Biol 110 Exam 1 Experiments 02 05 2014 Hypothesis formed Supported Rejected by experimentation o If correct can predict results Measure response effects of a specific treatment o Does NOT have to happen in a laboratory o Scientific Inquiry Used with historical events Experiment not possible Attempt to determine causality o Independent variable What is manipulated Not affected by other variables present ie time o Dependent Variable What is being measured Experimental groups different levels of treatment vs control groups placebos o Ie Shape of flask in Pasteur s experiments o Done so that there is no other explanation for the results o A placebo is anything that mimics the treatment without containing the actual substance Looks taste smell saline injections sham surgeries Measure psychological impact Sometimes expectation can cause improvement benefits Biological impact Ingestion digestion may impact Bias Must be avoided by participants and researchers o Blind Studies Participants don t know exper control o Double Blind Researchers Observers participants o Order Effects Feeding cattle new food first doesn t prove o Random Assignment of exper control groups helps to avoid biases volunteering CAN be a bias Types of Controls Used to validate disprove hypothesis o Positive Controls Known to have desired response o Negative Controls Known NOT to have desired response o If these work can trust other controls Correlation does NOT mean causation Observational studies are good when o Ethics are involved smoking lung cancer o Issue of availability dinosaurs o Ease of collection questionnaires surveys Data o Qualitative Descriptive The fish swam in a zigzag motion o Quantitative Measurements The fish swam at a speed of 7 m s What Is Life Biology is the study of life To be considered living order need for growth energy development internal regulation evolutionary adaption Natural Selection Process by which a population becomes better o Results in change of frequency of genes alleles o Must have variation in a population for it to occur Natural selection can preserve distribute beneficial mutations but CANNOT create them ADVANTAGEOUS ALLELES DON T ARISE ON DEMAND o Differential Reproduction means that those better adapted for the environment are more likely to reproduce and pass on traits that make them better suited o Types of Selection Directional Selection Extreme trait is selected for Population shifts to one side of the average Ie Brown and white fur in the Arctic Stabilizing Selection Average trait is selected for Population shifts towards the average Ie Size of babies born not too big or too small Disruptive Selection Either extreme is selected for Population shifts to either side of the average with a big decrease around the average Seashells are camouflaged on either brown OR white rocks Increases genetic variation Adaptions Traits that help an organism survive Evolution Changes in the genetic structure of a population o Driven by changing environments o Fitness Contribution to the next generation s gene pool o Human Evolution Path with many branches Natural Selection is one way by which evolution occurs The Age of Earth Universe 13 7 billion yo Milky Way 4 5 billion yo Early atmosphere was methane ammonia H water and little O o Highly reductive Not much O which oxidizes o Miller Urey Things can arise from abiotic conditions Tectonic Plates Continental drift constant rearrangement o Pangea movement drives evolution Supported by fossil record etc Tree of Life o Fossil records support Provide geological time scale Precambian Paleozoic Mesozoic Cenozoic now Relative dating Sedimentary rock o Absolute dating Radiometric dendrochronology Half lives used to calculate age radiometric Carbon 14 decays in Nitrogen 12 Half life 5 000 years Growth rings on trees dendrochronology Can also provide insight into conditions Chemical Bonds Element Substance that cannot be broken down into another Atom Smallest amount of an element Molecule 2 atoms that are chemically joined Compound Molecule with 2 types of elements Electrons o Inner most shell 2 Outer shells want 8 valence Last column unreactive because they have 8 Others will gain lose join to fill shells BONDS Ionic Bonds Transfer of electrons no sharing involved o Results in ions atoms with or charge o Ionic pair is then attracted to each other due to difference in charge this is the bond Covalent Bonds Sharing of electrons between atoms o Stronger than ionic bonds o Can share multiple pairs of electrons double triple bonds o Polarity of bonds depends on electronegativity ability to attract electrons of atoms involved Polar Covalent Unequal sharing of electrons Nonpolar Covalent Equal sharing of electrons Water Polar molecule Exists naturally in all three states on Earth Cells are more than 70 water Partial charges due to polarity allow for interactions between molecules and with other molecules O and H partially Partial O of one molecule interacts with partial H of another o Hydrogen Bonding Each water molecule can be joined to four others Responsible for adhesion high surface tension and cohesion capillary action plants Adding polar ionic substances to water will surface tension o DECREASE High Specific Heat Large amount of energy requires to change temperature absorbs stores energy well High Heat of Vaporization Relatively resistant to phase change Expands during freezing ice less dense floats Solvent Capable of dissolving many compounds anything polar o Hydrophillic Water Loving anything with charge o Hydrophobic Water Fearing fats and oils o Amphipathic Both hydrophilic and hydrophobic Phospholipid molecules dish soaps Carbon Organic Contain carbon prevalent in living systems Inorganic Do not contain carbon water rock etc Structure o 4 valence electrons can form 4 bonds o Long chains are common 4 classes of organic molecules o Carbohydrates Lipids Proteins and Nucleic Acids Monomers join to form polymers o Joined by anabolism o Broken down by catabolism Hydrolysis and Condensation Hydrolysis Broken down with addition of water molecules Condensation Combining water as a byproduct o OH is removed from one and H from the other both join Metabolism Set of chemical reactions that happen in living organisms allowing it to grow reproduce maintain Carbohydrates ose Consist of monomer and polymers Structure C H2O n usually Glucose is one of the most common o Glucose is a molecule and will in water POLAR DISSOLVE Used for energy storage structure and