All cells have primary cell wall some cells have additional layers of cellulose

All cells have primary cell wall some cells have

This preview shows page 2 - 4 out of 5 pages.

○ All cells have primary cell wall, some cells have additional layers of cellulose that increase the strength of the cell wall called secondary cell wall ○ Primary wall is located outside of secondary wall because additional cellulose is produced at cell membrane ○ 3 plant tissues ■ Dermal ■ Ground ■ Vascular ● Dermal tissue ○ Function: protection ○ Epidermis is dermal tissue from the embryo apical meristem and is one cell layer thick ■ Similar to skin of multicellular animal ■ Epidermis covered by cuticle which waterproof plants surface ■ Gas exchange occurs through stomata which are epidermal openings that a pair of guard cells that regulate size of opening and controlling water loss and gas exchange ■ Trichomes: outgrowths of epidermal cells, hairlike ● Function: protect leaves from light intensity ■ Root hair which increase surface area for absorption of water and minerals ● Ground Tissue ○ Carries out storage of carbohydrates and water, photosynthesis, and support ○ 3 types of cells of ground tissue ■ Parenchyma: most abundant cell in primary tissue (spongy and palidade mesophyll) ● Primary cell walls, large vacuole, living at maturity ● Many chloroplast for photosynthesis ■ Collenchyma: living at maturity, irregular thickened primary walls ● Thickened cell walls provide flexible support for plant organs ■ Sclerenchyma: thick walls, secondary cells walls with ligden ● Ligden makes cell walls rigid ● Dead at maturity ● Strengthen tissue ● Give fruit a gritty texture
Image of page 2
(Lec 1: Les 2) 3 ● Example: fibers ● Vascular tissue (Xylem) Vascular Tissue (Xylem) Similar to an animal’s circulatory system except in plants, they have separate transport systems for water and food molecules Xylem is vascular tissue specialized for conducting water and minerals In angiosperms, xylem is composed of conducting cells called vessels and tracheids. Both vessels and tracheids are dead at maturity Cells are elongated in shape and form hollow tubes Vessels are larger in diameter and stack end-to-end Tracheids are smaller in diameter and have tapered ends that overlaps Vessels conduct water more than efficiently than tracheids Both tracheids and vessels have liquefied secondary cell walls and also contribute to the support of the plant In addition to these conducting cells, xylem often has parenchyma cells for lateral transport and storage, and fibers for additional strengthening Secondary xylem produced by the vascular cambium forms wood Vascular Tissue (Phloem)
Image of page 3
Image of page 4

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture