Someone with an above-average IQ of 115-120, like your average undergrad, visibly struggles with 101 / 201 level work and is deeply resistant to higher-level concepts. Actually getting through grad school takes about a 130 as previously mentioned, and notable scientists tend to be in the 150+ range.
Where did you get those numbers?
Not reality. 41% of people in the US are enrolled in college (in 2010) Source. If we assumed that the US has representative IQ and use a 15 SD IQ scale, then the top 41% of IQs are all people with IQ of at least 103.41. I calculated that average IQ of a the top 41% of the population on wolfram alpha. (It is easy, because by definition, IQ follows a normal distribution.) I got 114.2.
If US citizens between 18 and 24 are representative of the entire population in terms of IQ, it is literally impossible for the average IQ of an undergrad student to be 115 or higher.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.