Which traits are characteristic of multicellular organisms? choose all answers that are correct.
a. different cells for different functions
b. develop into specialized cells after they are formed
c. all cells are smaller than those of single-celled organisms
d. all cells are the same size and shape

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.