for correct answer, ) in cattle, a single gene with two alleles determines fur color. the fur can be red, white, or roan. roan fur has both red and white hair. which of the following is true about alleles for fur color in cattle? the allele for roan fur color is dominant over red and white fur color. the allele for red fur color is dominant over white and roan fur color. the roan and white alleles are expressed independently of the other. the red and white alleles are expressed independently of the other.

Astudy by solloch and et. al., in 2017, gives the map above which shows the frequency of alleles with a ccr5-delta32 mutations over 87 different countries. this mutation deletes the presence of a co-receptor (ccr5) on the outside of human t-cells (lymphocytes). some viruses, such as the one responsible for the black death and human immunodeficiency virus (hiv), require this receptor for attachment to host cells during the infection process. the black death was an epidemic that passed over northern europe during the 14th century killing nearly 60% of europeans. according to this information, which explanation best explains why northern europeans show a greater immunity for hiv than some other parts of the world?