AP Biology Unit 1 Study Guide

AP Biology Unit 1 Study Guide

• Standard Deviation (s): Indicates the amount of variation in a dataset; larger values mean data points are more spread out. Example: 2, 3, 5, 2 (small) vs. 2, 200, 903, 45 (large).

• Standard Error of the Mean (SEM): Used to compare averages of different data sets; error bars on graphs, if they do not overlap, suggest statistically significant differences between groups. 2 times SEM (2 SEM) is often used for graph comparisons.

• Empirical Rule: In a normal distribution:

• 68% of values fall within ±1 standard deviation of the mean.

• 95% of values fall within ±2 standard deviations of the mean.

• 99.7% of values fall within ±3 standard deviations of the mean.

• Sample Size (n): The number of data points in a set. Example: 5, 5, 6, 7, 9 has n = 5.

• Mean (aka average): Sum of values divided by the sample size (n).

• Degrees of Freedom: n-1

• Experimental Design: Controlled experiments have a control group and controlled variables (consistent factors).

• Hypotheses: Testable statements (e.g., "Studying for tests results in higher scores"). Avoid phrases like "I think".

• Independent Variable: The factor being tested or manipulated in an experiment.

• Dependent Variable: The factor being measured in an experiment.

• Control Group: Does not receive the experimental treatment.

• Controlled Variables: Factors kept consistent between experimental and control groups (e.g., same test, same time).

• Data Analysis: Comparing group averages (e.g., ±2 SEM), if averaged are separated by more than ±2 SEM, their values are likely statistically different (error bars do not overlap).

Chemical Bonding

• Covalent Bond: Strong bond between nonmetal atoms; atoms share electrons.

• Ionic Bond: Strong bond between a metal and a nonmetal; metal loses electron(s), becoming positively charged, and nonmetal gains electron(s), becoming negatively charged. These oppositely charged ions then attract. This forms crystalline lattices.

• Hydrogen Bond: A type of intramolecular force occurring between polar molecules where a slightly positive hydrogen of one molecule is attracted to a slightly negative atom of another molecule. It's a weak bond.

Water Properties

• Polarity: Oxygen does not share electrons equally with hydrogens in water molecules, creating a slightly negative charge around the oxygen (δ-) and slightly positive charges around the hydrogens (δ+).

• Cohesion/Adhesion: Water molecules stick together (cohesion) and to other surfaces (adhesion).

• Surface Tension: Water's tendency to form a thin layer due to cohesion at the surface.

• High Specific Heat: Requires a large amount of energy to increase water's temperature.

• High Heat of Vaporization: Needs a large amount of energy to change liquid water to gas.

• Density: Liquid water is denser than ice (ice floats), unusual for most substances.

Large Biological Molecules

• Four main types: Carbohydrates, Lipids, Proteins, and Nucleic Acids.

• Carbon's Importance: Carbon forms 4 covalent bonds, crucial for building diverse molecules of life.

Functional Groups

• Functional groups are specific groups of atoms within molecules that are responsible for most of the chemical reactions of that molecule. Knowing the structures is key to understanding the specific properties.