Chapter – 2C : Plants and Animal Tissues | Chapter Solution Class 9

(c) Tissue

Explanation: As defined in the chapter, a tissue is a group of organized cells having a common origin, structure, and function.

(c) Meristematic tissue

Explanation: According to the chapter, meristematic tissue is composed of immature cells that are actively dividing and responsible for plant growth.

(a) Permanent tissue

Explanation: The chapter classifies xylem as a complex permanent tissue, responsible for transporting water and nutrients.

(a) 4 types

Explanation: The chapter states that meristematic tissues are classified based on position and origin into four types.

(b) Collenchyma

Explanation: Collenchyma is a simple permanent tissue with unevenly thickened walls, providing mechanical support.

(a) Sclerenchyma

Explanation: Sclerenchyma is a simple permanent tissue with evenly thickened lignified walls, and its cells are dead.

(b) Xylem

Explanation: Xylem is a complex permanent tissue responsible for conducting water in plants.

(c) Mechanical

Explanation: Sclerenchyma provides mechanical support and strength to plants.

(b) Ground tissue

Explanation: Parenchyma forms the ground tissue in plants and helps in storage, photosynthesis, and transportation.

(b) Epithelial tissue

Explanation: Epithelial tissue forms coverings on free surfaces internally and externally.

(c) Basement membrane

Explanation: Epithelial tissue is tightly packed and rests on a basement membrane.

(a) Connective tissue

Explanation: Connective tissue is primarily non-vascular and functions as binding tissue.

1. uneven
2. lignified
3. mechanical support
4. meristematic tissue
5. living
6. embryonic
7. smooth
8. sensory, motor

False

Explanation: Collenchyma is a living tissue with unevenly thickened cell walls that provide mechanical support to growing plant parts.

False

Explanation: Meristematic tissue is composed of actively dividing cells, which help in growth and development of plants.

True

Explanation: Parenchyma cells have large vacuoles and intercellular spaces, allowing them to store water, food, and gases.

True

Explanation: Sclerenchyma is a complex permanent tissue composed of dead cells with thick, lignified walls, providing structural strength to plants.

True

Explanation: Bast fibers (Phloem fibers) are elongated, thick-walled fibers that provide mechanical support to the plant.

True

Explanation: Nerve cells do not undergo cell division after maturity because they lack centrioles, which are required for mitosis.

Xylem

Reason: Parenchyma, Collenchyma, and Sclerenchyma are simple permanent tissues, while Xylem is a complex permanent tissue responsible for water conduction.

Sieve tubes

Reason: Tracheid, Trachea, and Xylem parenchyma are components of Xylem, whereas Sieve tubes belong to Phloem (food-conducting tissue).

Cardiac muscle

Reason: Epithelial, Connective, and Nerve tissues are basic tissue types, whereas Cardiac muscle is a specialized muscle tissue found only in the heart.

Meristematic tissue consists of actively dividing cells that help in plant growth.

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

Lateral meristem is present along the sides of roots and stems, responsible for secondary growth (increase in thickness).

Parenchyma is a simple permanent tissue with thin-walled living cells involved in storage, photosynthesis, and transport.

Xylem is a complex permanent tissue that conducts water and minerals from roots to other parts of the plant.

Sclerenchyma is a simple permanent tissue composed of dead cells with thick, lignified walls, providing mechanical support to plants.

Companion cells are formed in Phloem, assisting sieve tubes in transport of food.

Sclerenchyma provides structural strength and mechanical support to plants.

Xylem transports water and minerals from roots to the stem and leaves.

The characteristics of parenchyma tissue are:

1. Living cells with thin cell walls made of cellulose.
2. Cells have large vacuoles and intercellular spaces.
3. Found in all plant parts, including roots, stems, and leaves.
4. Functions include storage, photosynthesis, and transport of nutrients.

Structure:

• Cells are elongated, living, and have unevenly thickened walls.
• Found in leaf petioles, stem cortex, and midrib of leaves.

Function:

• Collenchyma provides mechanical support and flexibility to growing plant parts.
• Collenchyma possess chlorophyll, they help in photosynthesis.

The function of phloem are

1. Transports food (mainly sucrose) from leaves to other plant parts.
2. Bast fibres of phloem give mechanical strength to the plants

Structure:

• Made up of dead cells with thick lignified walls.
• Two types: fibers (elongated cells) and sclereids (irregular cells).

Function: Provides mechanical support and rigidity to plants.

The simple permanent tissues are

• Parenchyma
• Collenchyma
• Sclerenchyma

The complex permanent tissues are

1. Xylem
2. Phloem

Three types of muscular tissues are:

Skeletal Muscle Tissue

• Reason for naming: Named for its attachment to the bones of the skeleton, aiding in voluntary body movements. It has a characteristic striped or “striated” appearance under a microscope, leading to its alternative name, “striated muscle.”

