AP® Biology Cheat Sheet
The AP Biology – 2024 Cheat Sheet is a comprehensive guide designed to help students master essential biology concepts for the AP exam. It covers key units including Chemistry of Life, Cell Structure and Function, Cellular Energetics, Cell Communication and Cycle, Heredity, Gene Expression and Regulation, Natural Selection, and Ecology. Each unit provides condensed, easy-to-understand notes highlighting critical processes, functions, and relationships. This cheat sheet also offers practical exam tips, ensuring students are well-prepared to tackle Free Response Questions (FRQs). Use this guide to streamline your study sessions and achieve success in AP Biology.
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Unit 1: Chemistry of Life
Water's unique properties:
Cohesion: Water molecules stick to each other
Adhesion: Water molecules stick to other surfaces
Surface tension: Allows insects to walk on water
Hydrolysis breaks bonds; dehydration synthesis forms bonds
Nucleic acids: DNA and RNA, composed of nucleotides
Nucleotides: made of a sugar, phosphate group, and nitrogenous base
Proteins: Comprised of amino acids; structure determines function
Carbohydrates: Sugars that store energy
Lipids: Nonpolar molecules, found in cell membranes, vary in saturation
Unit 2: Cell Structure & Function
Key organelles:
Ribosomes: Protein synthesis
Endoplasmic Reticulum (ER): Detoxification and lipid production
Golgi Apparatus: Modifies and packages proteins
Mitochondria: ATP production, powerhouse of the cell
Lysosomes: Enzyme digestion
Cytoskeleton: Provides structural support and aids in cell movement
Phospholipid bilayer: Selective permeability for nutrients and waste
High surface area: Enhances transport efficiency
Active transport: Moves substances against concentration gradient using ATP
Endosymbiotic theory: Origins of mitochondria and chloroplasts
Unit 3: Cellular Energetics
Enzymes: Lower activation energy, speed up reactions
Active site: Where substrate binds
Factors affecting enzyme activity: pH, temperature, concentration
Competitive inhibitors: Block active site
Noncompetitive inhibitors: Change enzyme shape
Photosynthesis:
Light reactions produce ATP and NADPH
Calvin cycle uses ATP and NADPH to synthesize glucose
Cellular Respiration:
Aerobic respiration: Requires oxygen, produces ATP
Anaerobic respiration: Does not require oxygen, less efficient
Main steps: Glycolysis, Krebs cycle, Electron Transport Chain
Unit 4: Cell Communication & Cell Cycle
Types of signaling:
Paracrine: Nearby cells
Endocrine: Distant cells via bloodstream
Autocrine: Same cell
Signal transduction pathway: Reception, transduction, response
Reception: Ligand binds to receptor
Transduction: Signal is relayed and amplified
Response: Cellular response, such as gene expression
Feedback mechanisms:
Negative feedback: Reduces stimulus (e.g., insulin regulation)
Positive feedback: Amplifies stimulus (e.g., childbirth)
Cell cycle stages: Interphase (G1, S, G2), Mitosis, Cytokinesis
Mitosis: Division of nucleus, produces identical daughter cells
Unit 5: Heredity
Meiosis:
Meiosis I: Homologous chromosomes separate
Meiosis II: Sister chromatids separate
Results in four genetically unique haploid cells
Genetic variation:
Crossing over: Exchange of genetic material between homologous chromosomes
Independent assortment: Random distribution of chromosomes
Pedigree analysis: Tracking inheritance patterns
Environmental influences: Can affect gene expression (e.g., temperature influencing fur color)
Genetic disorders: Result from mutations or chromosomal abnormalities
Unit 6: Gene Expression & Regulation
DNA replication: Semi-conservative process, 5’ to 3’ direction
Key enzymes: Helicase (unwinds DNA), DNA polymerase (builds new strand), Ligase (joins fragments)
Transcription: DNA to mRNA
Processing: Addition of 5’ cap, poly-A tail, and splicing of introns
Translation: mRNA to protein
Ribosomes read mRNA, tRNA brings amino acids
Gene regulation:
Transcription factors: Proteins that control gene expression
Operons: Found in prokaryotes, regulate gene clusters
Mutations: Changes in DNA sequence, can be beneficial, neutral, or harmful
Biotechnology tools:
Gel electrophoresis: Separates DNA fragments
PCR: Amplifies DNA
Bacterial transformation: Introduces new genes into bacteria
Unit 7: Natural Selection
Evolution: Change in allele frequencies over time
Natural selection: Process where organisms better adapted to their environment tend to survive and reproduce
Genetic drift: Random changes in allele frequencies
Hardy-Weinberg equilibrium: Describes a non-evolving population
Phylogenetic trees: Show evolutionary relationships
Extinction: Leads to new niches and opportunities for survivors
Population dynamics: Study of how populations change over time
Unit 8: Ecology
Homeostasis: Maintenance of a stable internal environment
Net energy gain/loss: Affects an organism's survival
Endotherms vs. Ectotherms:
Endotherms: Regulate body temperature internally
Ectotherms: Depend on external sources for body heat
Adaptations: Traits that improve survival and reproduction
Biodiversity: Variety of life, important for ecosystem resilience
Ecological relationships:
Commensalism: One benefits, other is unaffected
Mutualism: Both benefit
Parasitism: One benefits, other is harmed
Predation: Predator and prey interactions
Competition: Organisms vie for the same resources
Energy transfer: Only about 10% of energy is transferred to the next trophic level in an energy pyramid