Taking a college prep physics course, but I’ve also taken/will be taking AP bio, AP stats, AP calc bc, AP chem, CP Physics…
interned at professional lab this summer and have 4.0 gpa, 34 on act, 800 sat bio and chem, 780 on math (yikes retaking). ive taken all the most challenging honors STEM courses over the years but knowing cal tech thats probably not enough. if not taking cp physics is an automatic turn off to admissions officers can you let me know? greatly appreciate it 
No need for AP stats, however you need at a minimum honors physics or AP physics 1 or a community College’s General Physics 1. It’d be MUCH MORE important than AP bio.
Physics is necessary at any level for any stem major or any selective university. For a top stem university the expectation will be that you took physics honors or AP Physics1 junior year, and if possible a second level of physics (through a cc or AP physics C) senior year.
If your school offers nothing but CP physics then take that but you’d have to somehow offset such an essential class taken at such a low level with a very strong background in math or CS (post AP).
AP calc BC is basically the lowest Caltech students can have upon entrance - many have accelerated through summer classes and dual enrollment.
If you ended up going to Caltech, you would have to take a physics placement test that includes AP Physics C level material. That is not to place out of a class, but just to see whether you should be in one of the lower sections or one of the higher sections. If someone hypothetically admitted to Caltech had only taken CP Physics, I would guess they would end up in a lower physics section.
If you are not that interested in physics, you might want to consider whether Caltech is a good fit for you, as even the bio majors have to take 3 quarters of physics beyond what is covered in both AP Physics C courses.
Agree with @MYOS1634 that if you are taking AP Stats senior year, it’s not that helpful for Caltech unless that is the only math course available to you. Perhaps you can substitute an AP Physics of some sort?
I’m at caltech without ever taking AP physics. You might struggle a bit in the physics courses, but other parts of your application will matter more.
Hm, I ended up taking ap physics, but dropped ap calc bc for ap calc ab. Lol we’ll see how things go… I plan to go into bio anyways.