Non humans - plants and insects

Question 1

Tropism

Answer 1

• Response of plants to stimuli
  via growth
• can be positive (growing
  towards stimulus) or negative
  (growing away from stimulus)
• controlled by specific growth
  factors (IAA)

Question 2

Specific
tropisms

Answer 2

Response to light
phototropism
response to gravity
gravitropism

Question 3

Indoleacetic
acid

Answer 3

Type of auxin (plant growth factor)
controls cell elongation in shoots
inhibits growth of cells in roots
made in tips of roots/shoots
can diffuse to other cells

Question 4

Phototropism
in shoots

Answer 4

Shoot tip produces IAA
diffuses to other cells
IAA accumulates on shaded
side of shoot
IAA stimulates cell elongation
so plant bends towards light
positive phototropism

Question 5

Phototropism
in roots

Answer 5

Root tip produces IAA
IAA concentration increases on
lower (darker) side
IAA inhibits cell elongation
root cells elongate on lighter side
root bends away from light
negative phototropism

Question 6

Gravitropism
in shoots

Answer 6

Shoot tip produces IAA
IAA diffuses from upper side to
lower side of shoot in response
to gravity
IAA stimulates cell elongation
so plant grows upwards
negative gravitropism

Question 8

Gravitropism
in roots

Answer 8

Root tip produces IAA
IAA accumulates on lower side
of root in response to gravity
IAA inhibits cell elongation
root bends down towards
gravity and anchors plant
positive gravitropism

Question 9

Taxis

Answer 9

Directional response by simple
mobile organisms
move towards favourable
stimuli (positive taxis) or away
from unfavourable stimuli
(negative taxis)

Question 10

Kinesis

Answer 10

Non-directional response to a
stimulus
organism changes its rate of
movement and rate of turning in
response to a stimulus
if an organism moves to a region of
unfavourable stimuli, it will increase
rate of turning to return to its origin
if surrounded by negative stimuli,
rate of turning decreases so the
organism moves in a straighter line