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Transcript
Scientists use the scientific method to inquire WHY and HOW?
Science provides a method for generating explanations of
events and patterns that we observe.
•
Hypotheses ARE these explanations
•
Hypotheses lead to predictions (If ____, then_____)
that can be tested.
•
Predictions are outcomes of future events,
observations or experiments
•
If predictions are incorrect, we reject the hypothesis
•
If predictions are correct, the hypothesis is supported
and accepted (for now)…but it may or may not be
TRUE
Conclusion: Observations can be used to generate
hypotheses that are used to make predictions that can
be tested in experiments. Data/results of experiments
support or refute hypotheses and allows us to draw
tentative conclusions. These conclusions help us
make decisions about future behavior including
lifestyle, how we spend money and more ….
Data are recorded observations or
items of information
• Qualitative, or descriptions rather than
measurements
• Quantitative, or recorded
measurements, which are sometimes
organized into tables and graphs
Using the Scientific Method
Observation: Your flashlight doesn’t work
Question:Why doesn’t your flashlight work?
Observations
Generate hypotheses:
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Test falsifies hypothesis Test does not falsify hypothesis
Hypothesis
Olestra® causes intestinal cramps.
Prediction
Experiment
Results
Conclusion
.
Stepped Art
Fig. 1-10, p. 14
Scientific Method: Observing
Observations:
• Both Cactus mice and Curved bill thrashers eat chiles
(fruits + seeds inside the fruit).
• Chile seeds eaten by thrashers germinate;
• Chile seeds eaten by mice do not.
• Some species of chiles contain capsaicin, some do not.
Capsaicin makes the chiles pungent (HOT/SPICY).
Scientific Method: Generating Questions that lead to hypotheses
Does capsaicin deter some eaters but not others?
Hypothesis 1:
Hypothesis 2 (null):
Hypotheses lead to predictions and experiments
Prediction: If ___________, then _________________.
•
H1Prediction:
•
H2Prediction (null):
Analyzing the Results
H = Hackberry
NP = non-pungent
P = pungent (contains capsaicin)
Check your understanding
Does capsaicin (P) deter some predators and not others?
Inquiry: Butterflies and Birds
•
•
Observations about peacock butterflies:
–
Have spots on their wings
–
Flick their wings when predators are near
–
Rest with spots hidden
–
Make clicking noise when their wings flick
Question
–
Why does a peacock butterfly flick its wings?
•
Two hypotheses
•
Two predictions (If _____________, then ________________)
Design an Experiment
Four groups of butterflies were
exposed to predators (birds)
–
Butterflies without spots
–
Butterflies without sounds
–
Butterflies without spots or
sounds
–
Control group
Scarlet kingsnake (nonpoisonous) – MIMIC?
Key
Range of scarlet
kingsnake only
Overlapping ranges of
scarlet kingsnake and
eastern coral snake
North Carolina
Eastern coral snake (poisonous)
South Carolina
Scarlet kingsnake (nonpoisonous) – MIMIC?
Hypothesis: Non-poisonous snakes mimic toxic snakes to avoid being eaten
Observations:
–
Many poisonous species are brightly colored,
which warns potential predators
–
Mimics are harmless species that closely
resemble poisonous species
–
Two different species of snake have similar
colorations.
–
Habit is overlapping.
Hypothesis: Predictions?
Experiment with artificial snakes?
Results?
RESULTS
Artificial
kingsnakes
Percent of total attacks
on artificial snakes
100
84%
83%
80
60
40
20
17%
16%
0
Coral snakes
absent
Coral snakes
present
Brown
artificial
snakes
Data Interpretation
Water snakes on islands in Lake Erie vary in coloration from banded to unbanded.
Researchers hypothesized that unbanded snakes escape predation from hawks at
higher rates than do banded snakes. Imagine that you tested survival rates on four
different islands. You put banded and unbanded snakes on islands. After some time,
you recaptured the snakes and measured how many you could catch (recapture rates
of banded and unbanded snakes). You collected the data shown below. Which of the
following conclusions are best supported from your data?
–
Lack of bands helps snakes escape
predation by hawks.
–
Lack of bands improves snake
survival but the mechanism is
unknown.
–
Lack of bands decreases snake
survival rate.
–
The two groups do not differ in
survival rate.
–
Survival rates of banded snakes differ
among islands.