Rna primer constructed during dna replication needs to be replaced because rna differs from dna. what does it contain?

Structurally speaking, RNA and DNA are different. One clear distinction between the two is that RNA is single stranded, while DNA is double stranded. Another way they differ is found in their nitrogen bases. The four bases for DNA are Adenine, Thymine, Cytosine, and Guanine (think, ATCG). The bases for RNA are the same, except Thymine is replaced with Uracil (think, AUCG).

Another note is that RNA polymerase is unable to detect errors in base pairings, unlike DNA polymerase, but their syntheses are both in the 5’3’ direction. Hopefully this helps you answer this question.