Logical Reasoning

PT113 · S2 · Q20 Antarctic seals dive to great depths

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Antarctic seals dive to great depths and stay submerged for hours.

Hypothesis

Part of how antarctic seals manage to dive super deep and stay submerged for hours is that they store oxygenated blood in their spleens.

Goal

There's nothing to evaluate here. To strengthen a hypothesis, we either need to rule out an Alternate Explanation or increase the plausibility of the Author's Explanation (the latter being way more common).

So let's get rid of four answers that either add plausibility to the idea that part of how antarctic seals can stay underwater for so long is the oxygenated blood stored in their spleens (for example, ) or that rule out an alternate explanation for how antarctic seals manage to stay submerged for so long.

20.

Each of the following, if true, provides some support for the researchers' hypothesis EXCEPT:

  1. Horses are known to store

    Supports

    This increases the plausibility that oxygenated blood in the spleen could be an adaptation that helps antarctic seals. The fact that the adaptation exists in any animal by itself strengthens a little simply by showing that it's possible to store oxygenated blood in the spleen. The fact that horses use this blood for exertion lines up with the idea that seals would be using their oxygenated spleen-blood for the exertion of diving to great depths. Students are often nervous about strengthening by analogy, but it's very common (especially on EXCEPT questions). Say that I was trying to convince you that you should meditate after every LSAT study session because it will improve your score. Does it add some plausibility to that claim if I tell you that "the GRE students that I've worked with who added meditation to their post-study ritual had bigger score improvements than the students who didn't"? Sure, that adds some plausibility to my claim, even though we're talking about GRE, not LSAT, it's reasonable to think that if it works for GRE it would work for LSAT. Similarly, if oxygenated blood in the spleen helps one mammal (horses) during exertion, it's reasonable to think that it might also help a different mammal (seals) during exertion.

    25% picked this

  2. Correct

    Many species of seal can

    Why this is right

    This actually weakens by providing an Alternate Explanation for how seals manage to stay submerged for hours. In addition to the oxygen in their lungs and blood, maybe they're also storing oxygen directly in their muscle tissue. If that's the case, then we have less reason to speculate that the seals would need to have a secret blood bank account stored in their spleen. Some students see this answer as strengthening the plausibility that seals stash oxygen in different parts of their body (i.e. they keep some in the lungs, some in muscle tissue, some in the spleen). But we already knew they had the capacity to have extra oxygen somewhere besides the lungs (because we're told that they store extra oxygen in their blood). So we're not gaining any new knowledge by learning that "seals do in fact store extra oxygen outside of their lungs". Instead, this answer is just pointing to an Alternate Possibility of where the seal could be stashing some extra oxygen.

    Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.

    62% picked this

  3. The oxygen contained in the

    Supports

    This rules out the possibility that the seals are able to stay submerged simply by the oxygen held in their lungs and their blood. It establishes that "there must be some extra stash of oxygen somewhere in their bodies", which lays the ground for finding the spleen hypothesis more plausible.

    8% picked this

  4. The spleen is much larger

    Supports

    This asymmetric comparison suggests that there is some connection between diving for long periods of time and having a larger spleen. That adds some plausibility to the hypothesis that storying oxygenated blood in the spleen is an adaption to long dives.

    3% picked this

  5. The spleens of Antarctic seals

    Supports

    This helps the plausibility of the author's spleen hypothesis by suggesting that there's something special going on with the spleens of Antarctic seals. And "having a greater concentration of blood vessels" definitely sounds like a circumstantial corroboration of the notion that they store oxygenated blood in the spleen.

    3% picked this

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