When the cell concentrates potassium within, against the natural tendency of matter, it is performing
a. passive diffusion
b. facilitated diffusion
c. active transport
d. pinocytosis

Which of the following is the best definition of a eukaryota? a. a one-celled organism that does not have a membrane-bound nucleus b. a one-celled organism that does not have a cell wall c. an organism whose cells each contain a membrane-bound nucleus d. an organism whose cells each have a cell wall