Scientific MethodScientific Method

El Método CientíficoEl Método Científico

Estudio del Capítulo 1 Estudio del Capítulo 1

Págs. 1-18Págs. 1-18

PasosPasos

Hipótesis y TeoríasHipótesis y Teorías

Hipótesis verificadas repetidamente Hipótesis verificadas repetidamente e indefinidamentee indefinidamente

Teoría refutadaTeoría refutada

Teoría de la generación EspontáneaTeoría de la generación Espontánea De materia orgánica pueden surgir De materia orgánica pueden surgir

espontáneamente organismosespontáneamente organismos Surge controversia entre Defensores y Surge controversia entre Defensores y

OpositoresOpositores Ver experimento de las moscas de F. Ver experimento de las moscas de F.

RediRedi

Application to Everyday Application to Everyday ProblemsProblems

Assume you are late for an Assume you are late for an appointment and hurriedly try to appointment and hurriedly try to start your car start your car

1.1. ObservationObservation: The car won’t start: The car won’t start

Descubrimiento de la Descubrimiento de la PenicilinaPenicilina

1929: Alexander Fleming1929: Alexander Fleming Cultivaba bacteriasCultivaba bacterias Contaminación con el hongo Penicillium Contaminación con el hongo Penicillium

notatumnotatum Aplicó el método científico: Aplicó el método científico:

Observación, hipótesisObservación, hipótesis Descubrimiento de sustancia inhibitoria Descubrimiento de sustancia inhibitoria

de crecimiento de bacterias.de crecimiento de bacterias.

Science Is a Human Science Is a Human EndeavorEndeavor

1.1. In the 1920s, bacteriologist In the 1920s, bacteriologist Alexander Fleming grew bacteria in Alexander Fleming grew bacteria in cultures cultures

2.2. One of the bacterial cultures One of the bacterial cultures became contaminated with a moldbecame contaminated with a mold

3.3. Fleming nearly destroyed the Fleming nearly destroyed the culture when he noticed the mold culture when he noticed the mold ((PenicilliumPenicillium) inhibited bacterial ) inhibited bacterial growth in the culturegrowth in the culture

TeoríasTeorías

Hipótesis verificadas repetidamente.Hipótesis verificadas repetidamente. Se pueden descartar con el paso del Se pueden descartar con el paso del

tiempo a la luz del nuevo tiempo a la luz del nuevo conocimiento.conocimiento. Ej. La abiogénesisEj. La abiogénesis

Science is a Human Science is a Human EndeavorEndeavor

4.4. Fleming hypothesized that the mold Fleming hypothesized that the mold produced an antibacterial produced an antibacterial substancesubstance

5.5. Further tests using broth from pure Further tests using broth from pure PenicilliumPenicillium cultures lead to the cultures lead to the discovery of the first antibiotic, discovery of the first antibiotic, penicillinpenicillin

Science Is Based on Science Is Based on ReasoningReasoning

Inductive ReasoningInductive Reasoning Used in the development of scientific Used in the development of scientific

theoriestheories A A generalizationgeneralization is created from many is created from many

observationsobservations e.g., the cell theory (all living things are e.g., the cell theory (all living things are

made of one or more cells) arises from made of one or more cells) arises from many observations that all indicate a many observations that all indicate a cellular basis for lifecellular basis for life

The Scientific MethodThe Scientific Method

Scientific experimentation tests the Scientific experimentation tests the assertion that a assertion that a single single variablevariable causes a particular observationcauses a particular observation

The experiment must rule out the The experiment must rule out the influence of other possible variables influence of other possible variables on the recorded observationson the recorded observations

The Scientific MethodThe Scientific Method

ControlsControls are incorporated into are incorporated into experimentsexperiments

Controls keep untested variables Controls keep untested variables constantconstant

Scientific method is illustrated by Scientific method is illustrated by Francesco Redi’s experimentFrancesco Redi’s experiment