Chapter – 6B : Animal Tisssue | Chapter Solution Class 9

(a) Phloem

Explanation: The sieve tube is a component of the phloem tissue. Phloem is responsible for transporting food materials, primarily sugars, from the leaves to the rest of the plant. The sieve tube elements play a key role in this process by allowing for the movement of food.

(d) Xylem

Explanation: Xylem is the tissue responsible for conducting water and minerals from the roots to the rest of the plant. It consists of tracheids, vessels, and other specialized cells that help in the upward movement of water.

(b) Parenchyma tissue

Explanation: In dicotyledonous stems, the central portion (pith) is made up of parenchyma tissue. This tissue is typically composed of thin-walled cells that store nutrients and help with the overall metabolic functions of the plant.

(c) Sclerenchyma

Explanation: Sclerenchyma tissue consists of dead cells with thickened cell walls, and it provides structural support to the plant. Unlike parenchyma and collenchyma, which are involved in metabolism and support while still living, sclerenchyma serves only a supportive role after the cells die.

(a) Endarch

Explanation: In sunflower stems, the xylem is typically arranged in an endarch pattern, where the xylem elements develop towards the center of the stem, while the phloem remains toward the outside. This is common in dicot stems.

(c) Nervous tissue

Explanation: Nervous tissue is responsible for coordinating the activities of different organs in the human body by transmitting signals. The neurons within nervous tissue are the main components responsible for communication.

(c) Neuron

Explanation: The neuron is the structural and functional unit of the nervous system. It is responsible for transmitting nerve impulses throughout the body, which enables coordination and response to stimuli.

(b) Bone

Explanation: Bone is the hardest dense connective tissue. It provides structural support to the body, protects internal organs, and helps in movement through its connection to muscles. The hardness is due to the high mineral content, primarily calcium phosphate.

(b) Blood

Explanation: Blood is a special type of fluid connective tissue. It consists of cells like red blood cells, white blood cells, and platelets suspended in plasma. Blood plays a crucial role in transporting nutrients, gases, and waste products throughout the body.

Nodes.

Sclerenchyma.

Transportation of food.

Leaf

Xylem parenchyma.

Tracheids, Vessels.

Sieve tube

Endodermis

Aerenchyma

Chlorenchyma

Meristematic

Sclerenchyma

Sclerenchyma

Aerenchyma

Leaf

Root

Permanent

Pith

Sclerenchyma

Parenchyma

Stomata

Transportation of nutrients.

Epithelium

Dense connective tissue

Skeletal

Cardiac muscle

Neurone

Axon

Synapse

Middle layer

Simple tissues are made up of one type of cell that performs a specific function. Examples of simple tissues include parenchyma, which stores food and provides flexibility; collenchyma, which provides structural support to growing parts of the plant; and sclerenchyma, which strengthens the plant body.

Sclerenchyma tissue provides mechanical strength to the plant body. It is composed of thickened, lignified cell walls that help support and protect mature parts of the plant. The cells of sclerenchyma are usually dead when mature, which makes them strong and rigid, allowing them to resist mechanical stress.

Meristematic tissues are located in specific regions of the plant where growth occurs. These tissues are found at the tips of roots and shoots (apical meristem), at the internodes (intercalary meristem), and in the lateral cambium (lateral meristem). Meristematic tissues are responsible for producing new cells for growth.

Aerenchyma is a specialized type of parenchyma tissue found in aquatic plants. It contains large intercellular spaces that allow for the exchange of gases such as oxygen and carbon dioxide. Aerenchyma also helps the plant to float by providing buoyancy, making it essential for aquatic plant survival.

Chlorenchyma is a type of parenchyma tissue that contains chloroplasts, enabling the tissue to carry out photosynthesis. It is usually found in the green parts of plants, such as the leaves. The primary function of chlorenchyma is to produce food for the plant through the process of photosynthesis.

Stomata are small openings or pores found mainly on the surface of plant leaves and stems. These openings allow for the exchange of gases, including carbon dioxide and oxygen, between the plant and the atmosphere. Stomata also help regulate water loss through transpiration, maintaining the plant’s water balance.

The Casparian strip is a waxy, impermeable layer found in the cell walls of the endodermis in plant roots. It prevents water and dissolved substances from passing freely through the apoplast (cell walls) into the vascular system. This forces water to pass through the plasma membrane, regulating the flow of water and nutrients into the plant’s vascular system.

