ExperimentationExperimentation

G.T. BiologyG.T. Biology

Questions about the pictureQuestions 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?

Importance of Observation in Importance of Observation in ScienceScience

Allows you to come up with scientific Allows you to come up with scientific questions in the first placequestions in the first place

Allows you to detect discrepancies and Allows you to detect discrepancies and problems within an experiment while problems within an experiment while running itrunning it

Allows you to gather data – both Allows you to gather data – both qualitative and quantitative and use the qualitative and quantitative and use the observations to draw conclusionsobservations to draw conclusions

Go to observation vs. inference pwrpt.

Observation is clouded by what Observation is clouded by what you pay attention toyou pay attention to

selective attention video

FINISHED FILES ARE THE RE-SULT OF YEARS OF SCIENTIFIC

STUDY COMBINED WITH THEEXPERIENCE OF YEARS

Examples of Important Examples of Important Observations in ScienceObservations in Science

Why jellyfish glow – GFPWhy jellyfish glow – GFP

Milkmaids that got cow pox didn’t get cow Milkmaids that got cow pox didn’t get cow pox – led to first vaccinepox – led to first vaccine

Bacteria have different enzymes that can Bacteria have different enzymes that can cut DNA at specific sequences – led to all cut DNA at specific sequences – led to all genetic engineeringgenetic engineering

ObservationObservation QuestionQuestionHypothesisHypothesis

AndAndPredictionPrediction

Design the Design the ExperimentExperiment

Collect DataCollect DataAnd And

AnalyzeAnalyzeConclusionConclusion

TheoryTheory

BackgroundBackgroundResearchResearch

SpecificSpecificInformedInformed

AnswerableAnswerable

Include Control GroupsInclude Control GroupsControl all VariablesControl all Variables

RepeatRepeat

Hypothesis: What you think the answer to the question Hypothesis: What you think the answer to the question Is based on background knowledgeIs based on background knowledge

There may be many possible answers so it is the one you There may be many possible answers so it is the one you want to pursue first because you think it is most likelywant to pursue first because you think it is most likely

Prediction: What you will see in the experimentPrediction: What you will see in the experimentif the hypothesis is trueif the hypothesis is true

Conclusion: What you think the answer is Conclusion: What you think the answer is based on your controlled, repeatable experimentbased on your controlled, repeatable experiment

When you write a conclusion:When you write a conclusion:a.a.Summarize the dataSummarize the data

b.b.Tell the readers what it means (make an inference)Tell the readers what it means (make an inference)c.c.Tell the reader why it is important or what is the Tell the reader why it is important or what is the

next step to pursue – where it is going next step to pursue – where it is going

Theory: What you think the answer isTheory: What you think the answer isBased on multiple experimentsBased on multiple experiments

Are these good questions?Are these good questions?

Is it bad luck to walk under a ladder?Is it bad luck to walk under a ladder?

Do plants’ thorns deter herbivores?Do plants’ thorns deter herbivores?

Do people make pheromones that attract Do people make pheromones that attract the opposite sex?the opposite sex?

What is the cure for cancer?What is the cure for cancer?

Why is proper experimental Why is proper experimental design important?design important?

Goddard – ran a home for the “feeble-Goddard – ran a home for the “feeble-minded” – concluded that poverty, mental minded” – concluded that poverty, mental retardation, and criminality are all geneticretardation, and criminality are all genetic

Lysenko – convinced Russian government Lysenko – convinced Russian government that genetics were false science and that that genetics were false science and that acquired traits are passed on – geneticists acquired traits are passed on – geneticists were put to death and the people were were put to death and the people were starvingstarving

Red meat studyRed meat study

Red Meat Consumption and MortalityResults From 2 Prospective Cohort Studies FREEAn 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 AffiliationsArch 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.

But the group who ate the most meat also:Had the highest percentage of smokersHad the highest percentage of people with hypertensionHad the highest percentage of family history of diabetesHad the highest intake of total caloriesConsumed the most alcoholConsumed the most trans fatsConsumed the most soft drinks

Study MethodBased 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.

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

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

Vitamin C LabVitamin C Lab

Question: Does OJ contain Vit. C?Question: Does OJ contain Vit. C?Hypothesis?Hypothesis?Prediction?Prediction?Controls – Positive and Negative?Controls – Positive and Negative?ProcedureProcedure– Put 5 drops of indophenol indicator into each Put 5 drops of indophenol indicator into each

of the 3 tt labeled water, vit. C, and OJof the 3 tt labeled water, vit. C, and OJ– Observe the color changeObserve the color change

Draw a conclusion including inferencesDraw a conclusion including inferences