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    Heredity and Evolution
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    Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?
    Homologous organs are those which have a common origin but perform different functions. The wing of a butterfly and wing of a bat are used for the same function of flying, however, they are structurally very different and do not have a common ancestor. Thus they are not homologous organs.
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    Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?
    No, Asexually reproducing organisms have very little variation over generations as they involve only one parent. The variations result from the DNA mutations . But these variations are very few and are not capable of giving rise to a new species. Thus geographical isolation will not be a major factor in the speciation of the orgnaism that reproduces asexually.
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    What are fossils? What do they tell us about the process of evolution?
    Fossils are preserved traces of living organisms. They are any impression or imprint left by some previous organism in the soft mud which subsequently hardened or the moulds and casts of entire organisms which became preserved.
    Fossils tell about the organisms that lived long ago and help us to establish evolutionary relationship with the present organisms. They tell about the structure of such organisms and the time period during which they lived. The fossils found in upper strata of rocks are considered to be newer than those found in the lower strata. It is also seen from the fossils that the organisms become more complex in the upper strata when compared to the lower strata which indicates towards the evolutionary process. 
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    Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species?
    The genetic makeup of humans may be slightly different in different races of people, but there is no reproductive isolation. Reproductive isolation differentiates one species from the other. Human beings different in size, colour and looks can marry among themselves and produce fertile offspring and thus they are considered to belong to the same species.
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    Give an example of characteristics being used to determine how close two species are in evolutionary terms.

    Structure of forelimb in a frog, lizard, bird and horse is similar with similar bones which are modified to suit the function they perform. From this it can be safely assumed that they may have evolved from a common ancestor.
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