Help what should I repeat?

Ok so I really messed up, got C and D in sciences when I expected A and B in the least going to send a few for re correction but for the moment assuming my grades remain as it is can someone please tell me if I could still get an A if I repeat the following papers, I'm sort of confused at the moment.

Biology A is 480 UMS (generally) what I got (C)
Unit 1: 93/120
Unit 2: 84/120
Unit 3: 48 (not sure out of what, sat in 2013 june)
Unit 4: 84/120
Unit 5: 63/120
Unit 6: 44/60
Total = 416

So do I still stand a chance of getting A if I only repeated units 2,4 and 5 (and according to my calculations I need to get about 94 UMS each out of 120)?

Chemistry A is 480 UMS (generally) what I got (D)
Unit 1: 84/120
Unit 2: 70/120
Unit 3: 48 (not sure out of what, sat in 2013 june)
Unit 4: 54/120
Unit 5: 34/120
Unit 6: 53/60
Total = 343

Once again would repeating only units 2,4 and 5 and getting about 98 UMS for each paper get me an A overall?

Thanks in advance for the help Hope everyone's happy with what they got (unlike myself lol) and hopefully not as depressed as I am rn