Chapter 36, Problem 8
Suppose that a mutant plant is unable to make methyl salicylate. Explain why it is not likely to survive in the wild.
Verified Solution
This video solution was recommended by our tutors as helpful for the problem above.Video transcript
Why was it logical to predict that amyloplasts function as statoliths? a. They are dense and settle to the bottom of gravity-sensing cells. b. They are present only in gravity-sensing cells. c. They make a direct physical connection with membrane proteins that have been shown to be gravity-receptor molecules. d. Their density changes in response to gravity.
Phytochromes can be considered 'shade detectors,' while phototropins such as PHOT1 can be considered 'sunlight detectors.' Explain why these characterizations are valid.
To explore how hormones function, researchers have begun to transform plants with particular genes. In one experiment, a gene involved in cytokinin synthesis was introduced into tobacco plants. Which one of the following results would be expected? a. Individuals produced more lateral branches. b. Stems grew extremely tall and slender. c. Roots were incapable of responding to gravity. d. Stomata were closed most of the time.
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.
In many species native to tropical wet forests, seeds do not undergo a period of dormancy. Instead, they germinate immediately. Predict the role of ABA in these seeds. How would you test your prediction?
Leaflets of Mimosa pudica (common names: sensitive plant, touch-me-not) have a remarkable ability to close up in response to being touched or physically moved. How fast can the leaflets close? How does this occur? And more importantly, what benefit could this unusual response provide to the plant? Researchers studied the rate of closing and reopening of leaflets by measuring changes in the distance between opposing leaflets after being touched. Their results are shown in the accompanying graph (d/dmax is actual leaflet distance relative to maximal leaflet distance). How long does it take for leaflets to close? How long to reopen?