Which food contains the material needed to build muscle, but does not contain the macromolecules that give quick energy?
a. steak
b. broccoli
c. bread
d. potatoes?

Scientists discover two populations of mice on either side of a major river. the two populations have almost identical genes but the mice from one side cannot breed with mice from the other. this is most likely because

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

Which line in the graph above best illustrates an effect of the carbon dioxide level in the blood on breathing rate before, during and after a period of exercise? 1.b,2.c,3.a,4.d