BIL 150 notes exam 1

BIL 150 notes exam 1 - Major theories of life 1 Evolution...

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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 4.5 billion--- sun & solar system 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 Important ions Ca, K, Na & Cl 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 water Acid precip. Can damage life in lakes and soil Take home problems How many times as much acid in rain compared to normal? (pH 4.2 vs. 5.6)
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