EVOLUTION
1. to understand the changes in flaura and fauna that have occurred over millions of years on earth, we must have an understanding of the context of origin of life.
2.when we look at the stars on a clear night sky we are,in a way,looking back in time. 3.stellar distances are measured in light years. 4.huge cluster of galaxies comprise the universe. 5.according to the theory of spontaneous generation life came out of decaying and rotting matter like straw and mud,etc. 6.oparin of russia and haldane of england proposed that the first form of life could have from pre-existing non living organic molecules and that formation of life was preceded by chemical evolution. 7.analysis of meteorite content also revealed similar compounds as present in early atmosphere of earth indicate that similar processes are occurring elsewhere in space. 8.all early life forms originated in water environment only. 9.the first form of life arose slowly through evolutionary forces from non-living molecules. 10.different-aged rock sediments contain fossils of different life forms who probably died during the formation of the particular sediment. 11.a study of fossils in different sedimentary layers indicate the geological period in which they existed. 12.comparative anatomy and morphology shows similarities and differences among organisms of today and those that existed years ago. 13.same structure developed along different directions due to adaptations to different needs are called momologous organs. 14.homology indicating common ancestry. 15.different structures evolving for the same function and having similarity are called analogous organs. 16.similarities in proteins and genes performing a given function among diverse organisms give clues to common ancestry. 17.Excess use of herbicides and pesticides has resulted in selection of resistant varities in a much lesser time scale. 18.industrial melanism in case peppered moth support evolution by natural selection. 19.appearance of resistant microorganisms appearing in time scales of months or years represent example of evolution caused by antropogenic action. 20.evolution is based on chance events in nature and chance mutuation in the organisms. 21.gala pagos island from finches with original seed-eating features,many other forms with altered break arose,enabling them to become insectivorous and vegetarian finches. 22.placental mammals in australia also exhibit adaptive radiation in evolving in to varieties of such placental mammals each of which appears to be 'similar' to a corresponding marsupial. 23.In 1938,a fish caught in south africa happened to be a coelacanth which was thought to be extinct and those animals called lobefins evolved into the first amphibians. 24.giant ferns(pteridophytes) were present during mesozoic era ,but they all fell to form coal deposits slowly. 25.tyrannosaurus rex was about 20 feet in height and has huge fearsome dagger like teeth. 26.mammals were viviparous and protected their unborn young inside the mothers body. 27.mammals were more intelligent in sensing and avoiding danger as compared to other vertebrates. 28.when reptiles came down , mammals took over this earth. 29.due to the continental drift,pouched mammals of australia survived because of lack of competition from any other mammal. 30.the most successful story is the evolution of man with language skills and self-consciousness. 31.conventional religious literature tells us about the theory of special creation. 32.there had been extinctions of different life forms and new forms of life arose at different periods of history of earth. 33.the fitness,according to darwin,refers ultimately and only to reproductive fitness. 34.natural selection implies as a mechanism of evolution. 35.evolution by natural selection,in a true sense would have started when cellular forms of life with differences in metabolic capability originated on earth. 36.the essence of darwinian theory about evolution is natural selection. 37.some organisms are better adapted to survive in an otherwise hostile environment are selected by nature. 38.Fitness is the end result of the ability to adapt and get selected by nature. 39.according to lamarch,evolution of life forms had occured but driven by use and disuse of organs. 40.the inanimate and animate would around is only the success stories of evolution. 41.we describe evolution as a process on describing the story of life on earth, evolution is considered a consequence of a process called natural selection. 42.according to Darwin,he variations ,which are heritable and which make resource utilisation better for few will enable only those to reproduce and leave more progeny. 43.Devries had talked of inheritance 'factors' influence genotype. 44.Mutation causing evolution are the minor variations. 45.Darwinian variations are small and directional. 46.evolution for darwin was gradual while devries believed mutation caused speciation and hence called it saltation. 47.according to hardy weinberg principle allele frequencies in a population are stable and is constant from generation to generation. 48.the gene pool remains a constant and this is called genetic equilibrium. 49.factors known to affect hardy-weinberg equilibrium are gene migration or gene flow,genetic drift,mutation,genetic recombination and natural selection. 50.sometimes the change in allele frequency is so different in the new sample of population that they become a different species,the original drifted population becomes founders and the effect is called founder effect. 51.natural selection is a process in which heritable variations enabling better survival are enabled to reproduce and leave greater number of progeny. 52.natural selection can lead to stabilisation directional change and disruptional change. 53.Ramapithecus was more man-like while Dryopithecus was more ape-like. 54.Two mya,australopithecines probably lived in east african grasslands. 55.First human-like being the hominid was called homo habilis with brain capacities between 650-800cc. 56.homo erectus had a large brain around 900 cc. 57.modern homo sapiens arose during ice age between 75,000-10,000 years ago. 58.agriculture came around 10,000 years back and human settlements started. |
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