GenBio2 | Lesson 1 and 2

• Plants transport

  Food, water, and minerals through its system
• Materials needed to be transported

  Between the root and shoot system
• Xylem


  • Transports water and minerals in an upward direction
  • Its tracheary elements consist of cells: tracheids and vessel members

  
• Vessel elements

  Wide thin walled, hollow cells; dead at maturity (sclerenchyma tissue) transport & support
• Tracheids


  Narrower, tapered cells, have pits at ends that allow water support
• Water is still "collected" by the roots at night, when transpiration is occurring as much


  As water flows in, pressure is generated which forces the fluid to go up the xylem
• Root pressure


  The upward push of xylem sap
• Root pressure can only move xylem sap a few meters at most
• Phloem


  • Transports sugars and other items
  • It is composed of sieve tubes with companion cells and various support cells
• Sieve-tube elements

  Alive at maturity, long narrow with sieve plates at ends, no nucleus, ribosomes, and vacuole

  
• Companion cells


  Attached to side of sieve-tube element; organelles serve both cells, does NOT transport
• Phloem sap


  Food transported from a sugar source to sugar sink
• Sugar source


  An organ where sugar is being produced usually leaves
• Sugar sink


  An organ that consumes or stores sugar usually in roots, growing stems, buds, and fruits
• Pressure is created at the source as sugar is produced


  Pressure decreases in the sink as sugar is used
• Water diffuses into phloem from xylem

  Due to decrease water potential & pushes the sugar from source to sink
• Translocation


  The transport of materials in xylem and phloem
• Differences between xylem and phloem

  • Xylem transports water and minerals, no end walls between cells, one-way only, outer cells are not living
  • Phloem transports organic molecules, end walls (sieve plates), two-way movement, cells are living but need support
• The vascular tissue is arranged into bundles of xylem and phloem that are scattered throughout ground tissue

  
• The arrangement of vascular bundles: xylem and phloem varies depending on whether the plant parts or if it is classified as dicot or monocot

  
• In order for plants to sustain their metabolic processes, inorganic nutrients are obtained from the environment via soil, air, and water
• Photosynthesis formula

  6CO2 + 6H2O -> C6H12O6 + 6O2 (Carbon dioxide + Water -> Glucose + Oxygen)
• Essential elements for plant's nutrition

  • Nitrogen
  • Phosphorus
  • Potassium
  • Carbon
  • Hydrogen
  • Oxygen
  • Calcium
  • Magnesium
  • Sulfur
  • Boron
  • Chlorine
  • Copper
  • Iron
  • Manganese
  • Molybdenum
  • Nickel
  • Zinc
• Nitrogen


  Affects leaf growth and plant development for healthy green foliage
• Phosphorus


  Improves the roots, stems, flowers, and fruits
• Potassium


  Promotes photosynthesis and improves plant resistance
• Plant hormones


  Organic substances that regulate plant growth and development, and increase defense against pathogens and adapt to environmental stress
• Plant hormones

  • Auxin
  • Abscissic acid (ABA)
  • Cytokinin (CK)
  • Brassinosteroids (BR)
  • Ethylene (ET)
  • Gibberellins (GA)
  • Jasmonic acid (JA)
  • Salicylic acid (SA)
• Auxin


  Promotes cell growth and elongation of the plant
• Abscissic acid (ABA)


  Regulates plant growth, development, and stress responses
• Cytokinin (CK)


  Promotes seed development, cell expansion, cell differentiate, and N assimilation
• Brassinosteroids (BR)


  Promotes cell division, expansion, elongation, development, and immunity
• Ethylene (ET)


  Stimulates the opening of flowers, fruit ripening, and immunity
• Gibberellins (GA)


  Stimulate cell elongation and cause plants to grow taller in response to nutritional limitation
• Jasmonic acid (JA)


  Defense from necrotrophic pathogens and insects. Fruit ripening, tuber formation, and stomatal opening
• Salicylic acid (SA)


  Defense against a variety of biotic and abiotic stresses. Inhibit seed germination
• All living organisms reproduce to ensure the continued existence of the species
• Asexual reproduction


  • Produces individuals that are genetically identical to the parent plant
  • Advantages include an increased rate of maturity and a sturdier adult plant since the new plant is arising from an adult plant or plant parts
  • Can take place by natural or artificial (assisted by humans) means
• Vegetative propagation


  The process in which plants are grown from the old plants of another plant like roots, stems, shoots, and leaves, without involving any reproductive organ
• Apomixis


  An asexual mode of reproduction through seeds where progeny are clones of the mother plants, occurring without fertilization of sexual gametes but with the formation of embryo and seeds