Yes, failing physics in class 12th  most likely won't affect your eligibility for an MSc in Biochemistry  given that you have a BSc in Zoology (Hons).

MSc programs typically focus on your undergraduate degree for eligibility. Since you have a BSc (Zoology Hons.), which is relevant to the life sciences field, physics from 12th grade shouldn't be a hurdle.

While most universities focus on the graduation degree, a few might have specific requirements for the qualifying exam (12th grade). It is always best to check the eligibility criteria of the universities you are interested in. Their websites or admission brochures should have this information.

Overall, with a BSc in Zoology (Hons.), failing physics in 12th grade is unlikely to be a significant barrier to pursuing an MSc in Biochemistry. However, it's always good to check with the universities you're targeting to ensure you meet their specific requirements.

I hope it helps!