Biology Review (Everything)

Vocabulary flashcards generated from the biology notes on foundations of biology, evolutionary theory, population genetics, speciation, and geologic history.

Cellular Organization

The characteristic of living organisms where living entities are composed of one or more cells, serving as the fundamental structural and functional units of life.

Metabolism

The chemical processes undergone by living organisms to acquire, convert, and utilize energy and nutrients necessary to sustain life.

Homeostasis

The active process by which organisms regulate and maintain a stable internal environment despite fluctuations in external conditions.

Hypothesis

A tentative, testable, and falsifiable explanation for a specific set of observations or a narrow phenomenon.

Theory

A broad, comprehensive, and highly tested explanation for a wide range of natural phenomena supported by a vast body of empirical evidence, allowing for accurate predictions across context domains.

Scientific Law

A concise verbal or mathematical statement describing an observed, universal pattern or relationship in nature under specified conditions, stating what happens without necessarily explaining why it happens.

Spontaneous Generation

The long-held hypothesis that living organisms could arise spontaneously from non-living matter.

Biogenesis

The principle supported by Louis Pasteur's swan-necked flask experiment demonstrating that microorganisms do not arise spontaneously from non-living broth, but arise only from existing airborne microbes.

Evolution

Broadly defined as descent with modification; specifically defined in population genetics as any change in the allele frequencies or heritable traits of a population over successive generations.

Phenotypic Selection

Occurs when individuals with specific observable traits survive and reproduce at higher rates than individuals with other traits within a single generation, which can happen without evolution if the trait variation lacks a genetic basis.

Genotype

The specific genetic makeup or set of alleles present in an individual organism at one or more genetic loci.

Phenotype

The physical, physiological, morphological, or behavioral traits expressed by an organism, resulting from the interaction between its genotype and its environment.

Natural Selection

The non-random process by which individuals with favorable heritable traits survive and reproduce at higher rates than other individuals because of those traits, leading to an increase in the frequency of those traits in the population over time.

Biological Fitness

The relative reproductive success of an individual compared to other individuals in the population, quantified by the number of viable, fertile offspring contributed to the next generation's gene pool.

Adaptation

A heritable trait or feature that increases an individual's biological fitness in a specific environment relative to individuals lacking that trait.

Typological Thinking

A pre-19th century viewpoint proposed by Plato asserting that species are static, unchangeable entities created as ideal essences or types, dismissing individual variation as mere imperfect deviations.

Scala Naturae

A concept formulated by Aristotle organizing organisms into a rigid, linear hierarchy based on increasing complexity, with minerals at the bottom, plants and lower animals in the middle, and humans at the top.

Natural Theology

A 17th–19th century movement asserting that the complexity, order, and adaptation of living organisms provided direct evidence for the existence and benevolence of a divine Creator.

Watchmaker Analogy

William Paley's argument that finding a complex pocket watch implies a watchmaker, and by extension, complex anatomical structures in living organisms require an intelligent, conscious designer.

Catastrophism

Georges Cuvier's theory that Earth's geological features and major biological shifts were created by sudden, short-lived, violent global disasters caused by supernatural or unique physical forces.

Uniformitarianism

Charles Lyell and James Hutton's theory that geological features are shaped by slow, continuous, ongoing physical processes operating at the same constant rates today as in the past.

Use and Disuse

A tenet of Lamarckian evolution stating that organs or traits used extensively become larger and stronger, while unused structures deteriorate.

Inheritance of Acquired Characteristics

A tenet of Lamarckian evolution stating that phenotypic modifications acquired by an individual during its lifetime through use or environmental influence are passed directly to its offspring.

Struggle for Existence

The continuous competition resulting from population growth exceeding available environmental resources, leading Charles Darwin and Alfred Russel Wallace to realize that only a fraction of offspring survive to reproduce.

Transitional Forms

Fossil species displaying intermediate structural characteristics between ancestral and descendant lineages, such as Tiktaalik bridging fish and tetrapods, or Archaeopteryx bridging reptiles and birds.

Island Biogeography

The study of species distribution showing that oceanic islands are typically populated by species closely related to species on the nearest mainland, having adapted to distinct island ecological niches.

Homologous Traits

Structural similarities inherited from a common ancestor, despite potential differences in current function, such as the forelimbs of humans, bats, whales, and horses.

Analogous Traits

Morphological similarities that evolved independently in separate lineages due to similar selective pressures in similar environments, rather than shared ancestry.

