AP Biology Review Notes

A. Elements

  • All life forms made up of matter
    • All matter made up of elements
  • Elements:
    • Substances that cannot be broken down into smaller substances by chemical means.

B. Essential Elements of Life

  • 96% of the mass of all living things:
    • Oxygen (O)
    • Carbon (C)
    • Hydrogen (H)
    • Nitrogen (N)
  • Other elements (collectively 4% of biomass):
    • Calcium (Ca)
    • Phosphorus (P)
    • Potassium (K)
    • Sulfur (S)
    • Sodium (Na)
    • Chlorine (Cl)
    • Magnesium (Mg)
  • Trace elements:
    • Iron (Fe)
    • Iodine (I)
    • Copper (Cu)

C. Subatomic Particles

  • Atom:
    • Smallest unit of an element, building blocks of the physical world.
  • Subatomic Particles:
    • Protons:
    • Positively charged, found in the nucleus.
    • Neutrons:
    • No charge, found in the nucleus.
    • Isotopes:
      • Different amounts of neutrons in the nucleus, vary in mass.
      • Radioactive isotopes decay, giving off particles and energy.
    • Electrons:
    • Negatively charged, orbit around the nucleus.
    • Valence electrons are in the outermost shell.
  • Atomic Number: Number of protons in the nucleus.
  • Mass Number: Sum of protons and neutrons.
    • Atomic mass: Weighted average total mass.

D. Compounds

  • Compound:
    • Result from 2 or more elements combining in a fixed ratio.
  • Types of Bonds:
    • Ionic Bonds:
    • Occur between metals and nonmetals.
    • Electrons transferred between atoms to form cations and anions.
    • Covalent Bonds:
    • Occur between nonmetals.
    • Electrons shared between atoms (polar and non-polar).
    • Hydrogen Bonds:
    • Attraction between polar molecules.
    • Van der Waals Interactions:
    • Weak attractions that can result from asymmetry in electron distribution.

E. Water: The Versatile Molecule

  • Water's Characteristics:
    • Polar molecule due to uneven distribution of charge.
    • Hydrogen bonds:
    • Contribute to water’s cohesive and adhesive properties.
    • Cohesion enables surface tension.
    • Adhesion helps in capillary action.
  • Properties of Water:
    • High heat capacity: Stabilizes temperature.
    • High heat of vaporization: Cooling effects during evaporation.
    • Expansion on freezing: Ice floats because it is less dense than water.
    • Versatile solvent: Polar nature allows it to dissolve many substances.

F. Acids and Bases

  • pH scale:
    • Measures acidity (1-14).
    • 1-7: Acidic; 7: Neutral; 7-14: Basic.
  • Buffers:
    • Help maintain stable pH.

G. Organic Molecules

  • Organic Compounds:
    • Contain carbon and hydrogen.
    • Carbon is versatile with 4 valence electrons, allowing it to form complex molecules.
  • Functional Groups:
    • Hydroxyl (-OH), Carbonyl (>C=O), Carboxyl (-COOH), Amine (-NH2), Phosphate (-OPO3^2−).

H. Macromolecules

  • Carbohydrates:
    • Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
    • Monosaccharides:
    • Examples: Glucose (C6H12O6) and Fructose.
  • Proteins:
    • Made of amino acids, 20 different types exist.
    • Disease-related misfolding can occur, affecting functionality.
  • Lipids:
    • Hydrophobic molecules including triglycerides and phospholipids.
  • Nucleic Acids:
    • DNA and RNA, composed of nucleotides.

I. Cell Theory and Types of Cells

  • All organisms are composed of cells:
    • Prokaryotic Cells:
    • Simple, lack membrane-bound organelles, single circular DNA.
    • Eukaryotic Cells:
    • Complex, with organelles and enclosed DNA.

J. Transport Across Plasma Membrane

  • Passive Transport:
    • Includes diffusion and facilitated diffusion of substances.
  • Active Transport:
    • Requires energy to move substances against concentration gradients.

K. Cellular Energetics

  • Energy Transfer:
    • Glycolysis produces ATP from glucose.
    • Krebs Cycle generates NADH and FADH2.
    • Electron Transport Chain finalizes energy extraction.

L. Molecular Biology

  • DNA Structure:
    • Double helix formed by nucleotides.
    • DNA replication involves several enzymes for accuracy.
  • Transcription and Translation:
    • Processes of converting DNA to RNA and RNA to proteins.

M. Genetics and Heredity

  • Mendelian Genetics:
    • Explains inheritance patterns, genotype versus phenotype.
  • Sex-linked Traits:
    • Traits carried by genes on sex chromosomes affect inheritance patterns.

N. Evolutionary Biology

  • Natural Selection:
    • Proposed by Darwin, explains adaptation.
  • Speciation:
    • Two populations evolving into distinct species due to prezygotic/postzygotic barriers.

O. Ecology

  • Interactions between organisms and their environment:
    • Populations, communities, ecosystems analyzed in biological study.

P. Animal Structure and Function

  • Various organ systems work together to maintain homeostasis and respond to stimuli.

Q. Human Impact on Environment

  • Multiple stressors including pollution, deforestation, and climate change affect ecosystems.