Trophisms Flashcards
What happens to a plant when it is exposed to light
It grows towards the light
What is a geogtrophic response
A geotrophism is when a plant responds to the stimulus of gravity
What is a phototropism
When a plant responds to the stimulus of light
Give an example of a negative geotrophism
Shoots are negatively geotrophic because they grow upwards, against gravity.
Give an example of a positive geotrophism
Roots are positively geotropic because they grow downwards
Give an example of a positive phototropism
Shoot are positively phototropic because they grow towards sunlight
Give an example of a negative phototropism
Roots are negatively phototropic as they grow against the source of sunlight
In a shoot, what does auxin do?
Auxin is a plant hormone which controls growth at the tips of shoots and roots. In shoots it diffuses down the shaded side of the tip and causes cell elongation
In a root, what does auxin do?
In a root, auxin promotes cell elongation
Why do shoots grow towards the sun
Shoots grow towards the sun because:
. Auxin is produced at the tip
. Auxin. Diffuses downwards due to gravity
. Only found on the shady side as it is destroyed by sunlight
. Auxin promotes cell elongation
. This causes the stem to grow more on the shaded side meaning that it will bend towards the light.
Why are shoots positively phototropic
They grow towards the light
Why are roots negatively phototropic
Shoots grow agains light due to auxin in roots inhibiting cell elongation. Auxin in roots gathers at the bottom of the root due to gravity and inhibits cell elongation causing the root to grow downwards
Why are roots positively geotropic
Roots grow with gravity
Why are shoots negatively geotropic
Shoots grow against gravity
