General Biology Study Guide: Core Concepts and Foundations

CH 1: Foundations of Biology

7 Characteristics of Life

Living organisms share several fundamental characteristics that distinguish them from non-living matter.

• Organization: Living things are composed of one or more cells, which are the basic units of life.

• Metabolism: Organisms carry out chemical reactions to obtain and use energy.

• Homeostasis: Maintenance of a stable internal environment.

• Growth: Increase in size and/or number of cells.

• Reproduction: Ability to produce new individuals.

• Response to Stimuli: Reacting to environmental changes.

• Evolution: Populations change over time through genetic variation and natural selection.

Biological Levels of Organization

Life is organized in a hierarchical structure from smallest to largest:

• Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

The Scientific Method

The scientific method is a systematic approach to investigation.

• Observation: Gathering information about phenomena.

• Hypothesis: A testable explanation for an observation.

• Experiment: Testing the hypothesis under controlled conditions.

• Data Collection: Recording results.

• Analysis: Interpreting data to draw conclusions.

• Conclusion: Accepting, rejecting, or modifying the hypothesis.

Variables in Experiments

Experiments involve different types of variables:

• Independent Variable: The factor that is changed or manipulated.

• Dependent Variable: The factor that is measured.

• Controlled Variables: Factors kept constant to ensure a fair test.

• Example: Testing plant growth with different fertilizers (independent variable: fertilizer type; dependent variable: plant height).

Scientific Theory

A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of evidence.

• Example: Theory of Evolution by Natural Selection.

Natural Selection and Evolution

Natural selection is a process where organisms better adapted to their environment tend to survive and reproduce.

• Evolution: Change in the genetic makeup of populations over time.

• Evidence: Fossil record, comparative anatomy, molecular biology, biogeography.

Homologous vs. Analogous Structures

Structures in organisms can be compared to infer evolutionary relationships.

• Homologous Structures: Similar anatomy due to shared ancestry (e.g., human arm and bat wing).

• Analogous Structures: Similar function but different evolutionary origins (e.g., bird wing and insect wing).

• Genetic Relationship: Homologous structures indicate genetic relatedness.

Classification System and Taxonomic Levels

Organisms are classified into hierarchical categories.

• Levels: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

• Scientific Names: Binomial nomenclature (Genus species, e.g., Homo sapiens).

Domains and Eukaryotic Kingdoms

Life is divided into three domains and four major eukaryotic kingdoms.

• Domains: Bacteria, Archaea, Eukarya

• Eukaryotic Kingdoms: Protista, Fungi, Plantae, Animalia

CH 2-3: Chemistry of Life

Periodic Table and Atomic Structure

The periodic table organizes elements by atomic number and properties.

• Atomic Number: Number of protons in an atom.

• Atomic Mass: Sum of protons and neutrons.

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

Atoms, Ions, and Molecules

Atoms are the basic units of matter; ions are charged atoms.

• Cation: Positively charged ion.

• Anion: Negatively charged ion.

• Atoms Bonding: Atoms form chemical bonds to achieve stability.

Bonding and Electronegativity

Atoms bond through sharing or transferring electrons.

• Covalent Bonds: Electrons are shared.

• Ionic Bonds: Electrons are transferred.

• Electronegativity: Tendency of an atom to attract electrons.

• Polarity: Unequal sharing of electrons creates partial charges.

Properties of Water

Water is essential for life due to its unique properties.

• Cohesion: Water molecules stick together.

• Adhesion: Water molecules stick to other surfaces.

• High Specific Heat: Water resists temperature changes.

• Solvent Properties: Water dissolves many substances.

pH and Acidity

pH measures the concentration of hydrogen ions in a solution.

• Formula: $pH = -\log[H^+]$

• Acidic: pH < 7

• Neutral: pH = 7

• Basic: pH > 7

Macromolecules and Biochemistry

Dehydration Synthesis vs. Hydrolysis

Macromolecules are formed and broken down by specific chemical reactions.

• Dehydration Synthesis: Joining monomers by removing water.

• Hydrolysis: Breaking polymers by adding water.

Four Groups of Macromolecules

Biological macromolecules are classified into four major groups:

Macromolecule	Monomer	Function	Examples
Carbohydrates	Monosaccharides	Energy, structure	Glucose, starch
Lipids	Fatty acids, glycerol	Energy storage, membranes	Triglycerides, phospholipids
Proteins	Amino acids	Catalysis, structure, transport	Enzymes, hemoglobin
Nucleic Acids	Nucleotides	Genetic information	DNA, RNA

• Calories: Measure of energy content.

• Digestion Site and Enzymes: Enzymes catalyze breakdown in specific organs.

• Element Composition: C, H, O, N, P, S (varies by macromolecule).

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

• Hydrophobic vs. Hydrophilic: Hydrophobic molecules repel water; hydrophilic molecules attract water.

Carbohydrates: Categories and Examples

Carbohydrates are classified by the number of sugar units.

• Monosaccharides: Single sugar units (e.g., glucose).

• Disaccharides: Two sugar units (e.g., sucrose).

• Polysaccharides: Many sugar units (e.g., starch, cellulose).

Lipids: Types and Functions

Lipids are diverse molecules with various functions.

• Fats: Energy storage (saturated and unsaturated).

• Phospholipids: Major component of cell membranes.

Proteins: Structure and Functions

Proteins perform a wide range of functions in cells.

• Enzymes: Catalyze biochemical reactions.

• Transport: Move substances across membranes.

• Structure: Provide support (e.g., collagen).

• Defense: Antibodies fight pathogens.

• Regulation: Hormones control processes.

• Movement: Muscle proteins enable motion.

• Storage: Store amino acids or ions.

Denaturation

Denaturation is the loss of protein structure due to external stress (heat, pH, chemicals), resulting in loss of function.

Triglyceride and Phospholipid Anatomy

Triglycerides and phospholipids are key lipid molecules.

• Triglyceride: Composed of three fatty acids linked to glycerol.

• Phospholipid: Composed of two fatty acids, glycerol, and a phosphate group; forms bilayers in cell membranes.

Additional info: Some explanations and examples have been expanded for clarity and completeness.