Biological Biological ScienceScience

Biological Biological ScienceScience

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of basic scientific principles to of basic scientific principles to biological questionsbiological questions

What do scientists do?

• Scientists observe nature, ask questions about what they observe, and systematically go about answering these questions.

The Scientific Record• An enormous record of

observations, questions, and answers relating to the natural world has developed over time.

• This record provides a platform for the next round of observations, questions, and answers.

Scientific Method• The scientific method is a process that

tests possible answers to questions about nature that have been formulated from careful observations.

• Answers supported or refuted by the results of these tests are then added to the scientific record.

Attributes of the Method• The scientific method is used by

scientists to insure that the answers to their questions are based on objective evidence and verifiable.

• Ideas must be testable and cannot deal with things that are supernatural because they are not testable.

Common Elements• Observing nature• Asking a question• Proposing a hypothesis• Designing a test• Making Predictions• Conducting the test• Analyzing the results• Drawing conclusions

Observing Nature• Gathering information using the raw

senses or using equipment• Keeping careful records of

observations• Observation=an aspect of a

phenomenon that can be witnesses and recorded

Asking a Question• What causes something to

happen?• How will something affect

something else?

Proposing a Hypothesis• A hypothesis is a tentative

explanation which answers the original question and can be supported or refuted when tested

Hypothesis Generation

• Hypothesis generation uses inductive reasoning to jump to conclusions

• Inductive reasoning draws a general conclusion from individual facts

Designing a Test• Scientists design experiments to

test their hypothesis• Experiment=empirical test that

provides data to test the validity of a hypothesis

Making Predictions• Often in the form of an “if/then”

statement: “If the hypothesis is true, then such-and-such will occur”

• Uses deductive reasoning• Deductive reasoning draws a

specific conclusion from a general assumption

Conducting the Test• Performing the experiment and

collecting data, or little facts, that will support or refute the hypothesis

Analyzing the Results• Assembling and describing data

Drawing Conclusions• The data does/does not bear out the

predictions• The data does/does not support the

hypothesis• The data acts as additional

observations for asking new questions and proposing new hypotheses

Multiple Working Hypotheses

• A set of alternative explanations: H1, H2, H3, etc.

• Each one can explain the observations and is supported by tests but none can be chosen over any other.

• Further testing may refute some or all of them.

Strong Inference• After rigorous testing that involves

trying to refute all the working hypotheses one hypothesis may remain

• One can strongly infer that the remaining hypothesis is correct

Strong Science• Whenever you design an

experiment to test a hypothesis, try to think of the experiment that would disprove it.

• If you cannot disprove it you may be able to make a strong inference.

Null Hypothesis• The null hypothesis is the

hypothesis of no difference or nothing happening, H0

Strong Hypothesis• The null hypothesis is a strong

alternative hypothesis because when you reject a null hypothesis the alternatives all indicate a difference or something happening.

Strong Hypothesis• Since there is no positive proof,

scientific advances are made by the rejection of null hypotheses.

Theory• A hypothesis that has been

supported by many different repeatable tests and seems to have no major inconsistencies.

Theory• A theory is the surviving hypothesis

of a group of multiple working hypotheses

• A theory can also be used to predict behavior

Conditions for a Theory• Logically consistent• Nothing unnecessary (Occam’s

Razor)• Limited by boundary conditions• Falsifiable• Modifiable

Basic Properties of Nature• Scientists assume that the natural

world has some basic underlying properties

• Theories attempt to describe these properties

Basic Properties of Nature• Since theories can be falsified but

can never be proved beyond all doubt (Carl Popper’s Theorem) the basic underlying properties of nature can never be known with total certainty

Unifying Theory• It unifies a field of study.• It explains many seemingly

unconnected phenomena because it describes a basic underlying property of nature.

• It can be used to predict many outcomes.

Unifying Theories in Biology

• Cell Theory– Basic unit of structure capable of

performing all life functions.

• Evolution– Descent with modification from

common ancestry.

Unifying Theories in Geology and Physics

• Plate Tectonics• Relativity

Scientific Laws• Quantitative relationships between

measurable quantities that are predicted by unifying theories, often in the form of equations or algorithms that are accepted by just about all scientists

• Ex. Law of Gravity

Wrap UpWrap UpWrap UpWrap Up

What’s wrong with this order of common

elements?1. Observing nature2. Asking a question3. Designing a test4. Making Predictions5. Conducting the test6. Proposing a hypothesis 7. Analyzing the results8. Drawing conclusions

What’s wrong with this order of common

elements?1. Observing nature2. Asking a question3. Designing a test4. Making Predictions5. Conducting the test6. Proposing a

hypothesis 7. Analyzing the results8. Drawing conclusions

Common Elements• Observing nature• Asking a question• Proposing a hypothesis• Designing a test• Making Predictions• Conducting the test• Analyzing the results• Drawing conclusions

What’s wrong with this order of common

elements?1. Observing nature2. Making Predictions3. Asking a question4. Proposing a hypothesis 5. Designing a test6. Conducting the test7. Analyzing the results8. Drawing conclusions

What’s wrong with this order of common

elements?1. Observing nature

2. Making Predictions3. Asking a question4. Proposing a hypothesis 5. Designing a test6. Conducting the test7. Analyzing the results8. Drawing conclusions

What’s wrong with this order of common

elements?1. Observing nature2. Asking a question3. Proposing a hypothesis 4. Designing a test5. Conducting the test 6. Making Predictions7. Analyzing the results8. Drawing conclusions

What’s wrong with this order of common

elements?1. Observing nature2. Asking a question3. Proposing a hypothesis 4. Designing a test5. Conducting the test

6. Making Predictions7. Analyzing the results8. Drawing conclusions

Common Elements• Observing nature• Asking a question• Proposing a hypothesis• Designing a test• Making Predictions• Conducting the test• Analyzing the results• Drawing conclusions

Inductive Reasoning

• Inductive reasoning draws_____.• Inductive reasoning draws a

general conclusion from individual facts.

Inductive Reasoning

• Inductive reasoning is used to_____.

• Inductive reasoning is used to jump to conclusions.

• Inductive reasoning is used to generate hypotheses.

Deductive Reasoning

• Deductive reasoning draws_____.• Deductive reasoning draws a

specific conclusion from a general assumption.

Deductive Reasoning

• Deductive reasoning is used to_____.

• Deductive reasoning is used to make predictions.

• Deductive reasoning is used to generate if/then statements.

Hypotheses: H0, H1, H2, H3, etc.

What is H0?

• H0 is the null hypothesis of no difference or nothing happening.

What are H0, H1, H2, H3?

• H0, H1, H2, and H3 are alternative working hypotheses that can explain observations and are supported by tests.

Strong Inference• One can strongly infer that, ______,

the one remaining is probably correct.

• One can strongly infer that, after trying to refute all working hypotheses, the one remaining is probably correct.

Theory• A hypothesis that _____ and seems

to have no major inconsistencies.• A hypothesis that has been

supported by many different repeatable tests and seems to have no major inconsistencies.

Unifying Theory• It explains many _____ because it

describes a basic underlying property of nature.

• It explains many seemingly unconnected phenomena because it describes a basic underlying property of nature.

Unifying Theory• It can be used to _____ many

outcomes. • It can be used to predict many

outcomes.