Plant Responses

Question 1

biotic

Answer 1

living e.g. competition

Question 2

abiotic

Answer 2

non-living e.g. pH

Question 3

tannins

Answer 3

toxic to microorganisms/herbivores found in leaves which make them taste bad and prevent infiltration by pathogens in roots

Question 4

alkaloids

Answer 4

located in growing tips/flowers/stems/roots, taste bitter so feeding deterrent to animals

Question 5

pheromones

Answer 5

chemicals released by one individual and affect behaviour/physiology of another

Question 6

tropic (directional) response

Answer 6

if a plant responds towards or away from a stimulus

Question 7

nastic (non-directional) reponse

Answer 7

external stimuli e.g. Mimosa pudica responds to touch by sudden folding of leaves

Question 8

phototropism

Answer 8

shoot grows towards light for photosynthesis

Question 9

geotropism

Answer 9

roots grow towards the pull of gravity

Question 10

chemotropism

Answer 10

on a flower, pollen tubes grow down the style attracted by chemicals towards the ovary where fertilisation happens

Question 11

thigmotropism (touch)

Answer 11

shoots of climbing plants wind around other structures to gain support

Question 12

how do hormones work in plants

Answer 12

transported by active transport, diffusion, mass flow and bind to receptors on target cell membranes with complementary binding sites

Question 13

auxins

Answer 13

promote cell elongation, inhibit growth of side-shoots, leaf abscission

Question 14

gibberellins

Answer 14

promote seed germination and growth of stems

Question 15

cytokinins

Answer 15

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

Question 16

abscisic acid

Answer 16

inhibits seed germination/growth, causes stomatal closure when water stress

Question 17

ethene

Answer 17

promotes fruit ripening

Question 18

effects brought about by application of gibberellic acid

Answer 18

stem elongation in dwarf plants, bolting in long days, fruit development/growth, seed germination

Question 19

how to test phototropic responses

Answer 19

expose shoot to light

Question 20

how to test geotropic responses

Answer 20

constantly spin by a clinostat for even gravity, for experimental it is not switched on

Question 21

why can only meristem cells divide

Answer 21

the cell wall limits its ability to divide and expand so only immature cells can

Question 22

tropism

Answer 22

a directional growth response in which the direction of the response is determined by the direction of the stimulus

Question 23

apical dominance

Answer 23

inhibition of lateral buds further down the shoot by chemicals produced by the apical bud at the tip of a shoot

Question 24

coleoptile

Answer 24

a sheath and enclosed leaf on the root tip of an oat/barley/wheat seedling