Why do cells have plasma membrane? a. to separate the inside of cell from its environment b. to separate proteins from the nucleus c. to define the size of cell d. to distinguish plants from animals

cramming before a final is bad because it makes a student's stress level higher. students who embrace cramming to get through a final exam week find themselves struggling to perform consistently, once the brain adjusts to prolonged sleep deprivation.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.