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In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at exhibits protostome or deuterostome development?


A) There is evidence of cephalization.
B) The animal is triploblastic.
C) The animal is clearly bilaterally symmetrical.
D) The animal's coelom develops from the archenteron.

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Which of the following characteristics is shared among animals ranging from corals to monkeys?


A) a mouth and an anus
B) number of embryonic tissue layers
C) a lack of body symmetry
D) sexual reproduction

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At one time, sponges were lumped into one phylum. Then, they were separated into several different phyla. Now, they are considered one phylum again. These changes indicate which of the following?


A) Every phylogeny should be considered a hypothesis that must be revised in the light of new data.
B) We need more fossil evidence of sponges.
C) Molecular and morphological data often conflict when we try to reconstruct evolutionary history.
D) The goal of making all taxonomic groups monophyletic is unrealistic.

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Which of the following inferences can best be made from the fact that arthropods colonized land about 100 million years before vertebrates?


A) arthropods evolved after vertebrates did
B) extant terrestrial arthropods are better adapted to terrestrial life than are extant terrestrial vertebrates
C) vertebrates evolved from arthropods
D) arthropods have had more time to coevolve with land plants than have vertebrates

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Which of the following characteristics represents the oldest branch point in animal phylogeny?


A) radial or bilateral symmetry
B) diploblastic or triploblastic embryos
C) true tissues or no tissues
D) a body cavity or no body cavity

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A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45° and to lie in the grooves between larger, underlying cells. If we were to separate these eight cells and attempt to culture them individually, then what is most likely to happen?


A) All eight cells will die immediately.
B) Each cell may continue development, but only into a nonviable embryo that lacks many parts.
C) Each cell may develop into a full-sized, normal embryo.
D) Each cell may develop into a smaller-than-average, but otherwise normal, embryo.

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The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, though some have three Hox genes. On the basis of these observations, some scientists have proposed that the ancestral cnidarian's were originally bilateral and, in stages, lost Hox genes from their genomes. If true, what would this mean regarding the phylogeny of animals?


A) all radially symmetric animals should be grouped together in one clade
B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait
C) Hox genes play little actual role in coding for an animal's "body plan"
D) cnidaria may someday replace porifera as the basal bilaterians

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Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?


A) binary fission
B) random segregation
C) the origin of Hox genes and the addition of new microRNAs
D) chromosomal condensation

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Both animals and fungi are heterotrophic. Which of the following distinguishes animal heterotrophy from fungal heterotrophy?


A) most animals derive their nutrition by preying on other animals
B) most animals derive their nutrition by ingesting materials
C) most animals derive their nutrition by consuming living, rather than dead, prey
D) most animals derive their nutrition by using enzymes to digest their food

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Evidence of which structure or characteristic would be rare to find among fossils of the Ediacaran fauna?


A) true tissues
B) hard parts
C) bilateral symmetry
D) embryos

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A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45° and to lie in the grooves between larger, underlying cells. Which of the following organisms is this embryo most likely to develop into?


A) turtle
B) earthworm
C) sea star
D) sea urchin

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The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following is most directly involved in the evolution of these variations in metamorphosis?


A) artificial selection of sexually immature forms of insects
B) changes in the homeobox genes controlling early development
C) the evolution of meiosis
D) the origin of a brain

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Which of the following processes contributed the most to the successful evolution o of the millions of animal species?


A) meiosis and sexual reproduction
B) the arrangement of cells into tissues
C) development of multicellularity
D) the formation of an embryo and establishment of a basic body plan

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Which of the following statements concerning animal taxonomy is accurate?


A) Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.
B) Kingdom Animalia is polyphyletic.
C) Animals are more closely related to plants than to fungi.
D) In the kingdom Animalia, most clades based on body plan confirm clades based on molecular data.

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Based on the tree, which statement is true? Based on the tree, which statement is true?   A)  The animal kingdom is not monophyletic. B)  The Acoela are more closely related to echinoderms than to annelids. C)  Sponges are basal animals. D)  Bilaterians do not form a clade.


A) The animal kingdom is not monophyletic.
B) The Acoela are more closely related to echinoderms than to annelids.
C) Sponges are basal animals.
D) Bilaterians do not form a clade.

Correct Answer

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The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups-Lophotrochozoa and Ecdysozoa. What does this finding suggest?


A) These two subgroups have a common ancestor that exhibited deuterostome development.
B) Division of these two groups occurred before the protostome developmental sequence.
C) Division of these two groups occurred after the protostome developmental sequence appeared.
D) The lophotrochozoans are monophyletic.

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Placing sponges as the basal metazoans on the basis of lack of tissues implies which of the following?


A) Sponge ancestors never had tissues.
B) Modern-day sponges have lost the ability to form tissues.
C) Multicellular, modern-day choanoflagellates can form tissues.
D) Sponges do not have nerve cells.

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Which of the following is an advantage of using molecular data rather than morphological data for phylogenetic analysis?


A) Molecular data can be gathered in the lab, while morphological data must be gathered in the field.
B) Molecular data is based on genetic relationships rather than morphological similarities.
C) Morphological changes usually do not result from molecular changes.
D) Some phyla vary too widely in morphological characteristics to be classified accurately.

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