Scientific Method Chapter 1: Section 2 How Scientists Work Notes

Keys Lecture Outline – The Scientific Method PowerPoint Notes textbook questions

How Scientists Work: Solving the Problems How Scientists Work: Solving the Problems MMMMuch of biology deals with solving problems TTTThese problems can be environmental, ecological, health related, etc. NNNNo matter what types of problems are being studied, scientists use the same problem-solving steps called… TTTThe Scientific Method

Scientific Method Definition Scientific Method Definition TTTThe scientific method is- AAAA logical and systematic approach or process to problem solving. AAAAn organized way of using evidence to learn about the natural world. AAAAccording to Wikipedia - S S S S S cccc iiii eeee nnnn tttt iiii ffff iiii cccc method is a body of techniques for investigating p p p p p hhhh eeee nnnn oooo mmmm eeee nnnn aaaa and acquiring new k k k k k nnnn oooo wwww llll eeee dddd gggg eeee, as well as for correcting and integrating previous knowledge. It is based on gathering oooo bbbb ssss eeee rrrr vvvv aaaa bbbb llll eeee, e e e e e mmmm pppp iiii rrrr iiii cccc aaaa llll and m m m m m eeee aaaa ssss uuuu rrrr aaaa bbbb llll eeee e e e e e vvvv iiii dddd eeee nnnn cccc eeee subject to specific principles of r r r r r eeee aaaa ssss oooo nnnn iiii nnnn gggg, the collection of data through o o o o o bbbb ssss eeee rrrr vvvv aaaa tttt iiii oooo nnnn and e e e e e xxxx pppp eeee rrrr iiii mmmm eeee nnnn tttt aaaa tttt iiii oooo nnnn, and the formulation and testing of h h h h h yyyy pppp oooo tttt hhhh eeee ssss eeee ssss.

Scientific Method Listing the Steps Scientific Method Listing the Steps MMMMake an Observation DDDDefine the Problem RRRResearch the Problem SSSState the Hypothesis EEEExperiment to test Hypothesis CCCCollect and Record Data AAAAnalyze Data DDDDraw Conclusions DDDDetermine Limitations RRRReport Results If needed, Do more investigation

SCIENTIFICSCIENTIFICSCIENTIFICSCIENTIFIC METHOD OVERV IEW

SCIENTIFICSCIENTIFICSCIENTIFICSCIENTIFIC METHOD OVERV IEW Repeat steps 3-7 for competing hypotheses. Competing hypotheses may include revisions of the original hypothesis suggested by the results of the testing process. Hypothesis Findings (Conclusions) Data (Results) Procedures (Experiments) Scientific Method

SCIENTIFICSCIENTIFICSCIENTIFICSCIENTIFIC METHOD OVERV IEW Here is another example of how the steps may go…. Even though we show the scientific method as a series of steps, keep in mind that new information or thinking might cause a scientist to back up and repeat steps at any point during the process. Form a Hypothesis Make Observations Define / Identify the Problem Test Hypothesis Perform Experiments New Experiments Do Experiments and Observations Support Hypothesis? YES Organize and Analyze Data Draw Valid Conclusions NO Communicate Results Faulty Experiments?

Scientific Method Scientific Method LLLLet’s break each of these steps down into their individual components:

LLLLet’s break each of these steps down into their individual components: Ask Question Do Background Research Construct Hypothesis Test with an Experiment Analyze Results Draw Conclusion Think! Try Again Report Results Hypothesis is True Hypothesis is False or Partially True

1. Observing 1. Observing  Make an observation  See something unusual  Frogs with incorrect number of legs! As we all know, frogs have four legs. What’s up with these froggies?

2. Questioning 2. Questioning RRRRecognize, state or define the problem MMMMust be in the form of a question TTTThe obvious question is: WWWWhat is causing these deformities?

3. Researching 3. Researching  Gather information related to the problem  Read, observe, measure, take samples, etc.  How frogs normally develop from eggs  The % of frogs with the deformities  Number of other species in the pond with deformities  Previous or new pollutants in the pond  Change in amount of UV (sunlight) exposure on eggs  Etc.

4. Hypothesizing 4. Hypothesizing AAAA hypothesis is: AAAAn educated guess, trial answer, possible solution, prediction MMMMust be a statement MMMMust be testable or measurable IIIIs based on your research and previous experience

Hypothesizing Hypothesizing LLLList possible explanations (alternative hypotheses) based on your previous experience (what you already know); and on research you have done aaaall of the hypotheses must be testable (no demons allowed!)

