| 957935130 | animal cells are held together by this most abundant structural protein | collagen | | 0 |
| 957935131 | fertilization of animal eggs forms a diploid structure known as this | zygote | | 1 |
| 957935132 | after fertilization, a zygote undergoes this process, a succession of mitotic cell divisons without cell growth | cleavage | | 2 |
| 957935133 | cleavage leads to this multicellular stage | blastula | | 3 |
| 957935134 | this stage in animal development resembles a hollowed ball of cells | blastula | | 4 |
| 957935135 | in this process in animal development, layers of embryonic tissues that will develop into adult body parts are produced | gastrulation | | 5 |
| 957935136 | when embryonic tissues are produced in animal development, this stage is achieved | gastrula | | 6 |
| 957935137 | this is a sexually immature form of an animal that is morpologically different from the adult, may eat different food, and may have a different habitat | larva | | 7 |
| 957935138 | animal larvae undergo this process that turns the animal into a juvenile, but does not sexually mature it | metamorphosis | | 8 |
| 957935139 | these genes play important roles in development of animal embryos and controlling the expression of other genes | Hox (genes) | | 9 |
| 957935140 | these are likely the closest living protist relatives of animals | choanoflagellates | | 10 |
| 957935141 | these cells of sponges are nearly indistinguishable from choanoflagellates | choanocytes (collar cells) | | 11 |
| 957935142 | this is another name for choanocytes | collar cells | | 12 |
| 957935143 | this geologic era took place 1 billion to 542 million years ago | neoproterozoic era | | 13 |
| 957935144 | the first accepted macroscopic fossils of animals were found to be in this geologic era | neoproterozoic (era) | | 14 |
| 957935145 | the oldest animal fossils are members of this early group of multicellular eukaryotes | Ediacaran biota | | 15 |
| 957935146 | the Ediacaran biota existed during this geologic era | neoproterozoic (era) | | 16 |
| 957935147 | this geologic era took place 542 to 251 million years ago | paleozoic (era) | | 17 |
| 957935148 | animal diversification accelerated dramatically during the beginning of this geologic era | paleozoic (era) | | 18 |
| 957935149 | a rapid acceleration of animal diversification occurred during this geologic period | Cambrian (period) | | 19 |
| 957935150 | the rapid acceleration of animal diversification occurring 535-525 million years ago was known as this | Cambrian explosion | | 20 |
| 957935151 | this evolutionary process between predator and prey may have caused the Cambrian explosion | coevolution | | 21 |
| 957935152 | the increase in availability of these molecules in the atmosphere may have caused the Cambrian explosion | oxygen, ozone | | 22 |
| 957935153 | the evolution of these may have provided the developmental flexibility that allowed for the Cambrian explosion | Hox genes | | 23 |
| 957935154 | this era occurred 251-65.5 million years ago | Mesozoic (era) | | 24 |
| 957935155 | few fundamentally different animal groups emerged during this era | Mesozoic (era) | | 25 |
| 957935156 | this era was defined by animal phyla spreading into new habitats | Mesozoic (era) | | 26 |
| 957935157 | this era occurred 65.5 million years ago and continues to the present | Cenozoic | | 27 |
| 957935158 | this era saw the rise of mammals | Cenozoic (era) | | 28 |
| 957935159 | this era saw the rise and fall of dinosaurs | Mesozoic (era) | | 29 |
| 957935160 | this era saw the formation of most modern animal phyla | Paleozoic (era) | | 30 |
| 957935161 | this era took place before the Paleozoic era | Neoproterozoic (era) | | 31 |
| 957935162 | this era took place after the Neoproterozoic era | Paleozoic (era) | | 32 |
| 957935163 | this era took place before the Mesozoic era | Paleozoic (era) | | 33 |
