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what is cell and tissue.explain with details for class 12
Answers
Cell
The cell is the smallest structural and functional unit of life. There is no living creature existing on the planet earth without the cell. Therefore it is referred to as a fundamental unit of life. Every function of the body is executed through these minute cells.
The term cell was first coined in the year 1665 by an English scientist Robert Hooke. Among all the living organisms, some organisms are unicellular, consisting of only one cell, which is capable of performing all the life functions. These unicellular organisms include amoeba, algae, bacteria, fungi, Protista etc. Multicellular organisms consist of different types of cells which have specialized functions. Plants, animals, human beings, birds are examples of multicellular organisms.
There are two different types of cells, the prokaryotic cells and the eukaryotic cells and these differences are mainly based on the presence and absence of the nucleus in their cell.
Tissue
Tissues are groups of similar cells, working together to perform a specific function. They are structurally and functionally similar to the cells. The word tissue is mainly derived from a Latin word meaning weave.
In the plant kingdom, tissues are divided into two different types: Meristematic tissue and Permanent tissue.
In the animal kingdom, tissues are divided into four different types:
- Connective Tissue: Blood, bone, tendon, adipose, and ligament are examples of Connective Tissue.
- Muscle Tissue: Skeletal muscle, Cardiac muscle, and Smooth muscle are examples of Muscle Tissue.
- Nervous Tissue: Brain, spinal cord, and the peripheral nervous system are examples of Nervous Tissue.
- Epithelial Tissue: Surface of the skin, the reproductive tract, the airways, and the inner lining of the digestive tract are examples of Epithelial Tissue.