gen bio

• 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
• Root system 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

  1. Tendency of liquid to move up against gravity when enclosed in a capillary or small tube

  2. Surface Tension - forms between hydrogen molecules

  3. Adhesion - Molecular attraction between unlike molecules

  4. Cohesion - molecular attraction in like molecules
• Cohesion-Adhesion


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


  • Evaporation of water leads to this
  • A 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 - does not participate in the transport of sugar. Instead, it 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


  It is created at the source while producing sugar. It then decreases at the sink as it is used
• 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 the 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"

  4. Bulk flow helps sugars be rapidly removed from the sink, increasing the solute potential, forcing the water to move from phloem back to the xylem, leading to a lower solute potential
• Dicot


  • Vascular bundle with a ring-like structure
• Monocot


  • Vascular bundle with scattered structure
• 17 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, Zinc
• Growth Promoters


  Plant hormones
• Growth Inhibitors


  Plant hormones
• Nectarine


  Phytohormones released by certain trees that attract insects such as red ants
• Types of Reproduction


  • Asexual
  • Sexual
• Asexual Reproduction


  • Offspring are genetically identical to the parent
• Asexual Reproduction Types


  • Fission (binary fission)
  • Budding
  • Fragmentation
  • Parthenogenesis
• Fission (binary fission)


  Prokaryotic microorganisms split into two separate organisms
• Fission


  • Asteroid Echinoderms, Coral Polyps
• Budding


  Results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individual organisms
• Budding


  • Coral, hydra
• Fragmentation


  • Breaking the body into two parts with subsequent regeneration
  • Different from binary fission as here, an organism breaks into a new organism
  • Only a specific part breaks down into fragments
  • Fragments must have actively dividing cells in the middle otherwise fragmentation won't occur
  • If a part goes through fragmentation, it will break off eventually
  • Fragmentation forms a completely new organism
  • Regeneration repairs the damaged parts
• Parthenogenesis


  An egg develops into a complete individual without being fertilized. The resulting offspring can either be a haploid or diploid, depending on the process and the species
• Sexual Reproduction


  • Combination of haploid reproductive cells from two individuals to form a unique diploid offspring
• Sexual Reproduction Types


  • Hermaphroditism
  • Separate Sexes