LSAT 102 | Section 2 | Logical Reasoning: Q10

LR Question 10 Explanation

QUESTION TEXT: Insects can see ultraviolet light and are known to…

QUESTION TYPE: Strengthen

CONCLUSION: Insects probably fly into Glomosus webs (to their death) because the webs are shiny with ultraviolet light.

REASONING: Insects identify food and mates because they reflect ultraviolet light.

ANALYSIS: This is a reasonable argument, but it hasn’t proven its point.

There may be another reason that the webs are attractive. Without that reason, maybe the webs would just look like big shiny ultraviolet deathtraps.

The best way to test this would be to take two Glomosus webs and make only one of them ultraviolet. Then we’d see if insects preferred the ultraviolet web.

A few the wrong answers talk about other spider species, and don’t test whether ultraviolet webs attract insects. Useless.

___________

1. We only care about Glomosus webs, not all spiders webs. It might have been useful to tell us that only ultraviolet spider’s webs could attract insects, but this answer choice didn’t say that.
2. I’m not sure what this tells us. Are insects attracted to these spider burrows too? This answer choice doesn’t say.
3. Same as A. I don’t know what this tells us. Were insects attracted to the ultraviolet webs?
4. Many? That’s very vague. We don’t know if more flies flew to the Glomosus web or the synthetic web. And both webs reflected ultraviolet light, so this experiment was useless.
5. CORRECT. This does it. It tests two versions of the same thing: a Glomosus web. Then the experiment tests exactly the variable we want to test: ultraviolet light. And the flies mostly went to the ultraviolet web. So it’s probably the light that attracts them.

Recap: The question begins with “Insects can see ultraviolet light and are known to”. It is a Strengthen question. Learn more about LSAT Strengthen questions in our guide to LSAT Logical Reasoning question types.