What if you fail the 1st semester of an AP science? Does affect your chances of going into University? I heard that if you get C- or lower and not pass the class, UCs will not accept you. Can you make this up in the 2nd semester? Also why can you retake the class?
Why do you have this low grade in the AP class, and what have you done to pull that grade up?
Competition for UCB and UCLA is ferocious. Of course you need your ducks in a row. Try learning more about what it takes, so you can understand your position, can evaluate your own best targets.
If you targeting the California UC’s, then your Senior grades will not be considered in your admissions decision unless you are asked for a supplemental/augmented review and need to send in Mid-year grades. However, getting a D or F Senior year in any a-g course even AP could result in your acceptance being rescinded.
If you are a Sophomore or a Junior, then anything lower than a C will impact your GPA since the UC’s only used 10-11th grades in their UC GPA calculation. You can retake the semester or the entire course if you receive a D or F but you will be asked to report both the original grade and the repeat grade on your UC application.
Grade validation where if you do not pass 1st semester but get a passing grade 2nd semester, thus validating that course is only for Foreign Language and Math courses. If you do not retake the semester or course, then your D/F will remain and calculated into the UC GPA.
I agree that you need to find out why you are not doing well in this particular course and get some extra help from either a tutor or your teacher.
note that if you are a senior and have applied to UC schools, then if you get lower than a C you are required to notify the UCs immediately. See https://admission.universityofcalifornia.edu/how-to-apply/applying-as-a-transfer/after-you-apply/ for details and instructions