Given below is an experimental setup to demonstrate a particular tropic movement in germinating seeds (seeds fixed to a perforated trough of moist sawdust). Study the diagram and answer the questions that follow: Given below is an experimental setup to demonstrate a particular tropic movement in germinating seeds (seeds fixed to a perforated trough of moist sawdust). Study the diagram and answer the questions that follow:
Part 1 is affected by two stimuli. Name them. Which one of the two is stronger?
Topic: Hydrotropism stronger than geotropism
Answer
The two stimuli are GRAVITY (geotropism) and WATER (hydrotropism).
WATER is the stronger. In this experiment the radicles bend towards the moist sawdust even though that means growing SIDEWAYS or UPWARDS, against gravity — which shows that HYDROTROPISM OVERCOMES GEOTROPISM.
The whole point of this apparatus is to set the two stimuli AGAINST each other and see which wins.
The seeds are fixed to a perforated trough of moist sawdust. Gravity would pull the radicles straight down and away from the trough; water would draw them towards it. They bend TOWARDS THE MOISTURE, curving upward if necessary — and that observation is the proof.
THE BIOLOGICAL SENSE of it: a root that followed gravity into dry soil would die. Water matters more to survival than depth, so natural selection has made the root respond more strongly to moisture.
State the OBSERVATION as your evidence, not merely the conclusion — that is what "which is stronger" is asking you to justify.