ok, it sounds like the residency plan will probably work out. What are your goals with a Bio degree? You should know that to get a decent job in the sciences these days it usually takes a PhD or going to a professional program such as med school.
Let me suggest that you go for the 5-year plan with 2 years at the CC. This will do several things for you. First off, it will allow you enough time at a CC to apply for TAG which guarantees admission to some UCs. Each UC has slightly different rules so you’ll have to look each of them up. Since you mentioned Santa Cruz here is there plan: http://admissions.ucsc.edu/apply/transfer-students/tag.html
Second, it will let you raise your overall gpa when you apply to a 4 year. Even though you may not get credit for all the units you take towards your 4-year degree, they will use all the classes you take in calculating your gpa when you apply. If it’s really the case you can earn a 3.5 at a CC, then 2 years of a 3.5 and 1 of 2.5 gives you a 3.17. Note, too, that if you apply during your 1st year at a CC all they will see is 1 semester of grades from the CC before they decide, meaning a 2.83 gpa.
I do have to ask, what is the plan to jump from a 2.5 to a 3.5? People are really good at making rational promises for what they’ll do in the future, but what they do today is a better predictor of tomorrow since the distractions and problems they face today are likely to also be present in the future and have the same degree of distraction. And vague goals like “study harder” don’t really translate into concrete behavior. It’s also possible, if you are getting a C+ average now, that your study skills can use some help. They have a learning center at just about every CC. There is also a great book you can read called “Make it Stick” that discusses what research shows about learning effectively and how college kids can apply it.