plant reponses

Question 1

biotic

Answer 1

living factors

Question 2

abiotic

Answer 2

non - living factors

Question 3

what are physical defences

Answer 3

include, thorns barbs, spikes hair and inedible parts of the plant

Question 4

list the chemical defenses

Answer 4

• tannins
• alkaloids
• terpenoids
• phermones

Question 5

what is a tropism

Answer 5

a directional growth response, determined by the direction of an external stimulus.

Question 6

what is a nastic response

Answer 6

• a non directional response.
• e.g. some plants close there leaves when touched

Question 7

how do hormones move around the plant

Answer 7

• xylem + phloem
• active transport
• diffusion

Question 8

where does plant growth occur

Answer 8

• at the tips of the roots and shoots
• at the lateral bud meristem
• at the intercalary meristem

Question 9

what are the 4 types of tropism

Answer 9

• thigmotropism
• chemotropism
• geotropism
• phototropism

Question 10

what are the main similarities between animal and plant hormones

Answer 10

• produce in one place and act in a different place
• both are chemical messengers
• both are long lasting and act over a long period of time
• both affect the activity of the target cells/ tissue

Question 11

what are the main differences between animal and plant hormones

Answer 11

• plant hormones, have an effect at low concentrations
• different concentrations of plant hormones, have different effects of different tissues in a plant
• animal hormones ae made by endocrine glands
• different plant hormones, can work together to have a synergistic effect on the growth

Question 12

what is effect Auxin

Answer 12

• controls cell elongation
• inhibits growth of side shoots
• inhibits leaf abscission
• stimulates the release of ethene

Question 13

what is the effect of Cytokinin’s

Answer 13

promote cell division

Question 14

what is the effect of Gibberellins

Answer 14

promote pollen tube growth in fertilisation seed germination and elongation of stems

Question 15

what is the effect of abscisic acid, i.e. ABA

Answer 15

maintains dormancy of seeds and buds, by inhibiting germination, stimulus = cold, protective response, e.g. antifreeze production or stomatal closure, when water availability is low.

Question 16

what is the effect of Ethene

Answer 16

promotes fruit ripening and leaf abscission

Question 17

what is abscission

Answer 17

the fall of leaves

Question 18

what is cotyledon

Answer 18

the seed leaf of a plant embryo and food storage tissue

Question 19

what is endosperm

Answer 19

food storage tissue, in monocots

Question 20

what is aleurone

Answer 20

protein granules, found in a single layer of cells

Question 21

what is monocot

Answer 21

a plant, whose seeds only contains a single cell during germination

Question 22

what is dicot

Answer 22

plants, whose seeds produce two cotyledons during germination

Question 23

why do plants produce tannins

Answer 23

bitter tasting, to prevent insects eating and they also deactivate digestive enzymes

Question 24

what is the difference between a nastic and tropic response

Answer 24

nastic is non - directional whereas tropic is directional

Question 25

what do we call the tropism, which causes a pollen tube to grow towards the ovary

Answer 25

chemotropism

Question 26

what are the three ways, that hormones can move through a plant

Answer 26

diffusion, via the xylem, phloem or active transport

Question 27

which hormone promotes fruit ripening

Answer 27

Ethene

Question 28

which hormone can promote elongation of stems and seed germination

Answer 28

Gibberellins

Question 29

what hormone is antagonistic to the hormone Gibberellin

Answer 29

ABA

Question 30

which hormone, promotes cell elongation

Answer 30

Auxin

Question 31

how does Auxin work?

Answer 31

• Auxin molecules, bind to specific receptor sites in the plant plasma membrane
• this causes, an ATPase enzyme in the plasma membrane to actively transport H+ ions form the cytoplasm to the cell wall.
• the resulting low Ph, provides optimum conditions for wall loosening enzymes (expanses) to work increasing the stretchiness of the cell wall.
• these break bonds, within the cellulose. So the walls become less rigid and can expand as the cells takes in water.