Final answer:
A chromosome in which the number of copies of a gene increase from one to two is said to have a gene duplication. Gene duplication occurs when a segment of DNA is repeated, resulting in multiple copies of a gene in the chromosome.
Step-by-step explanation:
A chromosome in which the number of copies of a gene increases from one to two is said to have a gene duplication.
Gene duplication occurs when a segment of DNA is repeated, resulting in multiple copies of a gene in the chromosome. This can lead to genetic variation within a species due to the presence of different versions of the duplicated gene.
For example, in humans, the gene sequences that code for blood type can have two copies of the same sequence (e.g., AA or OO) or two different sequences (e.g., AB). This is a result of gene duplication and the presence of multiple copies of the gene on homologous chromosomes.