Null Hypothesis Practice
An example of null hypothesis in AP Biology is that there is no correlation between variables.
Central Tendencies
In statistics, scientists collect data from a sample and then infer many things from it. Typical data shows a normal distribution. Central tendencies are described as the mean, median, and mode. The mean is the average of a data set. The median is the number in the middle of a data set, allowing scientists to measure with outliers. And the mode is the value that appears most often in a data set.
Variability and Standard Deviation
Variability is the measure of how far a data set diverges from the central tendency. The range is the difference between the largest and smallest value, with a large range indicating more variability. The standard deviation is a measure of how spread out the data is from the mean. A low standard deviation means that the data is closer to the mean, while a high standard deviation means that the data is more spread out.
The formula to calculate standard deviation is:
S = √(Σ(xᵢ - x)²/(n-1))
where x = mean, n = size of the sample, and xᵢ = measured value.
The standard error of the mean determines the precision of the mean value and is calculated using the formula: SEM = SD/√n.
Properties of Covalent Bonds and Hydrogen Bonds
Covalent bonds involve the sharing of electrons by two atoms, while ionic bonds can be nonpolar (electrons are shared equally) or polar (electrons are not shared equally). On the other hand, hydrogen bonds occur when the partially positive H atom in one polar covalent molecule is attracted to an electronegative atom in another polar covalent bond.
Polar Properties
Water, for example, shows polarity due to the unequal sharing of electrons. It also exhibits cohesion, the attraction of molecules for other molecules of the same kind, and adhesion, the clinging of one molecule to a different molecule. Additionally, water displays capillary action, temperature control, evaporative cooling, ice floating, and versatile solvent properties due to its chemical structure.
Organic Chemistry
Organic chemistry involves the study of compounds covalently bonded with carbon. Organic compounds are those that contain carbon and hydrogen. Carbon is known for its ability to form single, double, and triple bonds, and can form long chains mainly with hydrogen, oxygen, and nitrogen.
Macromolecules and Functional Groups
Macromolecules include hydrocarbons and functional groups such as hydroxyl, amino, phosphate, carbonyl, sulfhydryl, carboxyl, and methyl groups. Dehydration reaction involves bonding two monomers with the loss of water, while hydrolysis breaks bonds in polymers by adding water.
Enzymes
In biochemistry, enzymes are macromolecules that catalyze reactions by lowering the amount of energy needed to start the reaction. They are not consumed by the reaction and have an active site where the substrates bond and the reaction occurs. Enzyme activity is affected by temperature, pH, and chemicals, and can be regulated by cofactors, coenzymes, and inhibitors.
By understanding these key concepts in statistics, chemistry, and biochemistry, students can gain a deeper understanding of the principles and applications of these subjects in AP Biology.
