Sorry, I've been wanting to say this for a while, but could you at least think about your questions for a little bit more before you post them? MCAT material has hundreds of problems that are actually tricky and some of us are actually combing through and looking for things that people have real difficulty with. With few exceptions, all of your questions have been about very basic intro paragraph-type concepts that you could surely get by just reading the next page, stopping to think, or googling. The only way to get good at something is to struggle by yourself at least a little before asking for help. I apologize in advance if you are actually spending time trying to solve them before asking.