Survival & Response

Question 1

IAA action

Answer 1

IAA made in tip of root and shoot
IAA diffuses into shoot from tip
effects the elongation region
IAA attaches to protein receptors on cells and causes H+ ions to be released which lowers the pH of the cells
the change in pH breaks some of the h bonds holding the microfibrils in place in the cellulose cell wall
cellulose cell wall can stretch

Question 2

phototropism

Answer 2

plant growth in response to light
when light is uneven, IAA moves to shady side
IAA stimulates cell elongation on shady side, meaning the plant will grow towards the light

Question 3

geotropism

Answer 3

plant growth in response to gravity
columnellar cells near tip contain organelles called amyloplasts
they contain starch which makes them sink to the bottom of the cell
IAA is produced in tip but it moves to the side of the plant where the amyloplasts are
IAA inhibits elongation in root so the lower side elongates at a lower rate than upper side
moves downwards, towards gravity

Question 4

taxis

Answer 4

directional
positive- organism moves towards stimulus
negative- organism moves away from stimulus
whole organism moves

Question 5

kinesis

Answer 5

non directional
organism changes the speed it is moving at and
rate in which in which it turns
unfavourable- move rapidly, making lots of turns
favourable- move slowly, making tighter turns or stopping to stay in the condition

Question 6

protective effect of simple reflex

Answer 6

rapid
protect against damage to body tissues
do not have to be learnt
help escape from predators

Question 7

shoot tip sample

Answer 7

IAA is produced in shoot tip

affects shoot elongation/growth