1.
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. When the recombinant individuals matured, they produced more than the usual number of lateral branches. How does this experiment inform our understanding of how cytokinins function? Plants can also be transformed with antisense genes. Antisense genes code for products that disable specific mRNAs by binding to them. Suggest an experiment that uses an antisense gene to explore hormone function. Predict the result.
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
2.
Researchers have recently begun to identify genes that are activated in response to auxin. Based on your understanding of auxin's effects, what might these loci be?
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
3.
In many species native to tropical rain forests, seeds do not undergo a period of dormancy. Instead, they germinate immediately. Make a prediction about the role of ABA in these seeds. How would you test your predictions?
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
4.
Researchers have shown that stomata do not close if ABA is injected into guard cells. Stomata do close, however, if ABA is applied to the surface of guard cells. Based on these results, researchers claim that the ABA receptor must be on the surface of guard cells, and not in the interior. Do you agree? Why or why not?
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
5.
Even after years of effort, no one has been able to isolate the gibberellin or ABA receptor. One reason is that individuals with mutant GA or ABA receptors may die prior to germination, making them extremely difficult to study. Why might mutations in these genes be fatal? Suggest an alternative strategy for finding the GA and ABA receptor.
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
6.
Review the experiments diagrammed in Figure 35.2 (page 676 in your textbook). Suppose a critic argued that the phototropic signal was actually electrical in nature. Do the experiments in part (a) rule out electrical signaling? Do the experiments in part (b)? Explain.
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
