Answer:
The best answer for the question: The first major step of gene expression and genetic splicing of exons occurs in this specific aqueous environment of the cell:____, would be: The nucleus.
Step-by-step explanation:
Unlike prokaryotes, that do not possess a nucleus in their cells, eukaryotic cells contain all their DNA material inside a much smaller unit of the cell called the nucleus. Aside from containing DNA (genetic material) the nucleus contains also an aqueous solution in which the DNA lies.
During the first step of genetic expression, which is when the DNA strain is unwinded and genetic information is translated from the DNA strain into an mRNA, the process remains secluded to the nucleus. It is during transcription (decoding the DNA and transforming genetic material into a functional protein) that the process of gene expression leaves the nucleus and happens in the cytoplasm.