What is the function of the system shown below? * A. The digestive system takes in oxygen and releases carbon dioxide.
B. The digestive system controls hormones for growth, reproduction and nutrient use.
C. The digestive system takes in food, reduces food into smaller nutrients for absorption in the body.
D. Attaches to the bones to help the body move.

How are gene and protein sequences used to classify organisms?

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 arrows in the illustration point to