In 2007, a radio station based in Sacramento, CA had a contest titled: "Hold Your Wee for Wii". At the time, Nintendo Wii’s were very popular and nearly impossible to find in stores. About 20 contestants came into the station and were given 8oz of water every 15 minutes. Whoever could hold their wee the longest, won the Nintendo Wii. Tragically, a woman died during the competition due to a condition known as hyponatremia. Hyponatremia a disturbance in brain functions resulting from over-hydration in which essential electrolytes are pushed outside the cell. On a cellular level, explain what happens during these circumstance using the proper vocabulary.

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?