Scientific Investigation Lab Worksheet (M/C #1)

Transcription

1 Scientific Investigation Lab Worksheet (M/C #1) NAME: Ex. 1-1: QUESTIONS AND HYPOTHESES Lab Study A: Asking Questions On what basis should you decide which questions could be answered scientifically? Indicate whether or not each question below can be answered scientifically by circling yes or no : 1. Do kids who play violent video games commit more violence? (yes or no) 2. Did the consumption of seven cans of energy drink cause the heart attack of a motorcyclist in Australia? (yes or no) 3. Will increased levels of CO 2 in the atmosphere stimulate the growth of woody vines such as poison ivy and kudzu? (yes or no) 4. How effective are extracts of marigold and rosemary as insect repellents? (yes or no) 5. Should it be illegal to sell organs, such as a kidney, for transplant purposes? (yes or no) Lab Study B: Developing Hypotheses Write an explanatory hypothesis for each of the following questions: 1. Does supplemental feeding of birds at backyard feeders affect their reproductive success? 2. Do preschool boys in coed classes develop better verbal skills than boys in all-male classes? Indicate which of the following statements would be useful as a scientific hypothesis investigated using scientific procedures. Remember to consider if the hypothesis could be falsified and if a measurable and controllable experiment could be carried out to test it. 1. The use of pesticides in farming causes deformities in nearby frog populations. 2. Sea turtles are more likely to hatch during a new moon. 3. Drinking two or three cups of coffee a day reduces the risk of heart disease in women. 4. Manatees and elephants share a recent common ancestor. 5. Organic food is healthier than conventionally produced food. 1

2 Ex. 1-2: DESIGNING EXPERIMENTS TO TEST HYPOTHESES Lab Study A: Determining the Variables For the soybeans, several dependent variables are measured, all of which provide information about reproduction. What are they? What was the independent variable in the investigation of the effect of sulfur dioxide on soybean reproduction? Can you suggest other variables that the investigator might have changed that would have had an effect on the dependent variables? Why is it important to have only one independent variable? Why is it acceptable to have more than one dependent variable? What are the controlled/standardized variables in this experiment? Lab Study B: Choosing or Designing the Procedure What was the level of treatment in the soybean experiment? Describe replication in the soybean experiment. What was the control treatment in the soybean experiment? What is the difference between the control and controlled variables? Lab Study C: Making Predictions (i.e., predicting experimental outcomes based on hypothesis) State a prediction based on the following hypothesis: Exposure to sulfur dioxide reduces soybean reproduction. 2

3 List the components of a scientific investigation from asking a question to carrying out an experiment. List the variables that must be identified in designing an experiment. What are the other components of an experimental procedure? Ex. 1-3: DESIGNING AN EXPERIMENT Record the body parts and the corresponding questions chosen by the class below. Record the hypotheses for each of the questions below. Outline your experimental plans for testing each hypothesis. What is the dependent variable in each of your experiments? What is the independent variable in each of your experiments? What are the controlled variables? What is the control? Are there any levels of treatment? Describe the replication in these experiments. Predict the results of each experiment (in general) based on your hypotheses (if/then). 3

4 Height to ratio for students and newborns Subject Height (cm) part size (cm) H/BP ratio Height to ratio for students and newborns Subject Height (cm) part size (cm) H/BP ratio Newborns Newborns Ratios of Height to Two Parts for Each Student Student Part #1 Part #2 Student avg Part #1 Part #2 Ex. 1-4: PRESENTING AND ANALYZING RESULTS Lab Study A: Tables Using the student average data from above, design a table to present the results for students in your class for H/BP for each body part measured. Include in your table ratios for newborns. Compose a title for your table. 4

5 Lab Study B: Figures Using the data you ve gathered, draw a bar graph in the grid below that shows the relationship between the dependent and independent variables for both body parts. Be sure to label each axis clearly and indicate the units, if applicable, for each axis. Also, include a legend to distinguish newborn and student ratios, and give your graph an appropriate title. a) What is the independent variable for each experiment, and on which axis would you graph this? b) What is the dependent variable, and on which axis would this variable go? Ex. 1-5: INTERPRETING AND COMMUNICATING RESULTS Using your tables and figures, analyze your results looking for relationships between the variables and for general trends. Write a summary statement for your results being sure to also address whether the data support or falsify each hypothesis. Critique your experiment using the table below to indicate weaknesses and suggest improvements Weaknesses in Experiment 5 Improvement

6 REVIEWING YOUR KNOWLEDGE 1. Match each description on the right with the corresponding term on the left: control controlled variables level of treatment dependent variable replication procedure prediction hypothesis independent variable A. variables kept constant during experiment (not manipulated) B. tentative explanation for an observation C. what the investigator varies in the experiment D. process used to measure the dependent variable E. appropriate values to use for the independent variable F. treatment eliminating or standardizing independent variable G. what investigator measures or records, i.e. what is affected H. number of times the experiment is repeated I. statement of expected results based on the hypothesis 2. Circle the dependent variable and underline the independent variable for each experiment below: Scientists investigating the effects of increased temperatures on plants in urban environments measured the size of ragweed flowers in Baltimore city lots and rural fields. Scientists determined the abundance of apple aphids on leaves of 120 apple trees on 5 days in October. The autumn leaf color of the apple trees varied with 40 red trees, 40 yellow trees, and 40 green trees. Synapse number and level of synaptic proteins in the brains of fruit flies are measured during wakeful periods and periods of sleep. 3. Suggest a control treatment for each of the following experiments: Geneticists are studying the inheritance of wolfman syndrome, where the body and face are covered with dark hair. They studied three families in which 16 individuals had the syndrome. They discovered DNA deletions in four genes in each of the 16 persons. Nutrition experts investigate if eating yogurt every day will reduce gum disease. The number of T-lymphocytes are counted in the blood of vultures that feed on carcasses of livestock treated with antibiotics. 4. In a recent study of 10,000 women, scientists reported that women who had breast cancer had a history of heavier antibiotic use than women who did not have breast cancer. What possible explanations for this correlation can you suggest? 5. What is the essential feature of science that makes it different from other ways of understanding the natural world? 6