The Scientific Method - Experimental Variables

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A researcher investigates how different pH levels affect the survival of a certain plant species. Four groups of plants are watered with solutions of pH 2 (very acidic), pH 4, pH 6, and pH 7 (neutral). The number of dead plants in each group is recorded as shown in the image. What is the most reasonable conclusion from this experiment?

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Plants survive better as the pH approaches neutral.

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The graph below shows atmospheric carbon dioxide levels since the year 1880. Which of the following conclusions can be drawn from this graph: Atmospheric carbon dioxide levels are responsible for global temperature change., Atmospheric carbon dioxide levels have been rising at about the same rate for the past century., Atmospheric carbon dioxide levels have remained the same over the past century., Atmospheric carbon dioxide levels have been rising at an increasingly higher rate as the past century has progressed.

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Atmospheric carbon dioxide levels have been rising at an increasingly higher rate as the past century has progressed.

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In an appropriately designed experiment, a scientist is able to test the effect of: a single variable, multiple variables, the hypothesis, scientific observations

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a single variable

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Which statement best expresses a basic scientific assumption? Options: Interpretation of experimental results has provided explanations for all natural phenomena., If a conclusion is valid, similar investigations by other scientists should result in the same conclusion., For any conclusion to be valid, the design of the experiment requires that only two groups be compared., After a scientist formulates a conclusion based on an experiment, no further investigation is necessary.

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If a conclusion is valid, similar investigations by other scientists should result in the same conclusion.

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What is the dependent variable in the experiment that determines whether drinking caffeinated soda increases pulse rate?

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pulse rate of each group

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A series of steps used by scientists to solve a problem or answer a question.

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scientific method

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There are two types of data. Which type of data involves numbers that are obtained by counting or measuring?

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quantitative

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What type of variable is the fertilizer when experimenting with the growth of a plant using three plants, two different fertilizers, equal light, and equal water?

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Independent

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Research Question: Does the type of gasoline put in a car effect how fast the car can drive. What is the independent variable?

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Type of gasoline

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What step does every scientific experiment begin with? Options: hypothesis, question/problem, procedures, conclusion

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question/problem