Deck 37: Plant Sensory Systems, Signals, and Responses

Question 1

Which of the following is the correct sequence of events after a receptor perceives a signal?

A) The receptor is phosphorylated and then changes its shape. This leads to hormone release from the cell, which activates gene transcription.
B) The receptor changes its shape and then becomes phosphorylated. This leads to activation of gene transcription and finally to hormone release from the cell.
C) The receptor is phosphorylated and then changes its shape. This leads to activation of gene transcription and finally to hormone release from the cell.
D) The receptor changes its shape and then becomes phosphorylated. This leads to hormone release from the cell, which activates gene transcription.

Answer 1

B

Question 2

$\begin{array}{c}\begin{array}{|l|}\hline\\\text {Plant}\\ \hline \text {A}\\ \hline \\\\\text {B}\\ \hline \\\\\text {C}\\ \hline\end{array}\begin{array}{lll} \hline \\ \text {Growth Conditions}\\ \hline \text {14 hours of darkness}\\ \hline \text {14 hours of darkness,}\\ \text {interrupted by 10 minutes of }\\ \text {light during the fifth hour }\\ \hline \text {14 hours of light, interrupted }\\ \text {by 10 minutes of darkness}\\ \text { during the fifth hour}\\ \hline \end{array}\begin{array}{|l|} \hline \text {Result Flowers}\\ \text {or no flowers)}\\ \hline \text {No flowers}\\ \hline\\\\ \text {No flowers}\\ \hline \\\\\text {Flowers}\\ \hline \end{array}\end{array}$
Table 37.1

-Plant C is a long- day plant.

Answer 2

True

Question 3

The addition of a phosphate group to a protein is called _ _, and it usually results in .

A) phosphorylation; protein activation or inactivation
B) dephosphorylation; mutation
C) signal transduction; changes in gene transcription
D) oxidation; changes in growth patterns

Answer 3

A

Question 4

Put the following events of the acid growth hypothesis in order.
1) Cell wall softens and expands.
2) Sugar enters the cell via proton cotransporters.
3) Protons are pumped out of the cell by H⁺- ATPases.
4) Positively charged ions enter the cell.
5) New cellulose microfibrils are produced to extend cell length.
6) Water enters the cell via osmosis, and the cell swells.

A) 1, 3, 5, 6, 2
B) 3, 6, 4, 3, 2, 1
C) 6, 4, 3, 1, 2, 5
D) 6, 1, 2, 4, 3, 5
E) 3, 4, 2, 6, 1, 5

Question 5

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

A) The auxin receptor is a proton channel that opens in response to auxin binding, allowing protons to flow down their concentration gradient and into the cell.
B) A signal transduction cascade results in the opening of a water pore that allows water into the cell, causing it to swell.
C) A signal transduction cascade causes proton channels to open, and protons to flow down their concentration gradient and out of the cell.
D) The auxin receptor begins phosphorylating proton pumps, activating them to pump protons up their concentration gradient and out of the cell.
E) A signal transduction cascade causes additional proton pumps to be made, and those proteins pump protons up their concentration gradient and out of the cell.

Question 6

Which of the following events would be initially triggered by a signal transduction cascade?

A) activation of translation
B) change in the receptor protein's shape
C) activation of transcription
D) change in ion flow through a membrane channel

Question 7

Upon exposure to blue light, plants not only begin to grow toward the light, but move their chloroplasts to the sunny side of each cell. Why would it be advantageous to move chloroplasts within cells?

A) moving chloroplasts is not advantageous because it requires an input of energy
B) to maximize light absorption by the chloroplasts for photosynthesis
C) to maximize heat absorption by the chloroplasts for cellular respiration
D) to add weight to the sunny side of the plant so the plant will bend
E) to reduce stomatal opening on the sunny side of the plants

Question 8

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) when the block was placed on the right side of the coleoptiles in both dark and light treatments
B) when the block was placed on the left side of the coleoptiles in both dark and light treatments
C) as long as light was coming from the right, decapitated coleoptiles bent to the right independently of agar block placement
D) when the block was placed on the left side of the coleoptiles in dark only
E) when the block was placed on the right side of the coleoptiles in dark only

Question 9

Lettuce seeds need full sunlight to germinate; therefore, germination is inhibited when their phytochrome molecules are in the Pfr conformation.

