Biology by Samhita Drona https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe Made with a curious mind en-us 2021-08-11 07:40:38 UTC 2026-03-02 06:06:05 UTC hello@padlet.com Plant samhitadrona140464 https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675184254 Tissues are a group of cells performing specialized and specific functions. ]]> 2021-08-11 07:44:16 UTC https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675184254 Meristematic Tissue samhitadrona140464 https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675200169
  • The growth of plants occur only in certain specific regions.  This is because the dividing tissue known as the Meristematic Tissue is located only at these points.
  • Depending on the region where they are present, meristematic Tissues are classified as apical (present at the growing tips of stems and roots. It increases the length of the stem and the root.) , lateral (The girth of the stem or root increases due to lateral meristem). and intercalary (Is seen in some plants which is located near the node).
    • ]]>     2021-08-11 07:51:29 UTC https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675200169     Permanent Tissue samhitadrona140464 https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675218914
    • Complex permanent tissue: They are made of more than one type of cells. All these cells coordinate to perform a common function.
    • Xylem and phloem are examples of such kind. 
    • Xylem consists of tracheids, vessels and xylem parenchyma and xylem fibres.
    • Tracheids and vessels are tubular structures.
    • This allows them to transport H2o vertically.
    • The parenchyma stores food.
    • Xylem fibres are mainly for support.
    • Phloem is made of 5 types of cells: Sieve cells, sieve tubes, companion cells, phloem fibres and the phloem parenchyma.
    • Sieve tubes are tubular cells with perforated walls.
    • Phloem transports food from leaves to other parts of the plant.
    • Except phloem fibres (which give mechanical support), other phloem cells are living cells.

    ]]>     2021-08-11 08:16:24 UTC https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675218914     Permanent Tissue samhitadrona140464 https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675485942
  • The cells formed by meristematic tissue takes up a specific role and lose the ability to divide. As a result they form a permanent tissue.
  • Simple Permanent Tissue: A few layers of cells beneath the epidermis are generally simple permanent tissue.
  • Parenchyma is the most common simple permanent Tissue. These are living cells. They consist of relatively unspecialized cells with thin cell walls.
  • This tissue generally stores food.
  • The flexibility in plants is due to another permanent tissue, collenchyma. It allows bending of various parts of a plant like tendrils and stems of climbers without breaking and also provides mechanical strength.
  • Sclerenchyma, another type of permanent tissue makes the plant hard and stiff. These cells are dead. This tissue is present in stems, vascular bundles, in the veins of leaves and in the hard covering of seeds and nuts.
  • It provides strength to the plant parts.
  • Cells of cork are dead and compactly arranged without intercellular spaces.

    • ]]>     2021-08-11 13:54:43 UTC https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675485942     samhitadrona140464 https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675545570
  • The epidermis is the outermost layer of cells usually made of a single layer of cells.
  • In some plants which live in dry habitats, the epidermis may be thicker since protection against water loss is critical.
  • The epidermal cells on the aerial parts of the plant often secrete a waxy, water resistant layer on their outer surface. This aids in protection against loss of H2o, mechanical injury and invasion by a parasitic fungi.
  • Cells of epidermal tissue form a continuous layer without intercellular spaces.
  • We can observe small pores here and there in the epidermis of the leaf.
  • These pores are called Stomata. They are enclosed by 2 kidney-shaped cells called guard cells.
  • They are necessary for gaseous exchange.
  • Transpiration (loss of H2o in the form of vapour) also takes place through stomata.
  • Epidermal cells of the roots, whose function is H2o absorption, commonly bear long hair- like parts that greatly increase the total absorptive surface area.
  • In some plants like desert plants, epidermis has a thick waxy coating of cutin( chemical substance with waterproof quality) on its outer surface.
  • As plants grow older, the outer protective tissue undergoes certain changes.
  • A strip of secondary meristem located in the cortex forms layer of cells which are dead and compactly arranged without intercellular spaces.
  • They also have a substance called suberin in their walls that makes them impervious to gases and H2o.
    • ]]>     2021-08-11 14:34:04 UTC https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675545570     Plant Tissues samhitadrona140464 https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675550713 2021-08-11 14:37:57 UTC https://padlet.com/samhitadrona140464/83nmj4q7cemvmbe/wish/1675550713