Question

What do you understand by the term tissue?

Answer 1

Hint: Cells are the basic and functional unit of life and it is also the smallest unit of life. They are also known as the building blocks of life. A group of similar cells is known as tissue.

Complete Answer:
A group of morphologically comparative cells which act together is known as tissue. In plants and animals groups of cells called tissues carry out specific functions.
In plants meristematic tissue is primarily active tissue responsible for growth of plants. Meristematic tissue consists of actively dividing cells, and leads to increase in length and thickness of the plant. The primary growth of a plant occurs only in certain, specific regions, such as in the tips of stems or roots.

Different types of meristematic tissues are:
(I) Apical Meristem: It is present at the growing tips of stems and roots and increases the length of the stem and root. They form growing parts at the apices of roots and stems and are responsible for increase in length, also called primary growth.

(II) Lateral Meristem: It consists of cells which mainly divide in one plane and cause the organ to increase in growth and diameter. It is present beneath the bark of the tree in the form of cork cambium and in vascular bundles of dicots as vascular cambium. The activity of this cambium results in the formation of secondary growth.

(III) Intercalary Meristem: It is usually present at the base of node, inter node and on leaf base. They are responsible for growth in length of the plant.

Note: In humans, there are mainly four types of tissues,
1. Connective tissue - It provides shape to different organs and also helps in maintaining their position.
2. Epithelial tissue - It has a major role in sensory reception, filtration, and other metabolic activities.
3. Muscle tissue - It is involved in generating motion and producing force and it also helps in body movements.
4. Nervous tissue - It is the main component of the spinal cord and the brain.