The motor (somatic nervous) system can alter the activities of its targets, the skeletal muscle fibers, because .

“in 1492 columbus sailed the ocean blue” is an example of: a)explicit memory b) procedural memory c) semantic memory d)episodic memory

When the cell concentrates potassium within, against the natural tendency of matter, it is performing a. passive diffusion b. facilitated diffusion c. active transport d. pinocytosis

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?