Tissues

Introduction

All living organisms are made up of cells. A group of similar cells that work together to perform a specific function is called a tissue. In multicellular organisms, tissues help in the efficient functioning of the body. This chapter explains the different types of plant and animal tissues and their functions.

What is a Tissue?

Definition

A tissue is a group of similar cells having a common origin that work together to perform a particular function.

Importance of Tissues:

• Division of labour among cells.
• Increases efficiency of the body.
• Helps organisms perform complex functions.

Plant Tissues

Types of Plant Tissues

Plant tissues are of two main types:

• Meristematic Tissue
• Permanent Tissue

Meristematic Tissue

Characteristics and Types

Meristematic tissues consist of actively dividing cells that help plants grow.

Characteristics:

• Cells divide continuously.
• Thin cell walls.
• Dense cytoplasm.
• No vacuoles or very small vacuoles.

Types:

• Apical Meristem: Present at the tips of roots and shoots; increases the length of the plant.
• Intercalary Meristem: Present at the base of leaves or internodes; helps in the growth of stems and leaves.
• Lateral Meristem: Present along the sides of stems and roots; increases the thickness of the plant.

Permanent Tissue

Simple and Complex Permanent Tissues

Permanent tissues are formed from meristematic tissues after the cells stop dividing.

Simple Permanent Tissues:

• Parenchyma: Stores food and water; helps in photosynthesis.
• Collenchyma: Provides flexibility and mechanical support.
• Sclerenchyma: Gives strength and rigidity to the plant.

Complex Permanent Tissues:

• Xylem: Transports water and minerals from roots to other parts of the plant.
• Phloem: Transports food prepared by leaves to all parts of the plant.

Animal Tissues

Types of Animal Tissues

Animal tissues are classified into four main types:

• Epithelial Tissue
• Connective Tissue
• Muscular Tissue
• Nervous Tissue

Epithelial and Connective Tissues

Functions

Epithelial Tissue:

• Covers and protects body surfaces.
• Forms the lining of organs and cavities.

Connective Tissue:

• Connects different body parts.
• Supports and protects organs.

Examples include bone, cartilage, blood, tendons, and ligaments.

Muscular and Nervous Tissues

Functions

Muscular Tissue:

Muscles help in the movement of the body.

Types of Muscles:

• Skeletal Muscle
• Smooth Muscle
• Cardiac Muscle

Nervous Tissue:

Nervous tissue is made up of neurons, which receive and transmit messages between different parts of the body.

Differences Between Plant and Animal Tissues

Comparison

• Plant tissues mainly provide support and growth.
• Animal tissues perform specialized functions like movement, coordination, and protection.
• Plant growth occurs only in meristematic regions, while animal growth occurs throughout the body.

Key Points

• A tissue is a group of similar cells performing a specific function.
• Plant tissues are of two types: Meristematic and Permanent.
• Xylem transports water, while phloem transports food.
• Animal tissues are epithelial, connective, muscular, and nervous.
• Neurons are the functional units of nervous tissue.
• Tissues help in the efficient functioning of multicellular organisms.

Chapter Summary

Tissues are groups of similar cells that perform specific functions. Plants have meristematic and permanent tissues, while animals have epithelial, connective, muscular, and nervous tissues. Each tissue performs a unique role that helps the organism grow, survive, and function efficiently.