GEN BIO 2 | 3RD QUARTER

• Xylem


  Transports water and minerals in an upward direction
• Xylem tracheary elements


  • Tracheids
  • Vessel members
• Vessel elements


  Wide, thin walled, hollow cells; dead and maturity (sclerenchyma tissure); Transport and support
• Tracheids


  Narrower, tapered cells; have pits at the ends that allow water transport
• Transport system in plants

  1. Water is still "collected" by the roots at night, when transpiration is not occurring as much

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

  3. This upward push of xylem sap is called root pressure

  4. Can cause guttation (exuding water from margins of the leaf, not through stomata)

  5. This, however, can only move xylem sap a few meters at most
• Phloem


  Transports sugars and other items
• Phloem composition

  • Sieve tubes with companion cells and various support cells
• Sieve-tube elements


  Alive at maturity; long narrow with sieve plates at tends; no nucleus, ribosomes, vacuole
• Companion cell


  Attached to side of sieve-tube element; organelles serve both cells; does NOT transport
• Transport system in plants

  1. Phloem carries phloem sap (food) from a sugar source to a sugar sink

  2. Sugar source is an organ where sugar is being produced usually leaves

  3. Sugar sink is an organ that consumes or stores sugar usually roots, growing stems, buds, and fruits

  4. Pressure is created at source as sugar is produce

  5. Pressure decreases in sink as sugar is used

  6. Water diffuses into phloem from xylem due to decrease water potential & pushes the sugar from source to sink
• The vascular tissue is arranged into bundles of xylem and phloem that are scattered throughout the 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
• Essential elements for plant nutrition

  • Nitrogen
  • Phosphorus
  • Potassium
• 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


  Also called as phytohormones; Are organic substances that regulate plant growth and development; It also increases defense against pathogens and adapt to environmental stress
• Auxin


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


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


  Promotes seed development, cell expansion, cell differentiation, 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)


  Stimulates cell elongation and cause plants to grow taller; Response to nutritional limitation
• Jasmonic Acid (JA)


  Defense from necrotrophic pathogen 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 organisims reproduce to ensure the continued existence of the species
• Asexual reproduction


  Produces individuals that are genetically identical to the parent plant
• Advantages of asexual reproduction

  • Increased rate of maturity
  • Sturdier adult plant since the new plant is arising from an adult plant or plant parts
• Vegetative propagation


  The process in which new plants are grown from the old parts 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
• Sexual reproduction


  Results from fertilization, the union, of gametes (cells that have undergone meiosis) from two genetically different plants
• Advantages of sexual reproduction


  • Increase the genetic diversity of the population
  • Enhancing the evolutionary viability of the species in the face of changing environmental factors
• Pollination


  The process by which pollen is taken from 'anthers' (part of male sex organs, where the pollen is made) to the 'stigma' (female part of the flower)
• Angiosperms


  Flowering plants with stems, roots, and leaves; Produce seeds and have male and female organs within the flowers (pollination)

  
• Gymnosperms


  • seed-producing plants
  • A leafy green sporophyte generates cones containing male and female gametophytes; Female cones are bigger than male cones and are located higher up in the tree; Male cone contains microsporophylls where male gametophytes (pollen) are produced and are later carried by wind to female gametophytes
• Sexual spores


  The plants produce hundreds of spores and the spore sac bursts (sporangia); These spores are dispersed into the air, where they germinate and create a new plant under favorable conditions
• Plant tissue culture


  The use of mall pieces of plant tissue (explants) which are cultured in a nutrient medium under sterile conditions

  
• GM plant


  A technology that involves inserting DNA into the genome of an organism; To produce a GM plant, new DNA is transferred into plant cells; Usually, the cells are then grown in tissue culture where they develop into plants

  
• Asexual reproduction in animals


  Offsprings are genetically identical to the parent