The two functions of sclerenchyma are

1. It provides mechanical strength and rigidity to the plant body.
2. It strengthens non-growing parts, such as stems and vascular tissues, helping the plant maintain stability and protection.

The two characteristic differences are

• In the dicot stem, vascular bundles are arranged in a circle, while in the root, they are arranged in a star-like pattern.
• The root has a central vascular cylinder surrounded by cortex, whereas the stem has a central pith and vascular bundles.

Without xylem and phloem tissues, plants would be unable to transport water, nutrients, and food throughout their structure. Xylem is responsible for transporting water from the roots to other parts of the plant, while phloem transports the food produced during photosynthesis. Without these tissues, the plant would not be able to sustain itself and would die.

If plants lack meristematic tissue, they will be unable to grow or produce new cells. Meristematic tissue is responsible for plant growth, both in length and in the formation of new organs like leaves and flowers. Without it, plants would not be able to regenerate or increase in size.

If a plant’s leaves do not possess stomata, it will not be able to carry out gas exchange effectively. This would hinder photosynthesis, as carbon dioxide cannot enter the leaf, and oxygen cannot exit. Additionally, the plant would struggle with water regulation, as transpiration is also controlled by stomata.

Simple squamous epithelium consists of a single layer of thin cells, which is ideal for diffusion and absorption but not for protection. In contrast, stratified squamous epithelium is composed of multiple layers of cells, providing a thicker barrier. This multilayer structure enables better protection against mechanical stress, abrasion, and harmful substances.

Adipose tissue stores fat, which serves as a concentrated form of energy reserve. When the body requires energy, the stored fat is broken down into fatty acids and used for metabolic functions. Besides serving as an energy reserve, adipose tissue also provides cushioning for organs and insulates the body.

Striated muscles are called skeletal muscles because they are attached to the skeleton and help in voluntary movements. These muscles are also known as voluntary muscles because they can be consciously controlled to produce movements such as walking, lifting, and other voluntary activities. The striations refer to the banded appearance of the muscle fibers under a microscope.

The three characteristics of meristematic tissue are:

• Meristematic tissue consists of undifferentiated cells that divide actively to promote growth.
• The cells are small, tightly packed, and have a thin cell wall.
• These cells have large nuclei and small vacuoles, and they lack significant intercellular spaces.

The functions of phloem are

1. Phloem is responsible for transporting the products of photosynthesis (mainly sugars) from the leaves to other parts of the plant.
2. It also helps in the transport of organic compounds, hormones, and amino acids.

The three structural features of permanent tissue are

1. Permanent tissue consists of mature, differentiated cells that no longer divide.
2. It has thick or thin cell walls, and the structure varies depending on the function (e.g., collenchyma for support, parenchyma for storage).
3. The cells may contain vacuoles and chloroplasts, depending on the type of tissue.

The functions of xylem are

• Xylem is responsible for the upward conduction of water and minerals from the roots to the rest of the plant.
• It provides structural support to the plant through its thickened cell walls.

(i) The epidermal tissue system consists of the outermost layer of cells that protect the plant from water loss, disease, and mechanical injury.

(ii) The vascular tissue system includes xylem and phloem, responsible for the transport of water, nutrients, and food in the plant.

The conducting tissues of the plant are xylem and phloem.

Xylem consists of tracheids, vessels, and xylem parenchyma, while phloem is made up of sieve tubes, companion cells, phloem parenchyma, and phloem fibers.

Phloem is the tissue associated with the conduction of food matters.

The components of phloem are sieve tubes, companion cells, phloem parenchyma, and phloem fibers.

Simple squamous epithelial tissue is a single layer of flat, thin cells.

Its functions are to facilitate diffusion and filtration (e.g., in lungs and blood vessels) and to reduce friction between surfaces.

Connective tissue performs the following functions:

1. Provides structural support and connects different tissues and organs.
2. Acts as a cushion and insulates the body (e.g., adipose tissue).
3. Facilitates transport of nutrients, oxygen, and waste (e.g., blood).

Simple cuboidal epithelial tissue is composed of a single layer of cube-shaped cells that rest on a thin basement membrane.

Functions:

1. Provides protection to underlying tissues.
2. Involved in secretion and absorption (e.g., in the kidney tubules and glands).
3. Helps in storage and reproductive processes (e.g., in ovaries).

Areolar tissue is a loose connective tissue found between organs, muscles, and under the skin.

