What percent of species become extinct when mass extinction occurs?
a)About 30%
b)About 50%
c)About 70%
d)About 80%

How does the nervous system affect the excretory system?

The many stone tools, fragmentary animal bones, and teeth found at gran dolina, spain, indicate that hominids there? a. processed and consumed animals and other hominids. b. did not differ appreciably from earlier asian homo erectus. c. were similar to later homo sapiens. d. none of the above

Which of th following is needed for cellular respiration to occur