| 957935164 | this era took place after the Paleozoic era | Mesozoic (era) | | 34 |
| 957935165 | this era took place before the Cenozoic era | Mesozoic (era) | | 35 |
| 957935166 | this era took place after the Mesozoic era | Cenozoic (era) | | 36 |
| 957935167 | vertebrates made the transition to land during this era | Paleozoic (era) | | 37 |
| 957935168 | animals can be categorized into a relatively small number of major groups of these | body plans | | 38 |
| 957935169 | these are sets of morphological and developmental traits, integrated into a functional whole | body plans | | 39 |
| 957935170 | this protein marks the site of gastrulation and activates the transcription of genes necessary for gastrulation | beta-catenin | | 40 |
| 957935171 | beta-catenin activates the transcription of genes necessary for this process | gastrulation | | 41 |
| 957935172 | this is a group whose members share key biological features - it is not equivalent to a clade | grade | | 42 |
| 957935173 | this is a group that includes an ancestral species and all of its decendents | clade | | 43 |
| 957935174 | most sponges lack this characteristic in their body plans | symmetry | | 44 |
| 957935175 | this is the form of symmetry found in a flowerpot | radial (symmetry) | | 45 |
| 957935176 | sea anemones exhibit this form of symmetry | radial (symmetry) | | 46 |
| 957935177 | a shovel exhibits this form of symmetry | bilateral (symmetry) | | 47 |
| 957935178 | an animal with this form of symmetry has two axes of orientation | bilateral (symmetry) | | 48 |
| 957935179 | an animal with this form of symmetry has one axis of orientation | radial (symmetry) | | 49 |
| 957935180 | this is the top side of a bilateral animal | dorsal | | 50 |
| 957935181 | this is the bottom side of a bilateral animal | ventral | | 51 |
| 957935182 | opposite of dorsal | ventral | | 52 |
| 957935183 | opposite of ventral | dorsal | | 53 |
| 957935184 | this is the front side of a bilateral animal | anterior | | 54 |
| 957935185 | this is the back side of a bilateral animal | posterior | | 55 |
| 957935186 | opposite of anterior | posterior | | 56 |
| 957935187 | opposite of posterior | anterior | | 57 |
| 957935188 | the CNS is often concentrated at this end of a bilateral animal | anterior | | 58 |
| 957935189 | the evolutionary trend that leads to the concentration of sensory equipment being at the anterior end of animals is called this | cephalization | | 59 |
| 957935190 | this lifestyle means to live attached to a substrate | sessile | | 60 |
| 957935191 | this lifestyle is defined by drifting or weakly swimming | planktonic | | 61 |
| 957935192 | jellies have this type of lifestyle | planktonic | | 62 |
| 957935193 | sessile and planktonic animals most often exhibit this form of symmetry | radial (symmetry) | | 63 |
| 957935194 | these are collections of specialized cells isolated by membranous layers | true tissues | | 64 |
| 957935195 | these isolate true tissues from each other | membranous layers | | 65 |
| 957935196 | sponges notably lack these structures made of cells | true tissues | | 66 |
| 957935197 | these are formed during gastrulation; they are concentric | germ layers | | 67 |
| 957935198 | this is the germ layer surrounding the embryo | ectoderm | | 68 |
| 957935199 | the outer covering of an animal arises from this germ layer | ectoderm | | 69 |
| 957935200 | the CNS arises from this germ layer | ectoderm | | 70 |
| 957935201 | this is the innermost germ layer | endoderm | | 71 |
| 957935202 | this germ layer lines the archenteron | endoderm | | 72 |
| 957935203 | this is the developing digestive tube that is formed during gastrulation | archenteron | | 73 |
| 957935204 | this germ layer gives rise to the lining of the digestive tract/cavity | endoderm | | 74 |
| 957935205 | this germ layer gives rise to organs like the liver and lungs | endoderm | | 75 |
