Final answer:
Transposons are repetitive sequence DNA that can make up a significant percentage of non-coding DNA in eukaryotic genomes. They are often considered selfish genes or DNA, as their main purpose is self-replication.
Step-by-step explanation:
Transposons are a type of repetitive sequence DNA that make up a significant percentage of non-coding DNA in eukaryotic genomes. While the exact percentage varies between species, transposons can range from as low as 4% to as high as 70% of the genome. These transposable elements are often considered as selfish genes or selfish DNA, as they primarily replicate themselves and do not have a known function beyond that.