GENBIO 2

• • Shoot System - parts of a plant that are found above ground 
• • Root System - parts below the ground and can be sometimes seen above ground but only in certain occasions.
• • Leaves - these have cuticles that prevent the dehydration and withering o plants
• 1. Pit - allows water transport
• 1. Vessel Element - dies as a plant matures, causing dip hollows in trees.
• 1. Tracheids - as thin as hair. 
• PARTS OF A XYLEM:

  1. Pit
  2. Vessel Element
  3. Tracheids
  4. Xylem Parenchyma Cell 
• CAPILLARY ACTION - This is the tendency of liquid to move up against gravity when enclosed in a capillary or small tube.
• 1. Surface Tension - forms between hydrogen molecules.
• Adhesion - Molecular attraction between unlike molecules.
• 1. Cohesion - molecular attraction in like molecules.
• COHESION-ADHESION is a combined capillary action & transpiration (occurs in stomata)
• • Meniscus - evaporation of water leads to this. It is a concave shape formed due to the tension or air left in the position where water used to be.
• • PHLOEM - Transports sugar/other components
• 1. Companion Cell - does not participate in the transport of sugar. Instead, it supports the sieve tube by metabolism and regulation.
• • PHLOEM

  1. Sieve Pore
  2. Companion Cell
  3. Phloem Parenchyma
  4. 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

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

  • The potential results in movement from xylem to phloem. This movement creates high pressure potential called “high turgor pressure” within the phloem
  • High turgor pressure moves phloem sap from source to sink by “bulk flow”
  • 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, Sulfur

  • Micronutrients in Soil

  Boron, Chlorine, Copper, Iron, Manganese, Molybdenum, Nickel, Zinc
• 1. Growth Promoters - Auxin, Gibberellins, Cytokinins, Salicylic Acid, Brassinosteroids
• • Growth Inhibitors Ethylene, Abscisic Acid, Jasmonate
• Nectarine - phytohormones released by certain trees that attract insects such as red ants
• • Asexual - offspring are genetically identical to the parent.
• 1. Fission (binary fission) - prokaryotic microorganisms split into two separate organisms.
• • 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.
• 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,
• •  Sexual - combination of haploid reproductive cells from two individuals to form a unique diploid offspring. 
• 1. Hermaphroditism - one animal has both male and female parts. This may occur individually or with others, resulting in two offspring. 

  • Humans can be hermaphrodites.
  • Ex. Nudibranchs
• 1. Separate Sexes - 

  • Can be determined by a set of chromosomes (XX) for male, (XY) for females in humans.
  • Avians’ karyotype are determined by the z and w chromosomes. (ZZ) for male, (ZW) for female.
  • Can be determined by environmental sex determination for other species. Turtles give birth to males during cold season while females during hot.
  • Sex reversal may occur especially in aquatic organisms. An organism can change their sex from male or female.
  • Organisms that are female first are called “protogyny”, while those that are male first are called “protandry.”
• “spawning” - where females and males release eggs and sperm at each other.
• Internal Fertilization - occurs inside the female body. Most often found in land-based animals or in some aquatic animals.