Alabama Course of Study Objective 1

 Describe the steps of scientific method  Compare variable  Identify safe lab procedures  Use appropriate SI units

 Biology – study of life What does that mean? Formed by the concepts, principles and theories that allow people to understand the natural environment  What we do Forester Medical Fields Conservation Officer Engineers Astrobiologists Oceanographer Climatologists Physical Trainer TEACHER

 Scientific Method – common steps biologists use to gather information Cyclic vs. Linear processes Must be repeatable by others Why? Scientific Method subdivided into five steps

 Observation – act of gathering info Types of observation How to determine what information is relevant Hawthorne Effect – subjects react to observation by modifying their behavior

 Hypothesis – explanation for a question that can be formally tested What types of questions can be tested? Moral/Ethical Brown tree snakes of Guam

 Experiment – set of controlled conditions that tests a hypothesis All experiments must contain at least two groups  Control Group – standard by which the results are compared, does not receive the treatment  Test Group – receives the treatment

 Experiment All experiments contain three variables Independent Variable  Treatment or condition under study  only one tested at a time  Always found on x axis of graph Dependent Variable  Result of change in the independent variable  Always found on y axis of graph

 Experiment All experiments contain three variables  Controlled Variable  Any other factors that could influence the dependent variable  Must be the same for all groups Two types of data  Qualitative – descriptive  Quantitative - numerical

 Hypothesis: Fertilizer X will increase the growth rate of garden peas  Experiment: Test Group – receives fertilizer Control Group – does not receive fertilizer IV – Fertilizer DV – Growth rate of plants CV?

 Conclusion Judgment based on the information obtained in the experiment Must always accept or reject hypothesis Experimental results show that Fertilizer X increased plant growth rate by 40% Accept hypothesis/Repeat experiment

 Theory Explanation that has been supported by many experiments Results from continual verification and refinement of a hypothesis Ex. Evolution  Law Natural events that are generally known to be true Ex. Gravity

 SI System System de International International System of Measurement Decimal system based on powers of ten

 Length SI unit is Meter (m) Mechanism  Ruler  Meter Stick  Tape Measure Conversions  1 in = 2.54 cm  1 mile = 1.61 km  1 yard = meters

 Mass SI unit is kilogram (kg) Grams (g) are most commonly used unit Mechanism  Electronic balance  Spring Scale Conversions  1 kg = 2.2 lbs  1 ounce = g  1 ton = kg

 Volume SI unit is Liter (L) Cubic centimeter (cm 3 ) is used for dry measurements Mechanism  Graduated Cylinder  Beaker  Flask  Pipette

 Time SI unit is Second (s) Mechanism  Stopwatch  Temperature SI unit is Kelvin (K) Celsius also used Mechanism  Thermometer Conversions  C = (F – 32) x 5/9  F = C x 9/  K = C  C = K – 273

 Microscopy Compound Light Microscope  1 st developed in the 17 th century  Uses as series of images to magnify objects in steps  Total magnification power of 1500x  Used by Robert Hook to observe 1 st cells

 Microscopy Electron Microscopes  1 st developed in 20 th century  Uses beam of electrons to magnify objects up to x  Transmission Electron Microscope (TEM)  Used for viewing structures inside a cell (nucleus)  Scanning Electron Microscope (SEM)  Used for scanning the surface of cells to show 3D shape