Question

Right notes for tissues

Answer 1

Tissue are the group of cells the have similar structure and perform specific function.

Answer 2

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- INTERCALARY MERISTEM : it's the meristem that internodes on twigs.

characteristics of MERISTEMATIC TISSUE :-

• the cells of this tissue are very active.
• meristematic tissue have dense cytoplasm.
• they lack vacuoles.
• compactly arranged cells without intercellular space.

2. permanent tissue :-

when meristematic tissue divide it's cells, then they lose the ability to divide and form permanent tissue. and this process is known as differentiation.

types of permanent tissue :- simple permanent tissue and complex permanent tissue.

- SIMPLE PERMANENT TISSUE

the tissue made up of one type of cell which resembles each other and perform similar functions.

<> parenchyma - it consists wof unspecialised cells with thin walls and cells present here are live. they are loosely packed. this tissue provide support and strength to the plant and store food in the form of fat, oil and starch. sometime it contains chlorophyll and then performs photosynthesis. then it's called chlorenchyma. and in aquatic plants, large air cavities are present in parenchyma to help in floating. such type of parenchyma is called aerenchyma.

<> collenchyma - collenchyma is responsible for the flexibility of plants. it makes it easy to bend Various parts of plant like leaf, stem etc without breaking. it also provides mechanical support to the plants. the cells of this tissue are living and thickening at the corner with cellulose. therefore there is very little intercellular space between them and also provides rigidity to the plants.

<> schelerenchyma - this tissue makes the plant hard and stiff. the husk of a coconut is also made from schelerenchyma tissue. the cells in this Tissue are dead and long and narrow as the walls are thickened with lignin. the walls of the cells in this Tissue are so thick that there's no intercellular space. it provides strength to the plants.

the outermost layer of cells is called EPIDERMIS. this is usually made up of single layer of cells. and in some dry habitats, the epidermis are thicker to protect against water loss. there are many small pores on epidermis of the leaf called stomata. stomata is enclosed by two kidney shaped cells called guard cells. stomata are necessary for exchanging gases and for transpiration. epidermis cells of the roots increase water absorption and total absorption surface area.

- COMPLEX PERMANENT TISSUE

this tissue are made up of more than one type of cells and all these cells perform a common function.

<> xylem - it consists tracheids, vessels, xylem parenchyma and xylem fibres. it have thick walls and almost all are dead here. it helps to transport water and minerals vertically. xylem parenchyma stores food and helps in conduction of water and fibres give support.

<> phloem - it is made up of sieve tubes, companion cells, phloem fibres and phloem parenchyma. it transport food from leaves to other parts of the plant. cells in phloem are living.

-: ANIMAL TISSUE :-

1. epithelial tissue :-

the covering and protective tissues in the animal body are the epithelial tissue. it forms a barrier to keep body systems different. for example : the skin, lining of mouth, lining of blood vessels and kidney tubules are made up of epithelial tissues.

- SQUAMOUS EPITHELIUM

these cells are extremely thin and flat and form a delicate lining. skin is also made from squamous epithelium. since, they are arranged I a pattern of layers to prevent wear and tear, these are called stratified squamous epithelium.

- COLUMNAR EPITHELIUM

the columnar epithelium facilates movement across the epithelium barrier. this tissue have cilia which are hair like structures on the outer surface of epithelial cells.

- CUBOIDAL EPITHELIUM

it provides mechanical support. sometimes a portion of the epithelial tissue fold inward and a multicellular gland is formed. this is called glandular epithelium.

2. connective tissue

the cells of connective tissue are loosely spaced and embedded in an intercellular matrix. the matrix may be jelly like, fluid, dense or rigid. types of connective tissues are :- areolar Tissue, bone, blood, ligament, cartilage and tendon.

3. muscular tissue

it consists of elongated cells (muscular fibres). muscular tissue is responsible for the movement in animals. the cells of this tissue are long, cylindrical, unbranched and multinucleate. striated, instructed and cardiac are the three types of muscular tissue.

4. nervous tissue

cells of nervous tissue are highly specialised for being simulated and transmitting the stimulus very rapu from one place to another within the body. the brain, spinal cord and nerves are all made of nervous tissue. many nerve fibres bound together by connective tissue to form a nerve. nerve tissue is made of neurones that recieve and conducts impulses.

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