Campbell Biology Chapter 32 | Questions and Answers with complete solution

animals - multicellular, heterotrophic eukaryotes with tissues developed from embryonic layers collagen - the most abundant structural protein that helds together the animal cells cleavage - The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane; specifically, the succession of rapid cell divisions without growth during early embryonic development that converts the zygote into a ball of cells. blastula - The hollow ball of cells marking the end stage of cleavage during early embryonic development gastrulation - developmental process in which three distinct cell layers form in an embryo: the endoderm, mesoderm, and ectoderm gastrula - a stage of embryonic development characterized by the differentiation of the cells into the ectoderm and endoderm germ layers and by the formation of the archenteron larva - A free-living, sexually immature form in some animal life cycles that may differ from the adult in morphology, nutrition, and habitat. metamorphosis - the marked and rapid transformation of a larva into a juvenile, which resembles the adult but is not yet sexually mature. Hox genes - Series of genes that controls the differentiation of cells and tissues in an embryo choanoflagellets - closest living relatives to the animalia Ediacaran biota - An early group of soft-bodied, multicellular eukaryotes known from fossils that range in age from 565 million to 550 million years old.