PLANT RESPONSES

Question 1

toxic chemicals released by plants

Answer 1

alkaloids- bitter tasting, bad smell, poisonous

tannins- bitter taste and can bind to proteins in the gut making the plant hard to digest

Question 2

what are pheromones

Answer 2

alarm pheromones- causes nearby plants to detect these chemicals and start producing chemical defences
corn plants release pheromones when being eaten by caterpillars which attracts parasitic wasps

Question 3

what do carrots produce at low temps?

Answer 3

antifreeze proteins which bind to ice crystals and lower temperature that water freezes at

Question 4

what is a tropism

Answer 4

the response of a plant to a directional stimulus

Question 5

phototropism

Answer 5

plants response to light

Question 6

geotropism

Answer 6

growth of plant in response to gravity

Question 7

hydrotropism

Answer 7

plant growth in response to water

Question 8

thermotropism

Answer 8

plant growth in response to temperature

Question 9

thigmotropism

Answer 9

plant growth in response to contact with an object

Question 10

gibberellin

Answer 10

stimulates seed germination
stem elongation
side shoot formation
flowering

Question 11

auxins

Answer 11

growth of shoots by cell elongation

Question 12

what stimulates cell elongation

Answer 12

IAA

Question 13

how does IAA move around the plant

Answer 13

short distance- diffusion and active transport

long distance- phloem

Question 14

where does IAA move in phototropism and geotropism

Answer 14

phototropism- moves to shaded part of shoots and roots

geotropism- moves to underside of the shoots and roots

Question 15

apical bud

Answer 15

shoot tip of flowering plant

Question 16

apical dominance

Answer 16

auxins stimulate the growth of apical buds and inhibits the growth of side shoots from lateral buds

Question 17

how do side shoots grow when apical bud has been removed

Answer 17

cell division and cell elongation

Question 18

how do gibberellins stimulate seed germination?

Answer 18

triggering the breakdown of starch into glucose in the seed

the plants embryo can then use the glucose to begin respiring and release the energy it needs to grow

Question 19

what are gibberellins inhibited by?

Answer 19

abscisic acid

Question 20

which hormones inhibit leaf loss?

Answer 20

auxins- as leafs gets older the less auxin is produced causing leaf loss
ethene- as leaf gets older, more ethene produced

Question 21

what does ethene do

Answer 21

develops a layer of cells at the bottom of the leaf stalk
this abscission layer separates the lead from the plant
ethene stimulates the cells in the abscission layer to expand which breaks down the cell walls and causes the leaf to fall off

Question 22

how does abscisic acid trigger stomatal closure?

Answer 22

binds to receptors on guard cell membranes causing specific channels to open which allows calcium ions to enter the cytosine from the vacuole
increased concentration of calcium ions causes other ion channels to open
ion channels allow ions to leave guard cells which raises the water potential
water leaves guard cells by osmosis
guards cells become flaccid and the stomata close

Question 23

how is ethene used in the fruit industry?

Answer 23

stimulates enzymes that break down cell walls, it breaks down chlorophyll and converts starch into sugars
makes fruit ripe, soft and ready to eat

Question 24

how are auxins used by farmers and gardeners?

Answer 24

used in selective weed killers

used in rooting hormones- make plant cuttings grow roots which is quick and cheap