General Biology: Core Concepts and Study Guide (Chapters 1–7)

Chapter 1: Introduction to Biology

Core Concepts and Scientific Method

This chapter introduces the foundational principles of biology, the scientific method, and key terminology essential for understanding biological systems.

• The Seven Properties of Life: All living things share seven characteristics: order, response to stimuli, reproduction, adaptation, growth and development, regulation, and homeostasis.

• Levels of Biological Organization: From smallest to largest: atom, molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere.

• Emergent Properties: New properties that arise at each level of organization, not present at the preceding level. Example: Life emerges at the cellular level, not in individual molecules.

• Scientific Method: Steps include observation, hypothesis formation, experimentation, data collection, analysis, and conclusion.

• Controlled Experiment: An experiment in which only one variable is changed at a time, with all others held constant.

• Dependent vs. Independent Variables: The independent variable is manipulated; the dependent variable is measured.

• Null vs. Alternative Hypotheses: The null hypothesis states there is no effect; the alternative suggests a specific effect or difference.

• Graph Interpretation: Ability to label axes, plot data, and interpret trends on standard graphs.

Key Vocabulary: Biology, Emergent Properties, Science, Independent Variable, Dependent Variable, Controlled Experiment, Observational Study, Null Hypothesis, Alternative Hypothesis

Chapter 2: Chemistry of Life

Atoms, Elements, and Chemical Bonds

This chapter covers the basic chemistry underlying biological processes, including atomic structure, chemical bonds, and properties of water.

• Atoms and Elements: Atoms are the smallest units of matter; elements are pure substances consisting of one type of atom.

• Subatomic Particles: Protons (positive, in nucleus), neutrons (neutral, in nucleus), electrons (negative, in orbitals).

• Atomic Number and Mass Number: Atomic number = number of protons; mass number = protons + neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Compounds and Molecules: Compounds are substances formed from two or more elements; molecules are groups of atoms bonded together.

• Chemical Bonds: Ionic (transfer of electrons), covalent (sharing electrons), hydrogen bonds (weak attractions between polar molecules).

• Polar vs. Nonpolar Covalent Bonds: Polar bonds have unequal sharing of electrons; nonpolar have equal sharing.

• Properties of Water: Cohesion, adhesion, surface tension, high specific heat, solvent abilities.

• pH Scale: Measures acidity/alkalinity; 7 is neutral, below 7 is acidic, above 7 is basic.

• Buffers: Substances that minimize changes in pH.

Key Vocabulary: Atom, Element, Compound, Isotope, Electron Shell, Valence Shell, Polarity, Surface Tension, Cohesion, Adhesion, Specific Heat, Solution

Chapter 3: Biological Macromolecules

Structure and Function of Macromolecules

This chapter explores the four major classes of biological macromolecules and their roles in living organisms.

• Carbon: Central to organic molecules due to its ability to form four covalent bonds.

• Monomers and Polymers: Monomers are building blocks; polymers are long chains of monomers.

• Dehydration Synthesis and Hydrolysis: Dehydration joins monomers by removing water; hydrolysis breaks polymers by adding water.

• Carbohydrates: Monosaccharides (glucose), disaccharides (sucrose), polysaccharides (starch, cellulose). Function as energy sources and structural materials.

• Proteins: Made of amino acids; functions include enzymes, structure, transport. Levels of structure: primary, secondary, tertiary, quaternary.

• Lipids: Triglycerides (energy storage), phospholipids (membranes), steroids (hormones).

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

Key Vocabulary: Monomer, Polymer, Hydrolysis, Dehydration Synthesis, Macromolecule, Functional Group, Organic Compound, Hydrocarbon, Isomer

Chapter 4: Cell Structure and Function

Prokaryotic and Eukaryotic Cells

This chapter examines the structure and function of cells, the basic unit of life, and compares prokaryotic and eukaryotic cells.

• Cell Theory: All living things are composed of cells; cells are the basic unit of life; all cells come from pre-existing cells.

• Prokaryotic vs. Eukaryotic Cells: Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

• Cell Size: Limited by surface area-to-volume ratio.

• Plant vs. Animal Cells: Plant cells have cell walls, chloroplasts, and large vacuoles; animal cells do not.