| 957935206 | animals with two layers are called this | diploblastic | | 76 |
| 957935207 | cnidarians and comb jellies are these organisms (based on its germ layers) | diploblasts | | 77 |
| 957935208 | all bilateral animals have this third germ layer | mesoderm | | 78 |
| 957935209 | all bilateral animals are these organisms (based on germ layers) | triploblasts | | 79 |
| 957935210 | this germ layer forms the muscles and bones | mesoderm | | 80 |
| 957935211 | most triploblasts have this type of space in their body plans | body cavity | | 81 |
| 957935212 | this is a fluid- or air-filled space separating the digestive tract from the outer body wall | body cavity (or coelom) | | 82 |
| 957935213 | the body cavity that separates the digestive tract from outer body wall is known as this | coelom | | 83 |
| 957935214 | a "true" coelom forms from this germ layer | mesoderm | | 84 |
| 957935215 | triploblasts that possess structures that suspend the internal organs (from mesoderm tissue) are known as these | coelomates | | 85 |
| 957935216 | a body cavity formed from mesoderm and endoderm is known as this | pseudocoelom | | 86 |
| 957935217 | triploblasts that possess structures that suspend internal organs (from both mesoderm and endoderm tissue) are known as these | pseudocoelomates | | 87 |
| 957935218 | triploblasts that do not possess a body cavity are known as these | acoelomates | | 88 |
| 957935219 | all coelomates and pseudocoelomates possess this many germ layers | three | | 89 |
| 957935220 | are the terms "coelomates" and "pseudocoelomates" grades or clades? | grades | | 90 |
| 957935221 | this type of development is indicated often by spiral cleavage | protostome (development) | | 91 |
| 957935222 | this type of development is indicated often by determinate cleavage | protostome (development) | | 92 |
| 957935223 | this type of development is indicated often by radial cleavage | deuterostome (development) | | 93 |
| 957935224 | this type of development is indicated often by indeterminate cleavage | deuterostome (development) | | 94 |
| 957935225 | this type of cleavage is indicated when planes of cell division are diagonal to the vertical axis of the embryo | spiral cleavage | | 95 |
| 957935226 | this type of cleavage is indicated when the developmental fate of each embryonic cell is rigidly cast very early | determinate (cleavage) | | 96 |
| 957935227 | cleavage resulting from parallel/perpendicular cleavage planes | radial cleavage | | 97 |
| 957935228 | cleavage resulting from the retention of the ability for each cell to develop into a full embryo | indeterminate cleavage | | 98 |
| 957935229 | examples of this development pattern include molluscs, platyhelminthes, and annelids | protostome (development) | | 99 |
| 957935230 | examples of this development pattern include echinoderms and chordates | deuterostome (development) | | 100 |
| 957935231 | protostomes have ___ and ___ cleavage | spiral, determinate | | 101 |
| 957935232 | deuterostomes have ___ and ___ cleavage | radial, indeterminate | | 102 |
| 957935233 | in deuterostomes, folds of this structure become the coelom | archenteron | | 103 |
| 957935234 | in protostomes, this structure develops independently of the archenteron | coelom | | 104 |
| 957935235 | this opening develops first in protostomes | mouth | | 105 |
| 957935236 | this opening develops second in protostomes | anus | | 106 |
| 957935237 | this opening develops first in deuterostomes | anus | | 107 |
| 957935238 | this opening develops second in deuterostomes | mouth | | 108 |
| 957935239 | this is the indentation that leads to the formation of the archenteron | blastopore | | 109 |
| 957935240 | the first opening in development is known as this; the second opening develops at the other end | blastopore | | 110 |
