Biology2 - F r iday Evolution the process by which a modern...

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Friday August 27, 2010 Evolution- the process by which a modern organism descended, with modification, from preexisting forms of life. Evolution has been tested and driven from multiple theories and observations over time One way that evolution occurs is through a process that we call natural selection. Homeostasis- staying the same -sweating when hot, shivering when cold -keeps cells within their optimal ranges for survival Heterotrophs eat other things Autotrophs use sunlight for energy Homeostasis requires physical repair Monday August 30, 2010 Correctly indicates the sequence of increasing organization Atom, molecule, organelle, cell Atoms, Molecules, and Life Chapter 2 What are atoms? Atom -the basic structural unit of matter (i.e., the smallest piece of stuff) Protons-positive charge Neutrons-no charge Electrons-negative charge Elements differ in # of protons An element is defined by # of protons=atomic # -has specific physical and chemical properties -cant be broken down by chem rxns Atomic mass=#of protons+neutrons
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Building-up Principle Electrons fill the shell closest to the nucleus, then begin to occupy the next shell 1 st :2 electrons 2 nd : 8 elections 3 rd :8 electrons e.g., Atomic # of Carbon (C )=6 6 elections -2 in 1 st shell -4 in 2 nd shell Isotopes Atomic mass=# of protons + neutrons -isotopes vary in number of neutrons
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Biology2 - F r iday Evolution the process by which a modern...

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