4.5.4 plant hormones (SINGLE) Flashcards
What is positive phototropism?
When plant stems grow towards light
What is positive gravitropism?
When plant roots grow downwards, with the force of gravity
What type of plant hormone is responsible for cell elongation?
Auxin
What do we call the lengthening of specific plant cells as a result of hormones?
Cell elongation
What is Hydrotropism?
A plant’s ability to grow roots towards water
Auxins Experiments:
What happens when the tip is covered and light is shone to the side?
It grows upwards
On which side does auxin accumulate when light is shone from the side on a stem
The shaded side
Auxin Experiments:
What was used to create an impermeable barrier to stop hormone diffusion
Mica
Where are auxins mainly produced (2 places)
- Tips of shoots
- Roots
How do auxins travel in plants?
By diffusion
Describe an experiment that showed Auxin is produced in the shoot tip.
- Cut shoot tip off or cover it
- It will not bend towards the light
Auxin Experiments:
What is the difference between using a gelatine barrier and a mica barrier?
Gelatine - permeable to auxin
Mica - impermeable to auxin
Auxin Experiments:
If you place a mica barrier on the shaded side, why does the plant not bend?
- Mica stops Auxin diffusing down the shade side
- So, cells cannot elongate on shaded side (so cannot bend)
Auxin experiments:
Why does a plant still bend towards the light if a mica barrier is placed on the light side?
- Auxin diffuses down shaded side as normal
- Cells on shaded side can elongate as normal
