Exam 37: Plant Sensory Systems, Signals, and Responses

Figure 37.2 -Suppose you laid a seedling on its side so that the root was parallel to the ground. Several hours after the change in position, where in the root cells position A, B, or C in Figure 37.2 above) would you find the amyloplasts?

How does auxin binding to the auxin receptor trigger cell elongation?

Plant A B C Growth Conditions 14 hours of darkness 14 hours of darkness, interrupted by 10 minutes of light during the fifth hour 14 hours of light, interrupted by 10 minutes of darkness during the fifth hour Result Flowers or no flowers) No flowers No flowers Flowers Table 37.1 -Refer to the table above. How would Plant A be classified?

If cells in the _ are removed, roots will no longer respond to gravity.

Use the following information when answering the corresponding questions). The shade avoidance response is a plant's way of changing its growth pattern when it is being shaded by another plant. Upon to shade, many plants will grow taller, flatten their leaf angle, and extend their leaves further from their stems in order to reac sunlight. Research performed by Pierik et al. Interactions between ethylene and gibberellins in phytochrome- mediated shade avoidance responses in tobacco. 2004. Plant Physiology 136:2928- 36; online at "http://www.plantphysiol.org/cgi/content/full/136/2/2928)" http://www.plantphysiol.org/cgi/content/full/136/2/2928) examined the role of ethylene and gibberellins on the shade avoidance response in tobacco plants. The shade avoidance response is known to involve phytochromes. -When the researchers inhibited the synthesis of gibberellins in the tobacco plants, neither ethylene nor far- red light could trigger a shade avoidance response. Taken together with the data presented above, these data suggest that gibberellins

Use the following information when answering the corresponding questions). Researchers found that high doses of nitric oxide were not lethal to soybean cells. Likewise, high doses of reactive oxygen intermediates were not lethal to soybean cells. However, when combined, nitric oxide and reactive oxygen intermediates wer lethal to soybean cells. M. Delledonne et al. 2001. Signal interactions between nitric oxide and reactive oxygen intermediates i the plant hypersensitive response. Proceedings of the National Academy of Science, USA 9823):13454- 59.) -Why would the researchers study the association between cell death, nitric oxide, and reactive oxygen intermediates?

To understand how plant phototropic responses are regulated, a researcher performed the following experiment. He exposed oat seedlings to light and then cut off tips of coleoptiles and placed them on agar blocks. Later, the agar blocks were placed on decapitated coleoptiles of other individuals. Some seedlings were kept in darkness, while others were exposed to light. Based on your knowledge of auxin synthesis and mode of action, predict in what cases the decapitated coleoptiles would bend to the right.

A particular parasitoid is heterozygous for a gene that binds plant pheromones. Which of the following is true of that parasitoid?

Which of the following is not a characteristic of plant hormones?

In lettuce seeds, blue light initiates germination. If you measured hormone levels within the seed, which hormone would be produced upon exposure to blue light?

An increase in girth and decrease in height of a shoot is in response to which of the following environmental stimuli?

The transduction pathway that activates systemic acquired resistance in plants is initially signalled by which of the following?

Suppose a plant had a nonsense mutation in a gene that encodes for an enzyme required for the synthesis of gibberellic acid. If the plant is homozygous at this locus, what will its phenotype be?

Which of the following is the most likely plant response to an attack by herbivores?

Use the following information when answering the corresponding questions). The shade avoidance response is a plant's way of changing its growth pattern when it is being shaded by another plant. Upon to shade, many plants will grow taller, flatten their leaf angle, and extend their leaves further from their stems in order to reac sunlight. Research performed by Pierik et al. Interactions between ethylene and gibberellins in phytochrome- mediated shade avoidance responses in tobacco. 2004. Plant Physiology 136:2928- 36; online at "http://www.plantphysiol.org/cgi/content/full/136/2/2928)" http://www.plantphysiol.org/cgi/content/full/136/2/2928) examined the role of ethylene and gibberellins on the shade avoidance response in tobacco plants. The shade avoidance response is known to involve phytochromes. -When tobacco plants were exposed to far- red light, they exhibited increased stem length, petiole length, and petiole angle. These three responses are part of the shade avoidance response. When the same plants were exposed to small concentrations of ethylene while being exposed to far- red light, they exhibited even greater increases in stem length, petiole length, and petiole angle. In a subsequent experiment, tobacco plants showed an increase in ethylene production in response to far- red light. Moreover, mutant plants that are insensitive to ethylene did not show a shade avoidance response when exposed to far- red light. Taken together, these data suggest that ethylene

The cells that have phosphorylated phototropin receptors elongate in response to blue light.

Which of the following will occur when sensory hairs in a Venus flytrap are stimulated?

For a plant to initiate chemical responses to herbivory before it is directly attacked by herbivores, which of the following must have occurred?

in concentration of auxin in shoot cells and in concentration of auxin in root cells lead to cell elongation.

A certain bacterium infects a plant's upper leaves. A few days later, bacteria of the same species attempt to infect the same plant's roots but are unsuccessful. What process is responsible for the plant's ability to prevent this infection?