Scientific Method

THE PROCESS OF SCIENCE Scientists use two main approaches to learn about nature Science Is a way of knowing Seeks natural causes for natural phenomena Discovery Science Hypothesis Based Science

Discovery Science Scientists describe some aspect of the world and use inductive reasoning to draw general conclusions

Hypothesis-Based Science Hypothesis-Based Science Scientists attempt to explain observations by testing hypotheses

Hypothesis-based science involves Observations, questions, hypotheses as tentative answers to questions Deductions leading to predictions, and then tests of predictions to see if a hypothesis is falsifiable

Preliminary explanation to problem Hypothesis Questions or statements that are testable through experimentation or observation If - then format Preliminary explanation to problem

Observations Question Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Replacing bulb Test prediction Test falsifies hypothesis Test does not falsify hypothesis

Tests the predictions made by a hypothesis Double Blind Controlled Experiment Tests the predictions made by a hypothesis Double Blind Controlled

Researchers do not know which subject is receiving the actual drug Double Blind Test One group receives the drug to be tested; One group receives the placebo Researchers do not know which subject is receiving the actual drug Eliminates the bias that may influence the results

Controlled Experiment Experiment isolates a single factor that is directly responsible for an effect.

Condition in the experiment that differs Variable Condition in the experiment that differs

Independent Variable: Variable that is independent of experiment pH, time, temperature Dependent Variable: What you are testing Dependent of results of experiment

Control Provides a standard of comparison for the one factor in the experiment that varies

Hypothesis-Based Science A Case Study of Hypothesis-Based Science In experiments designed to test hypotheses The use of control groups and experimental groups helps to control variables Percent of total attacks on artificial snakes 100 80 60 40 20 83% 17% 16% 84% Artificial king snakes Artificial brown snakes Coral snakes absent present Figure 1.8B Figure 1.8C Figure 1.8D Figure 1.8E

Concept Check Not all science discoveries strictly follow the “scientific method”. Which of the following would best be described as discovery science? Sequencing the human genome. Describing a new bird species from the Philippines. A project to find preserved specimens of the probably extinct Rocky Mountain locust frozen in glaciers . All of the above.

Answer Not all science discoveries strictly follow the “scientific method”. Which of the following would best be described as discovery science? All of the above.

Interpreting Data These two snakes look remarkably similar to each other. The coral snake (right) is very poisonous to vertebrates. Hypotheses: H1: The coral snake’s bright color pattern serves to warn off potential predators. H2: The king snake suffers less predation because it mimics or looks like the coral snake. H3: The protection that king snakes receive by mimicking coral snake will depend on the presence of coral snakes.

Interpreting Data A team of scientists designed an investigation that used artificial snakes to test the previous hypotheses. Which of the previous hypotheses are supported by the results displayed at the right? H1: The coral snake’s bright color pattern serves to warn off potential predators. H2: The the king snake suffers less predation because it mimics or looks like the coral snake. H3: The protection that king snakes receive by mimicking coral snake will depend on the presence of coral snakes. Both 1 and 2

Answer A team of scientists designed an investigation that used artificial snakes to test the previous hypotheses. Which of the previous hypotheses are supported by the results displayed at the right? Both 1 and 2

Interpreting Data Biologists placed artificial snake mimics in two different localities to test the hypothesis that looking like a poisonous snake only works where the poisonous snake is found: Outside of the coral snake range—only king snakes present. Inside the coral snake range—both coral and king snakes are present.

Interpreting Data The data graphed at the right __________ the hypothesis that the effectiveness of mimic coloration depends upon the presence of the poisonous model is: supports does not support is irrelevant to

Answer The data graphed at the right __________ the hypothesis that the effectiveness of mimic coloration depends upon the presence of the poisonous model is: supports

Interpreting Data Based on this data which of the following is a logical hypothesis or prediction? King snakes outside of the range of coral snakes will more closely resemble coral snakes than populations of king snake living within the range of coral . King snakes outside of the range of coral snakes will not resemble coral snakes as closely as populations of king snakes that live within the range coral snakes. Neither prediction is valid.

Answer Based on this data which of the following is a logical hypothesis or prediction? King snakes outside of the range of coral snakes will not resemble coral snakes as closely as populations of king snakes that live within the range coral snakes.