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RS: Christine Goedhart CT: Analu Garcia Santa Ana High School

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1 RS: Christine Goedhart CT: Analu Garcia Santa Ana High School
Rain Upon The Radishes RS: Christine Goedhart CT: Analu Garcia Santa Ana High School Adapted from

2 Rain upon the Radishes Purpose: Student Learning Outcomes:
- Investigate the effects of pH on seed germination - Relate results to the environmental problem of acid rain Student Learning Outcomes: 1) Design an experiment via the scientific method. 2) Using an example scenario, describe why the scientific method—and strict methodologies based upon the scientific method—are standards in research. 3) Define hypothesis, observation, replicate, constants, independent and dependent variables, control, and theory as they relate to scientific experiments. 4) Effectively communicate the results of a scientific experiment, orally and in written form.

3 California Content Standards – 10th grade Biology
Cell Biology 1b. Students know that enzymes are proteins that catalyze biochemical reactions without altering the equilibrium and the activities of enzymes depend on the temperature, ionic conditions, and the pH of the surroundings. h. Students know most macromolecules (polysaccarides, nucleic acids, proteins, lipids) in cells and organisms are synthesized from a small collection of simple precursors. Ecology 6b. Students know how to analyze change in an ecosystem resulting from changes in climate, human activity, introduction of non-native species, or changes in population size. Investigation and Experimentation 1a. Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data. b. Identify and communicate sources of unavoidable experimental error. c. Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions. d. Formulate explanations by using logic and evidence. f. Distinguish between hypothesis and theory as scientific terms. j. Recognize the issues of statistical variability and the need for controlled tests. k. Recognize the cumulative nature of scientific evidence. m. Investigate a science-based societal issue by researching the literature, analyzing data, and communicating the findings. Examples of issues include irradiation of food, cloning of animals by somatic cell nuclear transfer, choice of energy sources, and land and water use decisions in California.

4 Human Fossil Fuel Use Nighttime lights 1994-1995

5 Burning Fossil Fuels Releases gases into the atmosphere
CO2 (global warming, ocean acidification) SO2 (acid rain) NOx (acid rain, nitrogen deposition) CO2

6 Acid Rain Formation Pollution mixes with water in the atmosphere
Atmospheric water becomes more acidic (lower pH)

7 pH describes the acidity or basicity of a solution (amount of H+ ions)
Soda Lemon juice Baking soda Ammonia Coffee Pure water Bleach Drain cleaner Stomach acid Tomato juice Battery acid

8 Rain water Unpolluted rain water has a pH ~ 5.5
Rain water with lower pH is known as acid rain

9 Effects of Acid Rain Structure damage Loss of aquatic life
Forest dieback Inability of seeds to germinate

10 Starch broken down into glucose by enzymes
Seed Germination Seed dormant until right conditions for growth Energy for growth stored as starch Starch must be broken down into glucose Requires enzymes Starch broken down into glucose by enzymes

11 Enzymes Protein complex that increases the rate of reactions
Lowers activation energy of reaction Activity affected by: - Temperature - Amount of substrate - pH

12 Rain upon the Radishes Lab
Question: Can changes in pH affect seed germination? Hypothesis: “If we make the pH more acidic, then radish seed germination will ______.” Independent Variable: Dependent Variable: Control: Constant Variables:

13 Methods 1) To initiate germination of seeds, soak the seeds in water for 30 minutes then drain and place on paper towels. 2) Label petri dishes with name, period, solution, and pH. 3) Fold a paper towel in half. Trace a circle using petri dish and cut out. Place 2 paper towel circles in each petri dish. 4) Using the pipette wet the paper towel with 1-2 ml of solution. 5) Place 10 radish seed inside each petri dish. 6) Place petri dishes in a darker location that is not too hot or too cold. 7) Record the germination process and results over a 3-5 day period.

14 Data Collection Solution Hypothesis Day Three Day Five

15 Data Analysis Graph data using bar graph (individual and class) 12 10
8 # of seeds germinated 6 4 2 2 3 4 6 7 Solution pH

16 Conclusion Questions Was your hypothesis supported or rejected? Explain. Identify your control in this experiment. Why was it important to have in your experimental design? What happens during the process of germination? Include glucose and starch in your answer. How is the pH of rain altered? (acid precipitation) Why do you hypothesize that pH would affect germination? What would be the implications of your lab data (economic, social, etc.)? Knowing the effects of pH on germination, what other factors do you hypothesize might have an effect on germination?

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