Acell must expend energy to transport substance using
a. a cell membrane pump b. facilitated diffusion c. ion channels d. osmosis

What factors contribute to the effect an environmental toxin has on the human body?

This is an active transport mechanism by which cells pump sodium and potassium ions against the concentration gradient

Prokaryotic and eukaryotic cells are different in many ways other than the presence or absence of a nucleus. if both archaebacteria and eubacteria are prokaryotic cells, then why are archaebacteria more closely related to eukaryotic cells than they are to eubacteria?