Chapter 6 — Tissues
Welcome to HSLC Guru. This page provides a complete English-medium study guide for ASSEB Class 9 Science, Chapter 6 — Tissues. You will find a clear chapter summary, all textbook questions with model answers grouped by marks, additional MCQs, fill in the blanks, true/false items, and a glossary of key terms. Use this resource to prepare for tests, finals, and quick revision before the HSLC examination.
Chapter Summary
A tissue is a group of cells with similar structure and origin that work together to perform a specific function in a multicellular organism. Tissues form the next level of organisation between cells and organs. Single-celled organisms like Amoeba do not need tissues because one cell carries out every life process, but in larger plants and animals, division of labour requires specialised tissues for support, transport, protection, contraction, and communication. Tissues are broadly grouped as plant tissues and animal tissues, since plants and animals have very different lifestyles, plants being stationary and autotrophic while animals are mobile and heterotrophic.
Plant tissues are of two main types — meristematic and permanent. Meristematic tissues contain actively dividing cells with thin walls, dense cytoplasm, and no vacuoles; they are responsible for plant growth. Based on location they are classified as apical meristem (at root and shoot tips, causing increase in length), lateral meristem or cambium (along sides of stems and roots, causing increase in girth), and intercalary meristem (at the base of leaves or internodes, helping in regrowth after grazing). Permanent tissues are formed when meristematic cells lose the ability to divide and take up a permanent shape, size, and function. Simple permanent tissues include parenchyma (living thin-walled cells for storage and photosynthesis when it contains chlorophyll, then called chlorenchyma; or for buoyancy when filled with air, called aerenchyma), collenchyma (living cells with corner thickenings of cellulose and pectin, providing flexibility to climbing stems and leaf stalks), and sclerenchyma (dead cells with thick lignified walls giving rigidity, found in coconut husk and seed coats). Complex permanent tissues are xylem, which conducts water and minerals upward through tracheids, vessels, xylem parenchyma, and xylem fibres, and phloem, which transports food made in leaves through sieve tubes, companion cells, phloem parenchyma, and phloem fibres. The outermost layer is the epidermis, often coated with a waxy cuticle to prevent water loss.
Animal tissues are classified into four major groups: epithelial, connective, muscular, and nervous. Epithelial tissue covers body surfaces and lines internal organs and cavities. Its types are squamous (flat scale-like cells in skin, alveoli, blood vessels), cuboidal (cube-shaped cells in kidney tubules and ducts), columnar (tall pillar-like cells lining the intestine and respiratory tract), ciliated (columnar or cuboidal cells with cilia, found in trachea and fallopian tubes, helping in movement of mucus or eggs), and glandular epithelium (cells modified to secrete substances, forming glands). Connective tissue binds and supports other tissues and contains cells in a non-living matrix. It includes areolar tissue (fills space between organs and supports internal structures), adipose tissue (fat-storing tissue beneath the skin and around organs, acting as an insulator), blood (a fluid connective tissue with plasma as matrix carrying RBCs, WBCs, and platelets), bone (a hard tissue with calcium and phosphorus salts that forms the skeleton), cartilage (a softer tissue with proteinaceous matrix found at the nose tip, ear pinna, and joints), ligament (joins bone to bone, very elastic), and tendon (joins muscle to bone, very strong but less elastic).
Muscular tissue is responsible for movement and consists of long cells called muscle fibres that contain contractile proteins. Striated or skeletal muscles are voluntary, attached to bones, and show alternate light and dark bands; their cells are cylindrical, unbranched, and multinucleate. Unstriated or smooth muscles are involuntary, spindle-shaped, uninucleate, and located in the walls of internal organs like the stomach, intestine, and blood vessels. Cardiac muscle is found only in the heart; its cells are cylindrical, branched, uninucleate, and involuntary, and they show rhythmic contraction throughout life. Nervous tissue is made up of highly specialised cells called neurons that conduct impulses rapidly from one part of the body to another. A neuron has a cell body containing the nucleus, branched dendrites that receive impulses, and a long axon that transmits the impulse to the next neuron, muscle, or gland. Together these tissues allow an animal to sense, respond, move, and maintain life processes efficiently.
Textbook Questions and Answers
1 Mark Questions
Q1. Define a tissue.
Answer: A tissue is a group of cells similar in structure and origin that work together to perform a specific function.
