So, your question @cooliocats is "IF i get accepted to a CS or Bio/Chem program AND then I decide that I have changed my mind AND apply to transfer within my current uni AND I don’t get accepted COULD I then apply as a transfer student into the other program at a different school?
Transfer students are accepted to CS programs- but for competitive programs transferring in is typically harder than first year admissions, if only b/c there are fewer places availble.
You have 18 months to choose one- OR to choose to apply to universities where those parts of the school are more fluid. If you don’t have a strong feeling towards one or the other by a year from now, start looking into LACs.
In the meantime, spend time learning more about what each pathway is like- and follow your instincts as to which is most interesting to you.