Functions:

1. Acts as a packing material by filling spaces between organs.
2. Provides flexibility and elasticity to tissues.
3. Helps in defense against infections by trapping pathogens.
4. Plays a role in tissue repair and inflammation.

Skeletal muscle, also known as striated muscle, is a type of voluntary muscle that is attached to bones and helps in movement. It has alternating dark and light bands (striations).

Functions:

1. Enables movement of body parts by voluntary contraction and relaxation.
2. Helps in maintaining posture and body balance.

Muscular tissue is a specialized tissue responsible for movement by contraction and relaxation of muscle fibers.

Types of muscular tissue:

1. Skeletal muscle – Voluntary, attached to bones, helps in movement.
2. Smooth muscle – Involuntary, found in internal organs like intestines and blood vessels.
3. Cardiac muscle – Involuntary, found only in the heart, responsible for pumping blood.

Skeletal muscle is a voluntary striated muscle attached to bones and responsible for body movement.

Functions:

1. Helps in movement and locomotion.
2. Provides body posture and support.

Axon: A long, thread-like part of a neuron that transmits nerve impulses from the cell body to other neurons or muscles.

Axon Hillock: The region where the axon originates from the cell body; it plays a role in the generation of nerve impulses.

Neurolemma: The outermost layer of the Schwann cell surrounding a nerve fiber; it aids in nerve regeneration.

Cardiac muscle is a specialized involuntary striated muscle found only in the heart. It has intercalated discs for coordinated contraction.

Functions:

1. Responsible for the rhythmic contraction and relaxation of the heart.
2. Pumps blood throughout the body.

Glandular epithelium is a specialized epithelial tissue involved in secretion.

Site of Occurrence:

• Found in glands like salivary glands, sweat glands, pancreas, thyroid gland.

Functions:

1. Produces and secretes substances like enzymes, hormones, and sweat.
2. Regulates various physiological processes by releasing secretions into ducts or directly into the bloodstream.

A tissue is a group of cells that have a common origin, structure, and function.

Classification of Plant Tissues:

1. Meristematic Tissue – Composed of actively dividing cells.
2. Permanent Tissue – Derived from meristematic tissue and does not divide further.

Functions of Plant Tissues:

Meristematic Tissue: Helps in plant growth by cell division.

Permanent Tissue: Provides strength, storage, and transport.

• Simple Permanent Tissue: Includes Parenchyma (storage, photosynthesis), Collenchyma (mechanical support), and Sclerenchyma (rigidity).
• Complex Permanent Tissue: Includes Xylem (water conduction) and Phloem (food transport).

Permanent tissues are those that have lost their ability to divide and perform specialized functions. They are classified into simple permanent tissues and complex permanent tissues

Parenchyma consists of thin-walled, living cells with large vacuoles and intercellular spaces. It is found in soft plant tissues such as leaves, stems, and roots and plays a role in photosynthesis and storage.

Collenchyma is made of elongated living cells with thickened corners due to cellulose and pectin deposition. It is found in leaf veins and stems and provides mechanical support while maintaining flexibility.

Collenchyma consists of living cells with unevenly thickened cell walls made of cellulose and pectin, providing support to young plant parts. It is flexible and allows plant stems and petioles to bend without breaking.

Function: Provides support and elasticity

Sclerenchyma, consists of dead cells with thick lignified walls and no intercellular spaces. It is extremely rigid and provides mechanical strength to mature plant parts such as stems, seed coats, and nuts.

Function: Provides rigidity and mechanical strength

The epidermal tissue system is the outermost covering of the plant and serves as a protective barrier against environmental factors. It consists of the following components:

1. Epidermis – It is a single layer of tightly packed cells that covers the surface of leaves, stems, and roots. It protects against mechanical injury, water loss, and infection.
2. Cuticle – A waxy, waterproof layer secreted by the epidermal cells, which helps in reducing transpiration and prevents excessive water loss.
3. Stomata – Small pores present in the epidermis of leaves and young stems, regulated by guard cells, that control gas exchange and transpiration.
4. Trichomes – Hair-like outgrowths on stems and leaves that help in reducing water loss, provide protection against herbivores, and in some cases, secrete substances.
5. Root Hairs – Extensions of epidermal cells in roots that increase surface area for water and nutrient absorption from the soil.

A tissue system is a group of tissues that work together to perform specific functions in a plant. In plants, tissues are classified into three main tissue systems based on their structure and function:

1. Epidermal Tissue System – Forms the outer protective covering of the plant (e.g., epidermis, cuticle, stomata).
2. Ground Tissue System – Includes all tissues except vascular tissues, responsible for storage, photosynthesis, and mechanical support.
3. Vascular Tissue System – Composed of xylem and phloem, responsible for the transport of water, minerals, and food.

