Evolution, Plant Biology, and Ecology – Vocabulary Review

A comprehensive set of vocabulary flashcards covering evolution, genetics, fungi, plant biology, ecology, and biogeochemical cycles from Weeks 4-7 lecture notes.

Population

A group of individuals of the same species living in the same area.

Evolution

A change in allele frequencies in a population over generations.

Allele

A variant form of a gene.

Gene Pool

All alleles present in a population.

Natural Selection

Evolutionary mechanism in which individuals with advantageous traits leave more offspring.

Genetic Drift

Random change in allele frequencies, strongest in small populations.

Gene Flow

Movement of alleles into or out of a population via migration.

Mutation

Random change in DNA that introduces genetic variation.

Adaptation

A heritable trait that increases fitness in a given environment.

Directional Selection

Natural selection favoring one extreme phenotype.

Stabilizing Selection

Selection that favors intermediate phenotypes.

Disruptive Selection

Selection favoring both extreme phenotypes over intermediates.

Hardy-Weinberg Equilibrium

Model in which allele frequencies remain constant; no evolution occurs.

Bottleneck Effect

Genetic drift caused by a drastic reduction in population size.

Founder Effect

Genetic drift when a new population is started by a few individuals.

Pleiotropy

A single gene influences multiple traits.

Polygeny

Multiple genes collectively affect one trait.

Endosymbiotic Theory

Hypothesis that mitochondria and chloroplasts originated from engulfed prokaryotes.

Phenology

Study of the timing of biological events in relation to climate.

Opisthokonts

Eukaryotic supergroup including fungi and animals.

Archaeplastida

Eukaryotic supergroup that includes red algae, green algae, and land plants.

Hyphae

Thread-like fungal filaments.

Mycelium

Interwoven mass of hyphae forming the fungal body.

Mushroom

Fruiting body of a fungus that produces spores.

Dikaryotic

Fungal stage with two genetically distinct nuclei per cell.

Ascomycota

Fungal phylum producing spores in sacs called asci.

Basidiomycota

Fungal phylum producing spores on club-shaped basidia.

Deuteromycota

“Imperfect fungi” lacking a known sexual stage.

Chytridiomycota

Basal fungal group with flagellated spores and alternation of generations.

Lichen

Symbiosis between a fungus and a photosynthetic partner (alga or cyanobacterium).

Mycorrhiza

Mutualism between plant roots and fungi; enhances nutrient uptake.

Ectomycorrhizae

Mycorrhizae with fungal hyphae outside root cells.

Arbuscular Mycorrhizae

Mycorrhizae with hyphae penetrating root cortical cells.

Taxonomy

Science of classifying organisms.

Systematics

Study of evolutionary relationships among organisms.

Cladogram

Diagram showing evolutionary relationships based on shared traits.

Phylogenetic Tree

Hypothesis of evolutionary relationships with branch lengths indicating change.

Homology

Similarity due to shared ancestry; useful for phylogenies.

Analogy

Similarity due to convergent evolution, not common ancestry.

Monophyletic Group

Set containing an ancestor and all its descendants.

Paraphyletic Group

Group containing an ancestor but not all descendants.

Polyphyletic Group

Group lacking the common ancestor of included taxa.

Alternation of Generations

Life cycle alternating between multicellular diploid sporophyte and haploid gametophyte.

Sporophyte

Diploid generation that produces spores by meiosis.

Gametophyte

Haploid generation that produces gametes by mitosis.

Spore

Haploid cell that can develop into a gametophyte without fertilization.

Gamete

Haploid sex cell (egg or sperm).

Mitosis

Cell division yielding two identical diploid daughter cells.

Meiosis

Cell division producing four genetically unique haploid cells.

Pollen

Male gametophyte of seed plants enabling fertilization without water.

Seed

Plant embryo with food supply and protective coat.

Fruit

Mature ovary that protects seeds and aids dispersal.

ABC Model

Genetic model explaining floral organ identity using A, B, and C genes.

Monocot

Angiosperm with one cotyledon, parallel veins, and scattered vascular bundles.

Dicot (Eudicot)

Angiosperm with two cotyledons and net-like leaf venation.

Auxin

Plant hormone promoting cell elongation and apical dominance.

Cytokinin

Plant hormone stimulating cell division and shoot formation.

Abscisic Acid (ABA)

Plant hormone inducing dormancy and stomatal closure.

Dormancy

Period of suspended growth and metabolism in seeds or buds.

Chromosome

DNA molecule with associated proteins; carries genetic information.

Haploid

Having one set of chromosomes (n).

Diploid

Having two sets of chromosomes (2n).

Fitness

Relative reproductive success of a genotype or phenotype.

Exponential Growth

Rapid population increase without limiting factors (J-shaped curve).

Logistic Growth

Population growth that slows near carrying capacity (S-shaped curve).

Carrying Capacity (K)

Maximum population size an environment can sustain.

Density-Dependent Factor

Limiting factor whose impact increases with population size.

Density-Independent Factor

Limiting factor acting regardless of population density (e.g., weather).

Keystone Species

Species with disproportionate effect on community structure.

Resource Partitioning

Division of resources to reduce competition among species.

Ecological Niche

Sum of a species’ use of resources and role in its environment.

Trophic Cascade

Indirect effects on lower trophic levels when predators change in abundance.

Semelparous

Reproducing once before death.

Iteroparous

Reproducing multiple times over a lifetime.

Species Richness

Number of species in a community.

Species Evenness

Relative abundance of each species in a community.

Shannon Index

Composite measure of biodiversity incorporating richness and evenness.

Biotic Factor

Living component of an environment (e.g., predation).

Abiotic Factor

Non-living environmental component (e.g., temperature).

Biogeochemical Cycle

Movement of elements through living organisms and the physical environment.

Reservoir

Storage compartment for a chemical in a cycle.

Flux

Rate at which material moves between reservoirs.

Eutrophication

Nutrient enrichment causing algal blooms and oxygen depletion in water.

Trophic Pyramid

Graphic showing energy or biomass loss across trophic levels.

Primary Producer

Organism that synthesizes organic molecules from inorganic sources.

Hadley Cell

Atmospheric circulation cell near the equator influencing rainfall patterns.

Biome

Large ecological region defined by climate and dominant vegetation.

Rainshadow Effect

Dry conditions on leeward side of mountains due to prevailing winds.

Milankovitch Cycles

Periodic changes in Earth’s orbit and tilt affecting climate.

Nitrogen Fixation

Conversion of atmospheric N₂ into biologically usable forms by bacteria.

Heterospory

Production of two sizes of spores (micro- and megaspores).

Antithetic Theory

Hypothesis explaining origin of alternation of generations in plants.

Bryophyte

Non-vascular plant group including mosses, liverworts, and hornworts.

Seedless Vascular Plant

Plant with vascular tissue but no seeds (e.g., ferns).

Gymnosperm

Seed plant with naked seeds, usually in cones.

Angiosperm

Flowering plant producing seeds within fruits.

Cone

Reproductive structure of gymnosperms bearing seeds or pollen.

Sepal

Outermost floral organ, typically green and protective.

Petal

Colorful floral organ attracting pollinators.

Radial Symmetry

Floral design with multiple planes of symmetry.