Plant Responses

Question 1

tropism

Answer 1

the growth response of a plant to a directional stimulus

Question 2

list 3 types of tropism

Answer 2

phototropism
geotropism
thigmatropism

Question 3

thigmatropism

Answer 3

growth response of a plant to touch eg ivy

Question 4

what is an auxin

Answer 4

plant growth regulator

Question 5

where precisely in a plant are auxins produced

Answer 5

in the meristem in the root or shoot tip

Question 6

through which part of a stem are growth promotors transported

Answer 6

xylem

Question 7

what is the precise benefit to plants that are phototrophic

Answer 7

to absorb more light for photosynthesis

Question 8

give 2 reasons why auxins are similar to horomones

Answer 8

both are chemicals
both are slow acting
produced in 1 location but acts in another

Question 9

write a note on phototropism

Answer 9

growth of a plant in response to light
shoot of a plant is positively phototrophic
this is positive as it allows plants to absorb more light for photosynthesis

Question 10

what is the name given to the region of plants that secrete growth regulators

Answer 10

meristem

Question 11

give an example of a growth regulator which inhibits growth

Answer 11

ethene

Question 12

give an example of a growth regulator that promotes growth

Answer 12

IAA

Question 13

give 2 uses of plant growth regulators in hormones

Answer 13

produce seedless fruit
ripen fruit

Question 14

what is meant by adverse environmental conditions

Answer 14

surroundings that are harmful to an organism

Question 15

give 3 ways plants protect themselves from adverse external environments

Answer 15

bark
stress proteins
heat shock proteins

Question 16

name the group of substances that control responses to external stimuli

Answer 16

growth regulators

Question 17

what does positively phototrophic mean?

Answer 17

shoot grows towards light

Question 18

explain the mechanism of a plant response with reference to the role of an auxin

Answer 18

phototropism:
IAA is produced int the meristem of the shoot and root tip
IAA diffuses down the shaded side of the plant causing cells to elongate
shoot bends towards light