- Created by: Jess Webber
- Created on: 20-05-13 19:14
Phototropism - the growth of a plant in response to light, shoots are positively phototropic (grow towards light), roots are negatively phototropic (grow away from light).
Auxin - the plant growth substance involved in phototropism, the first discovered was IAA.
Phytochrome - a molecule consisting of a protein component bonded to a non-protein light-absorbing pigment molecule, phytochromes trigger of inhibit germination.
Photoperiod - the relative day length of day and night, it is these environmental cues that determine flowering time.
Long-Day Plants - only flower when day length exceeds a critical value, need Pfr to stimulate flowering.
Short-Day Plants - need long periods of uninterrupted darkness to flower, Pfr inhibits flowering.
Etiolation - plants which are grown in the dark become tall and thin, with fragile stems and long internodes and small, plate, yellowish leaves.
Sensory Neurones - carry impulses from sensory cells to the CNS, cell body in the middle of the cell.
Relay Neurones - transmit impulses between sensory neurones and motor neurones, cell body at the end of the cell.
Motor Neurones - carry impulses from the CNS to effectors, cell body at the end of the cell.
Axons - fibres which carry impulses away from the cell body.
Dendrons - carry impulses towards the cell body.
Myelin Sheath - made of Schwann Cells wrapped around the axon, no depolarisation can take place here as the fatty material insulates the impulse.
Resting Potential - a neurones state when it is not being stimulated, the outside is positively charged compared to the inside.
Action Potential - the sequence of events after a stimulus big enough to trigger a rapid change in potential difference.
Nodes of Ranvier - the spaces between the Schwann Cells where depolarisation can take place, localised circuits are set up here.
Saltatory Conduction - impulses jump from node to node which speeds up transmission as the ionic movements associated with the action potential occur much…