class 9 biology subject chapter tissue-connective tissue note
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Notes
Tissues
1. Plant tissues- On the basis of dividing capacity, plant tissues are of two types-
(a) Meristematic tissue
(b) Permanent tissue
(a) Meristematic tissue- It consists of actively dividing cells. Meristematic tissues have three types.
• Apical meristem- present at the growing tips of stems and roots and helps in increasing the length of stem and roots
• Intercalary meristem- Present at the base of the leaves. It is required for longitudinal growth of plants.
• Lateral meristem- present on the lateral side of stem and roots and helps to increase the length of stem and roots.
(b) Permanent tissue- It is formed from the meristematic tissues, the cells in this tissue lose the ability to divide. They are further divided into –
• Parenchyma- It is composed of unspecialized living cells with relatively thin cell walls, intercellular space, present in soft part of the plants.
• Collenchyma- Composed of living and elongated cells with cell walls irregularly thickened at the corners. There is no inter-cellular space. It helps in bending of leaves and stems.
• Sclerenchyma- It is composed of long narrow, thick-walled cells. It is made of dead cells and there are no inter-cellular cells.
• Complex permanent tissue- It is made up of more than one type of cells.
2. Animal tissues- Animal tisues are divided into four types based on the functions performed by them.
(a) Epithelial tissues- They form the covering of the external surfaces, internal cavities and organs of the animal body. These are various types of epithelial tissues-
• Simple squamous epithelium
• Cuboidal epithelium
• Columnar epithelium
(b) Connective tissues- They connect various organs of the body. They are divided into:-
• Areolar tissue
• Adipose tissue
• Dense regular connective tissue
• Skeletal tissue
(c) Muscular tissue- Muscular tissue provides movement to the body. They are divided into three types:
• Striated/skeletal/voluntary muscles
• Smooth/involuntary muscles
• Cardiac muscles
(d) Nervous tissue- These are present in brain, spinal cord and nerves. Neurons are cells of nervous tissue which consist of a cell body, axon and dendrite.
Answer:
Blood is a connective tissue...
