Do I have to teach GCSE first to teach A-level? Biology A-level teaching experience?

Additional questions
There are the A Level subjects in which you can't (always) be a qualified secondary teacher - media, sociology, psychology, law, economics, etc. - is it necessary to not be this way to teach sciences & English because they are core subjects or because they happen to be taught in schools as well (so it is more economically viable)? Thanks

I have a BSc Biochemistry degree (First) and interested in being an A-level Biology teacher. I think I would not like to teach GCSE because it feels too basic and students might be less passionate.
Myself and my GCSE Biology teacher had a bad experience because most of my peers were disruptive as they were not interested, but in A-level it was a smaller class chosen by students. Is it selfish of me to think/want that? Can anyone else relate?
Also, I question if my physics/chemistry knowledge could be good enough to teach which is often required in triple GCSE e.g. I am not great with math.
Would I be able to go directly into teaching A-level after doing my teacher training?
Would this depend on if I do a PGCE, SchoolDirect, TeachFirst or SCITT?
My grades:
University: Biochemistry BSc - First in almost all my modules
A-level: A in Law and Psychology. B in Biology A-level but was predicted an A.
GCSE: B for all sciences.
Lastly, is anyone here a Biology A-level teacher that can share their experience/advice becoming and being one?
Many thanks,
Elena

Hi El199,
Let me try to answer some of your questions. Firstly, if you do a PGCE in Biology, your first job may be teaching A-levels. This would be if you got a position in a Sixth Form College. In this case, you may not be required to have a teaching qualification such as QTS at all as it is not a mandatory qualification for post 16 teaching. However, many A-levels are taught in schools which also teach KS3 and GCSE in which case QTS in needed. If you got employment in a school, you would almost certainly be expected to teach a number of year groups from Y6 to A-level. You may also be expected to teach other science subjects but normally to younger age groups.
Secondly, whether you choose a PGCE (taught through university or SCITT) or Teach First, it makes no difference. If you will be teaching below A-level, you need QTS.
I would suggest you speak to one of our Get into Teaching adviser team. We are all experiences teachers who can answer your questions in more detail. It is a free service and we can support you with any applications you do submit.
Good luck!
Tracy