A student investigated the effect of gravity on the growth of young bean shoots (plumules).
The student pinned several seedlings horizontally to a cork board in two different setups:
Both setups were kept in a dark cupboard at a constant temperature of 20∘C20^\circ\text{C}20∘C for 48 hours.
Explain why the student kept both setups in a dark cupboard.
Explain the purpose of using the rotating clinostat (Apparatus B) in this experiment.
Describe how the physical appearance of the shoots in Apparatus A will differ from those in Apparatus B after 48 hours.
Explain how the hormone auxin causes the response observed in the shoots of Apparatus A.