The Scientific Method Mr. Knowles Anatomy and Physiology Liberty Senior High School

Early Anatomists Hippocrates- Greek philosopher and physician, 400 B.C. Hippocratic Oath Four “Humours” of the body. Observations, little Experimentation

Greek and Roman Surgical Instruments

Early Black Bag

Claudius Galenus (Galen) Roman anatomist during the 1st Century. Described the human anatomy in detail. Little understanding of physiology.

Galen’s Office

Galen’s Specimens

Vesalius 16th Century anatomist who provided exquisite detail of systems. Experimentation with domestic animals. To determine function. Assumed Galen to be correct; not questioned.

Vesalius at Work!

William Harvey 17th Century English anatomist who questioned some of Galen’s conclusions. Determined how the CV system worked in 1628 publication. Used experimentation to prove CV function.

The Scientific Method An empirical way of explaining phenomena in the world.

With what does all good science research begin? A Question! 21 Questions to Conclusions!

Make a Concept Map to Relate the Following Terms Theory Hypothesis Principle Law

See My Concept Map Click to View

Some Definitions Law or Fact- a confirmed observation (direct/or indirect). Hypothesis- a testable prediction, based on prior knowledge and experience. Theory- a unifying explanation of several facts; a working model. Principle- who knows?

Based on our discussion… What would you call the idea of Spontaneous Generation? Germ Theory?

The Role of Hypotheses in Inquiry In science, a hypothesis –Is a tentative answer to a well- framed question, an explanation on trial –Makes predictions that can be tested

Hypothesis Comes from an observation ---> question or a problem. It is a Testable Prediction (Maybe True or False). Written as an If __I.V.___, then _D.V.____ statement.

Hypotheses in Everyday Problems Observations Questions Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test does not falsify hypothesis Test prediction Test falsifies hypothesis Figure 1.25

Deduction: The “If…then” Logic of Hypothesis-Based Science In deductive reasoning: –The logic flows from the general to the specific. If a hypothesis is correct: –Then we can expect a particular outcome.

Hypothetico-Deductive Reasoning Actually written as If… and …then…therefore. If …(your hypothesis)… and (planned experiment)…, then… (expected results)…therefore…(conclusion).

Hypothesis must be... Testable (Falsifiable) (ex. Absolute Zero---> Molecular Motion Stops) Unbiased (ex. Cancer statistics in North America; Utah vs, D.C.) Repeatable (ex. Cold Fusion, University of Utah experiment)

Pons and Fleischmann, University of Utah, 1989

An Unbiased Hypothesis? Research testing the hypothesis that cell phones--> brain tumors. Who funds this work? Motorola- the number one manufacturer of cell phones in U.S.

Writing a Hypothesis

Dangerous Breast Implants? Do breast implants cause connective tissue disease? How would you write a hypothesis?

What’s wrong with this?

The Scientific Method

Designing Controlled Experiments Experiments must be designed to test: –The effect of one variable by testing control groups and experimental groups in a way that cancels the effects of unwanted variables.

In mimicry –A harmless species resembles a harmful species Flower fly (non-stinging) Honeybee (stinging) Figure 1.26 A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations

In this case study –Mimicry in king snakes is examined –The hypothesis predicts that predators in non– coral snake areas will attack king snakes more frequently than will predators that live where coral snakes are present Scarlet king snake Key Range of scarlet king snake Range of eastern color snake Eastern coral snake North Carolina South Carolina Figure 1.27

Field Experiments with Artificial Snakes To test this mimicry hypothesis –Researchers made hundreds of artificial snakes, an experimental group resembling king snakes and a control group of plain brown snakes (a) Artificial king snake (b) Brown artificial snake that has been attackedFigure 1.28

After a given period of time –The researchers collected data that fit a key prediction Figure 1.29 In areas where coral snakes were present, most attacks were on brown artificial snakes Key % of attacks on artificial king snakes % of attacks on brown artificial snakes Field site with artificial snakes 17% 83% North Carolina South Carolina X X X X X X X X X X X X X X In areas where coral snakes were absent, most attacks were on artificial king snakes 84% 16% Key

If a hypothesis meets all criteria, then... Test hypothesis by experimentation. After repeated testing, a hypothesis may support a Scientific Theory.

A Theory must... Describe a real phenomenon (always true). Make accurate predictions about the world. Be dynamic, able to be refined or updated.

Model Building in Science Models of ideas, structures, and processes –Help us understand scientific phenomena and make predictions To lungs To body Right artium Right ventricle From lungs From body Figure 1.30

What is the difference between a fact and a theory? The Theory of Gravity: Ex. Newton and Einstein- both contributed to the theory. new information--->revision of theory.

Scientific Method Problem Hypothesis Materials Procedure 1. Number steps 2. Control Group/Experimental group 3. Constants

Data/Results 1. Title 2. Label axis: x-axis - IV y-axis - DV Conclusions (including discussion of errors)