stimulus and response

• what does IAA cause in roots and shoots?


  shoots = elongation

  roots = inhibition
• where is IAA released from?


  tip of the shoot or root
• how does IAA travel down the shoot?


  diffusion
• what is kinesis?


  non directional movement to a stimulus in order to find favourable living conditions
• what is taxis?


  directional movement to a stimulus in order to stay in favourable conditions
• describe the reflex arch


  stimulus , receptor , coordinator, effector , response
• what is an action potential?


  temporary depolarisation of the membrane
• whats a threshold value?


  minimal level of stimulus needed to generate an action potential
• what is a pacinian corpuscle?


  A sensory receptor in the skin that detects pressure and vibration.
• what is retinal convergence?


  many rods connected to one bipolar cell
• what pigment is in rods?

  rhodopsin produces black and white images
• what pigment is in cones?

  iodopsin which allows for trichromatic vision
• what type of contraction is done by the heart?

  myogenic
• what controls heart rate?

  chemoreceptors in carotid artery due to pH changes cause by carbonic acid
• what initiates an action potential in the heart?


  the sinoatrial node
• which part of the brain is responsible for heart rate regulations?

  medulla oblongata