6: Stimuli and Response Flashcards
(25 cards)
Stimulus definition?
a change in the internal or external environment of an organism
Tactic response (taxis) definition?
Directional movement in response to a stimulus
The direction of the stimulus affects the response
Kinetic response (kinesis) definition?
Non-directional, random movement in response to a stimulus
The intensity of the stimulus affects the response
Receptors definition?
Cells or proteins on cell-surface membranes that detect stimuli
What are the three main types of neurone?
Sensory, relay, motor
Sensory neurone function?
Transmit electrical impulses from receptors to the CNS
Relay neurone function?
Transmit electrical impulses between sensory neurones and motor neurones
CNS (coordinator) function?
Processes the information/ formulates an appropriate response and sends impulses along motor neurones
Simple reflex definition?
A rapid involuntary response to a stimulus
Relay arc?
Stimulus, receptor, sensory neurone, relay neurone, CNS, motor neurone, effector, response
3 Features of nervous communication?
Localised, short-lived, rapid
What is a tropism?
the response of a plant to a directional stimulus - respond by regulating their growth
What is the growth of a plant in response to light?
Phototropism
Shoots are ____ phototropic?
Positively
Roots are _____ phototropic?
Negatively
What is the growth of a plant in response to gravity?
Gravitropism
What are plant growth factors?
Hormone-like chemicals produced in the growing regions of a plant that speed up or slow down plant growth
Where are auxins produced?
the tips of shoots - diffuse backwards to stimulate the cells behind to elongate
What is IAA?
Indoleacetic acid
An auxin that is produced in the tips of shoots and roots in flowering plants
How is IAA moved around a plant?
Diffusion + active transport over short distances
Via the phloem for long distances
What does IAA do to root cells?
Inhibit growth
