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?
Percent of total attacks on artificial snakes RESULTS 100 80 60 83% 84% Artificial kingsnakes Brown artificial snakes 40 20 17% 16% 0 Coral snakes absent Coral snakes present
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.