AP Biology Unit 1 Study Guide PDF

AP Biology Unit 1 Study Guide: Standard deviation (s) you will not be asked to calculate, large stand dev means there is more variation in the data, meaning that the numbers are further apart from each other. For example 2, 3, 5, 2 (small stand dev) vs. 2, 200, 903, 45 (large stand dev) Standard err...

AP Biology Unit 1 Study Guide: Standard deviation (s) you will not be asked to calculate, large stand dev means there is more variation in the data, meaning that the numbers are further apart from each other. For example 2, 3, 5, 2 (small stand dev) vs. 2, 200, 903, 45 (large stand dev) Standard error of the mean – like stand dev, used when comparing average values of data sets to decide if they are likely statistically different. Error bars on graphs are = 2SEM (2SEM means 2 Xs the SEM) if error bars do not overlap on the graph then the two sets of data are likely statistically different. Empirical rule: 68% of values in normal distribution between ±1S, 95% between ±2S, 99.7% between ±3S, be able to apply this rule to find the standard deviation. Ex. x̅ = 12 and 68% are between 9 and 15 standard deviation would be 3. Sample size (n) number of data points in a data set, example data set: 5, 5, 6, 7, 9 n = 5 bc there are 5 numbers Mean (aka average x̅) the sum of values in set of numbers divided by n Degrees of freedom is n-1 Experimental design: our focus is on ED of a controlled experiment, in controlled experiment there is always a control group and there are multiple variables that are made constant between the experimental and control groups (this is confusing, but it is important to know, control group vs. controlled variables) Hypotheses are testable statements (ex. Studying for tests results in higher test scores), you should not say “I think” when you write a hypothesis Independent variable is what is being tested/manipulated in the experiment, (ex. Amount of studying) Dependent variable is what is being measured in the experiment (ex. Test performance/score) Control group does not get the experimental treatment (ex. Group of students that does not study, the group of students that does study would be the experimental group) Controlled variables are all the factors that are consistent between the groups in an experiment (ex. Students would take the same test, have the same amount of time to complete the test) Data analysis: when comparing averages of groups, we determine if they are likely statistically different based on the averages ±2 SEM. If averages of two groups are separated by more than ±2SEM (this is when the error bars on the graph do not overlap) then they are likely statistically different. Overlapping error bars = no statistical difference Chemical bonding: covalent bond is between two nonmetal atoms, it is a strong bond where the nonmetal atoms share electrons. ionic bond is between a metal and a nonmetal atom, in ionic bond the metal gives electron(s) to the nonmetal, the atoms have charges as a result of the e- (metal becomes positive and nonmetal negative charge ion) and the opposite charged ions are attracted to each other, ionic compounds form crystalline lattice (think of a grain of salt) ionic is weak. Hydrogen bond occurs between polar molecules (it is a type of intramolecular force), it is weak and occurs because polar molecules have partial charges. Example of water molecules hydrogen bonded (hydrogen bond is the dotted line between the two molecules. δ symbol indicates partial – or + charge) Water properties: based on its polarity; water is polar because Oxygen does not share electrons equally with hydrogen in the covalent bonds between O and H in a water molecule. Oxygen side is more negative and hydrogen side of a water molecule is more positive. Water does not mix with nonpolar molecules (think about when you attempt to mix water and oil together, the oil stays separate). Water does mix well with things that are charged or are polar Water molecules stick together (cohesion), water molecules stick to surfaces and other molecules (adhesion), water dissolves polar and charged substances (solvent property), liquid is more dense than solid (ice) water (ice floats), water molecules are more tightly linked together at the surface of liquid water (surface tension), large amount of energy is needed to heat liquid water (high specific heat), large amount of energy is needed to change liquid water to gas (high heat of vaporization) Isomers – same molecular formula but structurally different, molecules can be very similar but have different biological effects/properties (structure of molecules determines function) Sulfur, Phosphorus, Oxygen, Nitrogen, Carbon, and Hydrogen (SPONCH) are the elements that make up biological molecules 4 types of large biological molecules are carbohydrates (CHO), Lipids (CHO), Protein (CHONS), Nucleic acids (CHONP) Carbon importance: carbon atoms form 4 covalent bonds, carbon is used to build a variety of chemical structures Ex. Long chain molecules, large molecules with a lot of branching, ring structured molecules, and double/triple bonds in molecules. Carbon is the most important element in building molecules of life. Functional groups: know all the information in the notes handout below including structures: Functional Group Structure Properties Polar because of electronegative oxygen atom Hydroxyl Forms hydrogen bonds Acidic Carboxyl Found in cells in ionized form, has -1 charge Forms ionic and hydrogen bonds Basic Amino In ionized form has a +1 charge Forms ionic and hydrogen bonds Polar Sulfhydryl 2 sulfhydryl groups react forming a covalent bond between S atoms, called disulfide bridge Negatively charged Phosphate Forms ionic and hydrogen bonds Methyl Non-polar, uncharged, hydrophobic