| 957935241 | protostomes and deuterostomes are groups within this group of animals (based on germ layers) | triploblasts | | 111 |
| 957935242 | this is the name of the clade that contains all animals | Metazoa | | 112 |
| 957935243 | all animals, except sponges, fall under this clade with true tissues | Eumetazoa | | 113 |
| 957935244 | this word means "basic"; sponges are these animals, for example | basal | | 114 |
| 957935245 | Ctenophora and Cnidaria are basal members of this clade | Eumetazoa | | 115 |
| 957935246 | the earliest eumetazoans are ___blastic and feature ___ symmetry. | diplo, radial | | 116 |
| 957935247 | these distinguish Eumetazoa from basal Metazoa | true tissues | | 117 |
| 957935248 | this is the next clade down from Eumetazoa | Bilateria | | 118 |
| 957935249 | the Cambrian explosion was primarily a rapid diversification of this clade | Bilateria | | 119 |
| 957935250 | this clade includes chordates and echinoderms and is a subdivision of Bilateria | Deuterostomia | | 120 |
| 957935251 | Lophotrochozoa and Ecdysozoa replaced this clade, as it is not considered to be monophyletic | Protostomia | | 121 |
| 957935252 | this phylum is considered a basal bilaterian | Acoela | | 122 |
| 957935253 | this clade groups animals with exoskeletons together | Ecdysozoa | | 123 |
| 957935254 | the process of shedding an exoskeleton is known as this | ecdysis | | 124 |
| 957935255 | this is a crown of ciliated tentacles that function in feeding | lophophore | | 125 |
| 957935256 | individuals in Mollusca and Annelida undergo this distinctive developmental stage | trochophore larva | | 126 |
| 957935257 | animals that either possess lophophores or undergo a trochophore larva stage are grouped in this clade | Lophotrochozoa | | 127 |
| 957935258 | * Eumetazoa is split into ___ and Bilateria | Radiata | | 128 |
| 957935259 | * Eumetazoa is split into Radiata and ___ | Bilateria | | 129 |
| 957935260 | * ___ is split into Radiata and Bilateria | Eumetazoa | | 130 |
| 957935261 | * Bilateria is split into ___ and Deuterostomia | Protostomia | | 131 |
| 957935262 | * Bilateria is split into Protostomia and ___ | Deuterostomia | | 132 |
| 957935263 | * ___ is split into Protostomia and Deuterostomia | Bilateria | | 133 |
| 957935264 | * Protostomia is split into ___ and Ecdysozoa | Lophotrochozoa | | 134 |
| 957935265 | * Protostomia is split into Lophotrochozoa and ___ | Ecdysozoa | | 135 |
| 957935266 | * ___ is split into Lophotrochozoa and Ecdysozoa | Protostomia | | 136 |
| 957935267 | * Lophotrochozoa is split into ___ and Lophophorata | Spiralia | | 137 |
| 957935268 | * Lochotrophozoa is split into Spiralia and ___ | Lophophorata | | 138 |
| 957935269 | * ___ is split into Spiralia and Lophophorata | Lophotrochozoa | | 139 |
| 957935270 | * Spiralia is split into ___ and Trochozoa | Platyzoa | | 140 |
| 957935271 | * Spiralia is split into Platyzoa and ___ | Trochozoa | | 141 |
| 957935272 | * ___ is split into Platyzoa and Trochozoa | Spiralia | | 142 |
| 957935273 | * Porifera is within this clade | Parazoa | | 143 |
| 957935274 | * Ctenophora is within this clade | Radiata | | 144 |
| 957935275 | * Cnidaria is within this clade | Radiata | | 145 |
| 957935276 | Echinoderms are within this clade | Deuterostomia | | 146 |
| 957935277 | Chordates are within this clade | Deuterostomia | | 147 |
| 957935278 | * Platyhelminthes is within this clade | Platyzoa | | 148 |
| 957935279 | * Rotifera is within this clade | Platyzoa | | 149 |
| 957935280 | * Ectoprocta is within this clade | Lophophorata | | 150 |
| 957935281 | * Brachiopoda is within this clade | Lophophorata | | 151 |
| 957935282 | * Mollusca is within this clade | Trochozoa | | 152 |
| 957935283 | * Annelida is within this clade | Trochozoa | | 153 |
| 957935284 | Nematoda is within this clade | Ecdysozoa | | 154 |
| 957935285 | Arthropoda is within this clade | Ecdysozoa | | 155 |