Hypothesizing Hypothesizing SSSSome possible explanations (hypotheses) for the frog deformities: GGGG eeee nnnn eeee tttt iiii cccc m m m m uuuu tttt aaaa tttt iiii oooo nnnn CC hhhh eeee mmmm iiii cccc aaaa llll P P P P oooo llll llll uuuu tttt iiii oooo nnnn UU llll tttt rrrr aaaa vvvv iiii oooo llll eeee tttt R R R R aaaa dddd iiii aaaa tttt iiii oooo nnnn DD iiii ssss eeee aaaa ssss eeee ( ( ( ( vvvv iiii rrrr uuuu ssss o o o o rrrr p p p p aaaa rrrr aaaa ssss iiii tttt eeee o o o o rrrr ???? )))) LL oooo uuuu dddd R R R R oooo cccc kkkk & & & & R R R R oooo llll llll M M M M uuuu ssss iiii cccc AA llll iiii eeee nnnn ssss f f f f rrrr oooo mmmm o o o o uuuu tttt eeee rrrr s s s s pppp aaaa cccc eeee SS oooo mmmm eeee tttt hhhh iiii nnnn gggg e e e e llll ssss eeee Genetic mutation- If this hypothesis is true, then: If we mate deformed frogs the offspring should show similar deformities The deformities should be fairly uniform and predictable The particular deformities should only be found in one species Chemical Pollution- If this hypothesis is true, then: You should be able to find a likely chemical pollutant in the deformed frog ponds You should be able to isolate the chemical from the pond water You should be able to show that the isolated chemical can cause the exact same deformities in the lab These are minimal predictions; you may have already thought of the fact that chemical pollution should affect all four limbs equally, or that other organisms from the same ponds should show deformities as well Ultraviolet Radiation- If this hypothesis is true, then: We should be able to measure unusually high levels of UV radiation at deformed frog sites We should be able to use these same levels to induce the exact same kinds of deformities in the lab Can you think of other predictions based on this hypothesis? Disease (virus, parasite, etc.)- If this hypothesis is true, then: We should be able to find the disease-causing agent (for example, parasites) at the deformed frog ponds We should be able to find the parasites in the deformed frogs We should be able to use the same parasite to induce the exact same kinds of deformities in the lab Loud Rock + Roll Music- Okay, this is testable, but WHY test it??? (get real) Aliens from outer space- Sorry, this is not allowed because it is not testable using the Scientific Method. Sheesh! Something Else- Another possibility that we might think of is predation or cannibalism, which seems to be the best explanation for certain kinds of deformities (frogs with missing limbs). If this hypothesis is true, then, at minimum: We should find frogs and/or other pond critters with evidence that their legs have been damaged or bitten off

5. Experimenting 5. Experimenting  Testing the hypothesis  Pick the hypothesis that makes the most sense and is easy to test  Then design a controlled experiment

Experimenting Experimenting  Go to the web site for Hartwick College to see the experiments and how the scientific method was actually used to find out the cause of recently found frog deformities.  ntroduction/Exploration/explore.html ntroduction/Exploration/explore.html ntroduction/Exploration/explore.html

Experimenting Experimenting  Let’s look at the text book example of the Scientific Method using Redi’s Experiment on Spontaneous Generation  He was trying to disprove the idea of Spontaneous Generation (or actually that flies came from maggots, which came from flies) Francesco Redi (1668)

Stating the Problem  Example: How do new living things come into being?  Spontaneous generation once commonly accepted  Redi wanted to show what caused the appearance of maggots (and then flies) on meat

Belief based on prior observations Belief based on prior observations  If leaf lands on water it becomes a fish  If bale of hay left in barn it produces mice  Muddy soil gives rise to frogs  Meat hung out in the market is the source of flies

Belief based on prior observations Belief based on prior observations  Redi observed that maggots appeared on meat a few days after flies were on meat  No microscope = no way to see eggs  But Redi believed that maggots came from eggs that were laid by flies

Forming a Hypothesis Redi’s Hypothesis: Redi’s Hypothesis: Flies produce maggots. Flies produce maggots.  How could he test this?  Through a controlled experiment

