Biol6a - Introduction / Science WHAT IS SCIENCE ? n n n...

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Unformatted text preview: Introduction / Science WHAT IS SCIENCE ? n n n Attempts to discover the order in nature Makes predictions about what will happen Methodical process of discovery and understanding The Scientific Method n n WHAT IS SCIENCE ? n Discrimination of what is true (reality) from what only appears to be true (illusion, prejudice, & story-telling) “Science as a way of knowing” PROCESS SCIENTISTS USE TO ANSWER PROCESS SCIENTISTS USE TO ANSWER QUESTIONS ABOUT NATURE QUESTIONS ABOUT NATURE What is the Scientific Method? Why use this process? Hypotheticodeductive method 6C n 6A 6B – – – – – – Let the observations inspire specific questions! It all starts with Observations n Careful, meticulous, well-documented observations! n Naturalists and explorers – Detailed descriptions, illustrations, maps, & anecdotes n Published scientific reports n Personal experiences – Peer-reviewed journals Why do frogs call at night? Propose plausible answers to your question (inductive reasoning). n n n n Heyer Observations Question Hypothesis Prediction Experiment Conclusions reduced predation rates reduced loss of foraging reduced water loss rates reduced phone rates 1 Introduction / Science Proximate vs. Ultimate Questions The Hypothesis Proximate questions (descriptive) ß n ß what is it? ß how does it function? n Ultimate questions (causal) ß Hypotheses are possible explanations of an observation. Scientists formulate hypotheses based on: 1) previous knowledge 2) inference from similar situations 3) common sense ß why is something the way it is? ß what would be predicted about how it ß breaths ß reproduces ß is related to other organisms The Hypothesis specific prediction n Word it as falsifiable (testable) n n n Formulate a Formulate falsifiable alternative hypotheses (null hypothesis) Design tests of the prediction (experiments) Hypothesis Testing n RELATIONSHIP BETWEEN RELATIONSHIP BETWEEN HYPOTHESIS AND PREDICTION HYPOTHESIS AND PREDICTION Deductive reasoning — n If the hypothesis is correct.... n Then we predict the following outcome from our experiment SCIENTIFIC METHOD n n Reproducibility: Repeated testing n n Heyer of a hypothesis precedes its tentative acceptance. Only testable hypotheses are worthwhile. Untestable hypotheses are not generally considered science. The more basic facts you know, the better your questions & hypotheses. Hypothesis-driven science – Prediction • If … then – Test the prediction 2 Introduction / Science Test the Hypothesis n n n n Observations Questions Hypothesis/Predictions Tests (Experiments) • Control Group • Experimental Group n n Experiments test the Hypothesis n Experiments refute or support hypotheses: n WHY IS IT DIFFICULT TO DRAW A WHY IS IT DIFFICULT TO DRAW A CONCLUSION FROM AN EXPERIMENT CONCLUSION FROM AN EXPERIMENT THAT IS NOT CONTROLLED? THAT IS NOT CONTROLLED? Experiments involve an – good tests can be hard and must often be clever. • experimental group which has variable under study experimentally altered, and a • control group which receives the same treatment as the experimental group except for the variable in question. Experimental Variables n Tests (Experiments) – Control Group • Standardized Variables – Experimental Group • Standardized Variables • Independent Variable n n Heyer Data/Results Conclusion Data/Results • Dependent Variable Conclusion n n n Controlled experiment has two parallel tests – Experimental – Control Only the “tested variable” is different Without control you do not know if the outcome is caused by the variable in question A controlled study 1. Hypothesis: Antibiotic B is better at treating ulcers than Antibiotic A. 2. Alternative Hypothesis: Antibiotic A is better at treating ulcers than Antibiotic B. 3. Null Hypothesis: treatment of ulcers is uncorrelated with Antibiotic A or B. (endoscopy) “Double-blind” controls: Neither the subjects nor the endoscopists know which subject is in which group. 3 Introduction / Science A controlled study A controlled study Analysis of Results: Presentation of Results (the Graph): 1. Correlation: Dependent variable (% effectiveness) is dependent upon independent variable (treatment group). • 2. Affirmation: Hypothesis prediction supported. • Caution : correlation does not always mean causation! 3. Statistics: Groups are large enough & results are distinct enough, apparent correlation is not just coincidence. •Question: Observations: n Guppies live in river pools. Some pools have large cichlid fish predators. independent variable are in discrete groups • If values had been continuous (e.g., dosage of antibiotic B), use a line graph [regression]. X-axis : Independent variable is not dependent upon dependent variable — assignment to treatment group was made without knowing future % effectiveness. Field Study: Evolution of Life History Traits in Jamaican Guppies n Bar Graph : since values of Y-axis: Dependent variable is dependent upon independent variable — amount of % effectiveness varied because of treatment group. • Then Æ Conclusion: Hypothesis is supported! • More observations Does the type of predator present alter the growth rate/maturation of guppies? •Prediction: n n If guppies are exposed to a different predator, then they will alter their growth rate and maturation. Some pools have smaller killifish predators. Some pools have neither predator. Experiment Results Heyer 4 Introduction / Science Doing Science 1) Get all background information possible (lots of it normally) 2) Collect data (often several years of work) 3) Analyze data (can take months or years) 4) Write up results & submit for peer review and publication (often >1 year until publication) SOME QUESTIONS ARE OUTSIDE SOME QUESTIONS ARE OUTSIDE THE REALM OF SCIENCE THE REALM OF SCIENCE n n n Hypothesis - “Ulcers are caused by negative energy waves from extraterrestrial organisms” Design an experiment....? Questions/Predictions must be testable! Scientific Theories n Widely supported explanations of broadly occurring phenomena – Einstein's "theory of relativity" – Cell Theory – DNA (Gene) Theory of Inheritance – Darwin's "theory of evolution by natural selection" n They aren’t speculation or conjecture – “Stephen King killed John Lennon - it’s true or he’d sue!” Biophilia a love of life and its forms Biologist Carlos Rivera Gonzales examining a tiny tree frog in Peru Heyer 5 ...
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