Hi guys, I’m a high school senior who plans to major in biology while pursuing a premed program. The thing is, I know my English teacher very well, much better than I know any of my other teachers. She has written me a great rec. Would there be a downside to me submitting a rec. from an English teacher if I indicate that I plan to major in biology? Would it hurt my chances, or is it a rather insignificant factor? The schools I plan on submitting this rec. to are Boston U. and Northeastern.
Colleges like teacher recommendations because they like hearing from someone who knows you personally and as a student. They usually don’t care about the subject (though some schools require the rec to come from a core subject teacher). If your English teacher knows you well and has more/better things to say about you as a student than your biology teacher, there won’t be an issue. Schools would rather hear from a teacher who knows you well than a teacher who doesn’t have much to say. The subject is just a minor detail.
I’m also applying to Northeastern for science, by the way 
Agreed with above. Also, it would make you seem more well-rounded, esp if you have the grades/test scores to demonstrate your interest in Bio already. To put it in perspective, MIT (obviously STEM oriented) asks for a rec from a humanities teacher so they can gauge your well-roundedness. Good luck!