Abiologist is studying bacteria that can live in very salty environments

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?

The smallest parts of these that retain their original properties are called

Mendel made crosses between pure-breeding y’all pea plants with purple flowers and pure-breeding short pea plants with white flowers. the alleles for a y’all height and purple flowers were dominant. this cross is written a. ttpp x ttpp b. ttpp x ttpp c. ttpp x ttpp d. ttpp x ttpp