14 response to stimuli Flashcards
what is a stimulus?
a detectable change in environment, either external or internal
what is an effector?
responds to stimulation by the nerve cells
give an example of an effector
muscle
gland
organ
cell
why do organisms respond to changes in their environment?
to increase survival and reproduction by:
1. DISPERSING TO FIND NEW MATES
2. avoiding harmful environments
3. stay in favourable environment
is instinctive behaviour learned or inherited?
inherited
what are the types of simple responses to stimuli?
kinesis
taxes
reflex action
what is kinesis?
random movement responding to a change in stimulus by increasing or decreasing activity
change in rate of movement
give an example of kinesis
woodlice move around more when humidity is dry and the rate of movement is related to the intensity of the stimulus
what experiment would you use to investigate kinesis?
choice chamber
what statistical test would be used for a choice chamber?
chi squared
how do you calculate degree of freedom and what is the dof for a basic choice chamber?
n-1 so 3 for choice chamber
what is taxes?
directional movement towards or away from a stimulus
what are the types of taxes?
positive and negative
what is positive taxes?
movement towards the stimulus
what is negative taxes?
movement away from the stimulus
give an example of negative taxes
earthworms move away from light to find food and avoid predators
what are the types of tropism?
positive and negative
what is positive tropism?
growth towards a stimulus
what is negative tropism?
growth away from a stimulus
what does the prefix ‘halo’ mean?
salt
what does the prefix ‘geo’ mean?
gravity
what does the prefix ‘photo’ mean?
light
what does the prefix ‘hydro’ mean?
water
give an example of positive phototropism
plant shoots grow towards light
give an example of negative phototropism
plant root grow away from llight
what is a similarity between tropism and taxes?
both are directional
what is a difference between tropism and taxes?
tropism is part of the organism whereas taxes is al of the organism
what do plant growth factor do?
regulate growth in response to stimuli
give 2 examples of plant growth factors
gibrellins and indole acetic acid
what do gibrellins do?
promotes seed germination
where does mitosis occur in plants?
tip of shoots
tip of roots
what does IAA stand for?
indole acetic acid
what does IAA do in the shoots of plants?
promotes cell elongation
what des IAA do in the roots?
inhibits cell elongation
explain what happens with IAA in the shoots of plants and light
- IAA synthesised in shoot tips
- IAA diffuses into elongation region
- light causes IAA to move to shady side
- high conc of IAA on shady side
- causes greater cell elongation on shady side and for shoot to grow faster and bend towards light
explain what happens with IAA in the roots of plants and light
- IAA synthesised in root tips
- IAA diffused into elongation region
- light causes IAA to move to shady side
- high conc of IAA on shady side
- cell elongation inhibited on shady side so roots grow away from light and towards gravity
where is IAA synthesised?
in the root tips and shoot tips
what is tropism?
a growth movement of part of a plant in response to a DIRECTIONAL STIMULUS
what is a reflex arc?
an example of behaviour that a certain stimulus produces a specific short lived response
are reflex arcs learnt?
no
explain the advantages of simple reflex arcs
- rapid
- protect against damage to body tissue
- don’t have to be learnt
- help escape from predators
- enable homeostatic control
what is a receptor called that is found deep in the skin?
pacinian corpuscle