AP Biology summary notes by me

AP Biology Study Guide

Key Exam Details

  • Exam Structure: The AP® Biology exam lasts 3 hours and consists of:

    • 60 multiple-choice questions (1 hour 30 minutes; 50% of score)

    • 6 free-response questions (1 hour 30 minutes; 50% of score)

  • Content Categories:

    • Chemistry of Life: 8–11%

    • Cell Structure and Function: 10–13%

    • Cellular Energetics: 12–16%

    • Cell Communication and Cell Cycle: 10–15%

    • Heredity: 8–11%

    • Gene Expression and Regulation: 12–16%

    • Natural Selection: 13–20%

    • Ecology: 10–15%

Chemistry of Life

  • Water and the Elements of Life:

    • Water: made of two hydrogen atoms covalently bonded to an oxygen atom; polar compound.

    • Polar molecules allow for hydrogen bonding (weak bonds formed between slightly positive hydrogen and electronegative oxygen).

    • Cohesion and Adhesion:

      • Cohesion: Water molecules stick together due to hydrogen bonding, causing surface tension.

      • Adhesion: Water molecules stick to other polar surfaces, allowing capillary action, essential for plant water transport.

    • Elemental Composition: Carbon, hydrogen, nitrogen, oxygen form 99% of living matter.

    • Carbon can form four bonds, allowing diverse biological molecules (carbohydrates, proteins, lipids, nucleic acids).

Macromolecules

  • Structure and Properties of Macromolecules:

    • Carbohydrates:

      • Formula: (CH2O)n

      • Types: Monosaccharides (simple sugars), Disaccharides (two monosaccharides), Polysaccharides (many linked monosaccharides).

      • Glycosidic bonds link sugars.

    • Proteins:

      • Composed of amino acids linked by peptide bonds; diversity influenced by R groups and the sequence.

      • Structure levels:

        • Primary (amino acid sequence)

        • Secondary (α-helices, β-sheets due to hydrogen bonding)

        • Tertiary (3D shape due to R-group interactions)

        • Quaternary (multiple polypeptide chains)

    • Lipids:

      • Nonpolar molecules (fats, waxes); key for energy storage and membrane structure.

    • Nucleic Acids:

      • DNA and RNA compose genetic information.

      • Structure: nucleotides (sugar, phosphate, nitrogenous base).

DNA and RNA Structure

  • DNA: double helix structure, complementary base pairing (A-T, C-G).

    • RNA: single-stranded, includes uracil instead of thymine.

Cell Structure and Function

  • Cell Types:

    • Prokaryotes: unicellular, no membrane-bound organelles.

    • Eukaryotes: have membrane-bound organelles (nucleus, mitochondria, etc.).

  • Organelles:

    • Mitochondria (ATP production), Chloroplasts (photosynthesis), Nucleus (houses DNA), Ribosomes (protein synthesis).

  • Cell Membrane:

    • Fluid mosaic model composed of phospholipid bilayer, proteins, cholesterol.

    • Transport Mechanisms: passive (diffusion, osmosis) vs. active (requires energy).

Cellular Energetics

  • Enzyme Function:

    • Enzymes lower activation energy; affected by temperature, pH, and substrate concentrations.

  • Metabolism: All energy transformations, includes anabolism (building) and catabolism (breaking down).

  • Photosynthesis:

    • Light-dependent reactions in thylakoids produce ATP and NADPH, which are then used in Calvin cycle to produce glucose.

  • Cellular Respiration:

    • Glycolysis → Pyruvate oxidation → Krebs cycle → Oxidative phosphorylation. Converts glucose into ATP.

Cell Communication and Cell Cycle

  • Cell Communication Mechanisms:

    • Types: Paracrine (local), Autocrine (self-signaling), Endocrine (hormonal), Direct contact.

  • Cell Cycle Stages:

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

    • Mitosis: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis.

    • Checkpoints (G1, G2, M) regulate cell cycle progression.

Heredity

  • Meiosis: produces gametes, resulting in genetic variation.

  • Mendelian Genetics: Factors of inheritance, including segregation, independent assortment, and dominance.

  • Genetic Diversity: Beneficial for survival, influenced by mutations and gene shuffling.

Gene Expression and Regulation

  • DNA to Protein: Transcription (mRNA production) → Translation (protein synthesis).

  • Regulatory Mechanisms: Enhancers, promoters, transcription factors influence gene expression.

Natural Selection and Evolution

  • Natural Selection Principles:

    • Variation, competition, differential reproduction promote adaptation.

    • Evidence from genetics, fossils, and comparative anatomy supports evolution theory.

Ecology

  • Ecosystem Dynamics:

    • Interaction between biotic (living) and abiotic (non-living) factors.

    • Population dynamics influenced by factors like birth/death rates and resource availability.

  • Community Interaction: Includes various interspecific interactions (competition, predation, symbiosis).

  • Energy Flow: Energy cycling through ecosystems reliant on autotrophs and heterotrophs.

Sample Questions and Answers

  • Chemistry of Life: Water's role as a solvent and its unique properties due to its polar structure.

  • Cell Structure: Importance of organelles in maintaining cellular functions.

  • Photosynthesis and Respiration: Pathways of energy transformation in living organisms.

  • Gene Expression: Mechanisms that regulate gene activity and its consequences on phenotype.