Susan suffered from a heart attack. When the doctors tested the heart muscle they found that she had an increased ratio of lactic acid to pyruvic acid in her heart tissue. What does this say about
the availability of oxygen in her heart muscle cells?

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.