Cell wall protects the cell from bursting or shrieking. (maintains the shape of a cell) While cell membrane regulates the entry of substances into the cell and exit from the cell wall.
The precambrian era makes up about 90% of the earths history, but there was little to no living organisms at the time other than microscopic ones. The first eukaryotes were found in the cambrian period after the precambrian period, not only that but at the end of the precambrian era in the Proterozoic era there was a mass extinction of about 70-80% of all living organisms
C. to determine the compatibility of antibodies of donor and recipient.