PrepTest 113

Incorrect. While this answer doesn't add much to the argument, it does at least establish that spleens can hold excess oxygen, which was more than we knew based on the stimulus, so this strengthens the argument by a bit. Yes, it's about horses, but it's also about spleens, and it tells us that the hypothesis isn't completely without support—as it is in the stimulus.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Bizarro Strengthen

Stimulus Summary:
Phenomenon - Antarctic seals stay underwater for hours
Biology - They store oxygen in their lungs and blood
Hypothesis/Explanation - They store oxygen in their spleens

Answer Anticipation:
As with many arguments featuring a hypothesis, this one falls into a common pattern—a phenomenon/explanation pattern. Antarctic seals can stay underwater for hours. While it's noted that they do store oxygen in their lungs and blood, the hypothesis is that they also store blood in their spleens.

Unlike similar arguments, however, there are no premises that support the idea that they store oxygen in their spleens. It's not even noted that the oxygen stored in the lungs and blood is insufficient for them to stay submerged for so long! As such, we're wide open with what we can find in the answers—anything that suggests the seals may be storing oxygen in their spleens would serve to strengthen this hypothesis, as right now, we have no evidence for it whatsoever.

Answer Explanation:
This answer raises an alternative explanation—if these seals need more oxygen than they can store in their lungs and blood, then maybe they store it in their muscle tissue, not their spleens. In raising an alternative explanation, this answer weakens the argument and thus is correct in this Bizarro Strengthen question.

Key Takeaway:
Harder Bizarro Strengthen (and Bizarro Weaken) questions tend to have 1-2 answers that are a little more tenuous than we get in regular versions of the questions. Here, (A) can feel as if it barely strengthens the argument. That said, it does strengthen it, and (B) is a clear weakener, so knowing that you're likely to see such a tenuous answer in this question type is a good way to feel better about eliminating it—especially after reading the next choice.

Incorrect. If the oxygen in the lungs and blood isn't enough to allow the seals to dive for as long as they do, then they must be storing extra oxygen somewhere. While this doesn't point to the spleen in particular, it does establish that the existing explanation (blood/lungs) is incomplete, strengthening an argument that there's some stored in another organ.

Incorrect. Correlations don't prove causality, but they do provide evidence of it. If the spleens are bigger in these seals than in animals that don't dive for such long periods of time, then that strengthens the argument that the spleen has something to do with this ability.

Incorrect. We know that oxygen can be stored in blood, and this answer connects the spleen to something we already know can store oxygen. It also suggests that the spleen is more likely to be the site of additional oxygen storage compared to other organs because of the higher concentration of blood vessels there. Through both avenues, this answer strengthens the argument.