Question 10

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

A) They affect only cells with an appropriate receptor.
B) They are able to move from one cell to another cell through extracellular spaces.
C) They change their shape in response to stimulus.
D) They can be transported by xylem or phloem sap.
E) They exist in plant in very tiny amounts.

Question 11

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

Question 12

Which of the following signals indicates shade to a plant?

A) far- red light
B) blue light
C) lower temperature
D) green light

Question 13

Mammalian eyes sense light because they have cells containing molecules called opsins, which change structure when exposed to light. Which of the following plant molecules) would be analogous to mammalian opsins in their light- sensing ability?

A) statoliths
B) gibberellins
C) auxin
D) cytokinins
E) phytochromes

Question 14

When Charles and Francis Darwin first documented phototropism, why was it important that they germinated the grass seeds in the dark before beginning the experiment?

A) so the young shoots would be soft enough to bend
B) so the young shoots would grow slowly
C) so the young shoots would grow quickly
D) so the young shoots would grow straight

Question 15

To find the gene that encodes for the blue- light receptor, researchers inserted the gene for the PHOT1 protein into insect cells growing in culture. When they exposed the transgenic cells to blue light, they found that the PHOT1 protein became phosphorylated. No other plant proteins were present in the insect cells. Which of the following is a reasonable conclusion from this result?

A) The PHOT1 protein is photoreversible.
B) The PHOT1 protein phosphorylated itself in the presence of blue light.
C) The PHOT1 protein is not responsive to blue light.
D) The PHOT1 protein is not functional in insect cells.
E) The PHOT1 protein enabled the insect cells to photosynthesize.

Question 16

$\begin{array}{c}\begin{array}{|l|}\hline\\\text {Plant}\\ \hline \text {A}\\ \hline \\\\\text {B}\\ \hline \\\\\text {C}\\ \hline\end{array}\begin{array}{lll} \hline \\ \text {Growth Conditions}\\ \hline \text {14 hours of darkness}\\ \hline \text {14 hours of darkness,}\\ \text {interrupted by 10 minutes of }\\ \text {light during the fifth hour }\\ \hline \text {14 hours of light, interrupted }\\ \text {by 10 minutes of darkness}\\ \text { during the fifth hour}\\ \hline \end{array}\begin{array}{|l|} \hline \text {Result Flowers}\\ \text {or no flowers)}\\ \hline \text {No flowers}\\ \hline\\\\ \text {No flowers}\\ \hline \\\\\text {Flowers}\\ \hline \end{array}\end{array}$
Table 37.1

-Refer to the table above. Why did plant B fail to flower?

A) Flowering was inhibited by the excess of far- red light.
B) It sensed a nine- hour day.
C) It sensed a nine- hour night.
D) There was not enough blue- light exposure to trigger flowering.

Question 17

$\begin{array}{c}\begin{array}{|l|}\hline\\\text {Plant}\\ \hline \text {A}\\ \hline \\\\\text {B}\\ \hline \\\\\text {C}\\ \hline\end{array}\begin{array}{lll} \hline \\ \text {Growth Conditions}\\ \hline \text {14 hours of darkness}\\ \hline \text {14 hours of darkness,}\\ \text {interrupted by 10 minutes of }\\ \text {light during the fifth hour }\\ \hline \text {14 hours of light, interrupted }\\ \text {by 10 minutes of darkness}\\ \text { during the fifth hour}\\ \hline \end{array}\begin{array}{|l|} \hline \text {Result Flowers}\\ \text {or no flowers)}\\ \hline \text {No flowers}\\ \hline\\\\ \text {No flowers}\\ \hline \\\\\text {Flowers}\\ \hline \end{array}\end{array}$
Table 37.1

-Refer to the table above. How would Plant A be classified?

A) day- neutral
B) long day
C) short day

Question 18

An eccentric millionaire botanist has offered a $25,000 scholarship to anyone who can successfully get a plant to grow through a vertical maze in complete darkness. The maze is not in a box; the maze is simply drawn on the wall, and the contestants must get their plant to grow in a pattern that matches the path through the maze. You need the money and feel confident that you can accomplish this task. Which of the following techniques will help you succeed?

A) Apply auxin directly to the lower part of the stem opposite from the direction you want the stem to bend.
B) Apply auxin directly to the shoot tip on the side to which you want the tip to bend.
C) Plant the roots in two different pots, and apply auxin to the root bucket that is on the same side as the direction you want the plant to bend.
D) Inject compounds that block auxin receptors into the part of the stem opposite from the direction you want the stem to bend.

