Flashcards in 6.1 Organisms Repsond To Stimuli Deck (16):
What is Taxes?
Ie) woodlouse in sunlight
What is kinesis?
Ie) woodlouse in damp conditions
Rate of movement ~p~ stimuli intensity
What is tropism?
Directional plant growth
Positive- to stimuli
Negative- against stimuli
What is IAA?
A plant hormone or auxin
Made in shorts and root tips
What is the purpose of IAA in phototropism?
1) IAA moves away from light
2) shaded side grows more
3) directs plant towards the light which is advantageous for photosynthetis
What are the IAA experiments?
1) Darwin 1880 blocked the root tip
- no growth
2) Boysen Jensen 1913 inserted mica barrier
- shaded barrier- no growth
-sunny barrier- growth
3) Paal 1919 cut tip and set it off centre
- taxes occured. Growth to one side
4) Went 1926 placed gelatin w/ auxin on shoot
-growth still occurred
What are the three types of neurones?
Sensory- bn receptor and relay
Relay- bypasses brain but goes to CNS
Motor- connects relay to effector
What is a 3 neurone arc?
1) heat is a stimulus
2) detected by thermoreceptor
3) which starts impulse along SENSORY neurone
4) to the RELAY neurone in CNS
5) this passes an impulse to MOTOR neurone
6) to a muscle effector which pulls the hand away
What is a receptor?
A bundle of nerve endings which can be stimulated by a change in environment
What is the Pacinian Corpsucle?
Responds to pressure changes
Deep in skin
Surrounded by connective tissue
Separated by gel
What are stretch mediated Na+ channels?
Intrinsic protein in bilayer of P Corpsucle.
Open when pressure applies
Allows Na+ to flood in
What is the retina?
Photoreceptors in eye made of rods and cones
Light sensitive pigments absorb light.
What are rods?
Black and white
Respond to low light intensity
Rhodopsin pigment broken down to start impulse
Many-to-one allows small gen potential to build up
What is the summation effect?
When in the rods a small potential allows to build up due to rods being many-to-one
What are cones?
Respond to different light wavelengths
Idopsin pigment must be broken down to allow impulse to start
High light intensity required to break pigment