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Published byPhilomena Nash Modified over 8 years ago
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Alabama Course of Study Objective 1
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Describe the steps of scientific method Compare variable Identify safe lab procedures Use appropriate SI units
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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
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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
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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
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Hypothesis – explanation for a question that can be formally tested What types of questions can be tested? Moral/Ethical Brown tree snakes of Guam
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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
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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
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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
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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?
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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
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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
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SI System System de International International System of Measurement Decimal system based on powers of ten
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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 = 0.915 meters
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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 = 28.35 g 1 ton = 907.18 kg
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Volume SI unit is Liter (L) Cubic centimeter (cm 3 ) is used for dry measurements Mechanism Graduated Cylinder Beaker Flask Pipette
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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 9/5 + 32 K = C + 273 C = K – 273
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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
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Microscopy Electron Microscopes 1 st developed in 20 th century Uses beam of electrons to magnify objects up to 500 000x 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
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