the largest extinction, measured as a percentage of species that disappeared, occurred at the end of which geological period?

i think that you are smart and you should fit for it out

yes, because even though a theory has a  lot of evidence to support it, it is not always true

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.