Co-ordination Flashcards
what do receptors do
detect the stimulus
what does the co-ordination center do
it receives information from receptors and start a response
what do effectors do
they bring about responses
stimulus of eye(retina)
light
stimulus of ear(organ of balance)
mechanical
stimulus of ear(organ of hearing)
sound
stimulus of tongue
chemical
stimulus of nose
chemical
stimulus of skin(touch/pressure/pain)
mechanical
stimulus of skin(temperature)
heat
stimulus of muscle(stretch receptors)
mechanical
why are responses in plants much slower than in animals
-movement is brought by changes in the plant’s growth
what are tropisms
they are growth responses by part of a plant towards or away from a stimulus coming from one direction
what is a positive tropism
if growth is toward the stimulus
what is a negative tropism
growth away from stimulus
phototropism
-it is a growth response to light
geotropism
-it is a growth response to gravity
what is the tropic response of a shoot
-negatively geotrophic
-positively phototrophic
advantages of a shoot growing towards light
-it goes toward more light
-more light for photosynthesis
advantages of shoot growing away from gravity
-shoots of a germinating seed always grow upwards, whatever the direction of the seed
advantages of a root growing towards gravity
-anchors plant
-search for water and minerals
-ensures that roots of a germinating seed grows downward, away from gravity
what is a clinostat
a device that uses rotation to negate the effects of gravitational pull on plant growth
method of clinostat
-clinostats are turned on their sides, with germinating seeds attached to their discs
-one clinostat is switched on, the other switched off(control). They are both left for few days.
-Radicles of beans on the control clinostat will have grown downwards, under the influence of gravity
-those on the moving clinostat will have grown straight out horizontally
-this is because of the continuously changing direction of the gravitational stimulus acting on the seeds of the moving clinostats cancels out the geotrophic response
how does a plant move towards light
-the release of auxins
where are auxins made
in the tips of the shoots
what do auxins do
change the rate of elongation in plant cells, controlling how long they become
what happens when light only hits one side of the shoot
-there will be a high concentration of auxins on the shaded side of the shoot. This means cells on the shaded side elongates faster than the light side and the shoot bends toward the light
how does light affect the production of auxins
when there is less light, more auxins are produced
-why might scientists not consider auxins to be a type of hormone
-it isn’t produced by a gland
-auxins are transported in the phloem(not the bloodstream)
-auxins has a different effect on shoot and roots(in roots more auxins = inhibitory growth effect)
what is a stimulus
-a change in an animal’s surroundings(external or internal)
what is a receptor
-a cell which detects one form of energy and converts it into electrical energy(in the form of nerve impulses)
what does the central nervous system consist of
-the brain
-spinal cord
what does the peripheral nervous system consist of
-neurones/parts of neurones found outside central nervous system
the 3 types of neurones
- Motor
- Sensory
- Relay
what happens when a a sense organ detects a stimulus
-when the receptor in a sense organ detects a stimulus, they send electrical impulses along sensory neurones the the CNS
-the CNS then sends electrical impulses to an effector along a motor neurone. The effector then responds accordingly
myelinated
the presence of the myelin sheath, which speeds up nervous impulses
where is the sensory neurone located
PNS
where is the motor neurone located
inside the CNS
synapse
a gap between 2 neurones
how is the nerve signal transferred across a synapse
- Nerve impulse arrives at the synapse
- Neurotransmitter(chemical messenger) released into synapse
- Neurotransmitter diffuses across the synapse
- Neurotransmitter binds with a receptor on the membrane of the post-synaptic neurone
- Binding neurotransmitter to receptor stimulates impulse in postsynaptic neurone