Topic 6 - A : Stimuli and response

Question 1

Tactic response

Answer 1

directional movement in response to stimulus

Question 2

Kinetic response

Answer 2

non-directional movement in response to stimulus

Question 3

Sensory neurone

Answer 3

receptor to CNS (brain and spinal cord)

Question 4

Motor neurone

Answer 4

CNS to effector

Question 5

Relay neurone

Answer 5

sensory neurone to motor neurone

Question 6

Phototropism

Answer 6

Growth of plant in response to light
shoots go towards light and roots go away from light

Question 7

gravitropism

Answer 7

growth of plant in response to gravity
shoots go away from gravity and roots go towards gravity

Question 8

auxins

Answer 8

produced in tips of shoots and diffuse backwards to stimulate the cell behind tips to elongate
auxins stimulate growth but high conc. inhibits growth

Question 9

IAA

Answer 9

produced in tip of flowering plant shoots
moves by diffusion and active transport over short distance

Question 10

Resting potential

Answer 10

potential difference when cell is at rest between outside cell and inside cell
generated by ion pumps/channels

Question 11

Generator potential

Answer 11

when stimulus is detected cell becomes excited
ions move in and out of cell more changing the potential difference
this change is generator potential

Question 12

action potential

Answer 12

when generator potential is big enough it reaches threshold level
this triggers action potential
all action potentials are the same size so strength of stimulus is measured by frequency of action potentials

Question 13

Pacinian corpuscles