If two genes are completely linked, what is their expected behavior during gamete formation?

When two genes are completely linked, they are located very close to each other on the same chromosome. This proximity means that during meiosis, the process that leads to gamete formation, these genes are passed on together as a single unit rather than assorting independently.

Typically, the principle of independent assortment states that genes located on separate chromosomes will segregate independently into gametes. However, when genes are linked, they do not follow this pattern; instead, the alleles of these genes are inherited together, leading to gametes that carry only the combinations of alleles that exist on the parental chromosomes.

This lack of independent assortment is why the correct answer indicates that completely linked genes do not assort independently, resulting in a distinct inheritance pattern compared to unlinked genes. The other choices do not accurately reflect the behavior of linked genes: independent assortment refers to unlinked genes, the 9:3:3:1 ratio pertains to a dihybrid cross of unlinked genes, while incomplete dominance describes a different phenomenon in phenotypic expression rather than genetic linkage.