Q2. Name the tissue responsible for the growth of a plant.
Answer: Meristematic tissue is responsible for the growth of a plant.
Q3. What is the function of xylem?
Answer: Xylem conducts water and dissolved minerals from the roots to the leaves and other parts of the plant and also provides mechanical support.
Q4. Where is cardiac muscle found?
Answer: Cardiac muscle is found only in the walls of the heart.
Q5. Name the tissue that connects bone with bone.
Answer: Ligament connects bone with bone.
Q6. Which tissue stores fat in the human body?
Answer: Adipose tissue stores fat in the human body.
Q7. What is the structural and functional unit of nervous tissue called?
Answer: The structural and functional unit of nervous tissue is called a neuron.
Q8. Name the tissue present in the husk of a coconut.
Answer: Sclerenchyma tissue is present in the husk of a coconut.
Q9. What type of muscle is found in the iris of the eye?
Answer: Smooth (unstriated) muscle is found in the iris of the eye.
Q10. Which tissue forms the outer protective layer of plants?
Answer: Epidermis forms the outer protective layer of plants.
2-3 Marks Questions
Q1. Differentiate between meristematic tissue and permanent tissue.
Answer: Meristematic tissue contains actively dividing cells with thin walls, dense cytoplasm, and no vacuoles; it is found at growing regions like root and shoot tips. Permanent tissue is made of cells that have lost the power of division and have taken up a definite shape, size, and function; these cells often have thick walls and prominent vacuoles. Meristematic tissue causes growth, while permanent tissue performs functions such as support, storage, and conduction.
Q2. Mention any three functions of epithelial tissue.
Answer: (i) It covers and protects the surface of the body and internal organs from injury and infection. (ii) It helps in absorption of digested food in the intestine and reabsorption of useful substances in kidney tubules. (iii) It performs secretion through glandular epithelium, producing enzymes, hormones, sweat, and other substances.
Q3. Distinguish between xylem and phloem.
Answer: Xylem conducts water and minerals from roots to other parts of the plant and most of its cells (tracheids, vessels, fibres) are dead at maturity, providing rigidity. Phloem transports prepared food (sugars) from leaves to other parts and consists mainly of living cells (sieve tubes and companion cells), with only phloem fibres being dead. Xylem moves substances upward, while phloem can move food in both directions.
Q4. Why are striated muscles called voluntary muscles?
Answer: Striated muscles are called voluntary muscles because they are under the conscious control of our will. They are mostly attached to bones (skeletal muscles) and contract when we decide to perform actions like walking, writing, or lifting. Their fibres show alternate light and dark bands, which gives them the name striated, and they are cylindrical, unbranched, and multinucleate.
Q5. Differentiate between tendon and ligament.
Answer: A tendon is a strong, inelastic connective tissue made of dense collagen fibres that connects muscle to bone, transmitting the force of muscle contraction to the bone. A ligament is an elastic connective tissue with both collagen and elastic fibres that connects bone to bone at a joint, allowing controlled movement while keeping the joint stable. Tendons are tough but not very stretchy, while ligaments are flexible and elastic.
Q6. What are the functions of areolar and adipose tissues?
Answer: Areolar tissue fills the space inside organs, supports internal organs, and helps in the repair of tissues. Adipose tissue stores fat as a reserve food source, acts as an insulator preventing loss of body heat, and provides cushioning and protection to delicate organs such as kidneys and eyeballs.
5-6 Marks Questions
Q1. Describe the different types of meristematic tissue based on their location, with the function of each.
Answer: Meristematic tissues are growth tissues consisting of cells that divide actively. Based on location they are of three types. (i) Apical meristem is present at the tip of the root and the shoot. It is responsible for increase in length of the plant, called primary growth. As cells divide here, the root grows deeper into the soil and the shoot grows taller. (ii) Lateral meristem or cambium is present along the sides of stems and roots in dicot plants. It produces new cells that increase the girth or thickness of the plant, known as secondary growth, and is responsible for the formation of wood and bark. (iii) Intercalary meristem is found at the base of leaves or at the internodes (between two nodes), especially in grasses and monocot plants. It causes regrowth of parts that have been cut or grazed and contributes to the elongation of internodes. Together these three meristems allow continuous growth throughout the life of the plant.
Q2. Describe the structure and functions of the three types of simple permanent tissues in plants.
