Based on interpretations of rock units and changes in fossil life forms, geologists have dived earths history into manageable units that are represented by the a. geologic time scale b. fossil time scale c. geographical time scale d. precambrian time scale

What is the significance of the protein-lined pits? a. protein attracts other proteins needed for atp synthesis within the cell. b. protein-lined pits are able to transport one molecule at a time down the concentration gradient within the cell. c. the polarity of proteins allows other polar molecules to attach and be transported in the cell by transport channels. d. receptors within the pits allow ligands to fuse and be transported into the cell by endocytosis.