AP Biology Course and Exam Description Study Notes

The Seven Principles of the Advanced Placement Program

Principle 1: Clarity and Transparency: Teachers and students deserve clear expectations. The AP Program publishes its course frameworks and sample assessments to eliminate confusion about what is permitted in the classroom.
Principle 2: Unflinching Encounter with Evidence: AP courses emphasize the scientific method and evidence as the starting point for conversation, enabling students to develop as independent thinkers.
Principle 3: Opposition to Censorship: AP Biology requires specific topics, such as evolution, which are central to college biology. If a school bans required topics, the AP designation is removed from that course.
Principle 4: Opposition to Indoctrination: Students are expected to analyze various perspectives. No points are awarded on exams for agreeing with a specific viewpoint. The program focuses on assessing source credibility and drawing evidence-based conclusions.
Principle 5: Open-Minded Approach to Histories and Cultures: AP courses ground the study of nationalities, races, and ethnicities in primary sources so students can evaluate facts and evidence themselves.
Principle 6: Mutual Respect and Listening: Students are encouraged to evaluate arguments rather than one another. Diversity in backgrounds and viewpoints is respected, and personal attacks have no place in the classroom.
Principle 7: Choice for Parents and Students: Enrollment is a free choice. While parents do not define college-level topics, course descriptions are available online to ensure an informed decision. AP materials are validated by expert committees and the American Council on Education.

Course Overview and Requirements

College Course Equivalent: The AP Biology course is designed to be equivalent to a two-semester college introductory biology course for biology majors.
Prerequisites: Success in high school courses in biology and chemistry is required.
Laboratory Requirement: At least $25\%$ of instructional time must be dedicated to hands-on laboratory work. * Emphasis must be placed on inquiry-based investigations. * Students must engage in science practices: designing experiments, making predictions, collecting/analyzing data, applying mathematics, and communicating findings. * College Board recommends students maintain physical or digital laboratory notebooks/reports, as colleges may require them for credit validation.

Science Practices and Skills

Practice 1: Concept Explanation

Explicate biological concepts and processes presented in written format.
Skill 1.A: Describe biological concepts and processes.
Skill 1.B: Explain biological concepts and processes.
Skill 1.C: Explain biological concepts and processes in applied contexts.

Practice 2: Visual Representations

Analyze visual representations of biological concepts and processes.
Skill 2.A: Describe characteristics of visual representations.
Skill 2.B: Explain relationships between characteristics of biological models in theoretical and applied contexts.
Skill 2.C: Explain how biological models relate to larger principles, concepts, or theories.
Skill 2.D: Represent relationships within biological models (diagrams, flowcharts, mathematical models).

Practice 3: Questions and Methods

Determine scientific questions and methods.
Skill 3.A: Identify or pose a testable question based on an observation or model.
Skill 3.B: State the null hypothesis or predict experimental results.
Skill 3.C: Identify experimental procedures (independent/dependent variables, controls, and justification of controls).
Skill 3.D: Propose a new investigation based on an evaluation of the design or evidence.

Practice 4: Representing and Describing Data

Skill 4.A: Construct a graph ( $x-y$ graphs, scatter plots, box and whisker plots, pie charts) including units, scaling, legends, and trend lines.
Skill 4.B: Describe data from a table or graph, identifying specific points, trends, and variable relationships.

Practice 5: Statistical Tests and Data Analysis

Skill 5.A: Perform mathematical calculations ( $means$ , $rates$ , $ratios$ , $percentages$ , and curriculum-specific equations).
Skill 5.B: Use confidence intervals and error bars to estimate if sample means are statistically different.
Skill 5.C: Perform chi-square hypothesis testing.
Skill 5.D: Use data to evaluate a hypothesis (rejecting or failing to reject the null hypothesis).

Practice 6: Argumentation

Skill 6.A: Make a scientific claim.
Skill 6.B: Support a claim with evidence from biological principles and data.
Skill 6.C: Provide reasoning to justify a claim by connecting evidence to theories.
Skill 6.D: Explain the relationship between experimental results and larger biological concepts.
Skill 6.E: Predict the causes or effects of a change or disruption to a biological system.

The Four Big Ideas

Big Idea 1: Evolution: Evolution drives the diversity and unity of life. It is the change in the genetic makeup of a population over time, primarily through natural selection. Speciation and extinction have occurred throughout Earth’s history.
Big Idea 2: Energetics: Biological systems use energy and molecular building blocks to grow, reproduce, and maintain dynamic homeostasis. Organisms employ various strategies to capture, use, and store energy.
Big Idea 3: Information Storage and Transmission: Living systems store, retrieve, transmit, and respond to information essential to life. DNA typically carries this information from parent to offspring.
Big Idea 4: Systems Interactions: Biological systems interact at levels from molecules to ecosystems. These interactions result in emergent properties and biocomplexity, which provides robustness and resiliency to environmental changes.