Smooth Muscle Tissue

• Reason for naming: Called “smooth” because it lacks the striations (bands) seen in skeletal and cardiac muscles. It has a uniform, smooth appearance and is involuntary, commonly found lining internal organs such as the stomach, intestines, and blood vessels.

Cardiac Muscle Tissue

• Reason for naming: Named “cardiac” due to its exclusive presence in the heart (cardia). It is striated like skeletal muscle but differs in structure and function, notably being involuntary, rhythmic, and capable of continuous contractions to pump blood throughout the body.

Fibrous connective tissue: A connective tissue composed mainly of collagen fibers that provides strength and flexibility, forming structures like tendons and ligaments, is called fibrous connective tissue.

Liquid connective tissue: A connective tissue having a liquid extracellular matrix, involved in transport and immunity, such as blood and lymph, is called liquid connective tissue.

Blood cells are absent in epithelium because epithelial tissues lack blood vessels (avascular). Nutrients and oxygen reach epithelial cells through diffusion from underlying connective tissues, eliminating the need for blood cells within epithelial layers.

Meristematic tissue is a type of plant tissue composed of actively dividing cells responsible for growth, is called meristematic tissue.

Types of Meristematic Tissue:

Apical Meristem: Meristematic tissue located at the tips of roots and shoots, responsible for increasing the length of the plant, is called apical meristem.

• Structure: Small, actively dividing cells found at root and shoot tips.
• Function: Vertical (primary) growth of plant.

Lateral Meristem: Meristematic tissue found along sides of roots and stems responsible for increasing the girth (thickness) of plant organs, is called lateral meristem.

• Structure: Cylindrical layers of dividing cells (vascular cambium and cork cambium).
• Function: Secondary growth; increases thickness.

Intercalary Meristem: Meristematic tissue located at internodes or base of leaves (especially in grasses) that helps regenerate parts removed by grazing or cutting, is called intercalary meristem.

• Structure: Actively dividing cells found at leaf bases or internodes.
• Function: Rapid growth and regeneration of damaged parts.

Parenchyma is a simple permanent tissue consisting of living cells with thin cell walls.

Characteristics: Parenchyma cells are isodiametric, thin-walled living cells. They may be oval or polygonal in shape, and their cell walls are made of cellulose. These cells contain large vacuoles and intercellular spaces. They are living, with dense protoplasm and a prominent nucleus. Intercellular spaces are commonly present, and their cell walls are uniformly thin.

Distribution : Parenchyma form the ground tissue of all plant cells such as epidermis, ground tissue, mesophyll in the leaves etc.

Collenchyma is a simple permanent tissue with unevenly thickened walls, providing mechanical support to the plant.

Characteristics: Collenchyma cells are living cells whose corners are comparatively thickened. They appear polygonal in transverse section (T.S.) and rectangular in longitudinal section (L.S.). Intercellular spaces may be absent. These cells show uneven thickening on their cell walls and contain vacuolated protoplasm. Their cell walls are composed of cellulose, hemicellulose, and pectin. Collenchyma is commonly found in the endodermis of dicotyledonous plants, especially in the midrib and petioles of leaves and stems. They may also be present in the pedicels of flowers.

Function:

• Collenchyma provides mechanical support and flexibility to growing plant parts.
• Collenchyma possess chlorophyll, they help in photosynthesis.

Xylem is a complex permanent tissue responsible for water conduction.

Components of Xylem:

• Tracheids – Long, narrow dead cells with tapered ends, conduct water.
• Vessels – Tubular structures, allow efficient water conduction.
• Xylem parenchyma – Only living cells in xylem, helps in storage and lateral conduction.
• Xylem fibers – Dead fibers, provide mechanical support.

Functions of Xylem:

• Transports water and minerals from roots to other parts.

Sieve tubes and companion cells are part of phloem, which transports food in plants.

Structure:

1. Sieve Tubes – Elongated tube-like structures, arranged end to end with perforated sieve plates.
2. Companion Cells – Small living cells that support sieve tubes in food conduction.

Functions:

• Sieve tubes transport food (sucrose) from leaves to other plant parts.
• Companion cells help sieve tubes by providing energy for transport.

Meristematic tissue is classified into three main types based on its location in the plant. Each type has distinct characteristics:

Apical Meristem

Location: Found at the tips of roots and shoots.

Characteristics:

• Responsible for primary (lengthwise) growth.
• Cells are small, densely packed, and actively dividing.
• Leads to elongation of roots and shoots.

Lateral Meristem

Location: Along the sides of stems and roots (e.g., vascular cambium, cork cambium).

Characteristics:

• Responsible for secondary (thickness) growth.
• Cells divide to increase girth of plant organs.
• Present in mature regions of the plant.

Intercalary Meristem

Location: At the base of leaves or internodes (mainly in grasses).

Characteristics:

• Helps in regrowth of parts removed by grazing or cutting.
• Promotes elongation between mature tissues.
• Cells are actively dividing and contribute to rapid growth.

