IV. The Method of Science A. The Scientific Method Step 1: Make Observations: --this will allow you to formulate an idea, ask specific questions and define a problem

Example: Experiment done by Francis Redi in attempt to disprove spontaneous generation – that life comes from nonliving matter sample observations & questions: 1. flies are landing on uncovered meat 2. maggots appear on the meat soon after 3. where do maggots come from? 4. does rotting meat produce maggots?

Step 2: Background Research -- gather information on all aspects & phenomena involved -- what is the best way to go about solving the problem & avoiding duplication/mistakes Ex. define who, what, why, where, when, how are any equations needed what materials are needed has experiment been done before

Step 3: Generate a Hypothesis -- Hypothesis: a tentative explanation for the observations made & info gathered. Often in an “if…then” format & used to help guide further observations and experiments.  you will use deductive reasoning to predict what will happen during the experiment  deductive reasoning is a means of inferring a specific conclusion. What was Redi’s hypothesis??

His Thinking: rotten meat probably doesn’t turn into flies; Only flies can make more flies, but they need a source of nutrition… 1. If flies land on rotten meat, then new flies will appear 2.If meat is placed in a sealed container; then no maggots will appear. 3.If meat placed in an open container is exposed to flies, then maggots will appear after they lay their eggs on the meat.

Step 4: Conduct Experiment a. the key to experimentation (IN LAB) is the ability to control & manipulate the environment & factors that might influence the outcome. (Ex. time, temp., location, portion size) b. experimentation should combine both lab and field testing. Organisms may behave differently in natural environment d. repeat the experiment several times c. The data should be observable & objective

e. variables tested: 1. Independent/Experimental Variable – the factor that is being tested in an experiment. It will cause a change in the dependent variable (test one factor at a time) Ex. Redi? “openness” of container 2. Dependent Variable – that which “depends” on the experimental variable. It is what is being observed to change as a result Ex. Redi? appearance of maggots

3. The Control: -- a group that goes through the experiment but is NOT exposed to the factor that is being tested. Ex. Which is the control in Redi’s exp?

Step 5: Collect and Analyze Data -Data collected is put into tables -In order to analyze data… - put data into graphs - do statistical analysis -average -chi square -standard deviation

Step 6: Draw Conclusions & Report Findings -- No hypothesis can be rejected or proven w/ absolute certainty  wrong predictions, poor experimental design, various interpretations -- this method allows you to develop a high degree of confidence in interpretations. results may lead to a new hypothesis & exp. -- report findings to allow others access to your data; re-conduct the experiment; draw same or new conclusions

-- extensively tested hypothesis that is well supported & unifies a broad range of observations is called a theory -- extensively tested theory that is accepted by an overwhelming number of scientists b/c the conditions & results are always the same is referred to as a law/principle

Ex. Conclusions? 1. The container in which flies had no access to the meat did not produce maggots 2. Flies that came into contact w/ the meat laid eggs on the meat; maggots hatched 3. Flies laid eggs on gauze. Eggs fell thru the gauze and onto the meat; maggots hatched. 4. Maggots must arise from flies 5. Spontaneous generation does NOT work

Scientific Method summed up

V. Basic Biological Theories A. Cell Theory – all organisms are composed of cells B. Biogenesis Theory – Life comes from pre-existing life C. Gene Theory – organisms contain genetic info that dictates form, FXN and behavior D. Evolution Theory – all living things have a common ancestor but natural selection results in adaptation

VI. Measurement A. The SI System (i.e. metric system) 1. a decimal system whose units are based on multiples of The SI units: -- length = meters (m) -- volume = liters (L) -- mass = grams (g)

10 6 mega 10 3 kilo 10 2 hecto 10 1 deka deci centi milli micro nano pico 1,000, The SI prefixes:

** When converting from a larger unit to a smaller unit, MULTIPLY OR Count how many spaces from the unit you’re in to the unit you want to go to and move decimal that many times to the right Ex kg = __?__ g 10.0 kg = g

** When converting from a smaller unit to a larger unit, DIVIDE OR Count how many spaces from unit you’re in to the unit you want to go to and move decimal that many times to the left EX. 25 mg = __?__ dg 25 mg =.25 dg

Sample conversions: 50.0 kg = ____ g.212 ml = ____ L cm = ____ dm 6.00 g = ____ mg 44.4 nm = ____ m or 5.00 x or 2.12 x or 6.00 x or 4.44 x 10 -8