Chapter 1 – Biology: The Chapter 1 – Biology: The Study of LifeStudy of Life

Section 1.2 – The Methods of Section 1.2 – The Methods of BiologyBiology

p. 11-18p. 11-18

Answer this question…Answer this question…

Why do earthworms crawl to the Why do earthworms crawl to the surface after it rains?surface after it rains?

Observing + HypothesizingObserving + Hypothesizing

CuriosityCuriosity is often what motivates is often what motivates biologists to try to answer simple biologists to try to answer simple questions about everyday questions about everyday observationsobservations

The The knowledgeknowledge obtained when obtained when scientists answer one question scientists answer one question often generates other questions or often generates other questions or proves useful in solving other proves useful in solving other problemsproblems

Scientific MethodsScientific Methods Common steps that scientists use to Common steps that scientists use to

gather information and answer gather information and answer questionsquestions

No “fixed” set of steps to followNo “fixed” set of steps to follow Usually begin with an Usually begin with an observationobservation

Something seen that peaks a Something seen that peaks a scientist/person’s curiosityscientist/person’s curiosity

You want to know “why”You want to know “why”

HypothesisHypothesis

An explanation for a question or a An explanation for a question or a problem that can be testedproblem that can be tested

Formed once the observations are Formed once the observations are made to explain the observationsmade to explain the observations

Many hypotheses can be formed in Many hypotheses can be formed in any investigationany investigation

ExperimentingExperimenting An An experimentexperiment is generally an is generally an

investigation to test a hypothesis by investigation to test a hypothesis by collecting information under collecting information under controlled conditionscontrolled conditions

Parts of an ExperimentParts of an Experiment

Control GroupControl Group Part of experiment Part of experiment

that is standardthat is standard Used for comparisonUsed for comparison

Experimental Experimental GroupGroup The “test” groupThe “test” group Receives an Receives an

experimental experimental treatmenttreatment

Experimental ConditionsExperimental Conditions

Independent variableIndependent variable The one factor that was changed in the The one factor that was changed in the

two groupstwo groups For example, adding fertilizer to plantsFor example, adding fertilizer to plants

Dependent variableDependent variable An observed or measured second An observed or measured second

condition as a result of the independent condition as a result of the independent variablevariable

For example, the plant’s growth rateFor example, the plant’s growth rate

Tools used in ExperimentsTools used in Experiments

BeakersBeakers Test tubesTest tubes Petri dishesPetri dishes MicroscopesMicroscopes SpectrophotometersSpectrophotometers

Lab SafetyLab Safety

Importance?Importance? To minimize hazardsTo minimize hazards

Safety symbolsSafety symbols

Data gatheringData gathering

DataData Information obtained from investigationsInformation obtained from investigations Two types:Two types:

NumbersNumbers WordsWords

Data analysisData analysis Purpose?Purpose?

So the scientist can come up with a So the scientist can come up with a conclusionconclusion

Was the hypothesis supported by the dataWas the hypothesis supported by the data Was it not supported?Was it not supported? Are more data needed?Are more data needed?

Reporting + Verifying dataReporting + Verifying data By reporting data, scientists can By reporting data, scientists can

examine one another’s workexamine one another’s work Published in scientific journalsPublished in scientific journals

Scientists can then verify the Scientists can then verify the results by repeating an results by repeating an experimentexperiment If the results are the same, the If the results are the same, the

hypothesis can then be accepted by hypothesis can then be accepted by the scientific communitythe scientific community

TheoryTheory An explanation of a natural An explanation of a natural

phenomenon that is supported by phenomenon that is supported by large body of scientific evidence large body of scientific evidence obtained from many different obtained from many different investigations and observationsinvestigations and observations Examples:Examples:

The Cell TheoryThe Cell Theory The Theory of Evolution by Natural SelectionThe Theory of Evolution by Natural Selection Theory of RelativityTheory of Relativity Big Bang TheoryBig Bang Theory Atomic TheoryAtomic Theory

Laws/PrinciplesLaws/Principles

Facts of nature that are generally Facts of nature that are generally known to be trueknown to be true Examples:Examples:

Law of GravityLaw of Gravity