Question of the Day 1.) Explain how genetic engineering can improve food supplies. 2.) Describe one problem that scientists must overcome to develop a vaccine of HIV. 3.) Explain how gene therapy might be used to treat cystic fibrosis.

Scientific Process Unit 1

Objectives: Describe the stages common to scientific investigations. Distinguish between forming a hypothesis and making a prediction. Differentiate a control group from an experimental group and an independent variable from a dependant variable. Define the word theory as used by a scientist.

Observation: The Basis of Scientific Research All scientists, have a particular way of investigating. There are particular steps that need to be followed and it makes it quite interesting. The path leads you to the answer!

Solving Scientific Puzzles During the summer of 1988, David Bradford reflected on the silence around him. Spent the summer looking for a species of frog in the lakes of the Sequoia and Kings Canyon National Parks. Frogs were always there and very prevalent since records had been kept. However, in 1988, they had disappeared from 98% of the lakes.

Solving Scientific Puzzles Observation The act of noting or perceiving objects or events using the senses. As Bradford reported these observations, other scientists agreed with him with their observations of other amphibians. Amphibians have been around for >370 million years, why? This disappearance from their natural homes = alarm. Amphibians are sensitive to environment. Their moist skin absorbs chemical from the water.

Solving Scientific Puzzles B/w 1984-1988, John Harte (Cal Berkley) was also studying amphibians. Tiger Salamanders Live in ponds high on the western slopes of the Rocky Mountains in CO. Their numbers had decreased by 65% over those years. Harte was looking for the answer as to why this was happening. Started a scientific investigation. Key to this is that he did not form a conclusion, but a hypothesis.

Stages of Scientific Investigations There is no steadfast way of the “scientific method.” Still there are common stages: Collecting Observations Asking Questions Forming Hypotheses Making Predictions Confirming Predictions Drawing Conclusions

Stages of Scientific Investigations Collecting Observations This is the core of scientific investigation Harte studied the population for years Learned everything about them: How they eat Behaviors Reproduction Perfect environments Students collected water samples. Made frequent visits Realized population was decreasing. Kept careful records of the lake, population, overall conditions

Stages of Scientific Investigations Asking Questions Observations lead to questions Harte questioned why the number of salamanders was dropping Talked to other scientists, made further careful observations, and read scientific reports Answered many of his questions through observations but… Some key questions remained unanswered. In the natural world, the moisture that falls as rain and snow is very slightly acidic. In Rocky Mountains the moisture is high in sulfuric acid from power plants Acid precipitation released into mountain ponds When snow melts, goes into lakes.

Stages of Scientific Investigations Forming Hypotheses and Making Decisions A hypothesis is an explanation that might be true – a statement that can be tested by additional observations that can be tested by additional observations or experimentation. A hypothesis is not a guess It is an educated guess based on what is already known Harte formed two hypotheses: Acids that were formed in the upper atmosphere by pollutants were falling onto the mountains in the winter snows. Melting snow was making the ponds acidic and harming the salamander embryos. A prediction is the expected outcome of a test. Assuming the hypothesis is correct.

Stages of Scientific Investigations Forming Hypotheses and Making Decisions Harte predicted: He would find acid in the ponds after the snow melted. He also predicted that there would be enough acid in the ponds to harm salamander embryos. Harte set out to test his hypotheses.

Stages of Scientific Investigations Confirming Predictions Harte gathered data from many years of observations Measurement of acidity of the ponds before, during, and after snowmelt Water samples pH is explained by a number 0 to 14. Relative measure of the hydrogen ion concentration within a solution. Harte found that ponds became more acidic as the snow melted. For the second hypothesis Harte performed an experiment. Salamanders lay eggs in the pond after the snow melt.

Stages of Scientific Investigations Confirming Predictions This was a controlled experiment with an experimental group. Control Group – Group that receives to experimental treatment. Both the control and experimental groups are identical with one exception, the variable. Independent Variable – The factor that is changed. pH level Dependent Variable – The factor that is measured. Number of salamanders that hatched from eggs

Stages of Scientific Investigations Drawing Conclusions Once all the data is collected and analyzed, conclusions are made that either support or refute the hypothesis. Supported, NOT proven Why? Viewing Conclusions in Context Write it out properly and report it professionally in accordance with reporting rules.

Scientific Explanations Scientific progress is like erosion, a slow chipping away and weathering. Models – Hypothetical description… Theory – A set of related hypotheses that have been tested and confirmed many times by scientists. Unites and explains a broad range of observations. Constructing a Theory Involves considering contrasting ideas and conflicting hypotheses.

Critical Thinking Summarize how scientists use observations, hypotheses, predictions, and experiments in scientific investigations. What is the difference between the independent variable and dependent variable. What is the difference in the word theory in science vs. the general sense. A researcher finds that 90% of salamanders hatch from eggs in water with a pH of 7, 80% at pH of 6, 60% at 5, and 40% at 4. What is the approximate % at pH of 5.5? 55% 61% 70% 85%