Plant Tropic Flashcards
What happens if you cut the tips of a stem
No auxin is produced
The stem does not grow longer, or bend towards light
Proves auxin is made in the tip and is needed to stimulate cell elongation and therefore growth, so no auxin means no growth
What happens if you cover the tip with a opaque cap
No light reaches the tips
There is equal concentration of auxin on both sides of the tip
Stems grow evenly and longer on both sides
This proves that it is the effect of light that causes phototropism.
There is no uneven distribution of auxin throughout the short tip so growth is even.
What happens if u put a transparent cap over the shoot tip, or nothing?
More light reaches one side of the tip
Greater conc of auxin on the shaded side
The cells on the darker side of the stem grow longer and faster than cells in the light, as auxin stimulates growth
This proves that shoots grow towards the light because there is uneven distribution of auxin in the shoot tip, caused by auxins response to light
What would happen to a root, which is rotating on a clinostat
They grow in one direction, as the effect of gravity is cancelled out as it is revolving, so they show no gravitropic response
Experiment must be carried out in dark to cancer out the effect of light growth on the seeds
