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# 2.9: Unit 2 Practice and Assessment

#### Outcome 1

1) What are the steps in the basic scientific method?

2) Use the summary of this 25-year, 7-country smoking and mortality study to identify the observation, question, hypothesis, test method, analysis method, reported uncertainty or confidence interval, and conclusions.

3) Explain how you could you apply the basic scientific method to a question from your everyday life. Be sure to identify how you would complete each step: observation, question, hypothesis, test method, analysis method, reported uncertainty or confidence interval, and conclusions.

4) How is the scientific method related to the modern scientific process?

#### Outcome 2

5) Provide an example of each of the following: empirical model, physical model, hypothesis, theory, and law. List any sources you used to find examples.

6) State which of the following categories the ideas listed below fall under: empirical model, physical or mechanistic model, hypothesis, theory, or law. List any sources you used to help you decide.

• Foreign organisms were thought to be present inside tumors (microscopic studies never found evidence of this).
• Due to genetic instability, successive mutations, appearing in cells, lead to selection of cancer cells which feature specific phenotypic traits[1].
• Natural Selection
• All living organisms consist of membrane encased cells
• Plate Tectonics
• Statistical relationships are found between measured forest fire smoke exposure and other available air quality data. Those relationships are used to predict forest fire smoke exposure in geographic areas where it’s not easily measured[2].

#### Outcome 3

7) What is the height in meters of a person who is 6 ft 1.0 in. tall? (Assume that 1 meter = 39.37 in.)

8) The speed of sound is measured to be 342 m/s on a certain day. What is this in km/h?

9) Soccer fields vary in size. A large soccer field is 115 m long and 85 m wide. What are its dimensions in feet + inches? (Assume that 1 meter equals 3.281 feet.)

10) Tectonic plates are large segments of the Earth’s crust that move slowly. Suppose that one such plate has an average speed of 4.0 cm/year. (a) What distance does it move in 1 s at this speed? (b) What is its speed in kilometers per million years?

#### Outcome 4

11) Make an order of magnitude estimate of the number of cells in a hummingbird, assuming all the cells are the same size and approximating the the mass of an average cell to be ten times the mass of a bacterium. Be sure to cite your source for the size of a bacterium. (b) Making the same assumption, how many cells are there in a human?

(Exercises for outcomes 3 and 4 adapted from OpenStax College Physics [3]