Petrification occurs a. shell, bone, or wood is replaced with dissolved minerals. b. dead organisms are exposed to oxygen and calcium carbonate. c. a cast fossil is later filled with minerals. d. an organism is completely preserved in ice or oil.

Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins

The arrows indicate the direction of wind flow. which place experiences monsoons?

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.