Unit One: Chemistry of Life (8%–11%)

The Structure and Chemical Properties of Water

• Molecular Structure: H₂O, polar molecule with bent shape.

• Hydrogen Bonds: Water molecules attract via partial positive (H) and partial negative (O) charges.

• Unique Properties:

  • Cohesion: Water molecules stick together.

  • Adhesion: Water molecules stick to other surfaces.

  • High Specific Heat: Absorbs a lot of heat without a significant temperature change.

  • High Heat of Vaporization: Requires much energy to convert from liquid to gas.

  • Density: Ice is less dense than liquid water, allowing it to float.

  • Universal Solvent: Dissolves many substances, especially ionic and polar compounds.

The Make and Properties of Macromolecules

• Carbohydrates: Sugars and polysaccharides; primary energy source and structural material.

  • Monosaccharides: Glucose, fructose.

  • Polysaccharides: Starch, glycogen, cellulose.

• Proteins: Made of amino acids; serve as enzymes, transporters, structural elements, etc.

  • Levels of Structure: Primary, secondary, tertiary, quaternary.

  • Enzymes: Catalyze reactions; affected by temperature, pH, and substrate concentration.

• Lipids: Nonpolar molecules, including fats, oils, phospholipids, and steroids.

  • Functions: Energy storage, membrane structure, signaling (e.g., hormones).

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

  • DNA: Double-stranded helix; A-T and C-G base pairing.

  • RNA: Single-stranded; A-U and C-G base pairing.

The Structure of DNA and RNA

• DNA Structure:

  • Double helix with sugar-phosphate backbone.

  • Nitrogenous bases: adenine (A), thymine (T), cytosine (C), guanine (G).

  • Base pairing: A-T and C-G.

• RNA Structure:

  • Single-stranded.

  • Ribose sugar; uracil (U) replaces thymine.

  • Types: mRNA, tRNA, rRNA.

Unit Two: Cell Structure and Function (10%–13%)

Cellular Components and Functions

• Nucleus: Contains DNA; controls cell activity.

• Ribosomes: Protein synthesis; found in cytoplasm and on rough ER.

• Endoplasmic Reticulum (ER): Rough ER has ribosomes, synthesizes proteins; smooth ER synthesizes lipids.

• Golgi Apparatus: Modifies, sorts, and ships proteins and lipids.

• Mitochondria: Generates ATP (powerhouse of the cell).

• Chloroplasts: Site of photosynthesis (in plants).

• Lysosomes: Contains digestive enzymes for waste breakdown.

• Peroxisomes: Break down fatty acids and detoxify.

• Cytoskeleton: Provides structure, movement; includes microtubules, microfilaments, intermediate filaments.

• Centrosomes/Centrioles: Organize microtubules; involved in cell division.

• Vacuoles: Store water, nutrients, waste; large in plant cells.

Cell Interaction with Its Environment

• Cell Communication: Via signaling molecules, receptors.

• Gap Junctions: Direct communication between animal cells.

• Plasmodesmata: Direct communication between plant cells.

• Extracellular Matrix: Provides structure, support, and signaling in animal cells.

The Cell Membrane Structure and Function

• Fluid Mosaic Model: Phospholipid bilayer with embedded proteins.

• Membrane Proteins: For transport, signal transduction, cell recognition, adhesion.

• Selective Permeability: Allows certain substances to pass through.

  • Passive Transport: Includes diffusion and facilitated diffusion (no energy required).

  • Active Transport: Requires energy (e.g., ATP) to move substances against the concentration gradient.

Cell Regulatory Mechanisms

• Osmosis: Movement of water across a semi-permeable membrane from low to high solute concentration.

• Diffusion: Movement of particles from high to low concentration.

• Facilitated Diffusion: Diffusion via transport proteins.

• Active Transport: Movement against concentration gradient; requires energy (e.g., sodium-potassium pump).

Cellular Compartmentalization

• Eukaryotic Cells: Contain organelles that compartmentalize functions.

