Biology - Homeostasis

• Gibberellin


  Plant hormone involved in germination, flowering, fruit production
• Light falling on one direction

  Auxin diffuses away from light to shade, so cells on shade side elongate and grow faster, shoot grows toward light
• Light falling evenly on plant

  Auxin spreads evenly through shoot tip, grows steadily up
• Phototropism


  Growth towards a light stimulus
• Geotropism


  Stimulus of gravity
• Auxin sinks to lower side of root due to gravity


  Auxin in roots slows down growth, so allows root to bend downwards
• Auxin

  Controls growth in meristem, causing shoot cells to grow more and root cells to grow less
• Adenaline


  1. Increases heart rate

  2. Targets vital organs

  3. Boosts delivery of oxygen and glucose

  4. Diverts blood away from digestive system to muscles

  5. More energy released to muscles

  6. Allows body to respond quickly
• Adenaline


  Response to fear/stress
• Low levels of thyroxine

  Hypothalamus releases TRH for pituitary to release TSH so thyroid produces more thyroxine
• Normal levels of thyroxine


  Inhibits TRH release, which inhibits TSH, maintaining blood level
• Thyroxine 


  controls the speed of oxygen and food products reacting to create energy for the body to use. it's important for growth and development