Full Set (Updated)

Evolution

Change in populations over time as traits become more or less common.

Microevolution

Small-scale evolution within one population.

Macroevolution

Large-scale evolution that can create new species over long periods.

Creationism

The belief that life was created by a supernatural force instead of evolving naturally.

Catastrophism

The idea that major disasters shaped Earth’s history.

Gradualism

The idea that big changes happen slowly through many small changes.

Uniformitarianism

The idea that the same natural processes happening now also shaped the past.

Natural selection

When organisms with helpful inherited traits survive and reproduce more often.

Adaptation

A trait that helps an organism survive or reproduce in its environment.

Survival of the fittest

The idea that organisms best suited to their environment are more likely to survive and reproduce.

Fitness

How well an organism survives and reproduces in its environment.

Variation

Differences between individuals in a population.

Random mutation

A random DNA change that can create new alleles.

Genetic recombination

Mixing alleles during meiosis to make new gene combinations.

Gene flow

Movement of alleles between populations, usually through migration.

Gene pool

All the alleles in a population.

Descent with modification

The idea that populations change over generations from their ancestors.

Directional selection

Selection that favors one extreme trait, causing the population to shift that way.

Disruptive selection

Selection that favors both extremes and works against the middle trait.

Stabilizing selection

Selection that favors the average trait and works against extremes.

Allele frequency

How common an allele is in a population.

Mechanisms of microevolution

Ways allele frequencies change, including mutation, natural selection, genetic drift, gene flow, and non-random mating.

Genetic drift

Random changes in allele frequencies, especially in small populations.

Non-random mating

When organisms choose mates based on certain traits instead of mating by chance.

Sexual selection

Selection for traits that help an organism get mates.

Genetic equilibrium

When allele frequencies stay the same and the population is not evolving.

Hardy-Weinberg equilibrium

A model for a non-evolving population where allele and genotype frequencies stay stable. p + q = 1 and p² + 2pq + q² = 1

Speciation

The formation of a new species.

Species

A group of organisms that can reproduce and make fertile offspring.

Isolation

Separation between groups that stops them from reproducing together.

Gradual extinction

Extinction that happens slowly over time.

Mass extinction

Extinction of many species in a short time because of a major environmental event.

Punctuated equilibrium

Evolution pattern with long stable periods interrupted by quick bursts of change.

Divergent evolution

When related species become more different over time from a common ancestor.

Adaptive radiation

When one ancestor quickly gives rise to many different species adapted to different environments.

Convergent evolution

When unrelated species evolve similar traits because they live in similar environments.

Coevolution

When two species affect each other’s evolution.

Paleontology

The study of fossils and prehistoric life.

Morphology

The study of the form and structure of living things.

Biogeography

The study of where organisms live and how they are distributed.

Embryology

The study of embryo development.

Biochemistry

The study of chemical processes in living things.

Direct observation

Evidence from watching evolution happen directly, like bacteria becoming antibiotic-resistant.

Fossil

Preserved remains or traces of an organism.

Fossil record

The collection of fossils that shows what life existed in the past.

Transitional fossil

A fossil with features between an older ancestor and a later descendant.

Homologous structure

Body parts with similar structure because of common ancestry, even if they have different jobs.

Vestigial structure

A leftover body structure that has little or no current function.

Analogous structure

Body parts with similar function but different ancestry, like bird wings and insect wings.

Continental drift

The movement of continents over time.

Embryo

An early developing organism.

Taxonomy

The science of classifying organisms.

Domain

The broadest classification level of life.

Eubacteria

The domain of true bacteria, which are prokaryotes.

Archaebacteria

The domain of prokaryotes that often live in extreme environments.

Eukarya

The domain of organisms with eukaryotic cells.

Taxon

Any classification group, like genus, family, or domain.

Carolus Linnaeus

The scientist known as the Father of Taxonomy.

Binomial nomenclature

The two-part scientific naming system: Genus species.

Genus

The first part of a scientific name; it is capitalized.

Species

The second part of a scientific name; it is lowercase.

Phylogeny

The evolutionary history and relationships of a species or group.

Prokaryote

A cell without a nucleus.

Eukaryote

A cell with a nucleus and membrane-bound organelles.

Endosymbiosis

When one cell lived inside another and both benefited.

Endosymbiotic theory

The theory that mitochondria and chloroplasts came from ancient prokaryotes living inside other cells.

Common ancestor

An earlier organism that two or more groups evolved from.

Phylogenetic tree

A branching diagram that shows predicted evolutionary relationships.

Branch point

A place on a phylogenetic tree where one lineage splits into two.

Maximum parsimony

Choosing the simplest evolutionary explanation with the fewest changes.

Homologous feature

A shared trait from a common ancestor used to compare relatedness.

Allele

A version of a gene, like B for brown eyes or b for blue eyes.

Gregor Mendel

The monk who studied pea plants and discovered basic inheritance rules.

Law of dominance

The rule that a dominant allele can hide a recessive allele.

Law of segregation

The rule that allele pairs separate so each gamete gets only one allele for a gene.

Law of independent assortment

The rule that alleles for different traits usually separate independently into gametes.

Purebred

An organism with the same type of allele for a trait for many generations.

Either-or trait

A trait with two clear forms, like tall or short.

Cross

Mating two organisms to study offspring traits.

P generation

The parent generation in a genetics cross.

F1 generation

The first generation of offspring from a cross.

F2 generation

The second generation of offspring from a cross.

Dominant

An allele that shows its trait if it is present.

Recessive

An allele that only shows its trait when there is no dominant allele.

Homozygous

Having two matching alleles, like AA or aa.

Heterozygous

Having two different alleles, like Aa.

Genotype

The allele combination an organism has, like AA, Aa, or aa.

Phenotype

The trait you can see or observe, like purple flowers or brown eyes.

Punnett square

A box chart used to predict possible offspring genotypes and phenotypes.

Monohybrid cross

A genetic cross that tracks one trait.

Dihybrid cross

A genetic cross that tracks two traits at the same time.

Probability

The chance that something will happen.

Chromosome theory of inheritance

The idea that genes are on chromosomes and meiosis explains how traits are inherited.

Exception to Mendel’s laws

A trait pattern that does not work as simple dominant versus recessive.

Incomplete dominance

When neither allele fully covers the other, so the heterozygous trait looks like a blend. Example: red + white = pink.

Codominance

When both alleles show at the same time. Example: red and white make red-and-white spotted.

Blood type

A human trait controlled by A, B, and O alleles. It shows both codominance and multiple alleles.

Multiple alleles

When a gene has more than two possible allele versions in a population.

Agglutinogens

Markers on red blood cells that help determine blood type.

Antibodies

Proteins in plasma that attack foreign markers in the blood.