When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply? A) There are 20,000 genes. B) Each gene codes for one protein. C) Any other regions are "junk" DNA. D) There are also genes for RNAs other than mRNA. E) The species is highly evolved.

C

Explanation:

DNA especially I higher organisms contains coding and non-coding regions. Some of these non-coding DNA is transcribed into non-coding RNA such as regulatory RNA and t-RNA. These non-coding regions also form parts of centromeres and telomeres. It has been discovered that humans DNA has a lot of non-coding DNA.

The correct answer is: D) There are also genes for RNAs other than mRNA.

Explanation:

If the genome of a species has 20,000 protein-coding regions, this implies that there are regions with genes that do not code for proteins, but for other RNA molecules (like rRNA, which forms the ribosomes, and tRNA - both important elements in the process of translation).

Just because there are 20,000 protein-coding genes, it doesn't mean that there aren't any other genes. Most genomes are composed of coding regions and non-coding regions - and some coding regions may code to things that are not proteins as well! So option A is incorrect.

There are 20,000 genes that code for proteins in this species, but there's no data about how many proteins this species has. 1 gene can be used to synthesize different proteins. Option B is incorrect.

Even if there are 20,000 protein-coding regions, there's no evidence in the nature of the rest of the genes, so they could be coding or non-coding genes. Option C is incorrect.

Just because a species' DNA has many regions that code for proteins, it doesn't mean that is highly evolved.