3.1:ROOTS

• Monocots and Dicots


  • Differences in root structure
• Water movement from soil to leaves


  1. Absorption by roots

  2. Transpiration pull

  3. Movement up the stem
• The movement of water from stem to leaf tissue is called transpiration
• Root functions


  Absorb mineral salts (as ions) dissolved in water

  Water moves into the roots through osmosis

  Ions move in through active transport or diffusion
• Root structure

  • Region (zone) of cell division

  Region (zone) of elongation (growth)

  Region (zone) of root hairs
• Root structure

  Root cap pushes through the soil

  Root hairs stick to soil particles and absorb water and minerals

  Root hairs remain alive for a short time, new ones are produced as roots grow
• Dicotyledon roots


  • Epidermis

  Cortex (parenchyma cells, starch storage)

  Stele (xylem and phloem)

  Endodermis (controls entry of minerals)
• Monocotyledon roots


  • Cortex for starch storage

  Stele is circular with alternating clusters of phloem and xylem

  Central pith of parenchyma cells
• Monocots have simpler root anatomy compared to dicots
• The three main regions of a root are the region of cell division, region of growth, and region of root hairs