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Introduction to Life Science

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Why a Study of Biology is Important?

SocietalMedicinePublic Health Worldwide Water Crisis

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Why a Study of Biology is Important?

PhilosophicalEvolutionGenetics

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Why a Study of Biology is Important?

PersonalTo be informedSupport your causeMake it your life work

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[bahy-ol-uh-jee]

Bio = life

...ology = the study of

Biology is the science that studies life

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The Scientific Method in Action

A systematic way of gaining information

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The Scientific Method: Observation

An observation is a thoughtful and careful recognition of an event or a fact.

The careful observation of a phenomenon leads to a question.– How does this happen?– What causes it to occur?

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The Scientific Method:The Hypothesis

Hypothesizing – question an observation– propose possible solutions to questions based on

what is already understood about the phenomenon Hypotheses must:

– be logical– account for all current information– make the least possible assumptions– be testable

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Testing Hypotheses

Hypotheses need to be tested to see if they are supported or disproved.– Disproved hypotheses are rejected– Hypotheses can be supported but not proven

Ways to test a hypothesis:– Gathering relevant historical information

Retrospective Studies

– Make additional observations from the natural world– Experimentation

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The Scientific Method: Experimentation

Experiments– rigorous tests to determine if the solutions are

supported

Experiments attempt to recreation an occurrence– tests whether or not the hypothesis can be supported

or rejected

There are many types of experiments– laboratory, clinical trials, surveys, statistical analyses

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Experimental Design

All experiments have key elements in common:

– Experiments must be controlledthis means that all aspects except for one variable must be

kept constantusually include any two groups.

– Experimental group: variable is altered, independent variable – Control group: variable is not altered, dependent variable

– Experiments use models to recreate occurrences, but in a controlled setting

model organisms, ISS, cohorts

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Experimental Design

Experiments must:– use large numbers of subjects and/or must be

repeated several times (replication)– be independently reproducible

The validity of experimental results must: – be tested statistically

chi-squared test for statistical significance

– be scrutinized by other scientistspeer reviewed

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Theory

If the hypothesis is supported by ample experimental data, it leads to a theory.

A theory may be defined as a widely accepted, plausible general statement about a fundamental concept in science.– The germ theory states that infectious diseases are caused by

microorganisms. Many diseases are not caused by microorganisms, so we must be

careful not to generalize theories too broadly.– Theories continue to be tested

Exceptions identified Modifications made

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A Scientific Law

A scientific law is a uniform and constant fact of nature that describes what happens in nature.

– An example: All living things come from pre-existing living things.

Scientific laws promote the process of generalization.– Inductive reasoning– Since every bird that has been studied lays eggs, we can generalize

that all birds lay eggs.

Once a theory becomes established, it can be used to predict specific facts.

– Deductive reasoning– We can predict that a newly discovered bird species will lay eggs.

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Scientific Communication

Data is shared with the scientific community through research articles published in scientific journals.

– peer review

Scientists present preliminary data at conferences.

Scientists collaborate directly by phone and e-mail.

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A Sample Experiment

Scientific American August 2010

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A Sample Experiment

Article: Hardt, Marah J. and Safina, Carl. “Threatening Ocean Life from the Inside Out.” Scientific American August 2010: Vol. 303 2.

What types of observations were being made? State a hypothesis that was tested. Describe an experiment that was conducted. Discuss a variable that was studied and describe how

constants where maintained in the experiment. How was a model system was used to simulate the conditions

being studied. How were the complex processes being studied reduced to

their simplest parts? What was learned from the experiments?