Chapter 28

Distinguish between the following: circadian rhythm and circadian clock; phototropism and photoperiodism; thigmotropism and thigmonastic movement.

Explain how it is possible for a long-day plant and a short-day plant growing at the same location to flower on the same day of the year.

The flowers of some plants open in the morning and close at dusk. Design and describe an experiment that could be used to determine whether these daily rhythms are controlled by the plant's circadian clock or by the presence or absence of light.