In general, small seeds that have few food reserves must be exposed to red light before they will germinate. (Lettuce is an example.) In contrast, large seeds that have substantial food reserves typically do not depend on red light as a stimulus to trigger germination. State a hypothesis to explain these observations.

How may a plant respond to severe heat stress?

a. By reorienting leaves to increase evaporative cooling

b. By creating air tubes for ventilation

c. By producing heat-shock proteins, which may protect the plant's proteins from denaturing

d. By increasing the proportion of unsaturated fatty acids in cell membranes, reducing their fluidity

The signaling molecule for flowering might be released earlier than usual in a long-day plant exposed to flashes of:

a. Far-red light during the night

b. Red light during the night

c. Red light followed by far-red light during the night.

d. Far-red light during the day

If a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering?

a. 16 hours light/8 hours dark

b. 14 hours light/10 hours dark

c. 4 hours light/8 hours dark/4 hours light/8 hours dark

d. 8 hours light/8 hours dark/light flash/8 hours dark

Phytochromes can be considered 'shade detectors,' while phototropins such as PHOT1 can be considered 'sunlight detectors.' Explain why these characterizations are valid.

The discovery of auxin is a good example of how scientists build upon each other's work. For each of the three sets of researchers discussed in the chapter (the Darwins, Boyle-Jensen, and Went), write a one-sentence summary of what they discovered. If you were going to credit one person as being the 'discoverer' of auxin, who would it be?