Astumulus Is a detectable change in the internai or externol environment
ot an orgcnism. lnat leods to a change in the response o the organism.
increases hance ot surviva
stimulus ’receptor coordinator -’ etector ’response
Taxes'
Jax1s 1S a Simple drectional response to a stimulus
- Positve taxis - movement townds a stiulus
bactera move towards qluose (positive chemotas)
Negative tax1s movemênt away trom a stimlus
Le.g. iwoodlie move away trom hgnt (negative phototcxis)
Kinesis
Kinesis iS a response to less directional stimuli by changing speed
and rate at which the oryism changes aretion.
in a
taworabu enVironment, rate ot twning would inrease
to
inrease probabiliby ot remaining in tavowoble envronnent
- humdity and tempeatue
temperat may not prone dear gradient
trom one extreme to the othe
Experimenting
e.y maggot behaviour with choiu chamb es
pe between trials - mayyots leave scent trail
(ontrol varnables
even ight on both sides - posit1on lam ab ove
lots ot repeats to get repres entutue results
, PLANT G,ROLJTH ALIORS
n troprsm is the growth of port ot o plant in response to o
directional stimulus. For example, inght r gravity
Opisnns are controil ed by a plant arowth tator cal ed lndoleacet
acid (IAA), whih belongs to a aroup ot substonces caUed auxins
Plhototropsm in tlowering plnts
OCeus in the tp ot the shoot produa JAA, whic is trunspor te0 down
e Liqht causes IAA to move to shaded s1ce ot shoot
S IAA causes cel elongaticn i sh0ots
G shaded si£e eiongates faster than Iight sidi , ansing sh oct to bnd
towards hgnt.
Grauitopism nHloweing plaats
O (els in typ ct root produa lAA, which is traaspurted alcng
e Graity Lauses IAA to move to lower siae t roct
IAA inhibit ell elongatic (oot
Roots bend dolun towas jraviby
Aud Carowth Hypothesis
- lAA con nrease plastiaty ot plnt cel wals
young cels able to elongate
Aitve transport ot H* 0ns trom toplasm nto spaces in th
cel wa casng ceil wl to become more plastiu
b alows cel to elongute
LIGHT LIGHT
Positive photo tropsm
shoots
Posit1ve 4rowitrop1srn
oetropsm) in roots
, RI}LIX ARC
Central nervous system (CNS) brain amd spinal cord
Periphê rod nervous system (PNs) pairs ot nerves originating trom (NS
sensoy necrones (orry nerve impulses trom receptor to (NS
motor eurones carry nerve impuls es tromn (Ns to ettectors
voluntay nervous systen lconscious ontrol )
cutonoc nervous systemn (suboncous)
Spinal ord
Column ot nervous tissue pruteted bu vertebrae
Pairs ot nerves tmerqe trom spinal lord at ntevals
Sensory neurone
motor neurOne
Retlex Arc
e-g. wthdrawng hand trom hot objet
0 stinmulus - heat
Receptor - temperature receptor
9 Snsory neurone
-
recepto to CNS
Coordintor (relay neusone)
Motor neusone
-
(NS to musc
Eftector muscle stimulated to contract
Response pul hand away trom heat
lmportona
- don't overload the bran
-
lnvoluntary
lnnote and protet body trom birth
Rapid short neuonal pathway, tew synapses
ot an orgcnism. lnat leods to a change in the response o the organism.
increases hance ot surviva
stimulus ’receptor coordinator -’ etector ’response
Taxes'
Jax1s 1S a Simple drectional response to a stimulus
- Positve taxis - movement townds a stiulus
bactera move towards qluose (positive chemotas)
Negative tax1s movemênt away trom a stimlus
Le.g. iwoodlie move away trom hgnt (negative phototcxis)
Kinesis
Kinesis iS a response to less directional stimuli by changing speed
and rate at which the oryism changes aretion.
in a
taworabu enVironment, rate ot twning would inrease
to
inrease probabiliby ot remaining in tavowoble envronnent
- humdity and tempeatue
temperat may not prone dear gradient
trom one extreme to the othe
Experimenting
e.y maggot behaviour with choiu chamb es
pe between trials - mayyots leave scent trail
(ontrol varnables
even ight on both sides - posit1on lam ab ove
lots ot repeats to get repres entutue results
, PLANT G,ROLJTH ALIORS
n troprsm is the growth of port ot o plant in response to o
directional stimulus. For example, inght r gravity
Opisnns are controil ed by a plant arowth tator cal ed lndoleacet
acid (IAA), whih belongs to a aroup ot substonces caUed auxins
Plhototropsm in tlowering plnts
OCeus in the tp ot the shoot produa JAA, whic is trunspor te0 down
e Liqht causes IAA to move to shaded s1ce ot shoot
S IAA causes cel elongaticn i sh0ots
G shaded si£e eiongates faster than Iight sidi , ansing sh oct to bnd
towards hgnt.
Grauitopism nHloweing plaats
O (els in typ ct root produa lAA, which is traaspurted alcng
e Graity Lauses IAA to move to lower siae t roct
IAA inhibit ell elongatic (oot
Roots bend dolun towas jraviby
Aud Carowth Hypothesis
- lAA con nrease plastiaty ot plnt cel wals
young cels able to elongate
Aitve transport ot H* 0ns trom toplasm nto spaces in th
cel wa casng ceil wl to become more plastiu
b alows cel to elongute
LIGHT LIGHT
Positive photo tropsm
shoots
Posit1ve 4rowitrop1srn
oetropsm) in roots
, RI}LIX ARC
Central nervous system (CNS) brain amd spinal cord
Periphê rod nervous system (PNs) pairs ot nerves originating trom (NS
sensoy necrones (orry nerve impulses trom receptor to (NS
motor eurones carry nerve impuls es tromn (Ns to ettectors
voluntay nervous systen lconscious ontrol )
cutonoc nervous systemn (suboncous)
Spinal ord
Column ot nervous tissue pruteted bu vertebrae
Pairs ot nerves tmerqe trom spinal lord at ntevals
Sensory neurone
motor neurOne
Retlex Arc
e-g. wthdrawng hand trom hot objet
0 stinmulus - heat
Receptor - temperature receptor
9 Snsory neurone
-
recepto to CNS
Coordintor (relay neusone)
Motor neusone
-
(NS to musc
Eftector muscle stimulated to contract
Response pul hand away trom heat
lmportona
- don't overload the bran
-
lnvoluntary
lnnote and protet body trom birth
Rapid short neuonal pathway, tew synapses
