A student investigated the effect of gravity on the growth of young maize roots (radicles).
The student pinned several germinating seeds horizontally to a cork board in two different setups:
Both setups were kept in a dark cupboard at a constant temperature of 22∘C22^\circ\text{C}22∘C for 48 hours.
Explain why the student kept both setups in a dark cupboard.
Explain the purpose of using the rotating clinostat (Apparatus Y) in this experiment.
Describe how the physical appearance of the radicles in Apparatus X will differ from those in Apparatus Y after 48 hours.
Explain how the hormone auxin causes the response observed in the radicles of Apparatus X.