• Benefits: Allows specialization, efficiency, and coordination of cellular processes

Unit Three: Cellular Energetics (12%–16%)

Structure and Function of Enzymes

• Enzyme Structure:

  • Proteins with active sites where substrates bind.

  • Some require cofactors or coenzymes to function.

• Enzyme Function:

  • Lower activation energy for biochemical reactions.

  • Operate with specificity for substrates.

• Enzyme Regulation:

  • Allosteric Regulation: Binding at a site other than the active site.

  • Competitive Inhibition: Inhibitors bind to the active site.

  • Non-competitive Inhibition: Inhibitors bind to allosteric sites.

• Factors Affecting Enzymes:

  • Temperature, pH, substrate concentration, inhibitors, and activators.

The Role of Energy in Living Systems

• Energy Basics:

  • Energy Flow: Flows from the sun through producers (plants) to consumers.

  • Types of Energy: Potential energy, kinetic energy, chemical energy.

• Laws of Thermodynamics:

  • First Law: Energy cannot be created or destroyed.

  • Second Law: Entropy (disorder) increases in isolated systems.

• ATP (Adenosine Triphosphate):

  • Main energy currency in cells.

  • ATP hydrolysis releases energy for cellular processes.

The Processes of Photosynthesis

• Overview:

  • Converts light energy into chemical energy (glucose).

  • Occurs in chloroplasts in plants and some algae.

• Stages of Photosynthesis:

  • Light-Dependent Reactions: Occur in the thylakoid membranes; produce ATP and NADPH.

  • Light-Independent Reactions (Calvin Cycle): Occur in the stroma; use ATP and NADPH to fix carbon into glucose.

• Key Molecules:

  • Chlorophyll: Primary pigment for absorbing light.

  • NADPH: Electron carrier.

  • ATP: Energy source.

The Processes of Cellular Respiration

• Overview:

  • Converts glucose into ATP.

  • Occurs in the mitochondria in eukaryotes.

• Stages of Cellular Respiration:

  • Glycolysis: Occurs in the cytoplasm; breaks down glucose into pyruvate, produces a small amount of ATP.

  • Krebs Cycle (Citric Acid Cycle): Occurs in the mitochondrial matrix; produces ATP, NADH, and FADH₂.

  • Electron Transport Chain (ETC) and Oxidative Phosphorylation: Occur in the inner mitochondrial membrane; produce most of the ATP.

• Key Concepts:

  • Anaerobic Respiration: In absence of oxygen, leads to fermentation (lactic acid or alcoholic).

  • Aerobic Respiration: Requires oxygen; produces more ATP.

Molecular Diversity and Cellular Response to Environmental Changes

• Environmental Factors:

  • Temperature, pH, salinity, and other environmental conditions can affect cell function.

• Cellular Responses:

  • Stress Responses: Cells may adapt or undergo apoptosis (programmed cell death) under adverse conditions.

  • Gene Regulation: Cells can upregulate or downregulate specific genes in response to environmental changes.

    Unit Four: Cell Communication and Cell Cycle (10%–15%)

    Mechanisms of Cell Communication

    • Types of Cell Communication:

      • Direct Contact: Gap junctions (animal cells) and plasmodesmata (plant cells).

      • Paracrine Signaling: Local signaling to nearby cells.

      • Endocrine Signaling: Long-distance signaling via hormones.

      • Synaptic Signaling: In neurons; neurotransmitters across synapses.

    • Receptor Types:

      • G-Protein Coupled Receptors (GPCRs): Involved in signal transduction.

      • Receptor Tyrosine Kinases (RTKs): Phosphorylate proteins upon activation.

      • Ligand-Gated Ion Channels: Open or close in response to a ligand.

    Signal Transduction

    • Signal Transduction Pathway:

      • Reception: Signal molecule (ligand) binds to receptor.

      • Transduction: Series of relay proteins or second messengers that transmit the signal.

      • Response: Cellular response to the signal (e.g., gene expression, enzyme activation).

    • Second Messengers:

      • cAMP: A common second messenger derived from ATP.

      • Calcium Ions (Ca²⁺): Used in various signal transduction pathways.

    • Kinase Cascades:

      • Phosphorylation cascades that amplify the signal.