Question 19

You grew reed canary grass seedlings in the dark and cut off their tips. You then placed the tips on agar blocks, one in dark and one in light. Based on your knowledge of auxin movement and stability in light, predict the concentration of auxin in the agar blocks.

A) The block in the light should have more auxin; the one in the dark will have less.
B) The block in the dark should have more auxin; the one in the light will have less.
C) The block in the dark should have some auxin; the one in the light will have none.
D) The block in the light should have some auxin; the one in the dark will have none.
E) Both blocks will have an equal amount of auxin.

Question 20

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

A) gravity
B) pressure
C) wind
D) presence of water
E) pathogen- inflicted wound

Question 21

Which of the following is the strongest evidence that cytokinins regulate cell divisions?

A) induction of root growths in tissues exposed to cytokinin
B) induction of shoot growths in tissues exposed to cytokinin
C) decrease of cyclin gene expression in tissues exposed to cytokinin
D) ability of cytokinin to interact with auxin at the molecular level and change auxin biosynthesis and transport
E) increase of cyclin gene expression in tissues exposed to cytokinin

Question 22

Suppose a plant had a photosynthetic pigment that absorbed far- red wavelengths of light. In which of the following environments could that plant thrive?

A) on the floor of a lake, whose water contains abundant green algae
B) on the ocean floor, in very deep waters
C) on the forest floor, beneath a canopy of taller plants
D) on mountaintops, closer to the Sun

Question 23

Shoots that grow vertically toward the sun can be characterized as

A) negatively phototropic and positively gravitropic.
B) negatively phototropic and negatively gravitropic.
C) positively phototropic and positively gravitropic.
D) positively phototropic and negatively gravitropic.

Question 24

What will a plant sensitive to touch or vibration look like when it is repeatedly touched or exposed to wind?

A) It will be short and spindly.
B) It will be tall and spindly.
C) It will be tall and stocky.
D) It will be shorter and stockier.

Question 25

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

A) An increase; an increase
B) A decrease; an increase
C) A decrease; a decrease
D) An increase; a decrease

Question 26

Why does Arabidopsis have 5 genes that code for phytochrome?

A) All 5 phytochrome absorb different types of light, maximizing sensitivity of plant to it.
B) Some of the phytochromes do not function in light absorption, but regulate other processes.
C) Several of them sense red light and the others sense far- red light.
D) They mediate different types of responses to red/far- red light.

Question 27

Antisense gene sequences can be used to block the transcription of specific genes in a cell or group of cells. Suppose you took a cutting from a plant and treated it with an antisense gene that would block the transcription of an enzyme involved in auxin production. What would happen to your cutting?

A) It would grow to be very tall and thin.
B) Photosynthesis would decrease.
C) It would not be able to initiate a hypersensitive response.
D) Adventitious root growth would be greatly reduced.
E) Further differentiation of xylem and phloem would occur.

Question 28

What hormones are necessary for maintenance of plant tissue culture?

A) gibberellins and ABA
B) gibberellins and cytokinin
C) auxin and cytokinin
D) gibberellins and auxin
E) auxin and ABA

Question 29

If a Venus flytrap were treated with a drug that inhibited the H⁺- ATPase, which of the following would likely happen?

A) It would not be able to reopen its flytraps once closed.
B) Its cells would become depolarized.
C) It would not be able to close its flytraps.

Question 30

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?

A) bushy
B) short
C) underdeveloped seeds
D) tall
E) large fruit

Question 31

You have a bush in your yard that is the height that you want it, but not as bushy as you want it to be. How can you prune it to trigger it to get bushier?

A) Cut off the tips of the main shoots.
B) Cut off the leaves at the ends of several branches.
C) Cut some of the higher branches off at the stem.
D) Cut off the leaves at the base of most of the branches.
E) Cut off lower branches.

Question 32

Figure 37.2

-Suppose you laid a seedling on its side so that the root was parallel to the ground. Immediately after the change in position, where in the root cells position A, B, or C in the figure above) would you find the amyloplasts? The answer should be one of the positions show in Figure 37.2.

A) A
B) B
C) C

Question 33

Why does auxin move through the plant slower than sucrose does?

