Some topics are not as useful as other in video form but the ability to speed them up, minimal mistakes and colorful setup make them more engaging than some of the other youtube videos I have seen on the sciences. I used them throughout my prep to supplement my less-than-stellar NS content books. The aamc wouldn't sell as many Q packs or other materials if Khan was spot on. The interface stinks but that's because they are meant more to teach, rather than simulate the MCAT. I would still recommend them to anyone looking for topic-specific MCAT practice. I was reading online they used a bunch of different authors so that explains why some passages mimic the AAMC really well (psych/soc, some bio/biochem) but others are just a couple sentences and then some figures (a lot of phys/chem). I found the Khan stuff a mixed bag but overall very good, especially for the price (FREE!!). While of course it doesn't perfectly mimic the actual test, this can be good to do once in a while - it can be weirdly tough to get used to FULLY focusing on a single question otherwise. I really wanted to mention the format though - as far as I know, KA is one of the only current sources that shows one question at a time. I do advise lots of analysis though - KA is one of those sources where I wouldn't really take the number of questions you get wrong seriously - just treat every question like something new to learn. Starting out with somewhat similar but shorter passages is a good way to get exposed to a lot of different topics without having to devote massive amounts of time to single, longer passages. The new MCAT is so biochem/bio/'experiment'-heavy that it's going to be full of detailed passages, often with lots of graphs, etc.

Admittedly the length seems off, but I think it's actually a benefit that they're short - it can serve as a good transition. Khan Academy passages are hard, but I definitely recommend them.

Khan academy biology mcat