Logical reasoning PrepTest 114 · Section 4 · Question 21

Incorrect. This answer reverses the connection we need. We're looking for an answer that states more serotonin improves the mood, not that it's necessary in doing so.

Incorrect. Removing the cause should have an impact on the effect, but this answer goes too far. The argument requires failing to consume sugar resulting in no elevation to mood, not failing to consume foods rich in sugar leading to a lowering of mood.

Incorrect. The argument requires tryptophan to increase serotonin levels, but it doesn't treat that as necessary or the only way to do so. This answer reverses the connection in the argument.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Sugar increases insulin which removes sugar and proteins except tryptophan which enters the brain which increases serotonin.
Therefore - Sugar can elevate your mood

Answer Anticipation:
Don't get lost or confused by the science here! Instead, focus on what we know about Strengthen with Necessary Premise questions. They frequently bring up a new concept in the conclusion, and we need to figure out what concept from the premises needs to be connected to it.

Here, the conclusion talks about sugar and mood elevation. While the premises do talk about sugar, they don't talk about mood elevation, so that's the new concept we need to justify.

What do we know about sugar? Well, it's involved in a long and pretty complex causal chain that we don't need to fully understand—we just need to know the end result. And that end result? Sugar eventually results in more serotonin in the brain.
However, the argument never establishes a connection between serotonin and mood. As such, the correct answer should state that increasing serotonin levels also improves mood.

Answer Explanation:
This answer establishes the last step in the causal chain that allows the conclusion to be built from the premises. If more serotonin doesn't promote relaxation and freedom from anxiety, there's no reason to believe that sugar would have that effect. As such, this answer is necessary for the conclusion to hold.

Key Takeaway:
Don't get lost in the science! When you're confused by the content, start with the conclusion and see what overlaps with the premises, and what doesn't. This should help you identify elements related to the assumption without needing to get lost in amino acids and hormones.

Incorrect. The argument establishes that a certain part of protein is responsible for the supposed mood-boosting effect of sugar, so there's no need to assume that eating protein-rich foods results in bad things.