Survival And Response

Question 1

Stimulus

Answer 1

A detectable change in environment
External/internal

Question 2

Effector

Answer 2

Responds to stimulation by the nerve cells

Question 3

Simple reaction pathway

Answer 3

Stimulus-receptor-coordinator-effector-response

Question 4

Why organisms need to respond to changes in their environment

Answer 4

-avoid harmful environments, competition and predators
-keep in favourable environment
-grow towards/away from stimulus
-dispersing to find new mates

Question 5

Behaviour patterns

Answer 5

Instinctive behaviour is an innate response to stimuli
Innate behaviour is genetically determined

Question 6

Kinesis

Answer 6

Random
Animal responds to change is stimuli by increasing or decreasing activity
Change is rate of movement
Choice chamber

Question 7

Taxes

Answer 7

Directional
Directional movement of an organism
Direction of the response is related to the direction of the stimulus
Positive taxes , towards the stimulus
Negative taxes, away from stimulus

Question 8

A reflex action

Answer 8

Certain stimulus produces a specific short lived response
Responses are rapid and not learnt
-protect against damage to the body tissues
-help escape from predators
- find foods and mates

Question 9

Tropism in plants

Answer 9

Direction of growth can be towards/away from stimulus

Question 10

Plant growth factors

Answer 10

Synthesised in cells throughout the plant
Then diffuse from growing regions to other tissues
Regulate growth in response to stimulus
Eg gubrellins , auxins and IAA

Question 11

IAA

Answer 11

IAA is produced in tips of roots and shoots and diffuses to growing regions
Causes cell elongation in shoots
Inhibits cell elongation in roots
IAA transported to more shaded parts of roots and shoots
IAA moves to underside of roots and shoots

Question 12

IAA
in shoots - promotes cell elongation

Answer 12

IAA synthesised in shoots tips
IAA diffuses into growing region
Light causes movement of IAA from light side to shaded side
Higher concentration IAA on shaded side
Causes directional growth as there is greater cell elongation on shaded side
Shaded side grows faster and causes shoot to bend towards light

Question 13

IAA
in roots- inhibits cell elongation

Answer 13

IAA synthesised in the root tips
IAA diffuses into the growing region
Light causes movement of IAA from light side to shaded side and towards gravity
Higher concentration of IAA on the shaded side
Cell elongation inhibited on the shaded side
Results in directional growth away from light and towards gravity