Simple permanent tissues are composed of only one type of cell and are of three types:

Parenchyma

• Characters: Parenchyma cells are isodiametric, thin-walled living cells. They may be oval or polygonal, and their cell walls are made of cellulose. These cells have large vacuoles and intercellular spaces. They contain dense protoplasm and a nucleus. The cell walls are uniformly thin.
• Distribution: Parenchyma forms the ground tissue of all plant cells such as epidermis, ground tissue, and mesophyll in the leaves, etc.
• Functions: (i) Stores food, water, and nutrients. (ii) Provides temporary support and fills spaces in plant organs.

Collenchyma

• Characters: Collenchyma cells have corners that are comparatively thickened. They appear polygonal in T.S. (transverse section) and rectangular in L.S. (longitudinal section). These are living cells, and intercellular spaces may not be present. They have uneven thickening on their cell walls. The cells have vacuolated protoplasm, and cell walls are made of cellulose, hemicellulose, and pectin.
• Distribution: Found in the endodermis of dicotyledonous plants, especially in midrib and petioles of leaves, stem, etc. They may also occur in the pedicel of flowers.
• Functions: (i) Provides flexible support to growing parts of the plant (like stems and leaves).  (ii) Allows bending without breaking due to its elasticity.

Sclerenchyma

• Characters: Sclerenchyma are simple permanent tissues consisting of evenly thickened, lignified walls with simple pits. The cells are dead and do not contain protoplasm. They are of various shapes and sizes. Intercellular spaces are absent. This tissue has two types: sclerenchyma fibers and sclereids.
• Distribution: Found in the endodermis of stem, bundle caps of dicot plants, veins of leaves, and covering of seeds and nuts.
• Functions: (i) Provides rigid and permanent support to the plant. (ii) Makes plant parts hard and strong due to lignified walls.

Plant tissue is a group of cells in plants that work together to perform specific functions. It is mainly classified into two types: meristematic tissue and permanent tissue.

1. Meristematic Tissue

Tissue made of actively dividing cells that help in the growth of plants is called meristematic tissue.

Types of Meristematic Tissue:

1. Apical Meristem: Meristem present at the tips of roots and shoots, responsible for increasing plant length, is called apical meristem.
2. Lateral Meristem: Meristem found along the sides of roots and stems that helps in increasing thickness, is called lateral meristem.
3. Intercalary Meristem: Meristem located at internodes or base of leaves that helps in regrowth and elongation, especially in grasses, is called intercalary meristem.

2. Permanent Tissue

Tissue made of cells that have lost the ability to divide and are specialized for specific functions is called permanent tissue.

Types of Permanent Tissue:

a) Simple Permanent Tissue: Tissue made of only one type of cell performing similar functions is called simple permanent tissue.

1. Parenchyma: Living cells with thin walls that store food and water and help in photosynthesis and healing, is called parenchyma.
2. Collenchyma: Living cells with unevenly thickened walls that provide flexible support to growing parts, is called collenchyma.
3. Sclerenchyma: Dead cells with thick, lignified walls that give strength and rigidity to the plant, is called sclerenchyma.

b) Complex Permanent Tissue: Tissue made of more than one type of cell working together to perform a common function is called complex permanent tissue.

1. Xylem: Tissue that transports water and minerals from roots to other parts of the plant is called xylem.
2. Phloem: Tissue that transports food from leaves to other parts of the plant is called phloem.

Epithelial tissue is a type of animal tissue that covers the body surface, lines internal organs and cavities, and forms glands. It is classified based on cell shape and number of layers. Each type has unique characteristics.

Types of Epithelial Cells with Characteristics:

Squamous Epithelium: Epithelial tissue made of flat, thin cells that form a smooth lining is called squamous epithelium.

Characteristics:

1. Cells are flat and scale-like.
2. Allows diffusion and filtration.
3. Found in alveoli (lungs), blood vessels, etc.

Cuboidal Epithelium: Epithelial tissue made of cube-shaped cells is called cuboidal epithelium.

Characteristics:

1. Cells are cube-like in shape.
2. Involved in secretion and absorption.
3. Found in kidney tubules and gland ducts.

Columnar Epithelium: Epithelial tissue made of tall, pillar-like cells is called columnar epithelium.

Characteristics:

1. Cells are elongated and column-shaped.
2. Helps in absorption and secretion.
3. Found in the lining of the stomach and intestines.

Ciliated Epithelium: Columnar or cuboidal epithelium with hair-like cilia on the surface is called ciliated epithelium.

Characteristics:

1. Has cilia that move substances.
2. Found in the respiratory tract and fallopian tubes.

Stratified Epithelium: Epithelial tissue with multiple layers of cells for protection is called stratified epithelium.

Characteristics:

1. Cells arranged in layers.
2. Provides protection from wear and tear.
3. Found in skin, mouth, and esophagus.