In which of the following ways does the plasma membrane regulate the entry of molecules into a cell? a) the membrane allows only certain molecules to movie into the cell b)the membrane destroys most molecules so that they do not enter the cell c) the membrane changes only certain molecules into ions before they move into the cell d)the membrane allows most molecules to transfer energy into the cell without entering the cell

Which of these is true of the cytoplasm of an unfertilized egg? a. it is an unevenly distributed mixture of mrna, proteins, organelles, and other substances. b. it does not contain substances that are important in directing development. c. these substances are supplied by the sperm. d. it does not contain substances that are important in directing development. e. development is directed solely by the surrounding cells. f. it is a homogeneous mixture of mrna, proteins, organelles, and other substances. g. it does not contain substances that are important in directing development. h. these substances are produced by the dna of the fertilized zygote.