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Biology Sheet #1
| Question | Answer |
|---|---|
| factors preventing evolution: maintaining stability of the gene pool | -all mating is random -isolation from other populations of the same species -large population size -no gene mutation -lack of selection pressure (when the gene has no effect on survival or reproduction) |
| factors causing evolution: disturbing stability of the gene pool | -gene mutation (infrequent but inevitable) -gene flow (immigration/emigration) natural selection -genetic drift |
| gene mutations | heritable changes in DNA that give rise to altered gene products |
| can mutations be predicted? | no |
| how many gametes in a single reproductive season has a new mutation rate? | 100,000 in 1,000,000 |
| what can mutations cause? | changes in structure, function, or behavior |
| types of mutations | -lethal, if it has drastic effects -beneficial, when adds an advantage to the individual (eg. mutated corn growing faster) |
| mutation rates | number of events that produce mutated alleles per locus per generation |
| locus | position occupied by a gene on a chromosome |
| factors influencing mutation rate | -size of gene (larger genes = bigger target for mutation) -nucleotide sequence (repeats more likely to be mutated) -spontaneous chemical changes (GC bases more prone) -environmental factors (radiation and chemicals) -radiation -chemicals |
| emigration | individuals leave population |
| immigration | new individuals enter a population |
| gene flow | physical flow of genes |
| what does gene flow do? | helps keep separate populations genetically similar (ex. human population) |
| gene drift | random change in gene frequencies over generations |
| how is gene drift brought about? | by change only |
| founder's effect | when few individuals leave a population and establish a new one elsewhere |
| bottleneck effect | it is a severe reduction in population size brought about by intense selection pressure or natural calamity (ex. loss of habitat, contagious disease, volcano, hunting) |
| natural selection | -survival of the fittest -the outcome of difference in survival and reproduction among individuals that show variation in heritable traits |
| over generations, what does natural selection lead to? | increased fitness or an increase in adaptation to the environment |
| types of natural selection | -stabilizing -directional -disruptive -sexual -frequency dependent |
| evidence of ancient life | comes from fossils containing layers of sedimentary rocks over vast areas |
| geographical distribution of species | many similarities between animals from different continents show that animals must have evolved on the same land mass-part of early super continent - gondwana, earlier called pangea |
| theory of continental drift | over the past 3.8 billion years, changes in land, ocean, and atmosphere profoundly influenced the evolution of life (geographical distribution changes) |
| embryology | the early embryo of vertebrates strongly resemble one another because they have inherited the same ancient plan of development |
| homologous structures | similarity in one or more body parts in different organisms (ex. vertebrate forelimb) |
| biochemistry | biochemical similarities in DNA/RNA/proteins are greatest among the closely related species and weakest among the most distantly related |
| evidence for theory of evolution | -evidence of ancient life -geographical distribution of species -embryology -homologous structures -biochemistry |
| fossils | stone hard physical evidence of ancient life that are present in sedimentary rock with the deeper the layer resembling older fossils |
| fossilization | a slow process that starts when an organism of its traces become buried in volcanic ash or in sediments at the bottom of lakes, lagoons, or seas |
| where are similar fossils found? | similar fossils containing layers of sedimentary rock are found over vast areas, even on different continents |
| stratification | the layering of sedimentary deposits |
| Darwin's theory of evolution | -4 facts -2 deductions |
| 4 facts of Darwin's theory of evolution | -great prolificity in nature -no of individuals of a species remains constant over time -resources of earth are limited -individual variation is the raw material for evolution |
| 2 deductions of Darwin's theory of evolution | -struggle for existence, food, light, and, water -survival of the fittest occurs through the mechanism of natural selection |
| how much DNA is shared between monkeys and humans? | 99% of genes are shared. chimpanzees are closer to us than gorillas |
| how many kingdoms did Linnaeus originally propose? | 2 - plants and animals |
| whittaker's five kingdoms | -monera -protista -fungi -plantae -animalia |
| woese's three kingdoms | -eubacteria -archaebacteria -eukaryotes |
| monera | single celled organisms (bacteria) |
| protista | single celled or multi celled eukaryotes with greater internal complexity compared to bacteria |
| fungi | -multi celled eukaryotes -feed by digestion -decomposers, pathogens, parasites |
| plantae | -multicellular -eukaryotes |
| archaebacteria | -single celled prokaryotes -thrive in unusually harsh places like hot water near volcanos -differ from typical bacteria in chemical composition (cell wall and membrane characteristics) |
Created by:
studystack_0325