Genome size differs widely among different multicellular species of eukaryotes. What is the greatest contributing cause for these differences?
A) The number of protein-coding genes
B) The amount of noncoding DNA
C) The number of duplicated genes
D) The degree of concerted evolution
E) The amount of positive selection for change in protein-coding genes

Question

Quizplus · Accepted Answer

Noncoding DNA, also known as "junk DNA," makes up a significant portion of the genome and does not encode proteins. This noncoding DNA varies in amount among species and is believed to be a major contributor to the differences in genome size. As noncoding DNA accumulates over time, it can result in larger genomes without affecting the number of protein-coding genes. Thus, the amount of noncoding DNA is likely a major contributing cause for differences in genome size among multicellular eukaryotes.

Genome Size Differs Widely Among Different Multicellular Species of Eukaryotes