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24 Cards in this Set

  • Front
  • Back
What broad characterisics define animals?
Nutritional Mode
Cell Structure
Cell Specialization
Reproduction and Development
Describe the nutritional mode of animals.
Chemoheterotrophs with internal digestion (ingestive nutrition)
Describe the differences of animal cells to other organisms.
Lack cell walls; held together with structural proteins (collagen) or by junctions (tight, gap)
What specialized cells define animals?
Nerve and Muscle cells
When did animals arise?
800 million-1.2 billion years ago
What fossil assemblages document the origin and early diversification of animals?
(What are they, what period to they cover, and what types of animals are found in each fossil record?)
Doushantuo Fossils: Pre-Cambrian, microscopic marine organisms
Ediacaran Fossils: Pre-Cambrian, soft-bodied animals
Burgess Shale Fossils: Cambrian, all major phyla
What does Gould mean in his quote: "Three billion years of unicellular, followed by five million years of intense creativity and then capped by more than 500 million years of variation on set anatomical themes?"
Life began as unicellular and remained that way for the majority of life, then experienced a massive diversification in the Cambrian explosion, and became mere modifications to the original designs, since nearly all phyla were in place.
What is the Cambrian Explosion and when did it occur?
Cambrian explosion: the sudden appearance of many different phyla in the geologic record; reflects a sudden dramatic increase in diversity of animals; occured 542-521 million years ago.
Outline the Ecological, Genetic, and Geological Explanations for why the Cambrian Explosion occured when it did. Are these mutually exculsive or could more than one factor be operating at once?

Resource competition; terrestrial niches empty and waiting to be filled
Predator-prey relationships; natural selection increases
Mass extinctions

Evolution of Hox Genes

Climate Change
Atmospheric Change (more available oxygen after plant colonization of land)

What are Hox genes? What is their function with respect to body plan development? How do they contribute to the diversification of animal body plans?
Hox genes: homeobox containing genes regulating development of body segments
Homeobox: 180 bp DNA sequence in genes regulating development; give rise to transcription factors that bind to other genes responsible for development
Location on chromosome determines location of body part
Why don't we continue to see the generation of new animal phyla like we did in the Cambrian Explosion?
Niches filled; hard for another phyla to evolve when there are no niches available.
What are choanoflagellates and what is their relationship to animals?
Phylum Choanoflagella; multicellular protists, closest living relative to animals
Describe the characteristic early developmental pattern of animals. Do all animals follow this pattern?
Sperm-egg fertilize; zygote
Zygote cleaves/blastulates; blastula
Blastula gastrulates; gastrula

All animals follow pattern
What is meant by body symmetry, radial symmetry, and bilateral symmetry? How does body symmetry correlate with lifestyle?
Radial symmetry: animal parts radiate from a central axis; mostly sessile or planktonic animals
Bilateral symmetry; animal parts form two chiral halves; mostly free-living animals
In what ways do the traditional phylogeny of animals based on morphology/embryology and the molecular phylogeny of the animal kingdom agree and disagree?

1. All animals share a common ancestor
2. Sponges are basal animals
3. Eumetazoa is a clade of animals with true tissue
4. Most animals belong to the clade Bilateria
5. Vertebrates and some other phyla belong to the clade Deuterostomia

Disagreement: Relationship among Bilateria
Morphological/embryological cladogram two divisons: protostomes and deuterostomes
Genetic cladogram three: protostomes, ecdysosomes, locotrophozoans
What percentage of animal diversity is composed of invertebrates? What percentage of diversity of life is composed of arthropods
95% invertebrates
85% arthropods
What is the basic body plan of echinoderms, and how do the various classes within this phylum represent variations on this common body plan?
Five-point body plan
What are the four uniting characteristics of chordates? Do humans exhibit these four defining characteristics?
Pharyngel Gill Slits/Clefts
Dorsal Hollow Nerve Chord
Postanal Tail

Humand display characteristics while in developmental stages
What ancestral chordate feature gave rise to the vertebral column? To jaws?
Vertebral column arises from notochord; jaws arise from modifications to skeletal rods supporting pharyngeal gill slits
When did primates evolve? What are examples of the most primitive primates today?
45 million years ago; Lemurs, Lorises, Pottos, Tarsiers
What primates constitute the hominoids? How long ago did hominoids arise?
Constituted by great apes; Giabbons, Orangutans, Gorillas, Chimpanzees, Bonobos, and Humans

Arose about 20-25 million years ago
When did hominids split from the great apes?
7-6 million years ago
What is the closest LIVING relative of Homo sapiens? What is thought to be the CLOSEST RELATIVE of Homo sapiens?
Living: Chimpanzees (1.2% difference)
Closest relative: Homo Erectus
How can we tell if a fossilized skeleton exhibited bipedlaism?
Bone structure of pelvis and legs; entrance of vertebral column