different people bring very different backgrounds to CCs. There are people who’ve known since they were 7 that they want to study molecular bio at UCSC, they have plenty of time to take many of the math and science pre-reqs in high school and graduate in 4 years. Most, however, have foundational work to do in English, Math and Science so, it takes longer to transfer, and to graduate. Crowds plus semesters and class sequences of math and science make that extra tough at most CC’s in Ca. Deciding you want to pursue a hard science at a UC as you enter your second year is going to compound the problem.
Fortunately TAG makes it pretty easy to know what to take once you make up your mind.
https://admissions.ucsc.edu/apply/transfer-students/tag.html#bio2
Check it out at that link.
I’d make an appointment with an admissions counselor at UCSC ASAP - while you have time to adjust your Fall semester courses.
As to semesters in residence - basically, they want someone with a UCSC diploma to have spent more than ten minutes on campus… It is a pretty common requirement.
https://advising.ucsc.edu/transfer-guide/grad_reqs.html
This says it is just 3 semesters.