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Definition of Science
the orderly process of posing and answering questions about the natural world through repeated and unbiased experiments and observations
Scientific Method (8)
1. Make insightful observations
2. Pose and clarify testable questions
3. Formulate hypotheses
4. Experimentation to gather data
5. Quantify data
6. Test the hypotheses
7. Refine hypotheses and re-test
8. Answer questions and make conclusions
Observation 1: Fungi often grow on leftover food
Observation 2: Fungi such as mold and yeast grow more on leftover bread than on leftover meat
Observation 2 is most useful for further investigations
Posing/Clarifying testable questions
Which nutrients can yeast most readily metabolize? --> What classes of biological molecules are most readily absorbed and metabolized by yeast? --> Does yeast absorb and metabolize carbs better than it absorbs and metabolizes proteins?
A good hypothesis (3)
* identifies the organism or process being investigated
* identifies the variables being recorded
* implies how the variables will be compared
states that there is no difference and is testable; most common way to state a clear and testable hypothesis
A well designed experiment
links a biological response to different levels of the variable being investigated
standards for comparisons; verify that the biological response we measure is a function of the variable being investigated and nothing else; replicates with all of the conditions of an experimental treatment EXCEPT the treatment variable
Analyze data: mean
single number that represents the central tendency of the response variable; the average
simplest measure of variations; difference between smallest and largest (extreme measurements)
sum of squared deviations
E top N bottom i=1 ((measurement of individual sample) - (the sample mean)) squared
helps to understand the spread or variation among replicated treatments; calculate the mean, calculate the deviation of each sample from the mean, square each deviation, then sum the deviations
Test the hypotheses: significantly different
the differences between means must be due to the treatment and not just due to natural variation; if so, hypothesis is rejected; usually done with statistical methods
curved interface due to the surface tension and the adhesion of water to the sides of the cylinder
How many grams of sucrose would you dissolve in water for a total volume of 500 mL to make a 5% (weight/volume) solution?
500 X 0.05 = 25g
standard measure of the amount of a chemical; one mole of any substance had 6.02 X ten to the 23 molecules
How many grams of NaCL (molecular weight = 58.5 g mole 10 to -1) would you dissolve in water to make a 0.5 M NaCl solution with 500 mL final volume?
58.5 X 0.5 X 0.5 = 14.625 g
spreading a given amount of solute throughout a larger solution
initial vol X initial molarity = final vol X final molarity
How many mL of concentration (18 M) sulfuric acid are required to prepare 750 mL of 3 M sulfuric acid?
18(V) = (3M)(750)
V = 125 mL
release H+ when dissolved in water therefore increasing concentration of H+ in solution; low pH number
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