of plants. Lateral meristem – Present on the lateral sides of the stems and roots. Important function: To increase the thickness of stems and roots. |
2. Permanent tissues
| Formed from meristematic tissues, the cells in the tissue loose the ability to divider Permanent tissues are divided into two categories: Simple permanent tissue – Consist of only one type of cells. Types of simple permanent tissues Parenchyma – Composed of unspecialised living cells with relatively thin cell walls, intercellular space, present in soft parts of the plant. Their main function is storage. Collenchyma – Composed of living and elongated cells with cell walls irregularly thickened at the comers. No intercellular space. It provides mechanical support and elasticity to plant. It helps in bending of leaves and stems. Sclerenchyma – Composed of long, narrow, and thick-walled cells. This tissue is made up of dead cells and there are no intercellular spaces. Sclerenchyma cells are dead, present in seeds, nuts, the husk of a coconut, fibres of jute etc. Complex permanent tissue – Made up of more than one type of cells (Conducting tissues.) |
Types of complex permanent tissues
| Xylem – Conducts water and minerals from the roots to the different parts of the plant. Composed of four different types of cells—tracheids, vessels, xylem parenchyma and xylem fibres. Phloem – Conducts food material from the leaves to the different parts of the plant. Composed of four different types of cells—sieve tubes, companion cells, phloem parenchyma and phloem fibres. Protective tissue – It is made of a single layer of cells. E.g., epidermis. The epidermis of the leaf bears stomata. |
Animal tissues
| Animal tissues are classified into four types based on the functions they perform: • Epithelial • Connective • Muscular • Nervous 1. Epithelial tissues – Form the covering of the external surfaces, internal cavities and organs of the animal body. Various types of epithelial tissues are: Simple squamous epithelium – Single layer of flat cells. Location in the human body – Lining of the mouth, oesophagus, lung, alveoli, etc. Cuboidal epithelium – Consists of cube like cells. Location in the human body – Lining of the kidney tubules and ducts of the salivary glands. It’s function is secretion and absorption. Columnar epithelium – Consists of elongated or column-like cells. Location in the human body – Inner lining of the intestine and gut. Its function is of secretion and absorption. |
3. Connective tissues
| Specialised to connect various body organs. Various types of connective tissues:, are: Areolar tissue – Found in the skin and muscles, around the blood vessels, nerves, etc. Adipose tissue – Acts as the storage site of fats; found between the internal organs and below the skin; acts as an insulator for the body. Dense regular connective tissue – Main components are tendons and ligaments; tendons connect muscles to bones, while ligaments connect two bones together. Skeletal tissue – Main components of skeletal tissues are cartilage and bone. Fluid tissue – Blood is the vascular tissue present in animals. |
4. Muscular tissues
| Main function of muscular tissues is to provide movement to the body. Muscular tissues are of three types Striated muscles or skeletal muscles or voluntary muscles – Cells are cylindrical, unbranched and multinucleate. Smooth muscles or involuntary muscles – Cells are long, spindle-shaped and possess a single nucleus. Cardiac muscles or involuntary muscles – Cells are cylindrical, branched and uninucleate. |
5. Nervous tissues
| Present in the brain, spinal cord and nerves. Neuron – Cells of the nervous tissue. A neuron – consists of a cell body, an axon and a dendrite. |
Question 1. What are tracheids?
They are elongated cells with tapering ends.
Question 2. What are guard cells?
Each stomata is bounded by a pair of specialised kidney-shaped epidermal cells called guard cells.
Question 3. What are the functions of cuboidal epithelium?
It helps in absorption, excretion, secretion, it also provides mechanical support.
Question 4. Where is apical tissue found?
Present at the tips of roots and stems.
Question 5. Where is apical meristem found? .
It is present at the growing tips of stem and root, it increases the length of the stem and roots.
Question 6. Which tissue make up the husk of coconut?
Sclerenchyma.
Question 7. What are the constituents of phloem?
Phloem constitutes the sieve tubes, companion cell, phloem parenchyma and phloem fibres.
Question 8. Name the two types of tissues.
Plant tissues and animal tissues.
Question 9. Name the two types of plant tissue.
Meristematic tissue and permanent tissue.
Question 10. Name the tissues responsible for the movement of the body.
Muscle tissue and nervous tissue
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