Animals are distinguished from other groups of eukaryotic organisms in that they: (Select all that apply.)

a. produce collagen.
b. have embryos that include a gastrula stage.
c. are multicellular heterotrophs lacking cell walls.
d. are mobile.

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.