PT66.S4.10- Amino Acids and Lightning

edited May 2021 in Logical Reasoning 114 karma

I'm confused about B.

The passage doesn't say it's impossible for amino acids (AA) to form in a non-reducing atmosphere, it says AA do not form readily and tend to break apart when they do form in such an environment. Is this just LSAC's way of saying "impossible" in a convoluted way? Based solely on word strength ("readily" and "tend to") it seems like they leave open the possibility of it happening. It may be difficult for AA to form or even very difficult in this environment, but not explicitly impossible. Answer choice B resolves the apparent paradox by saying "yes it's difficult for AA to form in this environment and they usually break apart but you only need one molecule."

I realize that A is the credited response but I'm not really sure how A is stronger given that it requires a meteorite impact and then a bolt of lightning in the same place at around the same time since the reducing environment is temporary according to the question. I was left trying to weigh the relative likelihood of two vanishingly unlikely events.


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  • SSBM1000SSBM1000 Member
    614 karma


    For me, this is one of those cases where both answer choices technically work, but A is much stronger than B.

    A tells us that meteor strikes that turned the atmosphere into a reducing atmosphere occurred around the time life began. This increases the likelihood that a lighting strike could have created the first amino acids because the proper conditions for them to form were met.

    B is a really weak answer choice because it has too many variables involved. The stimulus tells us that amino acids essentially never form readily when it's not a reducing atmosphere, and that if they did, they usually break apart. B would add a lot more support if it said that a single amino acid was enough to create life on Earth, but the answer choice only says that it could have been enough. So on top of it being extremely rare that an amino acid would actually be created and survive, B at best tells us that maybe one would have been enough anyways, which doesn't really help us at all. While A does require a lighting strike to happen not too long after a meteor strike as you pointed out, the fact that the meteor strikes occur around the time life began does greatly support the theory that lightning works, and I think provides much more support than answer choice B.

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