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Animial Biology


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Life on Earth originated
3.5 and 4.0 bya(billion years ago)
Earth formed
4.5 bya
Oldest fossils of prokaryotes
3.5 bya
Towo domains of Prokaryotes
Archea and Bacteria
Tpyes of prokaryotes living near hrothermal vents and in shallow water communities that left fossils
Oxygen accumilated in the atmosphere
2.7 bya
Eurkaryotic life began
2.1 bya
Oldest fossils of eukaaryotic cells
2.1 bya
Eukaryotic cell evolveed from
Prokayotic ancestor that hosted smaller internal prokaryotes
Multiceluar eukaryotes evolved
1.2 bya
Oldest fossils of animals
600 mya
Animal diversity exploded (when?)
Cambrian period 540-520 mya
Plants, fungi and animals colonized the land
about 500 mya
Symbiotic relationship (between what two forms?) contributed to the move onto land
Plants and Fungi
The fisrt cells have originated
by chemical evolution on a young Earth (an overview p. 516 figure 26.9)
Life today arises from
Abiotic synthesis of organic momomers is a testable hypothesis
Lab experiments performed under conditions stimulating those of the primitive Eart have produced diverse organic molecules from inorganic precursors
What might have been the first genetic material?
Protobionts cna form by self assembly
Organic molecules synthesized in the lab have spontaneously assemble into a variety of droplets with some of the properties associated with life
The main explanation for the lack of a continuing abiotic origin of life on Earth today is that
Much less visible light is reaching Earth to serve as an energy source
RNA provides the template for nucleotides to assemble into what?
Fossilized mats called Stromatolites
Date 305 bya ad contain fossils that resembl;e modern filamentous prokaryotes
The oxygen reolution changed Earth's enviroment dramatically,What adaptation took advantage of the change?
The evolution of cuelluar respiration, which used oxygen to help harvest energy from fuel molecules
The oldest known fossils of muticelluar eukaryotes
Filamentous Algae that date from 1.2 bya
Competition among various protobionts may have led to evoutionary involvement only when?
Some kind of heredity mechanism developed
Which of the following represents a probabe order in the biological history of Earth?
Metabolism before mitosis
One current debate raises the issue that, rather than beginning in shallow pols, life could have begun
Near deep sea vents
What step has not been accomplished by scientists studying the origin of life?
Formation of protobionts that use DNA to direct the polymerization of amino acids
Current debates about the number and boundaries of the kingdoms of life center mainly on which groups of organisms?
Prokaryotes and single-celled eukayotes
What was the hypothesis that Stanly Miller and Harold Urey were testing with their experiments?
That conditions on the early Earth favored synthesis of organic miolecules from inorganic ingredients
What is a ribozyme?
An RNA miolecule that functions as a catlyst.
Why wa the origin of membranes enclosing protein-nucleic acid cooperatives a key step i nthe onset of Darwinian evolution (natural selection)?
In contrast to random mingling of molecules in an open solution, segregation of molecular systems by membranes resulted in seselection for the most successoful self-replicating aggregates
Put the following events in order from the earliest to the most recent: diversification of animals (cambrian explosion), evolution of eukaryotic cells, first humans, colonization of land by plants and fungi, origin of prokaryotes, evolution of multicellu
1. Origin of prokaryotes
2. Evolution of eukayotic cells
3. Evolution of muticelluar eukayotes
4. diversification of animals (Cambrian explosion)
5. Colonization of land by plants and fungi, evolution of land animals, first humans
What is the relationship between stromatolites and microbial mats?
Stromatolites are fossils of microbial mats
What are the two taxonomic domains of prokaryotes?
Archea and Bacteria
Structure, nutrition, and life history
Define animals
Multicelluear, heterotrophic eukayotes thgest their food and lack cell walls
Whats follows the blastula, resulting in the formation of embryotic tissue layers?
What genes regulate the development of body form?
Hox genes
Animal kingdom probably evolved from what?
Colonial, flagellated protist

