When you are thinking about dropping a course, what you should do is look at the ramifications of that action. Look ahead to 3rd or 4th year, read the course descriptions, decide which courses you want to take. Look at the prerequisites, and then use those prerequisites (and your audit) to decide which courses you should take in 2nd year. Be sure to ask yourself whether any of your required courses (from your audit) or any of the courses that you want to take or need to take (from your list or the audit) require the course you wish to drop. If yes, then ask yourself whether you can make that course up in the summer (if offered) or next year and still stay on track to complete your degree program in the time you wish to. If you can, then great. If not, then think long and hard about your choices.
Dropping 1st year physics or mathematics often doesn’t have strong ramifications in 2nd or 3rd year. Most biology programs require these courses, but you can take them in later years or often in the summer. Dropping 1st year chemistry or biology can have serious ramifications, as you may not be allowed to enrol in several second year required courses for your program. This means you will be put way behind, and will likely be unable to graduate on time.