#10 - Insects can see ultraviolet light and are known to

[Stephanie Oswalt]

We recently received the below question from a student. An instructor will respond below. Thanks!

"Hi PowerScore,

I have recently noticed a trend as I’m drilling Strengthen questions. As prescribed in the LR bible it has become second-nature to attempt to identify any gaps in the argument as I’m reading and then prephrase what I think could be a correct answer.

But it seems the more difficult Strengthen questions commonly don’t address obvious flaws or gaps at all in the answer choices – leading me to wasted time searching for something that would roughly summarize my prephrase. For instance:

PT25 S2 Q10- I think some obvious prephrases here would be something along the lines of Glomosus webs serve as a food source for (some insect) or (some insect) never uses any other location other than spider webs as a mating site. However, all the answer choices are vastly different from those.

What am I missing or how should I differently attack these types of difficult Strengthen questions so as not to waste too much time?

Thanks!"

[Zach Foreman]

I'm not sure I can speak to the trend that you see. But I can help with paraphrasing this particular question. "Since the conclusion contains the words "because of" we can see that it is causal. We know that the question stem is strengthen so we have a causal strengthen. So, we prephrase by diagraming the causal and recalling the five ways to strengthen a causal: eliminate alternate causes, cause with effect, no cause and no effect, eliminate reverse and data defense.
Pattern of UV reflections on web --> insects to be attracted to web
It doesn't make sense for the attraction of the insects to cause the UV patterns, so we eliminate 4. 5 is very rare and there are no indications that we should doubt the data. So we have three choices left. I don't see any clue as to an alternate cause to eliminate so I would focus on 2 and 3. So, my prephrase would be "another web did not have a UV pattern and insects were not attracted to it." We want to show that when the cause (UV pattern) is eliminated, so is the effect (attraction). And this leads us to E. All five answer choices involve shining a white light containing an ultraviolet component. After reading a couple of these, we could refine our prephrase to "a white light without an ultraviolet component was shined on a Glomosus web and insects were not attracted to it". And E is very close to that.
To help you skim the answer choices and get to E, you would focus on the words "no ultraviolet" or "without ultraviolet". Only E has that concept.

[dlehr99]

Thanks Zach - This makes a lot of sense. What I'm gathering out of this is that I need to better memorize and implement those 5 methods you described instead of somewhat arbitrarily developing a prephrase in this case. Appreciate the reminder!!