(colonial Choanoflagellate)
Sets of hypotheses that are rined to accomadate new data
Phylogentic trees
Traditional phulogentic trees of amimals was primarily based on grades in what?
Body Plans
Four major branchings in the animal kingdom
1. Parazoa-Emetazoa dichotomy
2. Radiata-Bilateria dichotomy
3. the presence vs absence of body cavities
4. the Protosome -Deuterostome dichotomy among animals with true coeloms
Most animal phyla originated in a relatively brief span of geologic time
The causes of the Canbrian explosion may have been one or some combination of ecological changes, or genetis changes associated with the evlution fof Hox genes
Evo-devo may clarify our understanding of the Cambiran diversification
Diversification of body plans based on the evolution of Hox genes probably accounts for the early branching of bilateria into the deuterosome and two protosome clades
The distinction between the parzoans and eumentazoans is based mainly on te absence versus the presence of
True tissues
As a group, acoelomates are characterized by
a solid body without a cavity surrounding internal organs
What is the main basis for placing the arthropods and nematodes in the Ecdysozoa?
Their SSU-rRNA sequences are quite similar and these sequences differ from those of the lophotrochozoans and deuterotomes.
How does the molecular based phylogenic tree differ from the grade-based tree?
1. placement of the acoelomates abd psudocoelomates within the Protostomia
2. division of the protostomes into clades Lophotrochozoa and Ecdysozoa
Bilateral symmetry in the animal Kindom is best correlated with
Motility and active predation and escape
A direct consequence of indeterminate cleavage is
The ability of cells isolated from the early embryo to develop into viable individuals
Which of the following was the least likely factor in the Cambrian explosion?
the movement of animals onto land
Among the characteristics unique to animals is
Which of the following combinations of phylum and description is incorrect?
Which of the following subdivisions of animal kingdom encompases all the others in the list?

e. deuterostomes
What is the function of Hox genes in animals?
They regulate the development of an embryo' body plan
Contrast the grade - based and the molecular-based phylogenies in their placement of the acoelomates (flatworms)
In the grade-based phylogeny, the aceolomate condition is considered to be primitive, and the flatworms thus moves the acoelomates up to the protosome branch, suggesting, that the acoelomate condition evolved secondarily from an encestor with a coelom.
Why have palentologists not been able to deduce the sequence of phylogentic branching among animal phyla from the fossil record?
On the vast scale of geologic time, the origins of all the anumal phyla are compressed into a very short span of time- the Cambrian explosion - thus the sequence of their appearance cannot be resolved.
Phylum Porifera
Sponges are sesile with porous bodies and choanocytes
Lack tissues and organs. They filter -feed by drawing water though pores
Endomembranes contributed to larger, more complex cells
Eukayotes may have evolved from specialized infoldings of the plasma membrane if ancestral prokaryotes
Evolved from enosybiotic bacteria
Mitochondria and plastids
Descendants of cyanobacteria and aerobic, heterotrophic prokaryotes, respectively, they took up residence within evolving eukaryotic cells
Mitochondria and chloroplasts
Eukaryotic cell is a chimera (collection) of prokaryotic ancestors
In the eukaryotic genome, some of the genes of the acestral endosymbionts have been transferred from the organelles to the nucleus
Research on the relationship between the three domains is changing ideas about the deepest branching in the tree of life
The base of the treee of life may not be represented by a "Trunk" (a singe common ancestor) but by a community in which genes were transferred extensively.
Plastids that are surrounded by more than two membranes are evidence of
secondary endosymbiosis of an algal protist by a hetertrophic protist, which left the new endosymbiont wrapped in vacuole membrane
Parasites of animals
Parasites disseminate as tiny infections cells
Aquatic photoautotrophs
The geleral term for the class of eurkaryotic organelles that includes chloroplasts, as well as other types of plastids both photosynthetic and nonphotsynthetic
The theory that proposes that mitochondria and chloroplasts were formerly small prokaryotes living with larger cells
Serial endosymbosis
Cell that lives with in another cell called the host cell
The gene of small robosomal subunit (SSU-rRNA)
Present in all organisms
Plastids of some algal groups, those with envelopes having more than two membrances wee acquired by
Secondary endosymbiosis
Eukayotes first acquired the ancestors of plastids by engulfing cyan bacteria
Primary endosymbiosis
Green algae and plants evolved from a sommon photoautrophic ancestor
Red algae lack flagella
Simplest chlorophytes are biflagellated unicells which resemble gametes and zoospores of complez chloroplasts
Cellular extensions
Actinpoda ("Ray Foot")
Heliozoans and Radolarians
A reference to the slender psudopodia that radiate from these exceptionally beautiful protists
Sun animals live in fresh water
Several groups of mostly marine actinpods with skeletons fused into one deicate piece, most commonly made of silica
All Marine, 90 % of all identified species are fossils, porous shells
Forams, Foraminifera
Feeding stage if the life cycle ia na amoeboid mass
Plasmodial slime molds
Stinging capsules
Phyla Cnidaria
Have radial symmetry, a gastrovascular cavity and cnidocytes
Phylum Ctenophora
Comb jellies posses rowss of ciliary plates and adhesive colloblasts

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