My opinion ...
while LORs in your intended field are most desirable, it is better to have really strong letters than weak ones as weak letters actually sort of count against you. That is they do more harm than good. Good, credible, LORs demonstrate that the professor knows you well beyond your performance in class and can discuss your character, ability, interests, weaknesses, etc.
Provided the LOR is from an academic who can talk about your abilities to do original work, succeed in a graduate program, etc. you shouldn't be too concerned about the fact they are from another field.
If you could come up with even on strong biology letter and two business letters you could be fine. The letters from business profs could address your success but also your desire to change fields. You should talk at length with professors before they write letters and discuss what they might say about you, and some of your concerns. Most good recommenders will want to be helpful and understanding.
You can't do much about the situation that you have no strong recommenders in your field - though that is an unfortunate reality and does actually demonstrate a hole in your preparation for a biology graduate program. But if your LORs and SOP along with GRE and GPA make a good package - and if you select the right program with a good fit - you could be successful.