Vestigial Traits

Reduced or rudimentary structures with no current function (or greatly diminished function) that were fully developed and functional in ancestral species, demonstrating evolutionary modification over time.

Acclimatization

A reversible, non-heritable physiological adjustment made by an individual organism during its lifetime in response to changing environmental conditions, as opposed to genetic adaptation across generations.

Pleiotropy

A genetic constraint where a single gene affects multiple traits, causing selection favoring one allele to increase the frequency of an unselected or detrimental secondary trait.

Fitness Trade-offs

An evolutionary compromise between competing biological traits where an increase in performance of one trait results in a decrease in performance of another.

Allele

An alternative sequence form of a gene located at a specific genetic locus.

Locus

The specific physical location of a gene on a chromosome.

Diploid

Organisms or cells carrying two complete sets of chromosomes, represented as $2n$, resulting in two alleles per locus.

Haploid

Gametes or organisms carrying a single set of chromosomes, represented as $n$, resulting in one allele per locus.

Homozygote

An individual carrying two identical alleles at a specific locus, such as $AA$ or $aa$.

Heterozygote

An individual carrying two different alleles at a specific locus, such as $Aa$.

Punnett Square

A visual matrix used to calculate predicted offspring allele and genotype frequencies based on parental gametes.

Gene Pool

The total collection of all alleles for all loci present within an interbreeding population.

Hardy-Weinberg Principle

A null hypothesis model stating that allele frequencies ($p + q = 1$) and genotype frequencies ($p^2 + 2pq + q^2 = 1$) in a population remain constant across generations in the absence of evolutionary forces and non-random mating.

Genetic Drift

Any change in allele frequencies in a population due to chance events or random sampling error in gamete selection, serving as a non-adaptive evolutionary process.

Fixation

The state in population genetics reached when an allele's frequency reaches $\text{frequency} = 1.0$ in a population, resulting in the complete loss of alternative alleles at that locus.

Founder Effect

A form of genetic drift occurring when a small subset of individuals separates from a larger source population to establish a new isolated population with only a fraction of the original genetic variation.

Bottleneck Effect

A form of genetic drift occurring when a sudden, severe reduction in population size randomly destroys individuals regardless of genotype, leaving a surviving population with reduced genetic diversity.

Gene Flow

The movement of alleles between different populations through the migration of breeding individuals or the dispersal of gametes.

Source Population

A stable, high-density population with high reproductive rates that produces excess individuals that migrate outward.

Sink Population

A low-density population maintained primarily by continuous immigration from a source population, without which it would decline toward extinction.

Mutation

A permanent structural change in an organism's DNA sequence, serving as the ultimate source of all novel genetic variation.

Positive Assortative Mating

A form of non-random mating where individuals mate preferentially with partners sharing similar physical phenotypes, increasing overall homozygosity without altering allele frequencies.

Negative Assortative Mating

A form of non-random mating where individuals mate preferentially with partners possessing dissimilar phenotypes, increasing overall heterozygosity in the population.

Inbreeding Depression

The loss of fitness that occurs when closely related individuals mate, increasing homozygosity across all loci and exposing deleterious recessive alleles to phenotypic selection.

Heterozygote Advantage

A pattern of selection, also termed overdominance, where heterozygous individuals ($Aa$) have higher biological fitness than either homozygous dominant ($AA$) or homozygous recessive ($aa$) individuals.

Sexual Dimorphism

Structural, morphological, physiological, or behavioral differences between males and females of the same biological species.

Fundamental Asymmetry of Sex

The principle that females invest substantial energy into producing few, large eggs and providing parental investment, limiting female fitness by resource access, while males produce vast quantities of cheap sperm, limiting male fitness by access to females.

Intersexual Selection

Sexual selection, often termed female choice, driven by females choosing mates based on specific phenotypic displays, elaborate visual structures, or courtship displays.

Intrasexual Selection

Sexual selection, often termed male-male competition, driven by direct physical competition or territorial defense among males for access to females.

Directional Selection

A pattern of natural selection that favors phenotypes at one extreme of the phenotypic distribution, shifting the mean phenotype toward that extreme while reducing overall genetic variation.

Stabilizing Selection

A pattern of natural selection that favors intermediate phenotypes and selects against extreme phenotypes, reducing overall phenotypic variation while keeping the mean phenotype constant.

Disruptive Selection

A pattern of natural selection that favors phenotypes at both extremes of the spectrum while selecting against intermediate phenotypes, maintaining or increasing overall genetic variation.

Morphological Species Concept

A species concept that identifies species based on distinct, observable structural features, applicable to fossil specimens and asexual organisms.

