Biology - Unit 5 Topic 8

  1. Describe how plants detect light using photoreceptors and how they respond to environmental cues
    • Plants detect light using phytochromes.
    • Phytochrome's exist in PR (absorbs red light 660nm) and PFRĀ (absorbs far red light at 730 nm) states.
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    • Different levels of PR and PFR control responses to light e.g. flowering
  2. Describe the structure of sensory, motor and relay neutron and role of Schwann cells and myelination.
  3. Describe how an action potential is conducted longhand axon
  4. Describe the function and structure of synapses
  5. Describe how we detect stimuli (eyes)
    • In the dark: Rods aren't stimulated
    • Na+pumped out of cell by active transport but diffuse back in through sodium channels
    • Cell becomes depolarised, causing the release of glutamate.
    • Neurotransmitter binds to bipolar neuron and inhibits it from sending an action potential down the optical nerve.
    • In dim light: Light causes bleaching of rhodopsin into retinal and opsin
    • Bleaching causes sodium channels to close, so sodium cannot diffuse back into cell.
    • Sodium build up outside of the cell and the cell becomes hyper polarised .
    • No glutamate is released, and the bipolar neurone is not inhibited.
    • The bipolar neurone depolarises, sending an action potential down the optic nerve.
  6. Explain how the nervous system results in effectors to respond (pupil dilation and contraction)
  7. Compare mechanisms of coordination in plants and animals
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Biology - Unit 5 Topic 8