When does the cell have to use active transport

a) when the cell is low on energy

b) when the cell is in a highly concentrated solution

c) to move molecules across the membrane quickly

d) to move molecules across the membrane against a gradient

Which of the following matches the organisms described with the correct domain? a. archaea--multicellular, eukaryotic organisms that do not have cell walls b. eukarya--single-celled and multicellular organisms, with a defined nucleus and a variety of nutritional sources c. bacteria--unicellular, eukaryotic organisms with cell walls that do not contain peptidoglycan d. bacteria--unicellular, eukaryotic organisms that always lack cell walls