Has he actually taken any study skills classes or got a 'how to study' book? Both very useful.
The student support department and or SU tend to run things about how to study. The OU publishes some fabulous books.
What kind of learner is he? Does he need music or silence, does he prefer to write notes or pictures.
One thing I found useful was to pic a topic to revise. Get notes and the CORE textbooks, too easy to end up with 15 - 20 books.
stage one - post it notes, the small ones.
Look in the index, and put a post it note on the page where each subject is mentioned so it could be 'phospholipidbilayer'.
I've found other people can be bribed to do this bit as you only need to look at a word and put a post it on the page.
OK now take 1 A4 piece of paper and describe that one thing using all the sources. Do you really understand it? Could that one page be given to someone and they understand the concept? Do the texts agree? Sometimes they appear not to but it is the way they have been written.
Keep it to just that topic. Do not include things like sodium channels or other parts of the cell. Each one of those gets it's own sheet.
A4 is a maximum, some he will be able to explain in a couple of lines.
Get someone else on the course to read them if he can and then it depends on his style of studying, I would put them in a ring binder. I have known people plaster them around their room and even inside cupboards and the fridge so that every time you pass the paper you read it.
Move the papers around after a few days, the one on the back of the toilet door will probably be the best read.
And remember
Sleep, good quality if you can get it. Eat well, and eat something before the exam.
My hippy technique when reading the notes is to have something smelly, if he is allowed an oil burner or candle then that's fine, if not scented tissues or even scent/aftershave on the pages.
Play some music, classical or at least nothing with words.
Eat something like mints or chew gum.
he idea is that the memories are stored in different bits of the brain (most probably BS) when you go to the exam wear the aftershave or rub scented oil on your wrist, listen to the music on the way to the hall and take the same mints with you.
You are then using all your senses to remember (told you it's hippy stuff) and a wiff of scent can trigger a memory, hopefully of what you have been learning.