The vascular tissue system is responsible for the conduction of water, minerals, and food throughout the plant. It consists of two main tissues:

1. Xylem – Conducts water and minerals from the roots to different parts of the plant.
2. Phloem – Transports food (sugars) from the leaves to other parts of the plant.

The vascular tissue system in plants is responsible for the conduction of water, minerals, and food. It consists of two main tissues: xylem and phloem. Each of these tissues is composed of different specialized cells that perform specific functions.

Components of Xylem and Their Functions

Components of Phloem and Their Functions

The internal structure of a dicot stem consists of the epidermis, cortex, vascular bundles, and pith. The epidermis is the outermost protective layer covered by a cuticle to prevent water loss. Below it, the cortex consists of collenchyma (provides support), parenchyma (stores nutrients), and the endodermis (regulates material flow). The vascular bundles, arranged in a ring, contain xylem (transports water), phloem (transports food), and cambium, which enables secondary growth. At the center, the pith is made of parenchyma cells that store nutrients and help in maintaining the stem’s structure. This organization supports transport, strength, and growth in dicot plants.

The internal structure of a dicot leaf consists of three main parts: epidermis, mesophyll, and vascular bundles. The epidermis is the outermost layer, present on both the upper (upper epidermis) and lower (lower epidermis) surfaces. It is covered by a cuticle to reduce water loss and contains stomata, which help in gas exchange and transpiration. The mesophyll is the middle region of the leaf, divided into palisade parenchyma and spongy parenchyma. The palisade parenchyma, located beneath the upper epidermis, contains chloroplasts and is responsible for photosynthesis. The spongy parenchyma, present below the palisade layer, has loosely packed cells with air spaces that facilitate gas exchange.

The vascular bundles, which include xylem and phloem, form the veins of the leaf and are responsible for transport. The xylem conducts water and minerals, while the phloem transports food. In dicot leaves, the vascular bundles are arranged in a reticulate venation pattern. The lower epidermis has more stomata than the upper epidermis to regulate transpiration

Differences Between the Internal Structure of a Dicot Root and a Dicot Stem

Differences Between the Internal Structure of a Dicot Root and a Dicot Leaf

Epithelial tissue is a type of animal tissue that forms a protective covering over the body surfaces, both internal and external. It lines the skin, organs, blood vessels, and cavities and plays a crucial role in protection, absorption, secretion, and sensory reception.

Characteristics of Epithelial Tissue (Any three)

1. Closely Packed Cells – The cells are tightly bound with little or no intercellular spaces.
2. Rests on a Basement Membrane – A thin layer that separates epithelial tissue from underlying connective tissue.
3. No Blood Vessels – Nutrients and oxygen are supplied through diffusion from nearby connective tissues.
4. Regenerative Ability – Can regenerate quickly to repair damaged cells.
5. Polarity – Has an apical surface (exposed to external environment or lumen) and a basal surface (attached to the basement membrane).

Areolar tissue is a type of loose connective tissue found in animals. It is widely distributed throughout the body and serves as a binding and supportive tissue. It connects the skin to underlying muscles, fills spaces between organs, and provides flexibility and cushioning.

Characteristics of Areolar Tissue

1. Loose Arrangement – The cells and fibers are loosely arranged, providing flexibility.
2. Highly Vascularized – Contains blood vessels that supply nutrients to nearby tissues.
3. Contains Different Cells – Includes fibroblasts (produce fibers), macrophages (help in immunity), mast cells (involved in inflammatory response), and plasma cells (produce antibodies).
4. Fibrous Composition – Contains collagen fibers (provides strength), elastic fibers (provides elasticity), and reticular fibers (supports other cells).

Muscular tissue is a specialized tissue responsible for movement in the body. It consists of elongated cells called muscle fibers, which have the ability to contract and relax, generating force for locomotion and other bodily functions.

Muscular tissue is composed of long, cylindrical, or spindle-shaped muscle fibers that contain contractile proteins (actin and myosin). These proteins allow the fibers to shorten (contract) and lengthen (relax), enabling movement.

