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Experimentation. G.T. Biology. Questions about the picture. Are there cars parked on the sides of the road? What color is the pickup truck driving in the road? Any minivans around? What does the blue sign say? What's the speed limit? Are there any pedestrians on the road?.

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  1. Experimentation G.T. Biology

  2. Questions about the picture • Are there cars parked on the sides of the road? • What color is the pickup truck driving in the road? • Any minivans around? • What does the blue sign say? • What's the speed limit? • Are there any pedestrians on the road?

  3. Importance of Observation in Science • Allows you to come up with scientific questions in the first place • Allows you to detect discrepancies and problems within an experiment while running it • Allows you to gather data – both qualitative and quantitative and use the observations to draw conclusions Go to observation vs. inference pwrpt.

  4. Observation is clouded by what you pay attention to selective attention video FINISHED FILES ARE THE RE-SULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THEEXPERIENCE OF YEARS

  5. Examples of Important Observations in Science • Why jellyfish glow – GFP • Milkmaids that got cow pox didn’t get cow pox – led to first vaccine • Bacteria have different enzymes that can cut DNA at specific sequences – led to all genetic engineering

  6. Question Hypothesis And Prediction Observation Background Research Specific Informed Answerable • Conclusion: What you think the answer is • based on your controlled, repeatable experiment • When you write a conclusion: • Summarize the data • Tell the readers what it means (make an inference) • Tell the reader why it is important or what is the • next step to pursue – where it is going Hypothesis: What you think the answer to the question Is based on background knowledge There may be many possible answers so it is the one you want to pursue first because you think it is most likely Prediction: What you will see in the experiment if the hypothesis is true Conclusion Collect Data And Analyze Design the Experiment Repeat Include Control Groups Control all Variables Theory: What you think the answer is Based on multiple experiments Theory

  7. Are these good questions? • Is it bad luck to walk under a ladder? • Do plants’ thorns deter herbivores? • Do people make pheromones that attract the opposite sex? • What is the cure for cancer?

  8. Why is proper experimental design important? • Goddard – ran a home for the “feeble-minded” – concluded that poverty, mental retardation, and criminality are all genetic • Lysenko – convinced Russian government that genetics were false science and that acquired traits are passed on – geneticists were put to death and the people were starving • Red meat study

  9. Red Meat Consumption and MortalityResults From 2 Prospective Cohort Studies FREE An Pan, PhD; Qi Sun, MD, ScD; Adam M. Bernstein, MD, ScD; Matthias B. Schulze, DrPH; JoAnn E. Manson, MD, DrPH; Meir J. Stampfer, MD, DrPH; Walter C. Willett, MD, DrPH; Frank B. Hu, MD, PhD [+] Author Affiliations Arch Intern Med. 2012;172(7):555-563. doi:10.1001/archinternmed.2011.2287. Background Red meat consumption has been associated with an increased risk of chronic diseases. However, its relationship with mortality remains uncertain. Methods We prospectively observed 37 698 men from the Health Professionals Follow-up Study (1986-2008) and 83 644 women from the Nurses' Health Study (1980-2008) who were free of cardiovascular disease (CVD) and cancer at baseline. Diet was assessed by validated food frequency questionnaires and updated every 4 years. Results We documented 23 926 deaths (including 5910 CVD and 9464 cancer deaths) during 2.96 million person-years of follow-up. After multivariate adjustment for major lifestyle and dietary risk factors, the pooled hazard ratio (HR) (95% CI) of total mortality for a 1-serving-per-day increase was 1.13 (1.07-1.20) for unprocessed red meat and 1.20 (1.15-1.24) for processed red meat. The corresponding HRs (95% CIs) were 1.18 (1.13-1.23) and 1.21 (1.13-1.31) for CVD mortality and 1.10 (1.06-1.14) and 1.16 (1.09-1.23) for cancer mortality. We estimated that substitutions of 1 serving per day of other foods (including fish, poultry, nuts, legumes, low-fat dairy, and whole grains) for 1 serving per day of red meat were associated with a 7% to 19% lower mortality risk. We also estimated that 9.3% of deaths in men and 7.6% in women in these cohorts could be prevented at the end of follow-up if all the individuals consumed fewer than 0.5 servings per day (approximately 42 g/d) of red meat. Conclusions Red meat consumption is associated with an increased risk of total, CVD, and cancer mortality. Substitution of other healthy protein sources for red meat is associated with a lower mortality risk.

  10. But the group who ate the most meat also: Had the highest percentage of smokers Had the highest percentage of people with hypertension Had the highest percentage of family history of diabetes Had the highest intake of total calories Consumed the most alcohol Consumed the most trans fats Consumed the most soft drinks Study Method Based on the way “Red Meat Consumption and Mortality” has been presented in the news, one would think it was brand new research, but the study group actually used data from two other studies that have been around for a while, and looked at the data in a different way. In these studies, participants were not asked to follow any specific diet. They were simply asked what they ate every couple years, and then they were tracked for associated health problems as the study went on. In total, data from 37,698 men and 83,644 women were included in the study.

  11. Experimental Design • Independent variable – what is being manipulated by the experimenter – it effects the dependent variable • Dependent variable – what is being measured – it is effected by the independent variable • Controlled variables – anything beside the IV that could effect the results (DV) – they are controlled because they must be kept the same throughout the experiment • Control group – even though you try to control all of the variables except the IV – you may not think of one. You must always accept the possibility that there is something you didn’t think of. The control group is a test group that does not include the independent variable; therefore, if the IV is actually causing the change, then there should be no change in the control group. The CG ensures that the conclusion drawn is due only to the IV and not something you haven’t thought of. • For a test – you need both a positive and negative control

  12. Practice • You want to know if a certain food contains starch. You will test by adding Lugol’s Iodine which is gold. The positive test will turn the solution black • You want to measure the affects of different amounts of oxygen on the rate of yeast growth by cell division • You hypothesize that a certain area of the brain is important to memory. You will test this by removing this part of the brain from the rats and test the affects on their memory. • You want to test the effectiveness of an anti-cholesterol drug.

  13. Vitamin C Lab • Question: Does OJ contain Vit. C? • Hypothesis? • Prediction? • Controls – Positive and Negative? • Procedure • Put 5 drops of indophenol indicator into each of the 3 tt labeled water, vit. C, and OJ • Observe the color change • Draw a conclusion including inferences

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