Unit 1: Chemistry of Life

Exam Weighting: $8-11\%$
Topic 1.1: Structure of Water and Hydrogen Bonding * Water is polar due to polar covalent bonds between hydrogen and oxygen. * Polarity allows for hydrogen bonding between and within molecules. * Properties of Water: * High specific heat capacity: Maintains homeostatic body temperature. * High heat of vaporization: Enables evaporative cooling. * Cohesion, Adhesion, and Surface Tension: Result from hydrogen bonds between adjacent polar water molecules.
Topic 1.2: Elements of Life * Carbon, hydrogen, and oxygen are prevalent in all biological molecules. * Sulfur: Used in building proteins. * Phosphorus: Used in phospholipids and nucleic acids. * Nitrogen: Used in nucleic acids.
Topic 1.3: Introduction to Macromolecules * Hydrolysis: Cleaving covalent bonds by adding water; a hydrogen ion ( $H^+$ ) and hydroxyl group ( $OH^-$ ) are added to the monomers. * Dehydration Synthesis: Joining two molecules with a covalent bond by removing a water equivalent.
Topic 1.4: Carbohydrates * Monosaccharides (simple sugars) are monomers for polysaccharides (complex carbohydrates). * Exclusion: Molecular structure of specific carbohydrate polymers is not assessed.
Topic 1.5: Lipids * Typically nonpolar and hydrophobic. * Fatty Acids: * Saturated: Only single bonds between carbon atoms. * Unsaturated: At least one double bond causing a "kink." * Increased unsaturation leads to increased liquidity at room temperature. * Functions: * Fats: Energy storage, insulation. * Steroids: Hormones (cholesterol, testosterone). * Phospholipids: Form lipid bilayers in membranes.
Topic 1.6: Nucleic Acids * Nucleotides consist of a five-carbon sugar (ribose or deoxyribose), a phosphate, and a nitrogenous base ( $A$ , $T$ , $G$ , $C$ , or $U$ ). * Directionality: Defined by $3'$ hydroxyl and $5'$ phosphate ends. Nucleotides are added to the $3'$ end.
Topic 1.7: Proteins * Amino acids consist of a central carbon, a hydrogen, a carboxyl group ( $-COOH$ ), an amine group ( $-NH_2$ ), and a variable $R$ group. * Levels of Structure: * Primary: Sequence of amino acids. * Secondary: Alpha-helices and beta-pleated sheets via backbone hydrogen bonding. * Tertiary: $3D$ shape via R-group interactions (hydrophobic, ionic, disulfide bridges). * Quaternary: Interactions between multiple polypeptides.

Unit 2: Cells

Exam Weighting: $10-13\%$
Topic 2.1: Cell Structure and Function * Ribosomes: Synthesize proteins; common to all life forms. * Rough ER: Protein synthesis and compartmentalization. * Smooth ER: Lipid synthesis and cell detoxification. * Golgi Complex: Folding and modifying proteins; packaging for trafficking. * Mitochondria: Double membrane; inner folds (cristae) increase surface area for ATP synthesis. * Lysosomes: Contain hydrolytic enzymes for digestion and apoptosis. * Vacuoles: Storage of water/nutrients; maintain turgor pressure in plants. * Chloroplasts: Site of photosynthesis; contain thylakoids and stroma.
Topic 2.2: Cell Size * Surface Area-to-Volume Ratio ( $SA/V$ ) affects material exchange. * Smaller cells have higher $SA/V$ ratios, allowing for more efficient exchange. * Formula for Sphere Volume: $V = \frac{4}{3} \pi r^3$ * Formula for Sphere Surface Area: $SA = 4 \pi r^2$
Topic 2.10: Origins of Cell Compartmentalization * Endosymbiosis: Mitochondria and chloroplasts evolved from free-living prokaryotes.

Unit 3: Cellular Energetics

Exam Weighting: $12-16\%$
Topic 3.1: Enzymes * Biological catalysts that lower activation energy. * Denaturation occurs when the complex $3D$ structure is disrupted by temperature or $pH$ , disrupting hydrogen bonds.
Topic 3.4: Photosynthesis * Captures sunlight to produce sugars. * Light Reactions: Occur in the grana (thylakoid stacks). Splits water to yield $ATP$ and $NADPH$ . Produces $O_2$ as a byproduct. * Calvin Cycle: Occurs in the stroma. Uses $ATP$ , $NADPH$ , and $CO_2$ to produce carbohydrates.
Topic 3.5: Cellular Respiration * Glycolysis: Cytosol; breaks glucose into pyruvate, $ATP$ , and $NADH$ . * Krebs Cycle: Mitochondrial matrix; releases $CO_2$ , produces $ATP$ , $NADH$ , and $FADH_2$ . * Electron Transport Chain (ETC): Inner mitochondrial membrane; creates a proton gradient to drive $ATP$ synthase (oxidative phosphorylation).