Functions of Muscular Tissue (Any three)

1. Locomotion and Movement – Skeletal muscles help in body movements like walking and running.
2. Involuntary Movements – Smooth muscles control movements in internal organs such as digestion and blood circulation.
3. Heart Contraction – Cardiac muscles enable rhythmic heartbeat and blood circulation.
4. Maintaining Posture – Skeletal muscles provide body stability and posture.
5. Generation of Heat – Muscle contractions produce heat, helping in thermoregulation.

Nervous tissue is a specialized tissue responsible for transmitting signals throughout the body. It is found in the brain, spinal cord, and nerves and plays a key role in coordinating bodily functions by transmitting electrical impulses.

The nervous tissue is composed of two types of elements: (a) Neurons and (b) Neuroglia. The tissue forms the structural basis by which information from one part of the organism is transferred to the other. It is responsible for the control and coordination of the activities of other tissues and organs in the body.

Connective tissue plays a vital role in binding, supporting, and protecting different structures in the body. It is composed of cells embedded in an intercellular matrix, which may be fibrous, fluid, or solid. Based on structure and function, connective tissues are classified into different types, each with specific functions.

Functions of Different Connective Tissues:

1. Areolar Tissue – Acts as a binding tissue, connecting skin to muscles and filling spaces between organs. It provides elasticity, flexibility, and support to body structures.
2. Adipose Tissue – Stores fat, provides insulation, and acts as a cushion to protect internal organs from mechanical shocks.
3. Fibrous Connective Tissue – Includes tendons and ligaments; tendons connect muscles to bones, while ligaments connect bones to other bones, providing strength and flexibility to joints.
4. Cartilage – Provides flexibility and support to structures like the nose, trachea, and joints, preventing friction between bones.
5. Bone – The hardest connective tissue, it forms the skeletal framework of the body, providing protection, support, and aiding movement.
6. Blood – A fluid connective tissue responsible for transporting oxygen, nutrients, hormones, and waste throughout the body.

Bone is the hardest and densest connective tissue that forms the skeletal framework of vertebrates. It is made up of osteocytes (bone cells) embedded in a solid matrix rich in calcium and phosphate. The matrix provides rigidity and strength. Bone tissue contains blood vessels, which supply nutrients, and is covered by a membrane called the periosteum.

Functions of Bone:

1. Bone provides support and structure to the body.
2. Bone protects vital organs such as the brain, heart, and lungs.

Cartilage is a flexible connective tissue made up of chondrocytes (cartilage cells) embedded in a firm and elastic matrix. It lacks blood vessels and receives nutrients through diffusion. It is found in joints, the nose, trachea, and ear.

Functions of Cartilage:

1. Cartilage provides flexibility and support to structures like the nose and ear.
2. Cartilage acts as a shock absorber in joints, preventing friction between bones.

Blood is a fluid connective tissue that circulates throughout the body. It plays a vital role in transporting nutrients, oxygen, and waste products and helps in maintaining homeostasis.

Structure of Blood: Blood is composed of two main components:

Plasma – The liquid part of blood that contains water, proteins, hormones, and dissolved nutrients.

Blood Corpuscles (Cells) – The solid components of blood, which include:

• Red Blood Cells (RBCs) – It Contains hemoglobin, responsible for oxygen transport.
• White Blood Cells (WBCs) – It helps in defense and immunity against infections.
• Platelets – It assists in blood clotting to prevent excessive bleeding.

Functions of Blood:

1. Transport of Oxygen and Nutrients – RBCs carry oxygen from the lungs to different body parts, while plasma transports nutrients.
2. Removal of Waste Products – Blood carries carbon dioxide and other waste materials to the lungs and kidneys for excretion.
3. Defense Against Diseases – WBCs fight against infections and pathogens.

Connective tissue is a tissue that supports, connects, and binds different tissues and organs in the body. It is widely distributed and plays an essential role in providing structure, protection, and transport of substances.

Characteristic Features of Connective Tissue:

1. Widely Spaced Cells – The cells in connective tissue are not closely packed but are scattered within a large amount of intercellular matrix.
2. Presence of Fibers – Connective tissue contains collagen fibers (for strength), elastic fibers (for flexibility), and reticular fibers (for support).
3. Varied Matrix Composition – The matrix can be fluid (blood), semi-solid (cartilage), or solid (bone) depending on the type of connective tissue.

Muscular tissue is responsible for movement, posture, and internal organ functions. It consists of elongated muscle fibers that contract and relax to generate force. Muscular tissue is classified into three types based on structure and function: skeletal muscle, smooth muscle, and cardiac muscle.

Types of Muscular Tissue, Their Occurrence, and Functions