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Notes Scientific Method Chapter 1: Section 2 How Scientists Work How Scientists Work: Solving the Problems Much of biology deals with solving problems These problems can be environmental, ecological, health related, etc.

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scientific method

Notes

Scientific Method

Chapter 1: Section 2

How Scientists Work

how scientists work solving the problems
How Scientists Work:Solving the Problems
  • Much of biology deals with solving problems
  • These problems can be environmental, ecological, health related, etc.
  • No matter what types of problemsare being studied, scientists use the same problem-solving steps called…
  • The Scientific Method
scientific method definition
Scientific Method Definition
  • The scientific method is-
    • A logical and systematic approach or process to problem solving. 
    • An organized way of using evidence to learn about the natural world.
    • According to Wikipedia - Scientific method is a body of techniques for investigating phenomena and acquiring new knowledge, as well as for correcting and integrating previous knowledge. It is based on gathering observable, empirical and measurableevidence subject to specific principles of reasoning, the collection of data through observation and experimentation, and the formulation and testing of hypotheses.
scientific method listing the steps
Scientific MethodListing the Steps
  • Make an Observation
  • Define the Problem
  • Research the Problem
  • State the Hypothesis
  • Experiment to test Hypothesis
  • Collect and Record Data
  • Analyze Data
  • Draw Conclusions
  • Determine Limitations
  • Report Results

If needed, Do more investigation

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Question

What does the scientist want

to learn more about?

First

Then

Research

Gathering of information

Scientific Method

An Overview

Next

Hypothesis

An “Educated” guess of an

answer to the question

Then

Procedure/

Method

Written and carefully

followed step-by-step

experiment designed to test

the hypothesis

Next

Data

Information collected during

the experiment

And

And

Observations

Written description of what

was noticed during the

experiment

Finally

Conclusion

Was the hypothesis correct

or incorrect?

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Question

What does the scientist want

to learn more about?

First

Then

Research

Gathering of information

Scientific Method

An Overview

Next

Hypothesis

An “Educated” guess of an

answer to the question

Then

Procedure/

Method

Written and carefully

followed step-by-step

experiment designed to test

the hypothesis

Next

Data

Information collected during

the experiment

And

And

Observations

Written description of what

was noticed during the

experiment

Finally

Conclusion

Was the hypothesis correct

or incorrect?

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Hypothesis

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Scientific

Method

Procedures

(Experiments)

  • S C I E N T IFIC

Findings

(Conclusions)

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Data

(Results)

Repeat steps 3-7 for competing hypotheses.

Competing hypotheses may include revisions of the original hypothesis suggested by the results of the testing process.

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Form a

Hypothesis

Define / Identify

the Problem

Make

Observations

Test Hypothesis

Perform Experiments

New

Experiments

Organize and

Analyze Data

NO

Faulty

Experiments?

Do Experiments

and Observations

Support Hypothesis?

YES

Communicate

Results

Draw Valid

Conclusions

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.

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Scientific Method

Ask Question

  • Let’s break each of these steps down into their individual components:

Do Background

Research

Think!

Try Again

Construct

Hypothesis

Test with an

Experiment

Analyze Results

Draw Conclusion

Hypothesis is True

Hypothesis is False

or Partially True

Report Results

1 observing

As we all know, frogs have four legs.

What’s up with thesefroggies?

1. Observing
  • Make an observation
    • See somethingunusual
    • Frogs withincorrectnumber oflegs!
2 questioning
2. Questioning
  • Recognize, state or define the problem
  • Must be in the form of a question
  • The obvious question is: 
    • 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 pollutantsin the pond
    • Change in amount of UV (sunlight) exposure on eggs
    • Etc.
4 hypothesizing
4. Hypothesizing
  • A hypothesis is:
    • An educated guess, trial answer, possible solution, prediction
    • Must be a statement
    • Must be testable or measurable
    • Is based on your research and previous experience
hypothesizing
Hypothesizing
  • List possible explanations (alternative hypotheses) based on your previous experience (what you already know);  and on research you have done  
  • all of the hypotheses must be testable (no demons allowed!)
hypothesizing16
Hypothesizing

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

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

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

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)

  • Some possible explanations (hypotheses) for the frog deformities: Genetic mutation

Chemical Pollution

Ultraviolet Radiation

Disease (virus or parasite or...?)

Loud Rock & Roll Music

Aliens from outer space

Something else

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.
  • http://www.hartwick.edu/biology/def_frogs/Introduction/Exploration/explore.html
experimenting19
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 SpontaneousGeneration (or actually that flies came frommaggots, which camefrom flies)

Francesco Redi (1668)

stating the problem
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 observations22
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
Forming a Hypothesis

Redi’s Hypothesis:

Flies produce maggots.

  • How could he test this?
    • Through a controlled experiment
redi s controlled experiment

Jars with meat

Uncovered jars

Covered jars

Redi’s Controlled Experiment
  • Redi used two groups of jars
    • Jars that contained meat and no cover
    • Jars that contained meat and gauze cover
control and experimental groups

Uncovered jars

Two groups of jars

Covered jars

Control and Experimental Groups

Control group:

  • used as a standard of comparison
  • the group containing the factor (variable) that has been changed

Experimental group:

(manipulated or independent variable)

variables in an experiment
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
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

variables in redi s experiment
Variables in Redi’s Experiment
  • Controlled Variables: jars, type of meat, location, temperature, time
  • Manipulated Variables: gauze covering that keeps flies away from meat
let s think about this

Two groups of Jars with meat

Uncovered jars

Covered jars

Let’s think about this.…

Uncovered jars

  • Which is the control group?
  • Which is the experimental group?

Covered jars

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Redi’s Experiment on Spontaneous Generation

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS: Flies produce maggots.

PROCEDURE

Covered jars

Uncoveredjars

Controlled Variables:

jars, type of meat,

location, temperature,

time

Several

days pass

Manipulated Variables:

gauze covering that

keeps flies away from

meat

Responding Variable:

whether maggots

appear

Maggots appear

No maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

6 collect and record data
6. Collect and Record Data

Data:

observations and measurementsmade in an experiment

Types of Recorded Data

  • Quantitative - observations that involve measurements/numbers; i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters
  • Qualitative - observations thatdo not involve numbers, are of a descriptive naturei.e. white maggots covered the meat, leaves were all wilting
7 analyze the 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
8. Draw Conclusions
  • Restate the hypothesis:

Example: Flies produce maggots.

  • Accept or reject the hypothesis.
  • Support your conclusion with specific, numerical data.
  • What was Redi’s conclusion?
    • Flies lay eggs too small to be seen.
    • Maggots found on rotting meat are produced

from the eggs laid by flies.

    • Maggots are not appearing due to spontaneous generation!
9 determine limitations
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
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
Repeating the Investigation
  • 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
Repeating the Experiment(continued)
  • Louis Pasteur further modified the experiment.
scientific method how scientists work solving the problems
Scientific Method How Scientists Work Solving the Problems

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.

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S C I E N T IFIC

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can you put these steps in order

Define the Problem

Report Results

Analyze Data

Make an Observation

State the Hypothesis

the Problem

Can you put these steps in order?

10

8

2

7

6

4

3

1

9

5

Determine Limitations

steps of scientific method in order

Define the Problem

Report Results

Analyze Data

Make an Observation

State the Hypothesis

the Problem

Steps of ScientificMethod in order

1

4

2

5

3

8

7

9

6

10

Determine Limitations

scientific theory
Scientific Theory
  • 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 Method

  • Scientific laws represent the cornerstoneof 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