General Biology II Study Guide Vocabulary

Vocabulary practice flashcards generated from General Biology II Exam 1 and Exam 2 study guides covering Chapters 22 through 30.

Evolution

The process of change over time that has transformed life on Earth, supported by evidence such as fossils, strata, direct observation, homology, and biogeography.

Strata

Superimposed layers of rock formed from sedimentary deposits, in which fossils document the history of life over geological time.

Lamarck's Hypothesis

An early evolutionary hypothesis proposing that species evolve through the use and disuse of body parts and the inheritance of acquired characteristics.

Natural Selection

A primary mechanism of evolution in which individuals with certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Artificial Selection

The selective breeding of domesticated plants and animals by humans to encourage the occurrence of desirable traits.

Adaptation

Inherited characteristics of organisms that enhance their survival and reproduction in specific environments.

Homology

Similarity in characteristics resulting from shared ancestry.

Biogeography

The scientific study of the geographic distributions of species.

Genetic Variation

Differences among individuals in the composition of their genes or other DNA segment sequences.

Gene Pool

The aggregate of all copies of every type of allele at all loci in all individuals in a population.

Hardy-Weinberg Equilibrium

 The state of a population in which frequencies of alleles and genotypes remain constant from generation to generation, calculated using $p^2 + 2pq + q^2 = 1$.

Genetic Drift

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.

Gene Flow

The transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.

Directional Selection

Natural selection that favors individuals at one extreme of the phenotypic range.

Disruptive Selection

Natural selection that favors individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes.

Stabilizing Selection

Natural selection that favors intermediate variants by acting against extreme phenotypes.

Speciation

The evolutionary process by which one species splits into two or more species.

Biological Species

A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

Reproductive Isolation

The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring; includes habitat, behavioral, mechanical, and gametic isolation.

Allopatric Speciation

The formation of new species in populations that are geographically isolated from one another.

Sympatric Speciation

The formation of new species in populations that live in the same geographic area, affected by polyploidy, sexual selection, and habitat differentiation.

Hybrid Zone

A geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry, leading to reinforcement of barriers, fusion of species, or stability over time.

Hydrothermal Vents

Areas on the seafloor where heated water and minerals gush from Earth's interior into the ocean, hypothesized as a potential site for the origin of life.

Alkaline Vents

Deep-sea vents that release warm water with a high pH (alkaline) and suitable chemical environments hypothesized to have facilitated the origin of life.

Protocells

Abiotic fluid-filled membrane-bound vesicles that represent a key step in the origin of life by maintaining an internal chemistry distinct from their surroundings.

Oxygen Revolution

The historical period during which photosynthetic prokaryotes caused atmospheric oxygen levels to increase dramatically on early Earth.

Continental Drift

The slow movement of the Earth's continents over tectonic plates through geological time.

Phylogeny

The evolutionary history of a species or group of related species.

Linnaean Classification System

A taxonomic hierarchy used to classify organisms into nested groups: Domain, kingdom, phylum, class, order, family, genus, and species.

Analogy

Similarity between two species that is due to convergent evolution rather than to shared ancestry.

Monophyletic Group

A group of taxa, also called a clade, that consists of an ancestral species and all of its descendants.

Paraphyletic Group

A group of taxa that consists of an ancestral species and some, but not all, of its descendants.

Polyphyletic Group

A group of taxa that includes distantly related organisms but does not include their most recent common ancestor.

Molecular Clock

A method for estimating the time required for evolutionary change based on the observation that some regions of genomes evolve at constant rates.

Gram-positive Bacteria

Bacteria that have simpler cell walls with a relatively large amount of peptidoglycan.

Gram-negative Bacteria

Bacteria that have cell walls with less peptidoglycan and an outer membrane that can contain lipopolysaccharides.

Chemotaxis

The movement of an organism toward or away from a chemical stimulus.

Transformation

A mechanism of horizontal gene transfer in bacteria in which foreign DNA is taken up from its surrounding environment.

Transduction

A process of genetic recombination in which phages (viruses) carry bacterial DNA from one host cell to another.

Conjugation

The direct transfer of DNA between two bacterial cells that are temporarily joined via plasmids or pili.

Nitrogen Fixation

The metabolic process carried out by certain prokaryotes that converts atmospheric nitrogen ($\text{N}_2$) into ammonia ($\text{NH}_3$).

Mixotrophs

Organisms (such as certain protists) capable of combining photosynthesis and heterotrophic nutrition.

Excavata

A protist supergroup characterized by morphological features such as modified mitochondria and unique flagella; includes clades like Giardia Intestinalis, Trichomonas Vaginalis, and Euglenids.

SAR

A highly diverse protist supergroup defined by DNA similarities, including representative clades such as Diatoms, Brown Algae, Dinoflafellate (which cause Red Tide), and Amoebas.

Archaeplastida

A protist supergroup consisting of red algae and green algae, which are the closest relatives of land plants.

Unikonta

A protist supergroup closely related to fungi and animals, featuring representative clades such as Entamoebas (e.g., Entamoeba histolytica).

Alternation of Generations

A plant life cycle in which both multicellular haploid (gametophyte) and multicellular diploid (sporophyte) generations alternate.

Gametophyte

The multicellular haploid stage in a plant life cycle that produces haploid gametes by mitosis.

Sporophyte

The multicellular diploid stage in a plant life cycle that produces haploid spores by meiosis.

Apical Meristems

Localized regions of cell division at the tips of roots and shoots that allow plants to grow in length.

Bryophytes

Nonvascular plants, including liverworts, mosses, and hornworts, whose life cycles are dominated by gametophytes.

Lycophytes

A clade of seedless vascular plants that includes club mosses, spikemosses, and quillworts.

Monilophytes

A clade of seedless vascular plants that includes ferns, horsetails, and whisk ferns.

Megasporangia

Structures in heterosporous seed plants that produce megaspores, which give rise to female gametophytes.

Microspores

Spores in heterosporous seed plants that develop into male gametophytes (pollen grains).

Pollination

The transfer of pollen to the part of a seed plant containing the ovules.

Gymnosperms

Seed plants whose seeds are not enclosed in chambers ("naked seeds"), comprising four phyla: Cycadophyta, Ginkgophyta, Gnetophyta, and Coniferophyta.

Angiosperms

Flowering seed plants with reproductive adaptations including flowers and fruits, divided into groups such as monocots, dicots, eudicots, and magnoliids.

Floral Organs

The four modified leaves of an angiosperm flower: sepals, petals, stamens (filament and anther), and carpels (stigma, style, and ovary).