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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 statement that clearly states the relationship between biological variable

A good hypothesis (3)

* identifies the organism or process being investigated
* identifies the variables being recorded
* implies how the variables will be compared

hypothesis can never be ____ ____

proven true

null hypothesis

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

levels of the variable


treatment variable

tested variable; independent

response variable

dependent variable


repeated measures of each treatment under the same conditions

controls (3)

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)

wide range

indicates much variation in the data

sum of squared deviations

E top N bottom i=1 ((measurement of individual sample) - (the sample mean)) squared


sum of squared deviations divided by N-1 where N= the total number of samples

standard deviation

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

Metric system

used virtually everywhere except the US; used to make measurements

1 cal

4.18 joules

1 joules

0.2389 cal

1 inch

2.54 cm

1 kg

2.2 pounds

1 gal

4 quarts

1 gal

3.8 liters

1 mi

1.6 km

1 quart

0.95 liters

1 pint

0.47 liters

1 ounce

28 grams

1 fl ounce

30 milliliters

1 ft

30.48 cm

1 yd

0.9144 m

1 cup

0.24 L

1 mi

5280 ft

1 kg

1000000 mg

1 ft cubed

28316.8466 milliliters

1 mL

1 cm cubed = 1 g

25 micrometers

2.5 times 10 to the -3 power cm
25 times 10 to the -4 power cm


10 to the -1


10 to the -2


10 to the -3


10 to the -6


10 to the -9


10 to the -12


10 to the 6


10 to the 9


basic unit of length


basic unit of volume


basic unit of mass

degrees C

basic unit of temperature


curved interface due to the surface tension and the adhesion of water to the sides of the cylinder


way to organize, summarize and describe data


the middle value of a group of measurements when arranged in order from greatest to least


consist of solute dissolved in solvent


substance dissolved in solvent


substance that dissolves solute

concentration of solute expressed as

percentage of total solution (weight/volume)

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


most common measure of concentration


standard measure of the amount of a chemical; one mole of any substance had 6.02 X ten to the 23 molecules

molecular weight

the sum of the atomic weights of its component element

1 M solution

contains one mole of a chemical in 1 L solution has 6.02 X 10 to 23 molecules

1 mM

in terms of milliliters

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

Stock Solutions

solutions in concentrations


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

H+ plus OH-

= 10 to -14


release H+ when dissolved in water therefore increasing concentration of H+ in solution; low pH number


remove H+ from solution therefore decreasing concentration of H+ in solution; high pH number

H+ increases

OH- proportionately less

pH =

-log [H+]

if pH goes up, concentration of H+

goes down


mixtures of a weak acid and a weak base that combine with a strong acid or strong base to limit changed in pH

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