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The word science is derived from a Latin verb meaning “to know”. Science is a way of knowing about the natural world.
At the heart of science is inquiry, a search for information and explanation.
Inquiry in Science
The field of science starts with curiosity and observations about the natural world.
Recorded observations are called data.
Curiosity and Observation
Science is a limited field that can only answer certain types of questions.
C=Consistency (repeatable experiments) O=Observability (with natural senses or tools) N=Natural (natural causes for natural events) P=Predictability (natural cause can be predicted) T=Testability (with experimentation) T=Tentative (can be changed with new evidence)
Science is limited to questions that can be answered by experimentation and evidence.
CONPTT
There is no formula for successful scientific inquiry—no single scientific method with a rule book that researchers must follow.
The Scientific Method—No Such Thing!
In science, a hypothesis is a tentative answer to a well-framed question—an explanation on trial.
It is usually an educated guess, based on experience and on the data available. Must be testable. Must be falsifiable.
Hypothesis
Fig. 1-24a
Observations
Question
Hypothesis #1:Dead batteries
Hypothesis #2:Burnt-out bulb
Fig. 1-24b
Test prediction
Hypothesis #1:Dead batteries
Hypothesis #2:Burnt-out bulb
Test prediction
Prediction:Replacing batterieswill fix problem
Prediction:Replacing bulbwill fix problem
Test falsifies hypothesis
Test does not falsify hypothesis
A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations
Many poisonous species are brightly colored, which warns potential predators
Mimics are harmless species that closely resemble poisonous species
Henry Bates hypothesized that this mimicry evolved in harmless species as an evolutionary adaptation that reduces their chances of being eaten
This hypothesis was tested with the poisonous Eastern Coral Snake and its’ mimic the non-poisonous Scarlet Kingsnake
Both species live in the Carolinas, but the Kingsnake is also found in regions without poisonous coral snakes
If predators inherit an avoidance of the Coral Snake’s coloration, then the colorful Kingsnake will be attacked less often in the regions where coral snakes are present
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 1-25
South Carolina
North Carolina
Key
Scarlet kingsnake (nonpoisonous)
Scarlet kingsnake (nonpoisonous)
Eastern coral snake (poisonous)
Range of scarletkingsnake onlyOverlapping ranges ofscarlet kingsnake andeastern coral snake
Field Experiments with Artificial Snakes
To test this mimicry hypothesis, researchers made hundreds of artificial snakes:◦ An experimental group resembling Kingsnakes ◦ A control group resembling plain brown snakes
• Equal numbers of both types were placed at field sites, including areas without poisonous Coral Snakes
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 1-26a
(a) Artificial kingsnake
Fig. 1-26b
(b) Brown artificial snake that has been attacked
• After four weeks, the scientists retrieved the artificial snakes and counted bite or claw marks
• The data fit the predictions of the mimicry hypothesis: the ringed snakes were attacked less frequently in the geographic region where Coral Snakes were found
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 1-27
Artificial kingsnakesBrownartificial snakes
83% 84%
17% 16%
Coral snakesabsent
Coral snakespresent
Perc
en
t of
tota
l att
acks
on
art
ificia
l sn
akes
100
80
60
40
20
0
RESULTS
Designing Controlled Experiments
A controlled experiment compares an experimental group (the artificial Kingsnakes) with a control group (the artificial brown snakes)
Ideally, only the variable of interest (the color pattern of the artificial snakes) differs between the control and experimental groups
A controlled experiment means that control groups are used to cancel the effects of unwanted variables
A controlled experiment does not mean that all unwanted variables are kept constant
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Graphs provide a visual image that allows you to analyze and organize your data in a meaningful way.
Graphing
Data points plotted accurately. Label both axis. Dependent variable on Y-axis. Independent variable on X-axis. Must have a concise, explanatory title. Key identifies symbols or colors. Each axis has an appropriate scale.
What is in a GOOD Graph?
←What’s wrong with this graph?
Line graphs are used when one variable (the independent variable) affects another, the dependent variable.
The data is continuous for both variables. The dependent variable is usually the
biological response. The independent variable is often time or the experimental treatment.
Line Graphs
Bar graphs are used for data that is non-numerical and discrete (separate) for at least one variable.
Data may be grouped into separate categories.
There are no dependent or independent variables.
Bars do not touch. Multiple sets of data may be displayed side-by-side.
Bar Graphs
Pie graphs can be used instead of bar graphs, generally in cases where there are six or fewer categories involved.
A pie graph provides strong visual impact of the relative proportions in each category (particularly where one is dominant).
Pie Charts
Histograms are plots of continuous data and are often used to represent frequency distributions, where the Y-axis shows the number of times a particular value was seen.
Data is numerical and continuous, so the bars touch.
X-axis usually records the class intervals. Y-axis usually records the number of individuals in each class.
Histograms