Biological Species Concept

A species concept defining a species as a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

Phylogenetic Species Concept

A species concept defining a species as the smallest monophyletic group on a phylogenetic tree that shares unique derived traits (synapomorphies).

Binomial Nomenclature

The standardized system developed by Carl Linnaeus for naming organisms using a two-part scientific name formatted as Genus species.

Prezygotic Isolation

Reproductive isolation mechanisms that prevent fertilization and zygote formation between distinct species.

Temporal Isolation

A prezygotic isolation mechanism where populations breed at different times of day, seasons, or years.

Habitat Isolation

A prezygotic isolation mechanism where populations breed in distinct habitats within the same general geographic area.

Behavioral Isolation

A prezygotic isolation mechanism where distinct courtship signals or displays prevent interbreeding between species.

Mechanical Isolation

A prezygotic isolation mechanism where structural incompatibility of reproductive organs prevents mating.

Gametic Isolation

A prezygotic isolation mechanism where incompatibility of egg and sperm cell surface molecules prevents fertilization.

Postzygotic Isolation

Reproductive isolation mechanisms operating after fertilization that prevent hybrid offspring from passing on genes.

Hybrid Inviability

A postzygotic isolation mechanism where hybrid zygotes or embryos fail to develop normally and die.

Hybrid Sterility

A postzygotic isolation mechanism where hybrid offspring mature successfully but are completely sterile.

Allopatric Speciation

Speciation initiated by physical or geographic separation of populations, preventing gene flow.

Vicariance Event

An allopatric speciation mechanism where a new physical barrier emerges within an existing population, splitting its geographic distribution.

Sympatric Speciation

The divergence and evolution of new species within the exact same geographical area without spatial isolation.

Polyploidy

A speciation mechanism resulting from a mutation that duplicates entire extra sets of chromosomes, creating instant reproductive isolation from diploid populations.

Autopolyploidy

A form of polyploidy resulting from the duplication of chromosome sets derived from a single parent species.

Allopolyploidy

A form of polyploidy resulting from hybridization between two distinct species followed by chromosome doubling, producing fertile polyploid hybrids isolated from both parent species.

Reinforcement

An outcome of secondary contact where natural selection favors prezygotic barriers when hybrid offspring have low fitness, completing the speciation process.

Hybrid Zone

A stable geographic boundary region where overlapping populations interbreed, producing hybrids for extended periods.

Fusion

An outcome of secondary contact where hybrid offspring have equal or higher fitness than parental populations, leading to unrestricted gene flow that completely merges two diverging populations back into one species.

Cambrian Explosion

A dramatic macroevolutionary event ~$541 offer \text{million years ago}$ during which virtually all major animal body plans (phyla) evolved within a brief geological window.

Burgess Shale Fossils

Exceptional soft-bodied fossil deposits in Canada preserving incredible morphological diversity from the middle Cambrian period.

Adaptive Radiation

The rapid diversification of a single ancestral lineage into a wide variety of ecologically diverse species adapted to distinct ecological niches.

Key Adaptations

The evolutionary origination of novel traits or morphological innovations that allow an organism to exploit new resources or niches.

Mass Extinction

An event resulting in the global elimination of at least $50\text{\%}$ or more of extant species within a geologically short period.

End-Permian Extinction

The largest mass extinction event in Earth's history (~$252\text{ million years ago}$), destroying over $96\text{\%}$ of marine species and $70\text{\%}$ of terrestrial vertebrate families due to flood basalt eruptions.

Cretaceous-Tertiary Extinction

A mass extinction event (~$66\text{ million years ago}$) caused by an asteroid impact in Chicxulub, Mexico, eliminating non-avian dinosaurs and ~$75\text{\%}$ of species.

Radiometric Dating

A geological dating method that determines absolute age based on measuring known radioactive decay half-lives ($t_{1/2}$) of unstable isotopes in igneous rock strata.

Molecular Clock

An evolutionary tool that uses accumulated neutral genetic mutations in DNA or protein sequences to estimate the absolute chronological timing of divergence events between lineages.

Observation

Gathering data or noting phenomena using sensory observation or instruments.

Generate Hypothesis

Constructing a tentative, testable, and falsifiable explanation for the observed phenomenon.

Make Predictions

Making specific logical predictions based on the assumption that the hypothesis is correct.

Test Predictions

Execute rigorous controlled experiments or observational studies to collect data.

Revise or Refine

Analyze the results to determine if the hypothesis was supported; systematically revise hypothesis, predictions, or experimental designs as necessary.