Which factor distinguishes the DNA molecules of different species?

The distinguishing factor of DNA molecules among different species primarily revolves around the sequence of nucleotides within the DNA. Each species has a unique arrangement of these nucleotides, which directly influences traits, genetic characteristics, and overall biological functions. Variations in nucleotide sequences contribute to diversity at the genetic level, helping to define what makes each species unique.

While the number of genes and non-coding regions can play a role in distinguishing species, it is primarily the specific sequences of nucleotides that provide the most critical differences. This variation allows for the vast diversity observed in the biological world. The number of base pairs and the size of the DNA molecule may vary among species, but these factors alone do not account for the genetic distinctions that arise from the specific sequence of nucleotides found in the DNA. Therefore, focusing on the nucleotide sequence encapsulates the essence of genetic distinction among species.