I'm in the second year of my studies of molecular biology and in the first year of my mathematics degree (in most german universities the concept of a "double major" does not really exist, so you need to "enroll" a second time in order to be granted two degrees at once). I'd certainly like to combine those two majors, in the sense that I'd like to eventually be able to apply the math I learn to solve biological questions. I've figured out that the best way to do this (beyond real analysis/multivariable calculus and linear algebra) is to get a decent treatment of Statistics, Probabilities, ODEs and PDEs, possibly graph theory. Nevertheless to fullfill my requirements of the mathematics major, I have to choose two from the following list of topics: Algebra I Algebra II Complex Analysis I Complex Analysis II Algebraic Topology I Algebraic Topology II Introductory Geometry Mathematical logic I am fairly certain that I'd enjoy algebra (the linear algebra courses so far have been rigorous - right now we study modules and their properties and since I've enjoyed them, I guess this is a good indicator that I will also like the algebra courses). Then again, I'm not sure how useful algebra is going to be. Also, I am not sure if it would be preferable to pick the first and second part of a course in order to get a deeper understanding or to just pick two different introductory courses in order to get a greater coverage of mathematical topics, which might eventually be of use. What would you suggest?