General Biology I – Exam 1 Vocabulary

A comprehensive set of vocabulary flashcards covering the essential terms and definitions from Chapters 1–4 of General Biology I to aid in Exam 1 preparation.

Homeostasis

The maintenance of a stable internal environment despite external changes (e.g., human body temperature around 37 °C).

Levels of Organization of Life

A hierarchy from atom → molecule → organelle → cell → tissue → organ → organ system → organism → population → community → ecosystem → biosphere.

Cell

The smallest structural and functional unit of life capable of performing all life processes.

Prokaryotic Cell

Cell without a nucleus or membrane-bound organelles; includes bacteria and archaea.

Eukaryotic Cell

Cell with a true nucleus and membrane-bound organelles; found in plants, animals, fungi, and protists.

Domain Prokarya

One of the two major domains; encompasses eubacteria and archaea.

Domain Eukarya

Domain containing all eukaryotic organisms—plants, animals, fungi, and protists.

Eubacteria

True bacteria; prokaryotes with peptidoglycan cell walls.

Archaea

Prokaryotes often living in extreme environments; lack peptidoglycan cell walls.

Kingdom Plantae

Multicellular, photosynthetic eukaryotes; producers in most ecosystems.

Kingdom Animalia

Multicellular, heterotrophic eukaryotes that ingest food (consumers).

Kingdom Fungi

Eukaryotic decomposers that absorb nutrients; include molds, yeasts, mushrooms.

Protists

Diverse group of mostly unicellular eukaryotes such as algae and protozoa.

Producers

Autotrophs that manufacture organic molecules from sunlight or chemicals.

Consumers

Organisms that obtain energy by eating other organisms or organic matter.

Decomposers

Organisms, often fungi or bacteria, that break down dead material, recycling nutrients.

Evolution

Change in the genetic composition of a population over generations by natural selection and other mechanisms.

Scientific Method

Systematic process: observation → question → hypothesis → experiment → analysis → conclusion.

Hypothesis

A testable, falsifiable explanation for an observation or phenomenon.

Control

A standard for comparison in an experiment; lacks the independent variable.

Double-Blind Study

Experimental design in which neither participants nor researchers know who receives the treatment, minimizing bias.

Sample Size

Number of subjects or observations in a study; larger sizes increase reliability.

Common Elements in Life

Mostly C, H, O, N, with P, S, Ca, K, etc.

Atom

Smallest unit of an element retaining its chemical properties.

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Neutral subatomic particle in the nucleus.

Electron

Negatively charged subatomic particle orbiting the nucleus.

Atomic Number

Number of protons in an atom; defines the element.

Atomic Mass

Total number of protons plus neutrons in an atom.

Isotope

Atoms of the same element with different neutron numbers; used in dating, tracers, medicine.

Compound

Substance formed when two or more elements combine in fixed ratios (e.g., H₂O).

Ionic Bond

Attraction between oppositely charged ions formed by electron transfer.

Covalent Bond

Chemical bond formed by sharing electron pairs between atoms.

Anion

Negatively charged ion resulting from electron gain.

Cation

Positively charged ion resulting from electron loss.

Nonpolar Covalent Bond

Equal sharing of electrons; no charge separation.

Polar Covalent Bond

Unequal electron sharing due to electronegativity differences, creating partial charges.

Electronegativity

Atom’s attraction for shared electrons in a bond.

Hydrogen Bond

Weak attraction between a hydrogen in a polar molecule and an electronegative atom (O or N).

Specific Heat (Water)

Amount of heat needed to change water’s temperature; high value stabilizes climates.

Universal Solvent (Water)

Water dissolves many polar and ionic substances due to its polarity.

Surface Tension

Cohesive force at water’s surface from hydrogen bonding.

pH Scale

Log scale (0-14) measuring hydrogen ion concentration; 7 is neutral.

Acid

Substance with pH < 7; donates H⁺ ions.

Base

Substance with pH > 7; accepts H⁺ ions.

Buffer

Solution that resists pH change by absorbing or releasing H⁺.

Functional Group

Specific cluster of atoms conferring characteristic chemistry (e.g., hydroxyl, carboxyl).

Dehydration Synthesis

Reaction that joins monomers by removing water; requires energy.

Hydrolysis

Reaction that breaks polymers by adding water; releases energy.

