6a
Survival and response
Receptors
Plants and animals have to respond to stimulus
For plants , this is to maximise photosynthesis
Tropism
Gravitropism is when plants respond to gravity
Phototropism is when plants respond to light
A stimulus is needed to affect an effector to cause a response
In plants and animals , stimulus are needed to communicate to different parts.
Homoroal response
electrical response
Made from proteins and are short lasting
caused by the generation of action potentials
Nervous system
Peripheral nervous system
Automatic nervous system
Reflex arc
stimulus
Receptors
CNS
Effector
Response
A response to a directional stimulus
Shoots are positively phototropic towards the light and roots are negatively phototropic
Shoots are negatively gravitropic and shoots are positively gravitropic
Growth factors
Plants respond to directional stimulus by using specific growth factors
Produced in specific growing regeons
Auxins stimulate the growth of the shoots by cell elongation.
IAA concentrations at the shoots overview
IAA concentratoins increase on the shaded side
the cells elongate
The shoot bends towards the light
IAA concentrations at the roots overview
IAA concentrations increase on the shaded side
Growth is inhibited so the root bends away from the light
IAA concentrations decrease on the lower side Overview
The cell elongate sop that the shoot grows upwards
IAA Concentrations in the roots
IAA concentrations increase on the lower side
Growth is inhibited so that the root grows downwards
Somatic nervous system
Controls the conscious actives
Sympathetic nervous system
Gets the body ready for action
Parasynthetic nervous system
Calms down the body for rest and digestion
Where the body responds to a stimulus without making a conscientious effort.