BIL 150 notes exam 1

BIL 150 notes exam 1 - Major 9/11/09 theories of life 1....

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9/11/09 Major theories of life 1. Evolution- living things evolve a. Darwin- evidence, not the idea Population--------elimination--------reproduction-----------frequency New species evolving, dying out 14 billion---big bang 3.5 billion--- life on earth 2+ billion--- first eukaryotic cells 4-6 million--- human-like 225,000 years--- homo-sapiens Elements other than cells Supernova a big star explosion therefore, our other elements came from stars Origins in Africa 14 x 10^9----4.5 x 10^9----3.5 x 10^9----2 x 10^9---- .006 x 10^9---- .0002 x 10^9 Exponential growth key: doubling time a constant N=Noe^rt 6.5 billion individuals Living things obey the laws of physics and chemistry Isaac Newton Vitalism- special, beyond science Discarded as a hypothesis Living organisms share certain properties 1. order 2. evolutionary adaptation 3. response to environment 4. reproduction 5. growth & development
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6. energy processing 7. regulation All living organisms are composed of cells (trillions in a human body) Prokaryotic- DNA---- no nucleus---- no membrane Eukaryotic- membrane---- cytoplasm---- organelles Human- .1 second is fast (reaction time) Cell level- millisecond 10^-3 second Molecular- microsecond… millions of collisions per second Genes specify proteins which in turn specify structure and function Science vs. nonscience (nonsense) One aspect of science is falsifability… all scientific hypothesizes must have a means with which to be proven wrong Freud’s theory of dreams Creation “science” No way to test against the theory, or falsify it. Therefore nonscience 25 elements essential to life--- starstuff C H N O P S- 981 all needed to make most molecules of life The rest= trace elements
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How much do all of the electrons in your body weigh, in total ? Assume: 1.# of protons= # of neutrons 2. weight of p+ approx 1280 times weight of electrons isotopes- same proton, different number of neutrons radioactive isotopes: decay spontaneously, giving off particles and energy electrons shells and subshells… first… second. . third 8/31/09 Hydrophilic (polar or charged) substance that fits well with hydrogen bonds. . affinity Hydrophobic (nonpolar) disrupts hydrogen bonds. . more soluble in oils, which are nonpolar. Ph A few water molecules may gain or lose a hydrogen ion (proton): 2h20 <> H30 + Oh- Adding certain solutions called acids and bases modifies pH Scientists use the ph scale to describe the concentration of hydrogen ions [H+] = 10^-pH Neutral solutions have a pH of 7, or concentration of hydrogen ions of 10^-7
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Buffers The internal pH of most living cells must remain close to pH 7… human blood =7.4 Buffers tend to hold pH constant Bicarbonate ion as a buffer: H+ + HCO3 > H2CO3 > H2O + CO3 Threats to water quality on earth Acid precip. Refers to rain, snow, or fog with a pH lower than 5.6 Caused mainly by pollutants, such as power plant emissions, mixing with
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BIL 150 notes exam 1 - Major 9/11/09 theories of life 1....

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