Answer: Simple permanent tissues are made of similar cells performing a common function. (i) Parenchyma consists of living, thin-walled, isodiametric cells with large vacuoles and intercellular spaces. It is found in soft parts of the plant such as cortex, pith, and leaves. Its functions include storage of food, photosynthesis (when chloroplasts are present, then it is called chlorenchyma), and providing buoyancy in aquatic plants (when air spaces are large, it is called aerenchyma). (ii) Collenchyma is made of living, elongated cells with thickened corners due to deposition of cellulose and pectin. It has very little intercellular space and is present below the epidermis of leaf stalks and young stems. It provides mechanical strength along with flexibility, allowing parts to bend without breaking. (iii) Sclerenchyma is made up of long, narrow, dead cells with thick walls heavily lignified and lacking protoplasm. It is found in stems around vascular bundles, in seed coats, and in nut shells. It provides rigidity and hardness to plant parts and makes them resistant to bending.
Q3. Describe the four types of animal tissues with one main function of each.
Answer: Animals have four major types of tissues. (i) Epithelial tissue forms a continuous protective sheet over the body and lines internal organs and cavities. Its main function is protection, absorption, secretion, and exchange of materials. (ii) Connective tissue connects, binds, and supports different tissues and organs. Examples are blood, bone, cartilage, ligament, tendon, areolar, and adipose tissue. Its main function is to join body parts, transport materials (as in blood), provide skeletal support (as in bone), and store fat (as in adipose tissue). (iii) Muscular tissue consists of elongated cells called muscle fibres that contain contractile proteins. Its main function is to bring about movement of body parts and locomotion of the whole animal; it also drives involuntary actions like heartbeat and peristalsis. (iv) Nervous tissue is composed of neurons capable of generating and transmitting electrical impulses. Its main function is rapid communication and coordination between different parts of the body, controlling responses to stimuli.
Q4. Describe the structure of a neuron and explain how it conducts an impulse.
Answer: A neuron is the structural and functional unit of nervous tissue. It has three main parts. (i) Cell body or cyton contains the nucleus, cytoplasm, and other cell organelles; this is the metabolic centre of the neuron. (ii) Dendrites are short, branched, finger-like projections extending from the cell body. They receive impulses from sense organs or other neurons and pass them towards the cell body. (iii) Axon is a single, long, cylindrical process that arises from the cell body and ends in fine branches called axon terminals. Many axons are covered by a fatty myelin sheath that increases the speed of impulse conduction. When a stimulus is received by the dendrites, it is converted into an electrical impulse that travels through the cell body, along the axon, and to the axon terminals. At the synapse (the small gap between two neurons), the impulse is transmitted to the next neuron through chemicals called neurotransmitters. In this way, neurons form a network through which messages travel from sense organs to the brain or spinal cord and back to muscles or glands, producing a coordinated response.
Q5. Compare the three types of muscle tissues in animals.
Answer: Animal muscle tissue is of three types: striated, unstriated, and cardiac. (i) Striated (skeletal) muscles are attached to bones, voluntary in action, and show alternate dark and light bands giving a striped appearance. Their cells are long, cylindrical, unbranched, and multinucleate. They cause body movements like walking and running and tire after prolonged use. (ii) Unstriated (smooth) muscles are found in the walls of internal organs such as the stomach, intestine, urinary bladder, and blood vessels. Their cells are spindle-shaped, uninucleate, and lack striations. They are involuntary and bring about slow, sustained contractions like the movement of food in the alimentary canal and the narrowing or widening of blood vessels. (iii) Cardiac muscles are found only in the wall of the heart. Their cells are cylindrical, branched, and uninucleate, with faint striations. They are involuntary and contract rhythmically throughout life without tiring, pumping blood continuously through the body.
Additional MCQs
Q1. Which of the following is a meristematic tissue?
(a) Parenchyma (b) Collenchyma (c) Apical meristem (d) Sclerenchyma
Answer: (c) Apical meristem
Q2. The tissue responsible for the conduction of food in plants is —
(a) Xylem (b) Phloem (c) Cambium (d) Epidermis
Answer: (b) Phloem
Q3. Which tissue has cells with thick corners due to cellulose and pectin deposition?
