Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?- gene duplicationWhatever its ultimate cause(s), the Cambrian explosion is a prime example of _____.- Adaptive radiationTriploblasts have tissues derived from three embryonic germ layers: endoderm inside, ectoderm outside, and mesoderm in the middle.The three basic body plans of triploblasts relate to the presence or absence of a body cavity.• No body cavity: acoelomate• Body cavity lined on the inner side by endoderm-derived tissue and on the outer side by mesoderm-derived tissue: pseudocoelomate• Body cavity lined entirely by mesoderm-derived tissue: coelomateOne of your answers is incorrect. Recall that a coelom is a body cavity in which internal organs are suspended.During embryological development, the anus forms before the mouth in _____.- Humans  During gastrulation, the developing digestive tube of the embryo initially has a single opening, the blastopore. After the archenterondevelops, a second opening forms at the opposite end of the gastrula. Themouth of many protostomes develops from the first opening, whereas in deuterostomes the mouth is derived from the second opening.Which tissue type, or organ, is NOT correctly matched with its germ layer tissue?- nervous – mesodermCorrect matches:  skin – ectoderm muscular – mesoderm stomach – endodermIn examining an unknown animal species during its embryonic development, howcan you be sure what you are looking at is a protostome and not a deuterostome?- You see a mouth, but not an anus.Among protostomes, which morphological trait has shown the most variation?- type of body cavity (coelom vs. pseudocoelom vs. no coelom)Soon after the coelom begins to form, a researcher injects a dye into the coelom of a deuterostome embryo. Initially, the dye should be able to flow directly into the _____.- ArchenteronIn terms of food capture, which sponge cell is most similar to the cnidocyte of a cnidarian?- ChoanocyteWhich of the following is true of annelids?- They perform gas exchange across their skin.The presence of a lophophore in a newly discovered species would suggest that the species _____.- is a suspension feederWhat would be the best anatomical feature to look for to distinguish a gastropod from a chiton?- number of shell platesNematodes and arthropods both _____.- grow by shedding their exoskeletonThe heartworms that can accumulate within the hearts of dogs and other mammals have a pseudocoelom, an alimentary canal, and an outer covering that is occasionally shed. To which phylum does the heartworm belong?- NematodaIf a tunicate's pharyngeal gill slits were suddenly blocked, the animal wouldhave trouble _____.- respiring and feedingThe earliest known mineralized structures in vertebrates are associated with _____.- FeedingThe diagnostic feature of Chondrichthyes is _____.- an endoskeleton of calcified cartilageJaws first occurred in which extant group of fishes?- ChondrichthyansLearning has the most influence on behavior when _____.- making mistakes does not result in deathWhich of the following is most likely associated with the evolution of matingsystems?- Sexual diorphismGeneralized global air circulation and precipitation patterns are caused by _____.- rising, warm, moist air masses that cool and release precipitation as they rise and then, at high altitude, cool and sink back to the surface as dry air masses after moving north or south of the tropicsIn most cases, the two major climatic factors affecting the distribution of organisms in terrestrial ecosystems are _____.- water and