Scientific Method - the universal approach to solving scientific problems. 1. Problem Statement - Define the problem - ask question

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1 Biology: 7 Character of Life: 1. Organization of Cells 2. Response to Stimuli 3. Homeostasis 4. Metabolism 5. Growth & Development 6. Reproduction 7. Change Through Time Levels of Organization Atoms molecules cells tissues organ systems organism The Scientific Method, Tools and Measurement Scientific Method - the universal approach to solving scientific problems. 1. Problem Statement - Define the problem - ask question 2. Background Information - Gather information 3. Formulate hypothesis - A hypothesis is a logical prediction, a possible explanation for an observed set of facts. It has to be testable. If then because. Once the hypothesis is supported by experimental evidence, it is called a theory. A theory attempts to explain everything about a phenomenon, including its cause. For example, Pasteur s Germ Theory of Disease. A Scientific Law describes some aspect of a phenomenon that is always true. It does not describe how or why something occurs; only that it does. For example, the Law of Gravity. 4. Variables

2 Independent variable (manipulated variable, cause, input) a factor that is intentionally (on purpose) varied by the experimenter. Only 1 independent variable per experiment. Dependent variable (resulting/measured variable, responding, effect, output) the factor that may change as a result of changes made to the independent variable. The dependent variable is the data collected. Controlled variable variable that is not changed or manipulated. Used for comparison. Constant variable all variables that are kept the same to ensure there is only 1 variable being tested at a time. 5. Experimentation Test hypothesis - design an experiment to verify or disprove the prediction. Minimum of 3 trials is recommended. Controlled Experiment - 6. Observe, Record, and Analyze Data Data = Observations and Measurements Quantitative Data: Numerical Data Qualitative Data: Descriptive Data using your 5 senses 7. Draw Conclusions 8. Repeat Experiment If the experiment can t be repeated the results are not valid. The results are correct, if all the predictable effects are observed and repeatable. has one independent variable there are two groups in a controlled experiment, the control group and the experimental group Control Group Group that receives the placebo Experimental Group Group receiving the independent variable

3 Scientific Theory vs Scientific Law: Scientific Theory: Science Law: Honesty: Bias: Scientific Measurement - Scientists only use the International System of Units (SI). This is a system that everyone understands and it is the only system of measurement that will be used in this class. It is based off the number 10. Metric System The Standard Units of Measurement Quantities Measured Length Mass Volume Time Temperature Light Intensity Electric Current Basic Unit Meters (m) Grams (g) Liters (L) Seconds (s) Kelvin (K) Candela (cd) Ampere (A)

4 Prefix Meaning Mega (M) Million Kilo (K) Thousand Hecto (H) 100 Hundred Deka (Da) or (D) 10 Ten Unit: Liters (l), Meters (m), 1 1 Grams (g), Seconds (s) Deci (d).1 One tenth Centi (c).01 One hundredth milli (m).001 One thousandth Micro (µ) one millionth Micrometer (um) is used to measure the diameter of cells. Cells range from 10 to 50 um.

5 Tools of Biologist - Instrumentation 1. Graduated cylinder 2. Beaker 3. Flask 4. Petri Dish 5. Triple Beam Balance 6. Simple Microscope = the magnifying glass. 7. Micro dissection Instruments - are used for minute dissection of parts of the cell. 8. Compound Light Microscope - magnifies specimens 4x, 10x, 40x, 100x used to view whole cells and large organelles. Specimens can be alive. 9. Electron Microscope - magnifies 250,000x - there is much more detail than a compound light microscope. This microscope is used to study small cells, externally and internally. a. Scanning electron Microscope allows scientists to view the external cell membrane or cell wall in detail. Specimens can not be living. They are stained. b. Transmission electron Microscope allows scientists to view the internal cell organelles in detail. Specimens can not be living. They are stained. 10. Dissecting Microscope - low power microscope that allows for a 3D image. This microscope is used for gross dissection and only magnifies 10x or 20x. 11. **The two jobs of the microscopes are magnification and resolution. a. Magnification: b. Resolution: 12. Staining - normally invisible parts can be viewed under the microscope after they are stained. The two stains used in the biology laboratory are Iodine and Methylene Blue. 13. Ultracentrifuge - a device used to separate cell parts by density.