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Introduction
Every organism, whether its body is unicellular or multicellular, is capable of performing all vital functions such as respiration, ingestion, excretion and reproduction. In multicellular organisms, because of the increase in body size, it is difficult for each cell to efficiently cope with the vast variety of the physiological needs of the organism. So cells group together to perform definite functions.
Plant Tissues
The plant body is made up of different kinds of tissues.
Meristematic Tissues (Meristems)
The main function of meristematic tissue is to continuously form a number of new cells and help in growth.
Permanent Tissues
These tissues are derived from meristematic tissues. They have lost the power of dividing, having attained their definite form and size. In their earlier stages the cells are more or less similar in structure but slowly they become specialized and form permanent tissues. They can be classified into simple and complex.
Protective Tissues
hese tissues are usually present in the outermost layer of the plant body such as leaves, stem and roots. It is one cell thick and covered with cutin and protects the underlying tissues present in the plant body.
Complex Tissues
Complex tissues are made up of more than one type of cells and they work together as a unit. They transport water, salt and prepared food material to various parts of the plant body.
Animal Tissues
Cells are organized into four types of tissues in higher animals including man.
Epithelial Tissue
This is a connective tissue in which the ground substance or matrix is composed of elastin, which is impregnated with salts of calcium and magnesium.
Muscular Tissue
Muscles of the body are made up of elongated muscle cells also known as muscle fibre. The movement of the body is brought about by the contraction and relaxation of contractile protein present in muscle cells.
