What are the benefits of going into the undergrad: Arts and Science, and getting a bachelor of arts and science, rather than just getting a bachelor of science in like life science?

Pretty sure Arts and Science actually has certain course requirements pretaining to the arts like writing, reading, history and stuff. You can find what is required in the undergraduate calendar. As a science student, such as life science, you're taking all science courses with the option of english/literature/history/other courses that are not required for your program

But in life science, the extra courses would be "electives" right? So are there any benefits to getting bachelor in arts and science?

The extra courses taken in life science would count as your electives and you'd probably be more flexible and have more options as to what you want to take. I think the benefit of ArtSci is just so that you have a balance between arts and science If you're interested in both

Of what I have heard, it has so many electives that you could take a major in biochem or something and have a minor in the arts. Overall, a solid program if that is your interest.