Self-study
Support In humans, ingested protein is broken down into amino acids, all of which must compete to enter the brain. ██████████ █████████ ██ ██████ █████ ██ ███ ██████████ ██ ████████ █ ███████ ████ ██████ ████ ███ ██████ ███ ████ ████ ███ ███████████ ██ ████████ █████ ██████ ██████ ███ ███████████ ██████████ ████ █████ ████ ███ █████ ███████████ ███ ██ ███████████ ████ ███ ████████ ██████████ ██████████ ███ ███████ █████████ ██████ █████ ██████ ███ ████ █ █████ ████ ██ ████ ██████████ ███████ ███ ██ ████ ███████ ███ █████████████
Summary
The author concludes that sugars can help one feel relaxed and anxiety-free.
Why does the author think this?
Because eating sugars after eating protein leads to the production of insulin. Insulin gets rid of amino acids in the bloodstream, but leaves tryptophan in the bloodstream. Tryptophan then get into the brain and is transformed into serotonin, which increases the brain’s serotonin level.
Notable Assumptions
The author assumes that serotonin contributes to relaxation and freedom from anxiety. (This is why the author thinks sugars can play a role helping one feel relaxed and anxiety-free. The premises established a causal chain from sugars to serotonin level. But the author didn’t explicitly state that serotonin helps one’s mood.)
22.
Which one of the following ██ ██ ██████████ ██ █████ ███ ████████ ████████
a
Elevation of mood ███ ███████ ████ ███████ ███████ ██████████ ███ █████ ██ █████████ ██ ███ ██████
Not necessary, because because even if increasing serotonin is NOT REQUIRED to elevate one’s mood, it can still causally contribute to elevation of mood. That’s all the author is committed to — that serotonin causally contributes to mood elevation.
b
Failure to consume █████ ████ ██ ██████ ███████ ██ ███████ ███ █ ████████ ██ █████
Not necessary, because although the author believes eating sugars can help one’s mood, that doesn’t imply that failing to eat sugars lowers one’s mood. Failing to eat sugars can simply leave one’s mood unchanged.
c
Serotonin can be ████████ █████████ ████ ██ ██████████ ██ ███████ ██ ███ ████████████
Not necessary, because although we know that tryptophan transforms into serotonin, that doesn’t imply that serotonin requires tryptophan in order to be formed. Maybe there are other chemicals that can also turn into serotonin. That doesn’t change the fact that we know tryptophan is one chemical that transforms into serotonin.
d
Increasing the level ██ █████████ ██ ███ █████ ████████ ██████████ ███ ███████ ████ ████████
Necessary, because this is the final link in the causal chain between sugars and mood elevation. If (D) were not true, then we’d have no reason to think that sugars can lead to mood elevation.
e
The consumption of ████████████ █████ ███████ ██ ███████ ███ █ ████████ ██ █████
Not necessary, because the causal chain begins by eating sugars after eating proteins. But if one merely eats proteins, without eating sugars, the author does not tell us what happens, and the conclusion doesn’t concern what happens if sugar isn’t ingested after eating proteins.