botany finals

• A group of cells performing essentially the same function(s) and commonly of similar structure is called

  Tissue
• These are composed of small, thin-walled, embryonic cells capable of active cell division.

  Meristematic tissues
• are responsible in increase of length of the plant body.

  Apical meristem
• are responsible for increase in diameter.

  Lateral meristem
• often one- cell thick; epidermal cells secrete a waxy, water resistant cuticle. The epidermis aids in protection against water loss, mechanical injury, and invasion by parasites. 

  Epidermis
• his tissue replaces the epidermis in older plants; it constitutes the corky outer bark of plants.

  Periderm
•  one of the most common and the most abundant plant tissue; usually thin-walled and closely packed cells that may function in photosynthesis, food or water storage.

  Parenchyma
•  cells with unevenly thickened cell walls which function primarily for support.

  collenchyma
• cells with uniformly thickened walls; also function in support; most are dead cells.

  Scelerenchyma
• transports water and dissolved substances upward in the plant body; also serves for support; its common name is wood.

  Xylem
• transports food from the leaves to the different parts of the plant.

  Phloem
• generally a non-green underground plant organ used for absorption of raw materials and for anchorage of the plant

  Roots
• True roots originate from where?

  hypocotyls
• 1. are the roots derived from the main trunk

  Primary roots
• 1. roots that arise from the primary roots.

  Secondary roots
• 1. roots that arise from other plant parts.

  Adventitious roots

   
• 1. he main root grows and  sends out lateral branches. e.g. most dicots i.e. mango

  Taproot
• 1. the primary root stops  growing or disappears, and numerous adventitious roots grow and develop from the base of the stem and take the place of the primary root; may be fibrous or fleshy  type. e.g. grasses (rice, Bermuda grass)

  Diffused root
• 1. This thimble-shaped mass of moderate-sized cells forms the apex of the root and protects the meristematic (dividing) cells just above it. The outer layer of cells is continually sloughed off to be replaced by newly formed root cap cells.

  Root cap
• 1. his area comprises a mass of small, nearly cubical cells with thin walls and dense protoplasm. It is the region which new cells are formed by mitosis. It is responsible for growth of root in length.

  Meristematic region
• 1. In this region, the cells formed in the meristematic region undergo rapid enlargement. The cell walls increase in length, new protoplasm is formed and vacuoles increase in size.

  Elongation region
• 1. his region is situated above the region of elongation. In this region, the enlarged cells become differentiated into the mature tissues of the root - xylem,

  phloem, etc.

  Region of maturation
• This region consists of irregular-shaped parenchyma cells with many intercellular spaces. The cortex is chiefly a water-and food-storage region.

  cortex
• he innermost cell layer  of the cortex is the

  endodermis
• functions as a water dam which prevents the outward passage of water from tissues inside the endodermis. 

  Endodermis
• a. is the outermost tissue of the vascular cylinder, and consists of one layer of small thin-walled cells within the endodermis. It gives rise to branch roots which force   their way out through the cortex and epidermis.

  pericycle
• s a group of thick-walled cells arranged in radial rows and altered with thin- walled phloem cells.

  xylem
• composed mainly of very small thin-walled cells which alternate with the xylem rays. 

  phloem
• are endodermal cells of the roots with thick bands found on the outside of the phloem and which prevent the outward passage of water from tissues inside the endodermis.

  Casparian strips
• 1.  (Central Cylinder) This is the innermost region. Xylem and phloem are alternate in arrangement.

  Stele
• Functions of the roots

  Absorption

  Anchorage

  Storage

  Conduction
• Roots that grow from the main stem

  brace roots
• Roots that grow from the branches

  prop roots
• Roots that grow from upper portion of large roots

  Buttress roots
• 1. . It is the slightly enlarged portion of the stem where leaves and buds arise.

  Node
• 1. It is the region of the stem between the two successive nodes.

  Internode
• 1.  It is a tiny raised pore on the surface of matured stems for gas exchange.


  Lenticels
• 1.  is the outermost part of the stem consisting of a single layer of cell with thick outer wall. Hairs or trichomes may or may not be present.

  epidermis
• a) three or more layers of cells with thick walls at the corner located toward the inner part.

   Collenchyma
• a) - two or more layers of cells with thin walls located toward the inner part.

  Parenchyma