Term
| How are animal tissues strengthened? |
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Definition
| have extracellular matrix instead of cell wall |
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Definition
| multicellular, heterotrophic eukaryotes |
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| common features of animal development |
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Definition
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Definition
| a hollow ball of cells in early development |
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Definition
| A blastula with an infolded layer of cells (early development) |
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Definition
| contain homeoboxes and are homeotic in function. function during development to specify features of an animal's body plan |
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Term
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Definition
| 180bp sequence of DNA that encodes a 60 amino acid homeodomain of a protein: three alpha-helices that can bind to a domain |
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Definition
| a gene that determines the placement and identity of body parts |
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Definition
| regulators of the transcription of genes |
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Definition
| no tissues (sponges, placozoans) |
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Definition
have tissues
can be radially or bilaterally symmetrical |
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Term
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Definition
| has 2 germ layers in embryo: ectoderm and endoderm |
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Term
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Definition
| 3 germ layers in embryo: ectoderm, endoderm and mesoderm |
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Term
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Definition
| found in triploblastic eumetazoans. important for muscle production |
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Term
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Definition
| associated with cephalization and motile animals |
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Term
| what is the significance of bilateral symmetry to the lifestyle of an animal? |
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Definition
| associated with cephalization (clustering of sensory apparatus, weapons and neurons in the anterior end). This suits an animal that is mobile and must deal with threats and opportunities that come from the direction in which it is moving |
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Term
| What is the difference between a homeotic gene and a Hox gene? |
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Definition
| A homeotic gene is a gene that controls the identity of body parts. A Hox gene is a gene that contains a homeobox (a certain DNA sequence) and that is homeotic in function. Hox genes are characteristic of animals; outside the animal kingdom, there exist genes with homeoboxes, but they are not homeotic in function, and homeotic genes, which do not contain homeoboxes. |
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Term
| Would you expect an acoelomatous worm to have a blood vascular system? |
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Definition
| No, you would not. In an acoelomate the mesoderm forms a solid mass of cells, and there is no room for the differentiation of separate organs or other structures, such as a blood vascular system, within this mass. |
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Term
| Suppose you dug up a fossil which your geologist friend estimates to be 700 million years old. What features would you look for to classify it as an animal and not an alga? |
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Definition
| You would expect the organism to be multicellular and to lack cell walls. Traces of cell walls persist in fossilized organisms much better than does the matrix that holds animal cells together in tissues, so it might be possible to determine the presence or absence of walls in your fossil. Also, if your fossil had a worm-like morphology, as many groups of animals do, that would strongly suggest that it was an animal and not an alga |
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Term
| Why, evolutionarily speaking, do animals have intercellular junctions unlike those of other organisms, such as algae, plants, and fungi? |
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Definition
| A reasonable hypothesis is that the common ancestor of animals, plants and fungi was unicellular, as was the later common ancestor of animals and fungi. Multicellularity evolved independently in each group after divergence occurred. It would not be surprising, therefore, if the structures that evolved in each lineage to serve the functions of support and communication between cells were different |
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Term
| Why are the Doushantuo fossils suspected to be animal embryos? |
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Definition
| They are composed of cells that become smaller the more numerous they get. This is an attribute of early animal embryos today |
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Definition
| the anterior concentration of neural processing power, sensory apparatus, and sometimes weapons |
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Definition
| One mouth (early development) |
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Definition
| two mouths (early development) |
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Term
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Definition
early cleavage products lose the ability to form complete embryos by themselves
when the cell begins to divide, the daughter cell is limited. If parts are missing, it will not develop fully |
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Term
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Definition
| early cleavage products can form complete embryos by themselves |
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Definition
| coelom is lined with mesoderm only |
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Definition
| lined with endoderm and mesoderm |
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Definition
| no coelom; mesoderm forms a solid mass of cells |
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Term
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Definition
provides space for the development of organs
cushions organs and allows independent movement of organs
allows for development of a blood vascular system
can serve as hydrostatic skeleton
separates gut muscles and body wall muscles
coelomates can be larger and more active than acoelomates |
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Term
| what is the closest relative to animals still alive today? |
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Definition
| Choanoflagellates. They have cells similar to choanocytes (collar cells) found in sponges |
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Definition
600-570 million years ago.
found in China about twenty years ago
look like animal embryos
cells become smaller as they become more numerous |
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Term
| 830-635 million years ago |
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Definition
| early animal evolution might have been stimulated by the end of the Snowball Earth phase |
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Term
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Definition
585-542 million years ago
the first multicellular organisms
looked like sponges, cnidarians (radially symmetric), molluscs, echinoderms, worm tracts |
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Term
| by what time were half of the animal phyla on Earth today represented? |
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Definition
| the Cambrian explosion (542-525 million years ago) |
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