Unit 5: Heredity

Exam Weighting: $8-11\%$
Topic 5.1: Meiosis * Produces four haploid ( $n$ ) daughter cells from one diploid ( $2n$ ) parent cell. * Meiosis I: Separation of homologous chromosomes. * Meiosis II: Separation of sister chromatids. * Crossing Over: Exchange of genetic material between non-sister chromatids during Prophase I.
Topic 5.3: Mendelian Genetics * Segregation: Two alleles for a trait separate during gamete formation. * Independent Assortment: Genes for different traits can segregate independently during the formation of gametes. * Probability Rules: * Sum Rule (Either/Or): $P(A \text{ or } B) = P(A) + P(B)$ * Product Rule (And): $P(A \text{ and } B) = P(A) \times P(B)$
Topic 5.4: Non-Mendelian Genetics * Linked Genes: Genes adjacent on the same chromosome that tend to be inherited together. * Sex-Linked Traits: Reside on X or Y chromosomes; often exhibit higher rates in XY individuals. * Non-Nuclear Inheritance: Mitochondrial and chloroplast DNA is typically inherited maternally via the ovum.

Unit 7: Natural Selection

Exam Weighting: $13-20\%$
Topic 7.5: Hardy–Weinberg Equilibrium * A model for predicting allele frequencies in a non-evolving population. * Conditions: 1. Large population size. 2. No migration. 3. No mutations. 4. Random mating. 5. No natural selection. * Hardy-Weinberg Equations: * $p^2 + 2pq + q^2 = 1$ * $p + q = 1$ * $p$ : frequency of allele 1; $q$ : frequency of allele 2.
Topic 7.12: Origins of Life on Earth * Earth formed approximately $4.6 \text{ billion years ago (bya)}$ . * Environment hostile until $3.9\,bya$ . Earliest fossil evidence: $3.5\,bya$ . * RNA World Hypothesis: RNA could have been the earliest genetic material due to its ability to replicate and store information.

Unit 8: Ecology

Exam Weighting: $10-15\%$
Topic 8.4: Effect of Density on Populations * Carrying Capacity ( $K$ ): Maximum population size an ecosystem can sustain. * Logistical Growth Equation: $\frac{dN}{dt} = r_{max} N \left( \frac{K-N}{K} \right)$
Topic 8.5: Community Ecology * Simpsons Diversity Index: $\text{Diversity Index} = 1 - \sum \left( \frac{n}{N} \right)^2$ * $n$ = total number of organisms of a particular species; $N$ = total number of organisms of all species.

Laboratory and Instructional Approaches

Levels of Inquiry: 1. Confirmation: Students confirm a known principle via a prescribed procedure. 2. Structured Inquiry: Teacher provides the question and procedure; student finds the solution. 3. Guided Inquiry: Teacher provides the question; student designs the procedure and finds the solution. 4. Open Inquiry: Student formulates the question, procedure, and solution.
Lab Safety: * Facilities must conform to federal/local laws. * Mandatory use of safety goggles, eye washes, fire blankets, and fire extinguishers. * Proper interpretation of Material Safety Data Sheets ( $MSDS$ ) is required.

Exam Information

Section I: Multiple-Choice ( $50\%$ \text{ of score}): * 60 questions; 90 minutes. * Includes individual and set-based questions (typically 4–5 questions per set).
Section II: Free-Response (50\% $\text{ of score})$ : * 6 questions; 90 minutes. * Q1: Interpreting and Evaluating Experimental Results ( $9\,pts$ ). * Q2: Interpreting and Evaluating Experimental Results with Graphing ( $9\,pts$ ). * Q3: Scientific Investigation ( $4\,pts$ ). * Q4: Conceptual Analysis ( $4\,pts$ ). * Q5: Analyze Model or Visual Representation of a Biological Concept ( $4\,pts$ ). * Q6: Analyze Data ( $4\,pts$ ).

Questions & Discussion (Sample Scoring)

Question: What is a positive control in a mosquito insecticide experiment?
Answer: Testing a strain that is known to be susceptible to the insecticides.
Question: Why expose some mosquitoes to untreated filter paper?
Answer: To confirm that mortality results from the insecticide and not the paper itself or other experimental conditions.
Question: How do different proteins arise from one gene (e.g., $TPM1$ )?
Answer: Through alternative splicing, where different exons are retained or spliced out of the primary transcript.

Appendix: Mathematical Constants and Formulas

Standard Error of the Mean: $SE_x = \frac{s}{\sqrt{n}}$
Chi-Square: $\chi^2 = \sum \frac{(o-e)^2}{e}$
Solute Potential of a Solution: $\Psi_s = -iCRT$ * $i$ : Ionization constant (1.0 for sucrose). * $C$ : Molar concentration. * $R$ : Pressure constant ( $0.0831\,L \cdot bars / mol \cdot K$ ). * $T$ : Temperature in Kelvin ( $^∘C + 273$ ).
Population Growth Rate: $\frac{dN}{dt} = B - D$