    Cellular Responses and Feedback Mechanisms

    • Cellular Responses:

      • Changes in gene expression, enzyme activation, or cellular behavior.

      • Apoptosis: Programmed cell death; part of cellular regulation and development.

    • Feedback Mechanisms:

      • Negative Feedback: Reduces output to maintain homeostasis.

      • Positive Feedback: Amplifies output; often associated with processes like childbirth or blood clotting.

    The Events in a Cell Cycle

    • Cell Cycle Stages:

      • Interphase: G1 (cell growth), S (DNA replication), G2 (preparation for mitosis).

      • Mitosis: Division of the nucleus (Prophase, Metaphase, Anaphase, Telophase).

      • Cytokinesis: Division of the cytoplasm.

    • Cell Cycle Regulation:

      • Checkpoints: Critical control points in the cell cycle.

      • Cyclins and CDKs: Proteins that regulate cell cycle progression.

      • Tumor Suppressors: Genes that prevent uncontrolled cell division.

      • Oncogenes: Mutated genes that can lead to cancer.

Unit Five: Heredity (8%–11%)

Process and Function of Meiosis

• Meiosis Overview:

  • Produces haploid gametes (sperm and egg).

  • Consists of two divisions (Meiosis I and Meiosis II).

• Key Events:

  • Crossing Over: Exchange of genetic material between homologous chromosomes during prophase I.

  • Independent Assortment: Random alignment of homologous chromosomes during metaphase I.

  • Reduction Division: Chromosome number reduced from diploid to haploid.

Concepts of Genetic Diversity

• Sources of Genetic Diversity:

  • Crossing Over: Increases genetic variation.

  • Independent Assortment: Leads to diverse combinations of chromosomes.

  • Random Fertilization: Further increases diversity.

• Importance of Genetic Diversity:

  • Contributes to evolutionary processes and adaptation.

Mendel's Laws and Probability

• Mendelian Laws:

  • Law of Segregation: Each gamete receives one allele from each gene pair.

  • Law of Independent Assortment: Alleles of different genes assort independently.

• Punnett Squares: Used to predict the probability of genetic outcomes.

• Monohybrid and Dihybrid Crosses:

  • Monohybrid: Examines inheritance of one trait.

  • Dihybrid: Examines inheritance of two traits.

Non-Mendelian Inheritance and Gene Expression

• Non-Mendelian Patterns:

  • Incomplete Dominance: Heterozygous phenotype is intermediate.

  • Codominance: Both alleles are fully expressed (e.g., blood types).

  • Multiple Alleles: More than two alleles for a gene (e.g., blood types).

  • Polygenic Inheritance: Multiple genes influence a single trait (e.g., skin color).

  • Epistasis: One gene affects the expression of another.

• Environmental Influence:

  • Environment can affect gene expression (e.g., temperature influencing coat color).

Unit Six: Gene Expression and Regulation (12%–16%)

Roles and Functions of DNA and RNA

• DNA Structure:

  • Double helix with a sugar-phosphate backbone and nitrogenous bases (adenine, thymine, cytosine, guanine).

• RNA Structure:

  • Single-stranded with ribose sugar and uracil instead of thymine.

  • Types: mRNA (messenger RNA), tRNA (transfer RNA), rRNA (ribosomal RNA).

• DNA Replication:

  • Semiconservative process; each new DNA molecule has one old and one new strand.

  • Key enzymes: DNA polymerase, helicase, ligase.

• Transcription:

  • Process of copying DNA into mRNA.

  • Key enzyme: RNA polymerase.

• Translation:

  • Process of translating mRNA into a polypeptide (protein).

  • Occurs in ribosomes; involves tRNA and rRNA.

Mechanisms of Gene Expression

• Gene Regulation:

  • Prokaryotes: Operons (e.g., lac operon) for coordinated gene regulation.

  • Eukaryotes: Regulatory sequences, transcription factors, enhancers, and silencers.

• Epigenetics:

  • Changes in gene expression without altering the DNA sequence.

  • Methylation and histone modifications affect gene expression.

