Rna is believed to be a more primitive molecule than dna because

Because it is present in the earliest cell that lived in earth

The main difference between DNA and RNA is that DNA contains double-stranded molecules and RNA contains single-stranded molecules. DNA stands for deoxyribonucleic acid and RNA stands for ribonucleic acid. Both DNA and RNA carry genetic information, but there are a few major differences between them. DNA consists of the sugar deoxyribose, and RNA contains the sugar ribose. Ribose contains one more -OH group than deoxyribose. Another difference is that DNA is stable under alkaline conditions while RNA is not stable.

I’m not exactly sure what your trying to ask, but if it’s how an organelle is similar to a body system or a part a nucleus is like a in function. but i don’t fully understand what you’re trying to ask