A) Auxin transport through phloem is slower than sucrose transport through parenchyma cells.
B) Both auxin and sucrose are transported through phloem and parenchyma cells, but auxin is a bigger molecule and moves slower by diffusion.
C) Auxin transport is active requires energy) while sucrose transport is passive.
D) Auxin is transported by diffusion while cotransporters are involved in sucrose transport.
E) Auxin transport through parenchyma cells is slower than sucrose transport through phloem.

Question 34

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?

A) A
B) B
C) C

Question 35

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

A) Venus flytrap sensory cells will become depolarized.
B) Positive ions will enter the Venus flytrap sensory cells.
C) The cytoplasm of the Venus flytrap sensory cells will become more negative.
D) A and B
E) A and C

Question 36

prevents seeds from germinating until conditions are favourable for the growth of the plant.

A) Gibberellin
B) Auxin
C) Salicylic acid
D) Ethylene
E) Abscisic acid

Question 37

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

A) root hairs
B) zone of elongation
C) statoliths
D) root cap
E) secondary meristem

Question 38

Species from sunny habitat (Chenopodium)


Species from shady habitat (Teucrium)
Figure 37.1

-The data in the figure above were taken from a study on the effects of far- red light on stem elongation. The data indicate that plants from shady habitats do not respond to far- red light by growing taller. Which of the following would be a logical hypothesis for why these plants do not respond to far- red light?

A) The shade plants do not have protein kinases.
B) The shade plants do not have phytochrome.
C) The shade plants do not have phototropin.
D) The shade plants do not have cryptochromes.
E) All of these are reasonable hypotheses.

Question 39

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?

A) gibberellin
B) salicylic acid
C) abscisic acid
D) alpha amylase
E) ethylene

Question 40

Antisense gene sequences can be used to block the transcription of specific genes in a cell or group of cells. Suppose you treated a seed with an antisense sequence that blocked the transcription of GAMyb transcription factor. What would happen to the seed?

A) It would not make abscisic acid.
B) It would not be responsive to gibberellins.
C) It would germinate too soon.
D) It would not grow a hypocotyl during germination.

Question 41

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?

A) sequential immunity
B) systemic acquired resistance
C) antivirulence response
D) pathogenesis resistance
E) none of the above

Question 42

You discover a chemical that inhibits the conversion of starch to sugar and inhibits the breakdown of chlorophyll and cellulose in fruit. Who might be interested in buying this chemical?

A) grocers, to spray on fruit to enhance ripening in the store
B) consumers, to spray on fruit before eating to enhance taste
C) farmers, to spray on fruit after picking to stall ripening

Question 43

In the fall, the leaves of some trees change colour. This happens because chlorophyll breaks down and the accessory pigments become visible. What hormone is responsible for this?

A) gibberellin
B) abscisic acid
C) salicylic acid
D) ethylene
E) cytokinin

Question 44

If you wanted to genetically engineer a plant to be more resistant to attack by pathogenic bacteria and viruses, which of the following hormones would you manipulate?

A) salicylic acid
B) auxin
C) abscisic acid
D) gibberellins
E) ethylene

Question 45

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

A) Volatile "signal" compounds must be perceived.
B) The hypersensitive response must be induced.
C) Vibrations must be sensed through the plant's leaves and stems.
D) A plant must have flowered at least once.
E) Systemin must be produced.

Question 46

Based on the findings presented above, combined with what you have learned about the hypersensitive respons sequence of events occurs when a pathogen infects a plant cell? Only some of the events will be used)
1) The R protein binds to the avr protein.
2) The pathogen releases avr proteins.
3) The plant cell produces nitric oxide.
4) The pathogen produces reactive oxygen intermediates.
5) A signal transduction cascade occurs.
6) The plant cell and the pathogen die.
7) The pathogen dies, the plant cell lives.
8) The plant cell produces both nitric oxide and reactive oxygen intermediates.

A) 2, 1, 5, 8, 6
B) 1, 5, 4, 3, 7
C) 2, 3, 4, 5, 7
D) 2, 5, 4, 3, 6
E) 1, 5, 8, 2, 7

Question 47

You have discovered a previously unidentified plant, and you cultivate it in your lab. You notice that its flowers close when people are talking, yet are open when the lab is relatively quiet. You suspect that this plant may have the ability to hear! Based on what you know about plant sensation, which of the following hypotheses is the most reasonable to explain this phenomenon?

