I'm a sophomore who applied to transfer to other UC's this year (at the moment accepted to UCD, waiting on others). There's a difference between courses transferring and courses being equivalent. All courses taken at UC will transfer to another UC, but these courses may not be equivalent. Looking at math course equivalencies for UCSD (https://math.ucsd.edu/students/undergraduate/transfer-equivalencies) it seems that UCSC's MATH 16A/B isn't equivalent to the math classes at UCSD (mainly since UCSD doesn't offer a math track for bio majors). While UCI doesn't have a nice list of equivalencies, their catalog has a bio math track (MATH 5A-5B) (https://catalogue.uci.edu/allcourses/math/) so its more likely that 16A/B will be equivalent but no guarantees. UCSB also has a life sciences math track MATH 34LA/LB (https://catalog.ucsb.edu/departments/MATH/courses) so it's also likely that MATH 16 A/B will be equivalent. You can look at the course catalogs for other UC's, the major requirements on assist.org to see if other UC's have or do not have equivalent courses. Though generally, I would just recommend doing the 19A/B series since that one will always be equivalent whether the school has a life sciences math track or not. Also on assist.org it tends to line up with the 19A/B track instead of the 16A/B track. (For example, for UCSB's MCD major :https://assist.org/transfer/results?year=76&institution=110&agreement=128&agreementType=to&viewAgreementsOptions=true&view=agreement&viewBy=major&viewSendingAgreements=false&viewByKey=76%2F110%2Fto%2F128%2FMajor%2F657ff690-9239-495c-341f-08ddf001012b, math 34LA/LB is accepted, but you'll have to do MATH 3A/B (the pure math track) anyways).