Organisms Response to Change - Taxis and Kinesis

Question 2

what is phototropism?

Answer 2

the growth of a plant in response to light

Question 3

what are the two types of phototropism?

Answer 3

positive and negative phototropism

Question 4

what part of a plant is positively phototrophic?

Answer 4

shoots

Question 5

what part of a plant is negatively phototropic?

Answer 5

roots

Question 6

what is positive phototropism?

Answer 6

growth towards light

Question 7

what is negative phototropism?

Answer 7

growth away from light

Question 8

what is a tropism?

Answer 8

the response of a plant to a directional stimulus

Question 9

what is gravitropism?

Answer 9

the growth of a plant in response to gravity

Question 10

what part of a plant is postively gravitopic?

Answer 10

roots

Question 11

what part of a plant is negatively gravitropic?

Answer 11

shoots

Question 12

what are growth factors?

Answer 12

hormone like chemicals that speed up or slow down plant growth

Question 13

where are growth factors produced?

Answer 13

in the growing regions of the plant

Question 14

which growth factor brings about tropism?

Answer 14

IAA

Question 15

what does IAA stand for?

Answer 15

indoleacetic acid

Question 16

where does IAA promote growth?

Answer 16

shoots

Question 17

where does IAA inhibit growth?

Answer 17

roots

Question 18

how does IAA promote plasticity of cells?

Answer 18

by actively transporting hydrogen ions from the cytoplasm to spaces in the cell wall, allowing cells to expand

Question 19

describe the process of phototropism in the shoots

Answer 19

IAA concentration increases on the shaded side of the plant

cells on the shaded side elongate and so the shoot bends towards the light

Question 20

describe the process of phototropism in the roots

Answer 20

IAA concentration increases on shaded side of the plant

growth inhibited so the root bends away from the light

Question 21

describe the process of gravitropism in the shoots?

Answer 21

gravity causes IAA to accumulate at lower side of shoots

elongation promoted so shoot grows upwards

Question 22

describe the process of gravitropism in roots

Answer 22

promotes elongation on lower side of roots - bending them downwards so the root grows towards down

Question 23

what is a taxis?

Answer 23

a simple response where the direction is determined by the direction of the stimulus

Question 24

what type of organism uses taxes?

Answer 24

simple and mobile organisms

Question 25

what is a positive taxis?

Answer 25

organism moves its whole body towards a stimulus

Question 26

what is a negative taxis?

Answer 26

an organism moves its whole body away from a stimulus

Question 27

what is kinesis?

Answer 27

stimulus response where speed and rate of change of direction change in response to a stimulus

movement is random and related to intensity of stimulus

Question 28

what happens during kinesis when the organism is in a favourable environment?

Answer 28

speed slows down

rate of change of direction increases

Question 29

what happens during kinesis when the organism is in an unfavourable condition?

Answer 29

speeds up

rate of change of direction decreases