Redi ’ s Controlled Experiment Redi ’ s Controlled Experiment  Redi used two groups of jars  Jars that contained meat and no cover  Jars that contained meat and gauze cover Jars with meat Uncovered jars Covered jars

Control and Experimental Groups  used as a standard of comparison  the group containing the factor (variable) that has been changed Uncovered jars Covered jars Two groups of jars Control group: Control group: Experimental group: Experimental group: (manipulated or independent variable)

Variables in an Experiment  Variables - Factors that can be changed  Controlled Variables - all the variables that remain constant  Manipulated Variable - (also called the Independent Variable ) - factor in an experiment that a scientist purposely changes  Responding Variable- (also called the Dependent Variable ) - the outcome or results, factor in an experiment that may change because of the manipulated variable…. what a scientist wants to observe

Setting up a Controlled Experiment  In a controlled experiment, only one factor is changed at a time.  Independent variable: the factor that is deliberately changed  Dependent variable: the factor that the scientist wants to observe; it changes in response to the independent variable the factor that the scientist wants to observe; it changes in response to the independent variable

Variables in Redi ’ s Experiment Variables in Redi ’ s Experiment CControlled Variables: jars, type of meat, location, temperature, time MManipulated Variables: gauze covering that keeps flies away from meat

Let ’ s think about this.… 1.W hich is the control group? 2.W hich is the experimental group? Two groups of Jars with meat Uncovered jars Covered jars Covered jars Uncovered jars

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Manipulated Variables: gauze covering that keeps flies away from meat Uncovered jars Covered jars Several days pass Maggots appearNo maggots appear Responding Variable: whether maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur. Controlled Variables: jars, type of meat, location, temperature, time Redi’s Experiment on Spontaneous Generation

6. Collect and Record Data Types of Recorded Data Types of Recorded Data  Quantitative - observations that involve measurements/numbers; i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters  Qualitative - observations that do not involve numbers, are of a descriptive nature i.e. white maggots covered the meat, leaves were all wilting observations and measurements made in an experiment Data:

7. Analyze the Data  Examine data tables, charts, and graphs  Examine experimental notes  Look for trends, patterns, and averages  What does the data show  Put your data into words

8. Draw Conclusions RRRRestate the hypothesis: Example: Flies produce maggots. AAAAccept or reject the hypothesis. SSSSupport your conclusion with specific, numerical data. WWWWhat was Redi’s conclusion? FFFFlies lay eggs too small to be seen. MMMMaggots found on rotting meat are produced from the eggs laid by flies. MMMMaggots are not appearing due to spontaneous generation!

9. Determine Limitations  Scientists look for possible flaws in their research  They look for faulty (inaccurate) data  They look for experimental error or bias's  They decide on the validity of their results  They make suggestions for improvement or raise new questions

10. Publish Results  Communication is an essential part of science  Scientists report their results in journals, on the internet, or at conferences  This allows their experiments to be evaluated and repeated  Scientists can build on previous work of other scientists Redi’s experiment on insects generation

Repeating the Investigation  Sometimes results are unexpected.  Sometimes results are unexpected.  John Needham challenged Redi’s experiment and designed his own to show that spontaneous generation CAN occur under certain circumstances.  Lazzaro Spallanzini designed a slightly different experiment to improve on Needham’s work Repeat the experiment!

Repeating the Experiment (continued)  Louis Pasteur further modified the experiment.

The reason scientific work is called “RE-search” rather than just "search " is because it is an ongoing process that often times changes our view of the natural world. It is subject to modification in light of new evidence and new ways of thinking. Scientific Method How Scientists Work Solving the Problems Scientific Method How Scientists Work Solving the Problems

SCIENTIFICSCIENTIFICSCIENTIFICSCIENTIFIC METHOD REV IEW

Can you put these steps in order? State the Hypothesis Make an Observation 1 the Problem 3 Determine Limitations 9 Define the Problem 2 Analyze Data 7 Report Results 10

Steps of Scientific Method in order State the Hypothesis Make an Observation the Problem Determine Limitations 9 Define the Problem 1 Analyze Data 2 Report Results

Scientific Theory AAAA theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers

Scientific Law Scientific Law  Scientific laws represent the cornerstone of scientific discovery  They must be simple, true, universal, and absolute  If a law ever did not apply, then all science based upon that law would collapse Scientific Method