• Post-Transcriptional Regulation:

  • Alternative splicing, mRNA stability, and RNA interference (RNAi).

How Genotype Affects Phenotype

• Genotype: The genetic makeup of an organism.

• Phenotype: The observable traits or characteristics.

• Gene-Environment Interaction: Environmental factors can influence phenotype.

• Epistasis: One gene affects the expression of another gene.

Mutations, Genetic Diversity, and Natural Selection

• Mutations:

  • Changes in the DNA sequence; can be beneficial, neutral, or harmful.

  • Types: Point mutations, frameshift mutations, insertions, deletions.

• Genetic Diversity:

  • Arises from mutations, recombination during meiosis, and sexual reproduction.

• Natural Selection:

  • Process by which advantageous traits increase in frequency in a population.

Genetic Engineering and Biotechnology

• Recombinant DNA Technology:

  • Combining DNA from different sources.

  • Uses restriction enzymes and ligases.

• Polymerase Chain Reaction (PCR):

  • Technique to amplify DNA sequences.

• Gel Electrophoresis:

  • Method for separating DNA fragments by size.

• CRISPR-Cas9:

  • Gene-editing technology.

• Applications:

  • Genetic engineering in agriculture, medicine, and industry.
    

Unit Seven: Natural Selection (13%–20%)

Evidential Support for Evolution and Common Ancestry

• Fossil Record:

  • Provides evidence of past life and evolutionary changes.

• Comparative Anatomy:

  • Homologous Structures: Similar structures with different functions, indicating common ancestry.

  • Analogous Structures: Similar functions but different origins, indicating convergent evolution.

• Comparative Embryology:

  • Similar embryonic development in related organisms.

• Molecular Biology:

  • DNA and protein sequence similarities among related species.

• Biogeography:

  • Geographic distribution of species supports evolutionary theory.

Mechanisms of Natural Selection and Speciation

• Natural Selection:

  • Process by which advantageous traits increase in frequency.

  • Types: Stabilizing, directional, disruptive selection.

• Sexual Selection:

  • Selection based on traits that affect mating success.

• Speciation:

  • Formation of new species.

  • Types: Allopatric (geographic isolation) and sympatric (no geographic isolation).

Environmental and Human-Caused Factors in Evolution

• Environmental Factors:

  • Changes in climate, habitat, and food sources can drive evolutionary change.

• Human-Caused Factors:

  • Pollution, habitat destruction, climate change, and overharvesting impact species and can drive evolution.

• Artificial Selection:

  • Human-driven breeding for specific traits.

Charting Ancestry Through Phylogenetic Trees and Cladograms

• Phylogenetic Trees:

  • Diagrams showing evolutionary relationships among species or groups.

  • Nodes represent common ancestors; branches represent evolutionary paths.

• Cladograms:

  • A type of phylogenetic tree focusing on shared derived characteristics.

• Outgroups:

  • Distantly related groups used for comparison.

Extinction

• Extinction Events:

  • Mass extinctions due to environmental changes or catastrophic events.

• Current Extinctions:

  • Caused by human activity and environmental changes.

Models of the Origin of Life on Earth

• Primordial Soup Hypothesis:

  • Early Earth conditions led to the formation of organic molecules.

• Miller-Urey Experiment:

  • Simulated early Earth conditions, producing amino acids.

• RNA World Hypothesis:

  • Early life forms may have been based on RNA.

• Endosymbiotic Theory:

  • Explains the origin of mitochondria and chloroplasts in eukaryotic cells.

    Unit Unit Eight: Ecology (10%–15%)

    Communication and Responses to Environmental Changes

    • Ecological Relationships:

      • Mutualism, commensalism, parasitism.

    • Behavioral Adaptations:

      • Animal communication, migration, and social behaviors.

    • Environmental Changes:

      • Changes in climate, food sources, and habitats affect ecosystems.

    Energy Flow Within and Across Ecosystems

    • Energy Flow:

      • Flows through ecosystems via food chains and food webs.

      • Primary producers (plants), primary consumers (herbivores), secondary consumers (carnivores), tertiary consumers.

