Plants

• Plant


  Transports food, water, and minerals through its systems
• Important parts of a plant

  • Roots
  • Stems
  • Leaves
  • Flower
  • Bud (apical)
  • Node (where stems/leaves bud)
  • Leaf Blade
  • Top Root
  • Lateral Root
• Shoot System


  Parts of a plant that are found above ground
• Root System


  Parts below the ground, can sometimes be seen above ground but only in certain occasions
• Leaves


  Have cuticles that prevent the dehydration and withering of plants
• Parts of a Xylem

  • Pit - allows water transport
  • Vessel Element - dies as a plant matures, causing dip hollows in trees
  • Tracheids - as thin as hair
  • Xylem Parenchyma Cell
• 1st Hypothesis: Root Pressure


  1. Water is collected at the roots

  2. Water flows in, creating pressure

  3. The previous pressure creates an upward flow of water
• Root pressure


  • Can cause guttation (exudes water from the margins of the leaf instead of the stomata)
  • Can only move xylem sap a few meters at most
• Straw Analogy


  1. Water moves through roots by osmosis

  2. Intake of water in roots increases the water potential

  3. When stomata is closed at night, guttation occurs

  4. Leaf margins must exude water as if too much water is evaporated, the plant will dehydrate
• 2nd Hypothesis: Capillary Action


  Tendency of liquid to move up against gravity when enclosed in a capillary or small tube
• Properties allowing Capillary Action

  • Surface Tension - forms between hydrogen molecules
  • Adhesion - Molecular attraction between unlike molecules
  • Cohesion - molecular attraction in like molecules
• Cohesion-Adhesion


  Combined capillary action & transpiration (occurs in stomata)
• Meniscus


  Concave shape formed due to the tension or air left in the position where water used to be
• Phloem


  Transports sugar/other components
• Parts of Phloem


  • Sieve Pore
  • Companion Cell - supports the sieve tube by metabolism and regulation
  • Phloem Parenchyma
  • Sieve tube elements
• Sugar Source


  Where sugar is produced; usually leaves
• Sugar Sink


  Consumes or stores sugar; usually roots, stems, buds, and fruits
• Sugar sinks and sources can change depending on the seasons and stages of development
• Pressure


  Created at the source while producing sugar
• Translocation


  Moves the sugar in the phloem to the parts that need it
• End of Dormancy Period


  The plant withers due to the onset of a new season
• Growing Period


  Parts of plants that were sugar sinks become sugar sources
• Pressure Flow Model


  1. A high concentration of sugar at the source leads to low solute potential

  2. The potential results in movement from xylem to phloem. This movement creates high pressure potential called "high turgor pressure" within the phloem

  3. High turgor pressure moves phloem sap from source to sink by "bulk flow"
• Transport System in Plants


  • Dicot - vascular bundle with a ring-like structure
  • Monocot - vascular bundle with scattered structure
• Elements for Growing Plants

  • Macronutrients from air and water: Carbon, Hydrogen, Oxygen
  • Macronutrients from soil: Nitrogen, Phosphorous, Potassium, Calcium, Magnesium
  • Micronutrients in Soil: Boron, Chlorine, Copper, Iron, Manganese, Molybdenum, Nitrogen, Nickle, Zinc
• Plant Hormones


  • Growth Promoters
  • Growth Inhibitors
• Nectarine


  Phytohormones released by certain trees that attract insects such as red ants