The diet of Heliothis subflexa caterpillars consists entirely of fruit from plants of the genus Physalis. These fruit...

Lizzie-Annerino on August 6, 2019

Why is the correct answer B and not A?

I was fairly confident the correct answer was A. Why is it B?

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Victoria on August 6, 2019

Hi @Lizzie-Annerino,

We know that "linolenic acid in an insect's diet is...necessary for the production of a chemical called volicitin."

Produce volicitin - > Have linolenic acid in diet
Don't have linolenic acid in diet - > Do not produce volicitin

We also know that "while most caterpillar species have volicitin in their saliva, H. subflexa does not."

Caterpillars - most - volicitin in saliva (produce volicitin)

Notice that the right half of the quantifier statement is the same as the sufficient condition. We can then use the transitive property to deduce:

Caterpillars - most - produce volicitin - > have linolenic acid in diet

Therefore: caterpillars - most - have linolenic acid in their diet.

This is directly restated by answer choice B making it the correct answer.

A is incorrect because the information provided does not allow us to draw this conclusion. We know that H. subflexa does not consume linolenic acid in their diet which means that they do not produce volicitin. This does not suggest nor refute that H. subflexa synthesizes linolenic acid within their bodies.

Hope this helps! Please let us know if you have any further questions.