    • Trophic Levels:

      • Different levels in a food chain; energy decreases at higher levels due to energy loss as heat.

    • Primary Production:

      • The rate at which energy is converted to organic matter in an ecosystem.

    Factors in the Growth, Density, and Success of Populations

    • Population Dynamics:

      • Growth rate, carrying capacity, and limiting factors.

    • Density-Dependent Factors:

      • Competition, predation, disease.

    • Density-Independent Factors:

      • Climate, natural disasters.

    Factors in Community and Ecosystems Dynamics

    • Community Structure:

      • Diversity and interactions among species.

    • Succession:

      • Gradual change in community structure over time.

      • Primary succession: Starts from a barren environment.

      • Secondary succession: Occurs after a disturbance in a previously occupied area.

    • Keystone Species:

      • Species with a significant impact on the ecosystem.

    • Ecosystem Services:

      • Benefits provided by ecosystems, such as pollination and nutrient cycling.

    Invasive Species, Human Interaction, and Environmental Changes

    • Invasive Species:

      • Non-native species that disrupt local ecosystems.

    • Human Interaction:

      • Habitat destruction, pollution, climate change, and overexploitation.

    • Environmental Changes:

      • Changes in ecosystems due to natural and human-caused factors.

        FRQ!!!!

        1. Understand the Prompt

        • Read Carefully: Read the question prompt thoroughly to understand what is being asked. Highlight key terms and note any specific requirements (e.g., explain, calculate, justify).

        • Identify the Components: Determine if there's a need for a graph, a calculation, or an explanation. Understand the context and the focus of the question.

        2. Graphing

        • Label Clearly: When creating a graph, ensure axes are labeled with appropriate variables and units. Typically, the independent variable (IV) goes on the X-axis, and the dependent variable (DV) goes on the Y-axis.

        • Use a Title: Provide a descriptive title that reflects what the graph represents.

        • Choose Appropriate Scale and Plot Accurately: Select a scale that accurately represents the data and plot points carefully. Use a ruler or grid for straight lines, and clearly indicate data points or trends.

        • Legend and Labels: If needed, include a legend and labels to clarify different data series or trends.

        3. Identification of Variables

        • Understand Variable Roles: The independent variable is what you change or manipulate, and the dependent variable is what you measure or observe. Understand the experiment's design to identify these variables.

        • Identify Controls: Note any control groups or conditions that remain constant for accurate comparison.

        4. Calculations

        • Show Your Work: Even if the question asks for a single answer, show your steps for full credit. This allows the grader to follow your logic.

        • Use Correct Units: Include units in all calculations and final answers.

        • Use Appropriate Formulas: Identify and apply relevant formulas for the calculation. Check your math to avoid simple errors.

        • Rounding and Significant Figures: Follow guidelines for rounding and use appropriate significant figures based on the data provided.

        5. Answer in Full Sentences

        • Be Clear and Concise: Write in complete sentences with proper grammar. Aim for clarity and avoid unnecessary words or complex phrases.

        • Address the Prompt: Make sure your answer addresses every part of the question. If there's a multi-part question, ensure you answer each part in a separate paragraph or section.

        • Justify and Explain: When asked to justify or explain, provide clear reasoning or evidence to support your answer. Use scientific terminology accurately.

        • Use Examples if Needed: If a question requires examples or scenarios, provide specific and relevant ones.

        6. Time Management

        • Allocate Time Wisely: FRQs can be lengthy, so divide your time among the questions based on their complexity and point value. Aim to leave time for review.

        • Outline Before Writing: Before diving into a long response, outline key points to stay focused and organized.

        • Keep Moving Forward: If you're stuck on one part, move on and return to it later. Don't dwell on one question for too long.

        7. Practice and Review

        • Practice with Past FRQs: Use past AP Biology FRQs to get familiar with the format and types of questions. Time yourself to simulate exam conditions.

        • Review Feedback: If you've completed practice FRQs or previous exams, review any feedback to identify areas for improvement.

        • Collaborate with Peers: Discuss FRQs with classmates to gain different perspectives and improve understanding.