Calculate the frequency of b cells specific for antigen a on day 36 if the antibody concentration on day 36 is about 8 × 103. (for practice doing calculations with proportions, try this exercise. for practice doing calculations with numbers written in scientific notation, try this exercise.)

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.