Tuesday, 29 March 2011

2.79, 2.80, 2.81 (Plants and stimuli, Geotropism, Phototropism)

2.79 main points:
  • Stimuli are changes in the environment (e.g. temperature changes and light changes)
  • Plants have receptors to which can detect these stimuli to create a responses
  • The responses often take before growth, this type of growth is called a tropism.
  • Two types of responses are: Phototropism (related to light) and Geotropism (related to gravity)
  • The connect between receptor and response is of plant hormones (e.g Auxin) 
2.80 main points:
  • Geo refers to gravity tropism refers to response of growth.
  • An example is a seed, if we observe a seed growing we can see seed growing downwards we can describe this as positive geotropism. 
  • If it grows upwards it is called negative geotropism.
  • If we rotate the seed around then geotropism will still happen.
2.81 main points:
  • Photo refers to light tropism refers to response of growth (grows towards light)
  • With uniform light growing all directions it will grow forward
  • With some places with light, it will grow towards the light called lateral light.
  • The hormones in the plant called Auxin leads plant to bend.

1 comment:

  1. well done, you have covered pretty much all the points