Our son got one B in AP physics second semester of junior year. I did feel like that was likely the end of his chances for UCLA. Irvine is his favorite and we’d be optimistic about his chances except for ZERO volunteer work, ZERO clubs, and varsity athletics as his only extracurricular. I think UC values well rounded applicants and would not reject a great applicant for one or two mediocre grades, unless you’re applying to the school of engineering, in which case all bets are off!