Plant Responses (only key points so refer to notes)

Question 1

tannins

Answer 1

toxic to MOs/herbivores
found in upper epidermis
leaf taste bad
prevent pathogens entering root
in cell vacuoles or surface wax on plants

Question 2

alkaloids

Answer 2

derived from amino acids
taste bitter
in tips, flowers
peripheral cell layers of stems and roots

Question 3

pheromones

Answer 3

affect behaviour/physiology of other individuals

Question 4

tropism

Answer 4

directional growth response

Question 5

thigmotropism

Answer 5

shoot of climbing plants wind around other plants/structures for support

Question 6

nastic response

Answer 6

non-directional response

Question 7

thigmonasty

Answer 7

respond to touch like fold leaf

Question 8

cytokinins

to do with bud growth

Answer 8

promote cell division
delay leaf senescence
overcome apical dominance
promote cell expansion

promote bud growth
override apical dominance if applied to bud
high auxin make shoot apex, sink for cytokinins produced in root
apex removed - cytokinins spread through plant

Question 9

abscisic acid

info to do with bud growth

Answer 9

inhibits seed germination and growth
stomatal closure when plant has low water availability

inhibits bud growth
high auxin in shoot keeps levels of acid high in bud
tip removed - abscisic levels drop so bud grows

Question 10

auxins

Answer 10

promote cell elongation
inhibit growth of side-shoots
inhibit leaf abscission (leaf fall)

Question 11

gibberellins

Answer 11

promote seed germination and elongation

growth of stems

Question 12

ethene

Answer 12

promote fruit ripening

promote lateral growth

Question 13

apical dominance

Answer 13

auxins from apical bud at tip of shoot prevent lateral buds from growing

Question 14

seed germination

Answer 14

seed absorbs water
embryo releases gibberellin
travels to aleurone layer in endosperm region of seed
enables production of amylase which breaks donw starch to glucose
substrate for respiration for embryo as grows

Question 15

auxin’s effect

Answer 15

increase stretchiness of cell wall
promote active transport of H ions by ATPase on plasma membrane to cell wall so low pH optimum for wall-loosening enzymes
break bonds within cellulose and H ions break H bonds
less rigid walls so expand as cell takes in water

Question 16

herbicides

Answer 16

man made auxin that kills weeds because difficult to break down so acts in plant longer leading to too much shoot growth, stem can’t support and dies