The nucleotide base that is present in RNA sequences but not DNA sequences is Uracil (U). Here's a breakdown of the differences between RNA and DNA in terms of nucleotide bases:
1. RNA contains the bases Adenine (A), Cytosine (C), Guanine (G), and Uracil (U).
2. DNA contains the bases Adenine (A), Cytosine (C), Guanine (G), and Thymine (T).
In RNA, Uracil replaces Thymine, which is found in DNA. This distinction is crucial in understanding the genetic differences between RNA and DNA molecules.
Therefore, the correct answer to the question is: Uracil.
