Module 5- Plant responses

Question 1

what is herbivory?

Answer 1

the consumption of plants by herbivores

Question 2

how do plants respond to herbivory (chemical)?

Answer 2

alkaloids, pheromones

Question 3

what are alkaloids?

Answer 3

bitter tasting compound found in plants e.g. coffee+tobacco
poisonous to many insects

Question 4

how do alkaloids affect animals?

Answer 4

act as drugs affecting the animals metabolism

Question 5

what is the role of hormones in leaf loss?

Question 6

what is phototropism?

Answer 6

A plant’s growth response to light

Question 7

what is positive phototropism and where is it seen and why?

Answer 7

It is growth towards light
seen in shoots to get maximum light for photosynthesis

Question 8

what is negative phototropism and where is it seen and why?

Answer 8

it is growth away from light
seen in roots to prevent drying out

Question 9

what is geotropism?

Answer 9

A plant’s growth response to the earths gravitational field

Question 10

what geotropism do roots display and why?

Answer 10

positive because they grow towards the gravitational attraction to ensure they grow in the ground

Question 11

what geotropism do stems/shoots display and why?

Answer 11

negative because they grow away the gravitational attraction to ensure they grow to the light

Question 12

what are pheromones?

Answer 12

A signal to nearby plants of the same species that they are under attack from herbivores, triggering other defences

Question 13

how do plants respond to herbivory physically?

Answer 13

folding in response to touch and thorns to wear off insects/scare animals

Question 14

what type of stress factor is herbivory?

Answer 14

biotic

Question 15

what are some of the commercial uses of plant hormones?

Answer 15

As selective weed killers
As rooting powders
To control ripening

Question 16

how can plant hormones be used as weed killers?

Answer 16

high auxin concentration can cause such rapid growth that roots get distorted+damaged allowing pathogens to enter the plant or/and die

Question 17

how can plant hormones be used as root powders?

Answer 17

low doses of auxin can be used to stimulate cuttings to grow new roots

Question 18

what hormone can be used as a fruit ripener and how?

Answer 18

ethene,, fruit is harvested unripe so it can be transported without damage then ripened artificially when needed to sell

Question 19

what does hormone gibberellin do?

Answer 19

cause stem elongation and seed germination

Question 20

what does hormone ABA/abscisic acid do?

Answer 20

stimulates stomatal opening/closure

Question 21

what does hormone auxin/IAA do?

Answer 21

-maintains apical dominance
-stimulates stem growth by causing cell elongation

Question 22

what does hormone ethene do?

Answer 22

stimulates the breakdown of cell walls in abscission layer, causing the leaf to drop off

Question 23

where is the abscission layer?

Answer 23

base of the leaf stalk

Question 24

what is apical dominance?

Answer 24

auxins produced at the growing tip at the apex (i.e. the top) of a plant stem causing the stem to grow upwards and also stop lateral (side) buds from growing

Question 25

what is the endosperm?

Answer 25

a starch-containing energy store surrounding the embryo

Question 26

what is the aleurone layer?

Answer 26

a protein-rich layer on the outer edge of the endosperm