How you prepare for the final exam depends on what kind of a mark you want to get.  Many students, anxious to complete the course, do not fully prepare and get 15% less on the final exam than on the average of their review assignments.  Some students relied for too much on internet resources to complete the assignments, score even lower.  
Hopefully you have made notes on Unit D and C, and can review them.  As for skill based learning, you need to work through the problems that you could do months ago and make sure you can still do them.
The review assignments are the best tool you have to prepare for the final exam!  Work through the skill based questions and make sure you can still do them.  Look at the knowledge based questions like a sample of possible questions.  For example, if the review assignment asks you about how gravitropism works, make sure you review phototropism, as well.  
Estimate how much time you need to prepare so you can get the grade you want.  Look at how much time you have in your schedule, then plan your review.