When huge numbers of species die out in a short period of time, it's known as a mass extinction.
a. true
b. false

Natural selection changes allele frequencies because some survive and reproduce more successfully than others.

About how many years does it take for one cycle of surface water to become deep water and then surface water again in the oceans? 101001,000

In response to framton's dialogue about his health issues, mr. sappleton replies: "no? " said mr. sappleton, in a voice which only replaced a yawn at the last moment. then she suddenly brightened into alert not to what framton was saying. what does this statement reveal about how mrs. sappleton feels about framton? a) she finds him boring. b) she's happy he came by. c) she finds him annoying. d) she feels sorry for him