A) There is a cell- surface receptor on root cells that becomes phosphorylated when the soil vibrates in response to sound waves.
B) There is a cell- surface protein on the epidermal cells that becomes phosphorylated in response to vibration by sound waves.
C) There are tiny hairs on epidermal cells that bend in response to the vibration of sound waves, triggering an action potential in epidermal cells.
D) All of the above answers are correct.

Question 48

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

A) herbivory
B) methyl salicylate
C) proteinase inhibitors
D) phytochrome production
E) systemin release

Question 49

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?

A) to gain insight into how R proteins recognize avr proteins
B) to gain insight into what happens after R- avr protein binding
C) to gain insight into how pathogens kill plant cells
D) to gain insight into how R genes are inherited

Question 50

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

A) production of physical defences, such as thorns
B) early flowering to reproduce before being eaten
C) production of chemical compounds for defence or to attract predators of the herbivores
D) leaf abscission to prevent further loss of tissue
E) production of thicker bark and cuticle to make it more difficult to eat

Question 51

You buy some fresh fruit at the grocery store. When you get home, you are in a hurry, and you put the fresh fruit in the crisper with some overripe fruit. At the end of the week you are disappointed to find that your new fruit has already become overripe. What happened?

A) The overripe fruit released ethylene that increased the rate of ripening in the fresh fruit.
B) The refrigerator was probably set too high. As a result, the production of auxin was induced in overripe fruit and caused production of ethylene in the fresh fruit.
C) The fresh fruit was damaged, producing ethylene that sped up the ripening process.
D) The fresh fruit was not washed before refrigerating, so ethylene was still present on the surface of the fruit, causing the fresh fruit to overripe.

Question 52

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 HYPERLINK "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

A) stimulates growth when tobacco plants are shaded by other plants.
B) inhibits growth when tobacco plants are shaded by other plants.
C) triggers leaf abscission when tobacco plants are shaded by other plants.
D) is not involved in the shade avoidance response.

Question 53

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 HYPERLINK "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

A) antagonize the effects of ethylene on the shade avoidance response.
B) are not involved in the shade avoidance response.
C) act in concert with ethylene to generate the shade avoidance response.

Question 54

What do phototropin and ABA have in common?

A) They regulate opening and closing of water pores in the plasma membrane.
B) They are localized in the plasma membrane.
C) They regulate activity of H⁺- ATPases.
D) They are blue light photoreceptors.
E) They induce stomata closing.

Question 55

You are out working in your garden, and you notice that one of your favorite flowering plants has black, dead spots on the leaves. You immediately suspect that the plant has been invaded by a pathogen and has initiated a

A) hypersensitive response.
B) pathogenic response.
C) virulence response.
D) resistance response.
E) avirulence response.

Question 56

Figure 37.3
Figure 37.3 is a Northern blot showing the expression of Myb mRNA in cultured aleurone layer cells that were treated with gibberellin versus control cells that were not treated with gibberellin. Only the gibberellin- treated cells expressed the Myb mRNA, but the Myb mRNA was not detectable until 6- 12 hours after gibberellin application. Why did it take so long?

A) Gibberellin had to enter the cells and find the Myb gene among the large plant genome.
B) Gibberellin had to bind to a receptor and initiate a signal transduction cascade that, in turn, had to activate a transcription factor that triggered the transcription of the Myb gene.
C) Gibberellin had to diffuse into the aleurone layer cells and be metabolized in order to trigger activation of a transcription factor that triggered transcription of the Myb gene.

Question 57

What do abscisic acid and gibberellins have in common?

A) They both induce the formation of transcription factors that bind to the a- amylase promoter.
B) They work together to induce germination by triggering the metabolism of endosperm nutrients.
C) They bind to the same cell- surface receptor on cells of the aleurone layer in seeds.
D) They are both released from roots to signal drought to the leaves and stimulate the opening of stomata.

Question 58

A population of plants experiences several years of severe drought. Much of the population dies due to lack of water, but a few individuals survive. You set out to discover the physiological basis for their adaptation to such an extreme environmental change. You hypothesize that the survivors have the ability to synthesize higher levels of than their siblings do.

