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The role of JAR1 in insect feeding response

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The Experimental Design

It was important for the UNL scientists to set up an experiment that would provide a fair test for their hypothesis. They needed to establish a testing environment that included three living things: 1) hungry cabbage loopers, 2) Arabidopsis plants that were considered genetically normal, and 3) Arabidopsis plants that were homozygous for the jar1 mutation. Scott could grow the needed plants and then order the insects from a supplier once he had his plants ready for the experiment. When all the conditions were met, they were ready to test their hypothesis. 

Question 4: Their research with plant mechanical wounding led the UNL scientists to create the above line graph. However, the draft of the graph is not fully labeled. The graph does not show which line went with which type of Arabidopsis plant as well as the time points along the x-axis. Based on the data depicted in the graph above:

A. Plant A must be the wild-type plant, and time c must be 60 min or less.
B. Plant A must be the wild-type plant, and time c must be more than 60 min.
C. Plant A must be the jar1 mutant, and time c must be 60 min or less.
D. Plant A must be the jar1 mutant, and time c must be more than 60 min.

 

Question 5: The UNL scientists hypothesized that insects feeding on the Arabidopsis plants might also cause the same response via JAR1 activity that occurs when the plants are mechanically wounded. How could this be tested?

A. Allow insects to feed on wild-type plants and on jar1 mutants and count the bites the insects take. Collect one sample to measure JA-Ile after a predetermined amount of bites.
B. Allow insects to feed on both wild-type plants and jar1 mutants for several select times, sample the plant tissue at the end, and compare the results between the wild-type and jar1.
C. Allow insects to feed on both wild-type plants and jar1 mutants for a fixed amount of time, sample the plant tissue at select time intervals, and compare the results between the wild-type and jar1.

 

Question 6: If JAR1 activity enables the Arabidopsis plants to mount a defense, insect feeding might somehow differ when feeding on the wild-type plants compared with the jar1 mutants. How could this hypothesis be tested?

A. First, weigh the insects, allow them to feed on wild-type plants for a fixed amount of time, and then weigh the insects afterward.
B. First, weigh the insects, allow them to feed on jar1 mutants for a fixed amount of time, and then weigh the insects afterward.
C. First, weigh the insects, allow them to feed at will on either wild-type plants and jar1 mutants or both, weigh the insects afterward, and compare the results.
D. First, weigh the insects, allow some to feed exclusively on wild-type plants and some to feed exclusively on jar1 mutants, weigh the insects afterward, and compare the results.

 

Question 7: When the UNL scientists were establishing their testing environment, their second requirement was “Arabidopsis plants that were considered genetically normal.” Why would they need this?

A. A positive “control” was needed to establish a baseline from which to compare data.
B. Their data would really not make much sense in the long run without having plants that were considered genetically normal.
C. Without genetically normal plants included, their research would likely not get published.
D. All of the above.
E. None of the above.

 

Question 8: When the UNL scientists were establishing their testing environment, their third requirement was “Arabidopsis plants that were homozygous for the jar1 mutation.” Why would this be important?

A. This would guarantee about half of all jar1 mutants used would have the reduced JAR1 activity.
B. This would guarantee about one-fourth of all jar1 mutants used would have the reduced JAR1 activity.
C. If Scott needed more jar1 mutants, he could grow any of the jar1 mutants to full maturity, allow them to flower and self-pollinate, then collect the seed to plant more.
D. If Scott needed more jar1 mutants, he could grow any of the jar1 mutants to full maturity, allow them to flower, and cross pollinate it with a wild-type plant to ensure good viability, and then collect the seed to plant more.

Photo: Scott Dworak

 
Question 9:  Above is a picture of some Arabidopsis plants in Scott’s preliminary studies with some hungry cabbage loopers (Trichoplusia ni) feeding on them. There is one visible; can you spot it?  Based on what you learned in the video from Scott, which of the following is correct?

A. These plants must be wild-type plants because cabbage loopers are feeding on them.
B. These plants must be jar1 mutants because cabbage loopers are feeding on them.
C. These plants could be either wild-type or jar1 plants because cabbage loopers can feed on either one.
D. None of the above


Click here to watch  the second video:



 

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