stimuli and response

Question 1

stimulus =

Question 2

taxis =

Answer 2

the directional movement of an organism in response to a stimulus

Question 3

kinesis =

Answer 3

a response that involves movement in random directions
(increases chance of finding favourable area)

Question 4

tropism =

Answer 4

a plants response to a stimulus via growth
(+ve —> towards stimulus)
(-ve —> away from stimulus)

Question 5

phototropism in shoots (+ve)

Answer 5

-IAA prod in shoot tips
-IAA diffuses to dark side of shoots
-causes elongation towards light

Question 6

phototropism in roots (-ve)

Answer 6

-IAA diffuses to dark side of shoots
-IAA inhibits elongation if roots

Question 7

reflex arc =

Answer 7

pathway in which an impulse is transmitted from a receptor to an effector —> involuntary response

Question 8

steps in reflex arc

Answer 8

1)stimulus
2)detected by receptors
3)impulse sent along sensory neurone to CNS
4)intermediate neurone relays impulse to motor neurone
5)effector carries out response

Question 9

advantages of reflex arc

Answer 9

-automatic
-minimises damage to tissue
-posture/balance

Question 10

receptor =

Answer 10

cell, tissue or organ that detects a stimulus and generates an electrical impulse

Question 11

types of receptors

Answer 11

• pacinian corpuscle
• rod/cone cells
• chemo/baro receptors