General Biology Study Guide: Units 1–4 (Scientific Inquiry, Chemistry of Life, Macromolecules, Cell Structure & Function, Metabolism, and Enzymes)

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Quantitative data: Numerical measurements (e.g., mass, volume, temperature).
Qualitative data: Descriptive observations (e.g., color, texture, behavior).

Hypothesis: A testable statement that explains an observation or answers a question.
Null hypothesis: States there is no effect or difference.
Control group: The group not exposed to the experimental variable; used for comparison.
Independent variable: The factor manipulated by the experimenter.
Dependent variable: The factor measured in the experiment.
Standard deviation: A measure of data spread around the mean.

Good experiments include controls, replication, and randomization.
Data analysis often involves calculating averages, standard deviation, and using statistical tests.

Atoms: Basic units of matter, composed of protons, neutrons, and electrons.
Elements: Substances consisting of one type of atom (e.g., C, H, O, N).
Covalent bonds: Atoms share electrons (e.g., H2O).
Ionic bonds: Transfer of electrons from one atom to another (e.g., NaCl).
Hydrogen bonds: Weak attractions between polar molecules (e.g., between water molecules).

Organic molecules: Contain carbon and hydrogen; form the basis of life.
Functional groups: Specific groups of atoms that confer properties (e.g., hydroxyl, carboxyl, amino, phosphate).

Carbohydrates: Sugars and polymers of sugars (e.g., glucose, starch, cellulose).
Lipids: Hydrophobic molecules (e.g., fats, phospholipids, steroids).
Proteins: Polymers of amino acids; perform many cellular functions.
Nucleic acids: DNA and RNA; store and transmit genetic information.

Macromolecule	Monomer	Function	Example
Carbohydrate	Monosaccharide	Energy, structure	Glucose, cellulose
Lipid	Fatty acid, glycerol	Energy storage, membranes	Triglyceride, phospholipid
Protein	Amino acid	Catalysis, structure, transport	Enzyme, hemoglobin
Nucleic acid	Nucleotide	Genetic information	DNA, RNA

Prokaryotic cells: No nucleus, no membrane-bound organelles (e.g., bacteria, archaea).
Eukaryotic cells: Nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

Nucleus: Contains genetic material (DNA).
Mitochondria: Site of cellular respiration; produces ATP.
Chloroplast: Site of photosynthesis (plants and algae).
Endoplasmic reticulum (ER): Protein and lipid synthesis; rough ER has ribosomes, smooth ER does not.
Golgi apparatus: Modifies, sorts, and packages proteins and lipids.
Lysosome: Digests macromolecules and old cell parts.
Plasma membrane: Controls movement of substances in and out of the cell.

Phospholipid bilayer: Hydrophilic heads face outward, hydrophobic tails inward.
Selective permeability: Only certain molecules can cross easily.
Transport proteins: Facilitate movement of substances across the membrane.

Passive transport: No energy required (e.g., diffusion, osmosis, facilitated diffusion).
Active transport: Requires energy (ATP) to move substances against their concentration gradient.
Endocytosis/exocytosis: Bulk transport into/out of the cell.

Metabolism: All chemical reactions in a cell.
Anabolic pathways: Build complex molecules from simpler ones; require energy.
Catabolic pathways: Break down complex molecules; release energy.

First law of thermodynamics: Energy cannot be created or destroyed, only transformed.
Second law of thermodynamics: Every energy transfer increases the entropy (disorder) of the universe.
Free energy (Gibbs free energy):
Spontaneous reactions have .

ATP (adenosine triphosphate): Stores and transfers energy for cellular work.
Energy is released when ATP is hydrolyzed to ADP and inorganic phosphate.

Enzymes: Biological catalysts that speed up reactions by lowering activation energy.
Active site: Region on the enzyme where the substrate binds.
Induced fit: Enzyme changes shape to fit the substrate.
Factors affecting enzyme activity: Temperature, pH, substrate concentration, inhibitors.
Competitive inhibitors: Bind to the active site, blocking substrate.
Noncompetitive inhibitors: Bind elsewhere, changing enzyme shape.
Allosteric regulation: Enzyme activity is regulated by molecules binding to sites other than the active site.
Feedback inhibition: End product of a pathway inhibits an earlier step.

Factor	Effect
Temperature	Increases rate up to optimum; denatures enzyme if too high
pH	Each enzyme has an optimal pH; extremes denature enzyme
Substrate concentration	Rate increases until enzyme is saturated
Inhibitors	Decrease enzyme activity

These notes cover core concepts from AP/General Biology Units 1–4, including scientific inquiry, chemistry of life, macromolecules, cell structure and function, and metabolism/enzymes.
For diagrams (e.g., cell structure, enzyme action), refer to your textbook or class resources.