The CCR5-delta 32 gene provided immunity to a deadly disease of bacterial origin, bubonic plague. . People who are homozygous for the CCR5-delta 32 gene variant are completely immune, while heterozygotes only have partial immunity and homozygous recessive have none.

hope this !

i took a test for bio that had this question and these were the correct answers, not sure if this is any now lol

the nervous system and the muscular system work together.  

sweat reaches the surface of the skin and evaporates into the air.

muscles underneath the skin relax, causing hair on the skin to lay flat.