what is tropism
a directional growth response to a stimulus in plants
positive phototropism ( illumination in one side)
-IAA is produced by cell in the shoot tip
- IAA diffuses down the shoot
- IAA diffuse over to the shaded side
- there’s more cell elongation on the shaded side
- plant bends towards the light
- absorbs more light, which means more photosynthesis
positive geotropism
- IAA is produced in the tip of the root
- IAA diffuses down the root
- IAA accumulates on lower side due to gravity
- inhibits cell elongation on the lower side
- upper side grows faster and roots grow downwards
what is a reflex
a protective, involuntary, rapid response to a stimulus
which type of receptor is a Pacinian corpuscle
a pressure or touch receptor
cardiac output equation
heart rate X stroke volume
what are synapses
junctions between neurones
chemicals diffuse across a synapse (neurotransmitter)
advantage of simple reflex actions
rapid
protect against damage to body tissue
they are automatic
they enable homeostasis control
why is it important for heart rate to increase when exercising
- speed up delivery of O2 to the cells and glucose
- to speed up removal of CO2 from the cells
- delays the onset of Ana
