Biology Unit Vocabulary Review (Units 1-5)

Vocabulary flashcards covering core terms and concepts from Biology Units 1-5.

Biosphere

The global sum of all ecosystems; the highest level of biological organization.

Ecosystem

All living things in a localized area plus the physical environment with which they interact.

Community

All the living organisms in a particular area.

Population

All individuals of a single species in a given area.

Organism

A living individual that can be part of a population.

Organ

A body part made of multiple tissues functioning together.

Organ system

A group of organs that cooperate to perform a broad function.

Tissue

A group of cells performing a common function.

Cell

The basic unit of life; must be alive.

Organelle

A specialized subcellular structure with a specific function.

Molecule

The smallest units of compounds composed of atoms.

Atom

The smallest unit of matter that retains properties of an element.

Taxonomy

The science of naming and classifying organisms.

Domain

One of three domains: Bacteria, Archaea, Eukarya.

Bacteria

A domain of prokaryotes; fundamentally different biochemistry from Archaea.

Archaea

A domain of prokaryotes with distinctive biochemistry.

Eukarya

Domain that includes animals, plants, fungi, and protists.

Virus

Not living; not cellular; can evolve; cannot reproduce independently.

Science

Systematic knowledge gained through observations and hypothesis testing.

Observation

Information gathered through senses or instruments to inform a hypothesis.

Hypothesis

A testable educated guess about how a system works.

Experiment

A controlled test to evaluate a hypothesis.

Scientific method

Cycle of observations, testable hypotheses, experiments, data, and conclusions.

Theory

A broad, testable framework explaining natural phenomena, supported by evidence and revised with new data.

Evolutionary theory

Theory that species change over time through differential survival and reproduction.

Atomic number

Number of protons in the nucleus of an atom.

Atomic mass

Sum of protons and neutrons in the nucleus.

Isotope

Same element with different numbers of neutrons.

Radioactivity

Spontaneous decay of unstable isotopes releasing radiation.

Ion

An atom or molecule with a net electric charge.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Covalent bond

Bond formed by sharing electrons between atoms.

Ionic bond

Bond formed by transfer of electrons, producing charged ions.

Hydrogen bond

Weak bond between polar molecules, often involving H attached to O, N, or F.

Van der Waals interactions

Weak attractions between molecules due to transient dipoles.

Valence electrons

Electrons in the outermost shell that determine bonding behavior.

Polar covalent bond

Unequal sharing of electrons between atoms in a covalent bond.

Hydrophilic

Molecules or parts that are water-attracting (often polar/ionic).

Hydrophobic

Molecules or parts that repel water (nonpolar).

Solution

A uniform mixture of two or more substances.

Solvent

The dissolving medium in a solution.

Solute

The substance dissolved in a solvent.

Acid

Substance that donates H+ (or increases H3O+) in solution.

Base

Substance that accepts H+ or donates OH- in solution.

pH

Measure of how acidic or basic a solution is; lower pH = more acidic; higher pH = more basic.

Buffer

A solution that resists pH changes by neutralizing added acids or bases.

Molarity

Concentration defined as moles of solute per liter of solution.

Avogadro's number

6.02 x 10^23; number of particles in one mole.

Macromolecule

Large biological molecule (carbohydrates, lipids, proteins, nucleic acids).

Polymer

A large molecule built from repeating monomer units.

Monomer

A small building block that can join to form polymers.

Dehydration synthesis

Bond formation between monomers with loss of a water molecule.

Hydrolysis

Polymers are broken down by adding water.

Carbohydrates

Sugars and their polymers; provides energy and structure.

Monosaccharide

Simple sugar, e.g., glucose.

Disaccharide

Two monosaccharides joined together.

Glycosidic linkage

Covalent bond joining sugars in carbohydrates.

Polysaccharide

Polymers of sugars with storage or structural roles.

Starch

Plant storage polysaccharide made of glucose; amylose is a simple form.

Amylose

Simplest form of starch; primarily glucose polymers.

Cellulose

Structural polysaccharide in plant cell walls; beta-linkages; not digestible by humans.

Alpha glucose

Ring form of glucose in starch (alpha linkage).

Beta glucose

Ring form of glucose in cellulose (beta linkage).

Glycosidic linkage (2nd mention)

Bond linking monosaccharides in disaccharides/polysaccharides.

Ribose

Five-carbon sugar essential for RNA as a building block.

Lipids

Not true polymers; hydrophobic; include fats, phospholipids, steroids.

Fat

Glycerol plus fatty acids; main energy-storage lipid.

Glycerol

Three-carbon alcohol backbone of fats.

Fatty acid

Carboxyl group attached to a long hydrocarbon chain.

Saturated fatty acid

No double bonds; maximum hydrogens; typically solid at room temperature.

Unsaturated fatty acid

One or more double bonds; typically liquid at room temperature.

Trans fats

Hydrogenated unsaturated fats with trans double bonds; health concerns.

Omega-3 fatty acids

Essential unsaturated fats not synthesized by the body; important for health.

Phospholipid

Glycerol with two fatty acids and a phosphate group; amphipathic; forms membranes.

Cholesterol

Steroid component of animal membranes and precursor to other steroids.

Steroids

Lipids with a four-ring core structure.

Functional group

Specific group of atoms responsible for characteristic chemical reactions.

Hydroxyl

–OH group.

Carbonyl

C=O group.

Carboxyl

–COOH group.

Amine

–NH2 group.

Sulfhydryl

–SH group.

Phosphate

–PO4 group; important in energy transfer (ATP) and membranes.

Methyl

–CH3 group; influences molecule properties.

Enantiomer

Non-superimposable mirror-image isomer; often requires a stereocenter.

Stereocenter

Atom (usually carbon) with four different substituents.

Isomer

Same molecular formula, different arrangement of atoms.

Structural isomer

Isomers with the same formula but different covalent bonding.

Cis-trans isomer

Isomers differing in the arrangement around a double bond.

Ribose (repeat)

Five-carbon sugar in RNA; building block of nucleic acids.

Nucleic acids

Polymers of nucleotides; store and transmit genetic information.

Monomers (repeat)

Basic building blocks that polymerize to form macromolecules.

Polymers (repeat)

Large molecules built from repeated monomer units.

Proteins

Macromolecules made of amino acids; perform varied cellular roles.

Nucleotides

Monomers of nucleic acids (DNA/RNA) consisting of a sugar, phosphate, and base.