2 OBJECTIVES:List and describe/ explain the 5 steps in the scientific method in the correct sequence.Apply/ use steps in the scientific method in a given problem.Analyze a scientific problem and be able to identify specific examples of a hypothesis, experiment, data, etc.Contrast a hypothesis and a theory.List the 2 functions of a good theory.Discuss the limitations of science.Contrast “science” vs “non-science”.Differentiate a control group from an experimental group and an independent variable from a dependent variable.Explain the work of Aristotle, Redi, Spallanzani, Needham, and Pasteur concerning the origin of new living organisms--- relate their work to the scientific method.Compare and contrast 3 kinds of microscopes used in biology--- gives some advantages and disadvantages for each.Identify and sequence the various levels of organization for the study of life.Describe common metric units used in science for length, mass, volume, and temperature.
3 Scientific Method 1. Observation Must be repeatable Correct observation is most difficult- due to unsuspected biasPeople see what they want to see; difficult to explain unconscious prejudiceSeveral scientists repeating it independently give observation more validity2. Statement of ProblemTo be valuable scientifically, a question must be relevant as well as testable and specificProper testing techniques must be availableIn general, science does best with “how” or “what” questions“Why” questions are more difficult/ Ex: “ Why does the universe exist?” untestable
4 Cont. Scientific Method 3. Formulation of HypothesisNot a random guessHypothesis a tentative answer or postulation based on numerous observationsScientist does not know if his “guess” was correct or incorrect until he has completed experimentation4. ExperimentationProvides enough evidence to explain hypothesisMost difficult step must be a controlled experimentRequires at least 2 parallel sets of tests, identical in all respects except oneControl Series provides a standard or reference for assessing results of the Experimental Series
5 Cont. ExperimentationEx: In drug experiments on people, up to 100,000 to 200,000 test, 2 of them controls and 2 experimental groupsControl SeriesExperimental Groupa. All conditions same as Experimental groupa. All conditions same as Control groupb. No drug takenb. Drug taken-specific dose
6 Cont. Experimentatione) Large samples (#) of organisms must be usedf) Even after careful execution, etc. results may not be clearg) Results of any experiment represents EVIDENCE the original guess about the answer is confirmed as correct or incorrect (invalid)h) If invalid, a new hypothesis and new experiments must be designed- Process must be repeated until a hypothesis is found that can be supported with experimental evidencei) Results of experiments cannot be called “proof” or “fact”, merely evidence for a hypothesis (some hypothesis have more evidence than others)
7 Cont. Scientific Method 5. Formulation of Conclusion: TheoryBased on evidence produce by experimentationTheory a hypothesis that has withstood repeated testing by many scientists doing independent workGood theory has predictive value forecasts certain results based on substantial evidence- Scientific forecast does not guarantee something will happen-- indicates that it is likely to happen with a stated degree of probabilityd) Natural Laws theories that have proved so universally valid to a high degree of probability- Ex: Apple falls from tree no exception even observed Law of Gravitye) Most theories are valid for a time, but with time, exceptions are foundf) Science is a steady progression, not revolution- Ex: Isolation and synthesis of a gene took 5 years
8 Limitations of Science Science is confined to use of the Scientific Method-- this is the beginning and end of science.2. Anything to which the scientific method can be applied now or in the future. Anything to which this method cannot be applied is NOT science.
9 Cont. Limitations of Science Does the idea of God lend itself to scientific study? a) Test hypothesis: God is universal and exists everywhere and ineverythingb) An experiment about God would require 2 situations: one w/ God,one without, but otherwise identicalc) If hypothesis is correct: God would exist everywhere-- be present inevery test and could never devise a situation in which God is NOTpresentd) If hypothesis is wrong: God would not exist-- would be absent fromany test and could never devise a situation in which God is presente) Hypothesis is untestable-- cannot run controlled experimentf) Concept of God falls out of scientific domaing) Are scientists godless? Science does not prove nor disprove God leaves anyone free to believe in any God or in none/ many first- rate scientists are priests, many are agnostics
10 Cont. Limitations of Science 4. The aim and purpose of science is to make and use theories. Science finds evidence for theories-- does not deal with truth or proof.5. Science does not make value judgments or moral decisions. Scientific results do not contain built-in values.6. Science cannot determine whether or not one should have moral standards or which set one should live by.
11 Cont. Limitations of Science 7. Forms of Sciencea) Basic Research (Pure Science)Done to further understand naturePractical applications are disregardedPublish papers, experiments, researchb) Applied Science (Practical Science)Applies the results of pure science to practical usesDoctors, engineers, criminologists, physical therapists, etc.Technology
12 Microscopes Used in Biology Light Microscope tissues, whole cells2. Transmission Electron Microscope (TEM) slices of cells3. Scanning Electron Microscope (SEM) surfaces of cells
13 SCOPEADVANTAGESDISADVANTAGESLIGHTLiving cellsColorMovementProcessesLow magnificationNo fine detailTEMVery high magnificationExtremely fine detailsNo living cellsNo colorNo movementNo processesSpecial technique ( fix, slice, stain, freeze, vacuum)SEMSurface details“3D” imageSame as TEM (no slicing)
15 Transmission Electron Microscope E. coliStriated muscle
16 Scanning Electron Microscope Mascara brush covered w/ dried mascara & flakes of skinCat flea flattened from side to side along with the spines on its head (have either simple eyes or no eyes at all)
18 The dentist drill is covered with tiny diamond chips The dentist drill is covered with tiny diamond chips. Diamonds are the hardest substance known and will easily wear away tooth particles as the drill spins at high speeds.
19 Redi’s Experiment on Spontaneous Generation Section 1-2OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.HYPOTHESIS: Flies produce maggots.PROCEDUREUncovered jarsCovered jarsControlled Variables:jars, type of meat,location, temperature,timeSeveraldays passManipulated Variables:gauze covering thatkeeps flies away frommeatResponding Variable:whether maggotsappearMaggots appearNo maggots appearCONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.
20 Spallanzani’s Experiment Section 1-2Gravy is boiled.Flask isopen.Gravy is teemingwith microorganisms.Flask issealed.Gravy is free ofmicroorganisms.Gravy is boiled.