Could I do a Master of Science if I have a Bachelor of Arts?

Is it possible to do a Master of Science with a Bachelor of Arts (or do you need to have a Bachelor of Science in order to do a Master of Science?)

How is it in the UK (or in USA/Canada)?

Thank you

What matters for grad school admission is the courses that you have taken and the grades you have earned in those courses, not whether or not your degree is a BA, BS, BSEng, AB, SB, BBA, BM, BFA or any of the other umpteen other letter combinations for the various kinds of bachelors degrees that are awarded.

^What @happymomof1 said. The title of your degree doesn’t matter at all. It’s just the coursework you’ve taken that matters.