Cool weather typically weakens muscle power in cold-blooded creatures. In the veiled chameleon, a cold-blooded animal...

shunhe on August 20, 2020

Hi @anchelle,

Thanks for the question! So let’s take a look at the stimulus first. We’re told that cool weather makes muscles weaker in cold-blooded creatures (like chameleons). And in this chameleon species, its tongue retraction speed goes down a lot as the temperature falls, but the extension speeds pretty much stays the same.

Now we’re looking for something to help explain this apparent discrepancy, or paradox. Now take a look at (D), which tells us that retraction is powered by muscles, and extension is driven by some stored energy. Well, if one’s powered by muscles, and one’s not, then it makes sense that one’s affected by the temperature falling, and the other isn’t. So (D) explains the difference, and is the correct answer.

(E), on the other hand, tells us that compared with muscles in the tongues of most cold-blooded animals, this chameleon’s retraction muscles are stronger. But how does that help explain the difference between the retraction and the extension? It doesn’t, and that’s why it doesn’t help resolve the paradox and isn’t the right answer.

Hope this helps! Feel free to ask any other questions that you might have.