10. The Production Possibilities Curve or Frontier illustrates both the economic concepts of scarcity and opportunity cost. O Agree
Disagree

Which of the following particles always has a positive charge? a. electronb. neutron c. proton d. ion

Molecules like glucose and amino acids are not lipid soluble, so cannot cross the cell membrane by simple diffusion. instead, they are shuttled across by carrier proteins in the membrane from high to low concentration. does this process require energy from the cell? this is an example of what type of molecular movement?

Scientists discovered fossils in several layers of the earth you see here. they found fossils of algae, snails, and clams in layer d. given that information, where do you think they found fossil evidence of simple land plants and amphibians? a. a b. e c. f d. g