Final answer:
The presence of 20,000 protein-coding regions suggests that the organism's genome contains this number of segments that provide instructions for making proteins, with each potentially leading to several different proteins due to splicing and other processes.
Step-by-step explanation:
When the genome of a particular species is said to include 20,000 protein-coding regions, it implies that there are 20,000 segments of DNA that provide instructions for making proteins. However, this does not mean that each gene codes for only one protein. Through processes like splicing, a single gene can code for multiple proteins. Furthermore, not all DNA sequences within a genome code for proteins; some play roles in regulation and stability of the genome. It is also incorrect to assume that regions not coding for proteins are 'junk' DNA, as they may have regulatory functions or be involved in creating types of RNA other than mRNA. Thus, while there may be 20,000 protein-coding genes, the entire genome includes both coding and non-coding regions, contributing to the organism's complexity.