definition taxis a direc tional movement
kinesics the speed of movement (more random)
the
photo response to light
chemo the response to a chemical
stimuli and Responses
stimulus detec table in the inter nal exter nal environment
a
change or
response a change in the behaviour of an organism to a stimulus .
Tropisms (plants)
tropism direc tional
growth of an
organism .
phototropism growth in response to light
geo gravitropism growth in response to
gravity
Indot acetic acid CIAA)
> used to be called auxin .
In a s n oot :
•
IAA diffuses to the
Shady side of a shoot
•
this causes t h e cells on the
Shady side to elongate
•
the s h oot then bends to
grow towards light .
light light light
1¥ .÷
" .
:
I
°
÷ 0 :
In a Root :
•
IAA diffuses to the underside of the ro o t
•
this inhibits cell
elongation
•
the cells on the top elongate
the ro o t grows towards gravity
• .
J.-iaa T.EE?I..
É÷g