(a) Parenchyma (b) Collenchyma (c) Sclerenchyma (d) Aerenchyma
Answer: (b) Collenchyma
Q4. The flat, scale-like cells of epithelial tissue are called —
(a) Cuboidal (b) Columnar (c) Squamous (d) Glandular
Answer: (c) Squamous
Q5. Blood is classified as —
(a) Epithelial tissue (b) Muscular tissue (c) Connective tissue (d) Nervous tissue
Answer: (c) Connective tissue
Q6. Which muscle is involuntary, branched, and uninucleate?
(a) Skeletal (b) Smooth (c) Cardiac (d) Striated
Answer: (c) Cardiac
Q7. Tendon connects —
(a) Bone to bone (b) Muscle to bone (c) Nerve to muscle (d) Bone to skin
Answer: (b) Muscle to bone
Q8. The husk of a coconut is made up of —
(a) Parenchyma (b) Sclerenchyma (c) Collenchyma (d) Phloem
Answer: (b) Sclerenchyma
Q9. Which of the following is a fluid connective tissue?
(a) Bone (b) Cartilage (c) Blood (d) Tendon
Answer: (c) Blood
Q10. The functional unit of nervous tissue is —
(a) Nephron (b) Neuron (c) Axon (d) Synapse
Answer: (b) Neuron
Fill in the Blanks
Q1. The growth of a plant in length is due to ___________ meristem.
Answer: apical
Q2. ___________ tissue stores fat in the human body.
Answer: Adipose
Q3. Cardiac muscles are found only in the ___________.
Answer: heart
Q4. The waxy coating on the epidermis of plants is called ___________.
Answer: cuticle
Q5. The long process of a neuron that carries impulses away from the cell body is called the ___________.
Answer: axon
True or False
Q1. Parenchyma cells are dead and thick-walled.
Answer: False (Parenchyma cells are living and thin-walled.)
Q2. Phloem transports food prepared by leaves to all parts of the plant.
Answer: True
Q3. Striated muscles are involuntary in action.
Answer: False (Striated muscles are voluntary in action.)
Q4. Cartilage is found at the tip of the nose and ear pinna.
Answer: True
Q5. A neuron is the longest cell in the animal body.
Answer: True
Glossary
| Term | Meaning |
|---|---|
| Tissue | A group of cells with similar structure and origin performing a common function. |
| Meristem | A plant tissue made of actively dividing cells responsible for growth. |
| Apical meristem | Meristem present at the tip of root and shoot causing growth in length. |
| Lateral meristem | Meristem along the sides of stem and root causing growth in girth. |
| Intercalary meristem | Meristem at the base of leaves or internodes that helps regrowth. |
| Parenchyma | Simple permanent tissue of living thin-walled cells used for storage and photosynthesis. |
| Collenchyma | Living cells with thickened corners providing flexibility and support. |
| Sclerenchyma | Dead, thick-walled cells made rigid by lignin, providing mechanical strength. |
| Xylem | Complex plant tissue conducting water and minerals upward. |
| Phloem | Complex plant tissue conducting prepared food from leaves to other parts. |
| Epidermis | Outermost protective layer of cells in a plant. |
| Cuticle | Waxy coating on epidermis that prevents water loss. |
| Epithelial tissue | Animal tissue covering body surfaces and lining cavities and organs. |
| Squamous epithelium | Flat, scale-like epithelial cells found in skin and alveoli. |
| Cuboidal epithelium | Cube-shaped epithelial cells found in kidney tubules. |
| Columnar epithelium | Tall pillar-like epithelial cells lining the intestine. |
| Connective tissue | Animal tissue that joins, supports, and binds other tissues. |
| Areolar tissue | Connective tissue filling spaces between organs. |
| Adipose tissue | Fat-storing connective tissue beneath the skin and around organs. |
| Cartilage | Soft, flexible connective tissue at joints, ear, and nose. |
| Bone | Hard connective tissue forming the skeleton. |
| Ligament | Elastic connective tissue joining bone to bone. |
| Tendon | Tough connective tissue joining muscle to bone. |
| Striated muscle | Voluntary skeletal muscle showing alternate dark and light bands. |
| Unstriated muscle | Involuntary smooth muscle without striations, found in internal organs. |
| Cardiac muscle | Branched, involuntary muscle found only in the heart. |
| Neuron | Structural and functional unit of nervous tissue that conducts impulses. |
| Dendrite | Branched projection of a neuron that receives impulses. |
| Axon | Long projection of a neuron that carries impulses away from the cell body. |
| Synapse | Junction between two neurons across which impulses are transmitted. |