Two genes, A and B, each with two alleles, control cucumber fruit color. In examining the results of genetic crosses, you find that the following genotypes are associated with specific colors: AllA or Aa produces white, ala; B/B or ala; B/b produces yellow and ala; b/b produces green cucumbers.
A. Determine the genotypes, phenotypes and phenotypic ratios of the P1 and F1 when two doubly heterozygous plants are crossed.
B. What type of gene interaction is illustrated in this cross?
C. Which allele is masking the expression of which allele?

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?