Contains low density minerals such as quartz

What does it mean for a cell membrane to be selectively permable

Which situation is an example of not doing work? lifting a couch throwing a baseball running up stairs carrying a box

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.