#3 - Concept Reference, Must Be True

[Administrator]

Please post below with any questions!

[hannahadams@ucsb.edu]

Hi. I am having a hard time understanding why it is not D?

Thank you!

[Jeremy Press]

Hi hannah,

It turns out that answer choice D is an opposite answer here. The end of the second-last paragraph says that "Researchers had thought that when muscles atrophy, the extra cell nuclei are killed by a cell death program called apoptosis." This, however, is what the researchers used to think in the past. The author presents research in the final paragraph that contradicts this viewpoint. The researchers in the last paragraph found that, in mice, when muscles that had previously been bulked up were allowed to atrophy, "the cells deflated to about 40 percent of their bulked-up size, but the
number of nuclei in the cells did not change." In other words, apoptosis (which kills extra cell nuclei) did not occur. The author goes on to comment that "ince the extra nuclei don’t die, they could be poised to make muscle proteins again, providing a type of muscle memory at the cellular level." Thus, this author believes that the lack of apoptosis (the fact that extra nuclei are not killed) is what allows for, or causes, the phenomenon of muscle memory, the opposite of answer choice D.

I hope this helps!