If I got a 4.0 in Santa Monica Community College how likely is admission

Depends on what science. There are so many biology majors graduating (many of them pre-meds who did not get into any medical school) that finding a biology-related job at the BA/BS level will be very competitive, and pay is not so good. The mathematical sciences (applied math and statistics) and computer science are the sciences that have the strongest major-related job prospects at the BA/BS level.