A) abscisic acid
B) ethylene
C) auxin
D) cytokinin
E) gibberellin

Question 59

A caterpillar eats a leaf of a plant. The next day it crawls to a nearby leaf to eat. But after eating the second leaf, the caterpillar gets very sick and falls off the plant. Which of the following molecules were involved in the plant's ability to defend itself against the second attack?

A) proteinase inhibitors
B) systemin
C) jasmonic acid
D) all of the above
E) A and C only

Question 60

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

A) It will be unable to respond to a plant's distress call.
B) It will be unable to infect its insect host.
C) It will be particularly successful at infecting plants.
D) It will be responsive to the signals released from several plants.

Question 61

Use the following information when answering the corresponding questions).
Some plants continually produce secondary defense compounds. Other plants are induced to form secondary defense compou when they are injured. Corn seedling leaves that are chewed on by the caterpillars of a type of cutworm moth emit immediate chemicals LOX products), and, after six hours, large amounts of terpenoid compounds are released into the air. The terpenoid are released not only from the leaf being chewed, but from all leaves of the plant. The terpenoid compounds attract a parasitoid wasp female that lays her eggs on the caterpillar. When the wasp larvae hatch, they eat and kill the moth caterpillar. T.C.J. Turlings, J. H. Loughrin, P. J. McCall, U. S. R. Rose, W. J. Lewis, and J. H. Tumlinson. 1995. How
caterpillar- damaged plants protect themselves by attracting parasitic wasps. Proceedings of the National Academy of Science
92:4169- 74.)
How could you test the hypothesis that caterpillar saliva and a wound are both necessary to attract the parasitoid wasps?

A) Put caterpillar saliva on an intact leaf.
B) Slash the corn leaves with a razor blade.
C) Put caterpillar saliva on a leaf wound.
D) All of the above actions are necessary for testing the hypothesis.

Question 62

Use the following information when answering the corresponding questions).
Some plants continually produce secondary defense compounds. Other plants are induced to form secondary defense compou when they are injured. Corn seedling leaves that are chewed on by the caterpillars of a type of cutworm moth emit immediate chemicals LOX products), and, after six hours, large amounts of terpenoid compounds are released into the air. The terpenoid are released not only from the leaf being chewed, but from all leaves of the plant. The terpenoid compounds attract a parasitoid wasp female that lays her eggs on the caterpillar. When the wasp larvae hatch, they eat and kill the moth caterpillar. T.C.J. Turlings, J. H. Loughrin, P. J. McCall, U. S. R. Rose, W. J. Lewis, and J. H. Tumlinson. 1995. How
caterpillar- damaged plants protect themselves by attracting parasitic wasps. Proceedings of the National Academy of Science
92:4169- 74.)
What can you conclude based only on the information in the preceding paragraph?

A) Physical injury by the caterpillar mouthparts causes the production of terpenoids.
B) The parasitoid wasp is attracted by compounds produced by an injured corn plant.
C) LOX products and terpenoids are the same kinds of chemical compounds.
D) The attracting terpenoid compounds are always present in the corn seedling.
E) Chemical signals from the caterpillar saliva attract the parasitic wasp.

Question 63

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 HYPERLINK "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.
Ethylene's role in the shade avoidance response in tobacco plants is related to its role in fruit ripening, leaf abscission, and senescence.

Question 64

Use the following information when answering the corresponding questions).
Some plants continually produce secondary defense compounds. Other plants are induced to form secondary defense compou when they are injured. Corn seedling leaves that are chewed on by the caterpillars of a type of cutworm moth emit immediate chemicals LOX products), and, after six hours, large amounts of terpenoid compounds are released into the air. The terpenoid are released not only from the leaf being chewed, but from all leaves of the plant. The terpenoid compounds attract a parasitoid wasp female that lays her eggs on the caterpillar. When the wasp larvae hatch, they eat and kill the moth caterpillar. T.C.J. Turlings, J. H. Loughrin, P. J. McCall, U. S. R. Rose, W. J. Lewis, and J. H. Tumlinson. 1995. How
caterpillar- damaged plants protect themselves by attracting parasitic wasps. Proceedings of the National Academy of Science
92:4169- 74.)
How could you test the hypothesis that compounds from the caterpillar alone do not attract parasitoid wasps?

A) Have caterpillars feed on different kinds of plants in the presence of the wasps.
B) Place intact corn seedlings in an enclosure with the wasps.
C) Place non- feeding caterpillars in an enclosure with the wasps.