Plant Responses: Plant Responses:
In response to light, phototropism occurs.
Auxins control phototropism.
Auxins move towards the shaded side of the plant/
are destroyed by high light intensity.
Auxins promote growths in the shoots & inhibit
growth in the roots.
This causes the shoots to bend towards light & the
roots to bend away from light.
In response to gravity, geotropism occurs.
It is controlled by auxins.
Auxins settle at the bottom edge of the shoots &
roots (as they move with gravity).
Auxins promote growths in the shoots & inhibit
growth in the roots.
This causes the shoots to bend upwards, away from
gravity & the roots to bend downwards towards
gravity.
Geotropism PAG: Geotropism PAG:
Line three petri dishes with moist (but not soaking
wet) cotton wool.
You should use the same volume of water & the
same amount of cotton wool in each dish.
Space out 10 cress seeds in the surface of the
cotton wool in each dish, then push each seed int
the wool.
Tape a lid onto each dish & wrap each dish in foil so
light intensity doesn’t affect the results.
Choose somewhere you can leave the dishes where
the temperature is likely to be warm & constant.
Prop one dish upright (90°) label it & mark the
direction of up on it.
Prop another at a 45° slant & label it accordingly.
In response to light, phototropism occurs.
Auxins control phototropism.
Auxins move towards the shaded side of the plant/
are destroyed by high light intensity.
Auxins promote growths in the shoots & inhibit
growth in the roots.
This causes the shoots to bend towards light & the
roots to bend away from light.
In response to gravity, geotropism occurs.
It is controlled by auxins.
Auxins settle at the bottom edge of the shoots &
roots (as they move with gravity).
Auxins promote growths in the shoots & inhibit
growth in the roots.
This causes the shoots to bend upwards, away from
gravity & the roots to bend downwards towards
gravity.
Geotropism PAG: Geotropism PAG:
Line three petri dishes with moist (but not soaking
wet) cotton wool.
You should use the same volume of water & the
same amount of cotton wool in each dish.
Space out 10 cress seeds in the surface of the
cotton wool in each dish, then push each seed int
the wool.
Tape a lid onto each dish & wrap each dish in foil so
light intensity doesn’t affect the results.
Choose somewhere you can leave the dishes where
the temperature is likely to be warm & constant.
Prop one dish upright (90°) label it & mark the
direction of up on it.
Prop another at a 45° slant & label it accordingly.
