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    Definitions and comparisons of following biology terms

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    Definition and comparison of the following:

    -molecular clock / cladogram
    -gradualism / uniformitarianism
    -extreme thermophiles / viroids
    -HIV / Creutzfeld-Jakob disease
    -biofilm / microbial fuel cell

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    -molecular clock / cladogram
    The molecular clock hypothesis states that DNA and protein sequences evolve at a rate that is relatively constant over time and among different organisms. A direct consequence of this constancy is that the genetic difference between any two species is proportional to the time since these species last shared a common ancestor. Therefore, if the molecular clock hypothesis holds true, this hypothesis serves as an extremely useful method for estimating evolutionary timescales. This is of particular value when studying organisms that have left few traces of their biological history in the fossil record, such as flatworms and viruses.
    A cladogram is a stylized diagram that looks like a series of Y's or forks in a road. At each branch, or "Y" junction, novel characters of evolutionary origin are used to separate off one group from the rest.

    -gradualism / uniformitarianism
    Gradualism is a hypothesis, a theory or a tenet assuming that change comes about gradually or that variation is gradual in nature.
    Gradualism is selection and variation that happens more gradually. Over a short period of time it is hard to notice. Small variations that fit an organism slightly better to its environment are selected for: a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die. Very gradually, over a long time, the population changes. Change is slow, constant, and consistent.
    Uniformitarianism is the principle or assumption that the same natural laws and processes that operate in the universe now have always operated in the universe in the past and apply everywhere in the universe. It has included the gradualistic concept that "the present is the key to the past" and is functioning at the same rates. Uniformitarianism has been a key first principle of geology ...

    Solution Summary

    Definition and comparisons of the following biology terms: molecular clock, cladogram, gradualism, uniformitarianism, extreme thermophiles, viroids, HIV, Creutzfeld-Jakob disease, biofilm, microbial fuel cell