• Organelles: Nucleus (DNA storage), mitochondria (energy production), chloroplasts (photosynthesis), endoplasmic reticulum (protein/lipid synthesis), Golgi apparatus (modification and transport), ribosomes (protein synthesis), cytoskeleton (structure and movement).

• Cell Wall: Provides structure and protection in plants, fungi, and some prokaryotes.

• Flagella and Cilia: Structures for movement.

Key Vocabulary: Plasma Membrane, Prokaryote, Eukaryote, Nucleus, Golgi Apparatus, Mitochondria, Chloroplast, Cytoskeleton, Extracellular Matrix, Cell Wall

Chapter 5: Membrane Structure and Function

Transport and Homeostasis

This chapter focuses on the structure of biological membranes and the mechanisms by which substances move across them.

• Plasma Membrane: Composed of a phospholipid bilayer with embedded proteins; selectively permeable.

• Passive Transport: Movement of substances down their concentration gradient (diffusion, osmosis, facilitated diffusion).

• Active Transport: Movement against the concentration gradient, requiring energy (ATP).

• Osmosis: Diffusion of water across a selectively permeable membrane.

• Hypertonic, Hypotonic, Isotonic Solutions: Affect cell volume and water movement.

• Membrane Proteins: Functions include transport, signaling, cell recognition, enzymatic activity, and attachment.

• Thermodynamics: First law (energy conservation), second law (entropy increases).

• Enzymes: Biological catalysts that speed up reactions by lowering activation energy; can be regulated by inhibitors.

• ATP: Main energy currency of the cell.

Key Vocabulary: Diffusion, Osmosis, Active Transport, Facilitated Diffusion, Hypertonic, Hypotonic, Isotonic, Chemical Reaction, Kinetic Energy, Potential Energy, Enzyme, Substrate, Active Site

Chapter 6: Cellular Respiration

Harvesting Energy from Food

This chapter explains how cells extract energy from organic molecules through cellular respiration.

• Cellular Respiration: The process by which cells convert glucose and oxygen into ATP, carbon dioxide, and water.

• Overall Equation:

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

• Stages: Glycolysis, Pyruvate Oxidation, Citric Acid Cycle, Oxidative Phosphorylation (Electron Transport Chain and Chemiosmosis).

• Aerobic vs. Anaerobic Respiration: Aerobic uses oxygen; anaerobic does not (fermentation).

• ATP Production: Most ATP is produced during oxidative phosphorylation.

• Fermentation: Produces lactic acid or alcohol in the absence of oxygen.

• Intermediates: Molecules from respiration can be used for biosynthesis.

Key Vocabulary: Aerobic Respiration, Glycolysis, Pyruvate Oxidation, Oxidative Phosphorylation, Chemiosmosis, Electron Transport, NADH, ATP Synthase, Oxidation, Reduction

Chapter 7: Photosynthesis

Energy Capture and Conversion in Plants

This chapter describes how plants and other autotrophs convert solar energy into chemical energy through photosynthesis.

• Chloroplast Structure: Site of photosynthesis, located mainly in leaf cells.

• Overall Equation:

$6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$

• Stages: Light Reactions (convert solar energy to chemical energy, produce ATP and NADPH) and Calvin Cycle (uses ATP and NADPH to fix carbon into glucose).

• Pigments: Chlorophyll absorbs light; different pigments absorb different wavelengths, affecting leaf color.

• Electron Transport: Light energy excites electrons, which are transferred through a chain to produce ATP and NADPH.

• Photophosphorylation: Production of ATP using light energy during the light reactions.

• Greenhouse Effect: The trapping of heat in Earth's atmosphere by greenhouse gases; related to climate change.

Key Vocabulary: Autotroph, Heterotroph, Producer, Photoautotroph, Chlorophyll, Light Reaction, Calvin Cycle, NADPH, Carbon Fixation, Carbon Intermediate, Photosystem, Photophosphorylation

Sample Table: Comparison of Prokaryotic and Eukaryotic Cells

Feature	Prokaryotic Cells	Eukaryotic Cells
Nucleus	No	Yes
Membrane-bound Organelles	No	Yes
Cell Size	Small (1-10 μm)	Larger (10-100 μm)
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Additional info: These study notes are based on a midterm review guide and cover the essential vocabulary, concepts, and processes from the first seven chapters of a General Biology course. The content is organized to facilitate exam preparation and understanding of foundational biological principles.