Answer:
a. southern blots hybridize a DNA probe to a digested DNA sample but northern blots hybridize a DNA probe to, usually, mRNA
Step-by-step explanation:
Both techniques are quite similar. The main objective of this technique is to identified specific either DNA or mRNA molecules. Hybridization is the process of forming a double - stranded DNA molecule between a single-stranded DNA probe and a single-stranded target DNA (which is the fragment that wants to be found. Northern blotting targets mRNA while Southern blotting targets DNA sequences.