What caused the earth to separate into layers

Which of the following is a common response to cell signaling?

The first generation of offspring from the cross of two parents is called the a. f1 generation b. f2 generation c. short generation d. p generation

Ascientist is designing an investigation to study the impact of invasive bird populations on local, native bird populations at backyard bird feeders. what population is most likely to be a control group for the investigation? amount of food number of bird feeders invasive bird populations local backyard birdfeeders without food