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Biology notes Exam 1

Biology notes Exam 1 - Key points about the nature of...

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Key points about the nature of science 1. Science originates in questions about the natural world 2. Science uses observations and evidence to construct explanations about phenomena and testable hypotheses a. The more observations and other kinds of evidence that support and hypothesis, the stronger is that hypothesis 3. Scientists employ a variety of techniques to investigate the natural wprld 4. Scientists make their explanations public through presentations and publications 5. Scientists present their explanations and critique the explanations proposed by other scientists Definition of Science-from the national academy of sciences and institute of 1. The use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process Range of conditions for life -cell/body temp from -2 to 132 C -Range of pressures: 1 atm to 1100 atm -Conditions at the average depth of the ocean 2C to 4C 380 atm of pressure No sunlight Sharks Live with ½ molar urea in there tissues Urea is a potent denaturant of proteins Halophiles Halophilic bacteria live in osmotic equilibrium with 3 molar salt Tuna Raise the temperature of their muscles above ambient (as much as 15 C)
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Are endotherms in contrast to ectothermic fish Gutless Tubeworms Thrive at deep-sea hydrothermal vents Midwater fish and invertebrates Organisms living in the water column achieve neutral buoyancy despite the high density of biological materials Elements: Pure substances which cannot be broken down into two or more simpler substances by methods ordinarily available in the laboratory. 92 naturally occurring elements 103 total Atom: the smallest unit into which an element can be divided and retain its identity Ion: difference in the number of protons and electrons What determines the number and type of chemical bonds? Number=Valence Type=Electronegativity Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons Measure of the attraction an atom has for electrons **FIGURE BIOLOGICAL MOLECULES** ON MOODLE Chemical Bonds Forces holding atoms together in molecules Characterized as Strong or Weak depending on the energy required to make/break bonds Strong=covalent bond-involves sharing of electrons Weak=non-covalent- does not involve sharing of electrons
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Ionic interactions-attraction of opposite charges. One atom donates an electron to another Hydrogen bond between partially charged atoms Valence vs. Valence Electrons Valence is the number of electrons needed to fill the outermost shell of an atom Valence electrons are the electrons contained in the outermost electron shell of an atom Moles and Molar Concentrations 1 mole= the mass of a substance equal to its gram molecular weight 1 molar solution=a solution containing 1 mole of substance per 1 liter of solution *dry protein is 1g/cm^3 Ionic bonds Weak bonds Transfer of electron from one atom to another Covalent Bonds Strong bond Sharing of electrons Polar bond
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