<p>I don’t know the first thing about math research, but it sounds to me like learning real analysis for math research is equivalent to learning basic experimental methods for biology research. In other words, this is a class that provides tools for performing research, not a class that is “relevant” to your research topic per se.</p>
<p>That’s pretty indispensable, as no amount of perseverance will help you succeed in research if you’re lacking even basic skills, but that again only has to do with a specific class and nothing to do with overall GPA.</p>
<p>If the same professor told you to take immunology before performing immunology research, protein folding before performing prion research, or cancer biology before performing cancer research, I would argue against the necessity of all three, as I have seen firsthand that not taking such classes beforehand has had no hindrance on the quality of student research in those fields.</p>