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biology 2

blueprint of life

Molly Clements

on 10 May 2011

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Transcript of biology 2

Blueprint of Life A Start on earth there is a huge diversity of life ( archeae-holophiles and methanogens, bacteria in soil, animals) but all of these organisms have common chemistry.
>mostly made of CHONPS
>these elements combine to make carbohydrates,fats, protein, nucleic acids.
> lots of H2O
>uses RNA and/or DNA as genetic material.
>use repiration as the chemical mechanism to provide energy for the cells.

these similarities of this range of organisms can be explained by their common ancestry. Theories of Evolution > living organisms originated from coomon ancestors or a common life form and have changed over time.
> differences that occur in groups of organisms imply that living things change over time.
> similarities in living things infer a common ancestory. "Evolution is a change in living things over a very long time" DARWIN and WALLACE proposed that natural selection was the mechanism that enabled some organism to survive AND at the same time MENDLE was studing inhertance. Outline the impact on the evolution of plants and animals of: physical/chemical environment and competition for resources. under constant environmental conditions a population of organisms will remain relatively unchanged, BUT evidence suggests that change in the environment is the driving force behind changes in living organisms.
the environment of an organism is made up of biotic and abiotic factors
>biotic-competition for resources.
> abiotic-physical/chemical conditions. physical conditions chemical conditions Include: -
>rainfall/moisture availability

physical changes that were thought to have impacted evolution: -
>changing australia envir. from cool and wet to dry and warm -> changed vegetation which changed animals.
>the increase in the incidence of fire-> lead to fire resistant plants with adaptations that favour fire (optimal reproduction)
>lack of light effect of meteorite impact-> reduced plant grow world wide. Include change in: -
>atmosheric gases
>soil conditions
>presence of herb/pesticide in/on living things

chemical changes that impacted evolution are: -
>atmosphere from anoxic to oxic -> O2 was first pumped into the atmosphere by P/synthetic bacteria. once O2 was used up in reactions (sea rusting) it accumulated in the atmosphere -> anaerobic orgamisms died aerobic orgamisms dominate now bec. of O2 used in resp. efficient way of producing energy allowed the evo. of a larger, complex more diverse range of living organisms.
>inland lakes dried up-> increase in salts in soils.lead to salt tolerant plants (saltbush)
>sheep treated for blowflies-> pesticide chanhges the chemical composition of the flesh of sheep-> change in blowflies, resistant to pesticide. Competition for Resources changes in physical and chemical environment lead to competition for resources such as soil moisture for trees. Competition for resources can cause extinctions, introduction of feral animals causes the reduction of native marsupials, reduce in habitat (urbanisation). Evolutionary Theory states that all organisms have developed from pre-existing organisms. all organisms have a common origin in some initial form of life which have given a varity of sources of organisms over billions of years. Darwin and Wallace proposes the mechanism for evolution was natural selection. this refers to the biological changes that have taken place as life changed from simple to more complex. D+W argues that by chance, some organisms possess characteristics more suited to their environment then others, these are more likely to survive and pass on their characteristics on.over many generations, organisms would better adapted to their environment would evolve.
D+W also noted that a mechanism of natural selection drove biological evolution-> which competition and environment pressure naturally selected the best adapted.
for a new species to evolve they must become isolated, this can be a physical barrier e.g. ocean. within pop. mutations occur (variability). NS acts in different ways on different isolated species because of different enviro pressures. eventually pop became so isolated that they can no longer interbreed. divergent evolution also called adaptive radiation and it is the evolution of one species into many species each adapted to its own environment.
common ancestor, individual inhabit diff enviro., enviro pressures allow only the most suited to reproduce, characteristics change, pop no longer interbreed, new species. covergent evolution is the evolution of similar adaptions in the distantly related organisms because they live in similar environments.
distantly related orgamisms inhabit similar enviro, similar enviro pressures, individuals from different species with similar characteristics survuve to reproduce, charac become more common, pops with similar chara but different ancestry occupy similar environments. Palaeotology fossils are unusual occurrences- most organisms that have livid have left no trace or have soft bodies that could never leave a trace so the fossil record is incomplete.
the fossil record show a change from simple to complex organisms, transition fossils are traces of organisms that have characteristics of 2 seperste groups of organsims, this provides evidence from one group evolving into another organism.e.g. achaeopteryx
Comparative anatomy similarities in skeletons of modern and extinct species suggest a common ancestor and are evidence for evolution. e.g. pentadactyl Comparative embryology is the study of the similarities and differences between embyros of different organisms. all vertebrate embryos have pharyngeal gill pouches in their development stage at some point, these only develop in fish and amphibians. gill pouches on the embryos of vertebrates suggests a common ancestor with aquatic vertebrates. Biochemistry Biogeography all living organisms have similar chemistry
>cell membrane structure
>common genetic codes of RNA and DNA
>use repiration to make energy available
>cytochrome C protein, common to most living things.(different AA sequence from each organism but if similar is can show how close a relation is/pathways of evolution) is the study of the distribution of living things.

types of plant/ animals are found in certain continents and not others. unique animals and plants result from periods of evolution in isolation.aus's marsupials are very different from Africas megafauna this suggests each contient has its own common ancestors. Describe how the theory of evolution is supported by the following areas of study how advances in technology have changed scientific thinking about evolutionary relationships
>ristriction enzymes break DNA into little pieces
>the 2 DNA strands are separated using heat
>single strands of DNA mixed with single strands of from another species
>strands from different species are allowed to cool
>strands very similar rejoin very closely. different strands rejoin less closely
>strands are reheated until .5 of the strands seperated
>the higher the temp at which .5 the strands are seperated the closer the 2 species. DNA Hybridisation: - humans were thought to be more closely related to gorillas in the primate famil. since DNA hybridisation technique, it is known that humans are more closely related to chimpanzees Primate % DNA similarity
chimp 97.6
gorilla 96.5 the historical development of the theories of evolution (the people involved) Leoardo(1452-1511)-
Gould and Elidridge-
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