Haryana State Board HBSE 9th Class Science Notes Chapter 6 Tissues Notes.
Haryana Board 9th Class Science Notes Chapter 6 Tissues
→ Cell division is essential for the development and growth of a living being.
→ In single celled or unicellular creatures all living activities are performed by a single cell.
→ In multicellular organisms groups of different cells perform different functions, it is called as labour division.
→ Groups of cells with identical structure and performing similar functions is called as tissues.
→ Plants and animals are living beings with different characteristics.
→ In plants and animals on the basis of structure and functions different tissues are found.
→ In plants, there are two types of tissues:
- Meristematic tissues
- Permanent tissues.
→ Meristematic tissues are found at the apex and at the root tips of the plant. .
→ Permanent tissues are also made up of meristematic tissues.
→ Simple tissues are of three types: Parenchyma, collenchyma and sclerenchyma.
→ Sclerenchyma (strong tissues) provides strength to the parts of the plant.
→ Strong tissues further converts in protective tissues.
→ Stomata (air-pores) help in exchanging of gases and evaporation.
→ Xylem and phloem tissues are the examples of complex tissues.
→ Xylem and phloem are conducting tissues.
→ Epithelial tissues are covering or protective animal tissues.
→ Muscular tissues are mainly of three types:
- striated muscles (skeletal or voluntary),
- unstriated muscles (involuntary or smooth muscles)
- cardiac muscles.
→ Blood and bones are the type of connective tissues.
→ Blood is a fluid tissue.
→ Bone is hard while, cartilage keeps flexibility.
→ Brain, spinal cord and nerves, all are nervous tissues.
→ Permanent tissues do not have the ability of division.
→ The unit of nervous tissue is neuron. It is a messenger.
→ In meristematic tissues, division occurs constantly.
→ Tissue: The group of cells originating from the common point having same structure and function is called tissue.
→ Meristematic tissues: The tissues having the ability to divide are called as meristematic tissues.
→ Differentiation: The activity conducted by the tissues to take a permanent shape and size to perform special functions is called differentiation.
→ Permanent tissues: Those meristematic tissues that lose the ability of division and become tissues are called as permanent tissues.
→ Simple tissues: Tissues formed of only one types of cells are called as simple tissues.
→ Complex tissues: The group of cells with different structures and functions are called as complex tissues.
→ Protective tissues: The tissues protecting the body of plants are called as protective tissues.
→ Phloem: Living transporting tissues is called phloem.
→ Epithelial tissues: The covering tissues in animals is called epithelial tissue.
→ Muscular tissue: The structures that form muscles, are called muscular tissue.
→ Connective tissues: Tissues that perform the function to interlink different organs in the body or provide supporting function are called as connective tissues.
→ Nervous tissues: The tissues that transmit feelings or impulses (messages) from one place to another are called nervous tissues.