Monomer

Small molecular subunit that can join to form polymers.

Polymer

Long chain of repeating monomers (e.g., polysaccharide, protein).

Carbohydrates

Sugars and starches; energy source and structural roles.

Lipids

Hydrophobic molecules (fats, oils, sterols) for energy storage, membranes, hormones.

Proteins

Polymers of amino acids; enzymes, structural, transport, signaling functions.

Nucleic Acids

DNA and RNA; store and transmit genetic information.

Monosaccharide

Single sugar unit such as glucose or fructose.

Disaccharide

Two monosaccharides linked (e.g., sucrose).

Polysaccharide

Polymer of many sugars; starch, glycogen, cellulose.

Glycosidic Bond

Covalent linkage joining monosaccharides in carbohydrates.

Starch

Plant storage polysaccharide of glucose; digestible by humans.

Glycogen

Animal storage polysaccharide of glucose, mainly in liver and muscles.

Cellulose

Structural polysaccharide in plant cell walls; indigestible to humans.

Saturated Fatty Acid

No C=C double bonds; solid at room temp, common in animal fats.

Unsaturated Fatty Acid

One or more C=C double bonds; liquid at room temp, common in plant oils.

Trans Fat

Partially hydrogenated unsaturated fat with trans double bonds; linked to heart disease.

Triglyceride

Lipid of glycerol plus three fatty acids; major energy storage molecule.

Phospholipid

Glycerol, two fatty acids, and phosphate; forms cell membranes.

Sterol

Four-ring lipid structure; includes cholesterol and steroid hormones.

Cholesterol

Key sterol in animal cell membranes and precursor to steroid hormones.

Amino Acid

Building block of proteins; contains amino, carboxyl, hydrogen, and R-group.

Peptide Bond

Covalent bond linking amino acids between carboxyl and amino groups.

Essential Amino Acid

Amino acid that must be obtained in the diet because the body cannot synthesize it.

Primary Protein Structure

Linear sequence of amino acids in a polypeptide.

Secondary Structure

Folding patterns (α-helix, β-sheet) stabilized by hydrogen bonds.

Tertiary Structure

Three-dimensional shape of a single polypeptide chain.

Quaternary Structure

Association of multiple polypeptide subunits in a protein.

Denaturation

Loss of protein’s native shape (and function) due to heat, pH, chemicals.

Nucleotide

Monomer of nucleic acids; sugar + phosphate + nitrogen base.

DNA (Deoxyribonucleic Acid)

Double-stranded helix storing genetic information; bases A-T, C-G.

RNA (Ribonucleic Acid)

Single-stranded nucleic acid; contains ribose and uracil (U) instead of thymine.

Base Pairing

Hydrogen bonding of A with T (or U in RNA) and C with G.

Light Microscope

Uses visible light and lenses to magnify living or fixed specimens.

Electron Microscope

Uses electron beams for much higher resolution imaging of cell ultrastructure.

Magnification

Ratio of image size to actual specimen size in microscopy.

Resolution

Ability to distinguish two close points as separate; clarity of detail.

Contrast

Difference in brightness between specimen and background.

Phospholipid Bilayer

Two layers of phospholipids forming the basic structure of cell membranes.

Hydrophilic Head

Water-loving phosphate/glycerol portion of a phospholipid.

Hydrophobic Tail

Water-repelling fatty acid chains of a phospholipid.

Nucleus

Membrane-bound organelle housing eukaryotic DNA.

Ribosome

Complex of rRNA and proteins that synthesizes polypeptides.

Rough Endoplasmic Reticulum (RER)

ER studded with ribosomes; synthesizes and folds proteins.

Smooth Endoplasmic Reticulum (SER)

ER without ribosomes; lipid synthesis, detoxification, calcium storage.

Golgi Apparatus

Stacks of membranes that modify, sort, and ship proteins and lipids.

Lysosome

Vesicle with digestive enzymes for intracellular digestion.

Nucleolus

Dense region inside nucleus where ribosomal RNA is produced.

Mitochondrion

Organelle where cellular respiration generates ATP in eukaryotes.

Chloroplast

Plant/algal organelle that conducts photosynthesis.

Thylakoid

Flattened membrane sac inside chloroplast where light reactions occur.

Grana

Stacks of thylakoids within chloroplasts.