Unit 3 and Unit 4 Biology Vocabulary

Vocabulary practice flashcards generated from Biology Unit 3 and Unit 4 notes, covering ecology, genetics, and evolutionary processes.

Biodiversity

The total diversity of living systems, encompassing genetic diversity, species diversity, and ecosystem diversity.

Species Diversity

The number of species (species richness) and their relative proportions (species evenness) within a community.

Genetic Diversity

The range of genetic material present in a population of a species.

Ecosystem Diversity

The range of different habitats in an ecosystem or biome.

Biological Species Concept

A biological definition defining a species as a group of similar organisms whose members can interbreed with each other in their natural environments to produce living (viable) and fertile offspring.

Linnaean Classification System

A hierarchical rank-based structure for classifying organisms that uses binomial nomenclature (Genus species) and morphological features.

Lincoln Index

A method used to estimate population size using mark-recapture data, given by the formula $N = \frac{M \times n}{m}$, where $M$ is the number of individuals initially caught and marked, $n$ is the total caught in the second sampling, and $m$ is the number of recaptured marked individuals.

Species Richness

The total number of different species present in an ecosystem or sample.

Menhinick Index

A mathematical measure of species richness calculated as $S = \frac{s}{\sqrt{N}}$, where $s$ is the total number of different species in the sample and $N$ is the total number of individual organisms.

Species Evenness

The relative abundance of each different species in a given area.

Simpson's Diversity Index

A measure of diversity taking into account species richness and relative abundance, calculated using the formula $SDI = 1 - \frac{\sum n(n - 1)}{N(N - 1)}$.

Random Sampling

A sampling method in which every member of a population has an equal chance of being selected, typically using a random number generator.

Systematic Sampling

A sampling method where samples are taken at uniform, predetermined intervals throughout an area.

Stratified Sampling

A sampling method where distinct areas or sub-habitats within an overall habitat are identified and sampled separately.

Ecological Niche

The role and space that an organism fills in an ecosystem, including all of its interactions with the biotic and abiotic factors of its environment.

Competitive Exclusion Principle

The principle stating that two species competing for the exact same limited resource cannot stably coexist.

Keystone Species

A plant or animal species that plays a unique and crucial role in maintaining the structure and function of an ecological community.

Carrying Capacity ($K$)

The maximum population size of a species that can be supported indefinitely by the available resources and services of an ecosystem.

r-Strategists

Species characterized by short life spans, rapid growth rates, early maturity, production of many offspring, and minimal parental care.

K-Strategists

Species characterized by long life spans, slower growth, late maturity, production of few large offspring, and high parental care.

Gross Primary Production (GPP)

The total rate at which solar energy is converted into organic photosynthetic products by primary producers.

Net Primary Production (NPP)

The rate at which energy is stored as biomass by primary producers, calculated as Gross Primary Production minus respiration ($NPP = GPP - \text{Respiration}$).

Ecological Succession

The process of change in the structure and species composition of an ecological community over time.

Pioneer Species

Effective colonizer species that initiate succession, characterized by ability to fix nitrogen, tolerance to extreme conditions, rapid seed germination, and efficient photosynthesis.

Primary Succession

Succession that occurs in an environment devoid of pre-existing vegetation and lacking organic soil.

Secondary Succession

Succession that occurs in an area where an existing community has been disrupted or destroyed by a disturbance, but the soil remains intact.

Conserved Sequences

Sections of DNA involved in key survival roles that have changed very little over millions of years due to natural selection.

Nondisjunction

An error in meiosis I or meiosis II where a pair of homologous chromosomes or sister chromatids fails to separate properly.

Aneuploidy

The presence of an abnormal number of chromosomes within all cells of an individual.

Heterochromatin

Tightly packed, condensed chromatin structure associated with reduced gene expression (genes switched off).

Euchromatin

Loosely packed chromatin structure that permits active gene expression and transcription (genes switched on).

HOX Genes

A family of master regulator transcription factor genes that control morphology and anatomical development along the body axis.

Microevolution

Small-scale variation of allele frequencies within a species or population, where descendants remain in the same taxonomic group.

Macroevolution

Large-scale variation of allele frequencies at or above the species level over geological time, resulting in the divergence of distinct taxonomic groups.

Gene Flow

The movement and exchange of alleles or gametes between different populations of a species.

Genetic Drift

Evolutionary change in allele frequencies caused by random chance events, which can significantly alter small populations.

Stabilising Selection

Phenotypic selection that favors average individuals and selects against extreme variations, narrowing the population curve.

Directional Selection

Phenotypic selection that favors one particular extreme phenotype over others, shifting the curve toward the favorable trait.

Disruptive Selection

Phenotypic selection that selects against intermediate phenotypes and favors individuals at both extreme ends of a spectrum.

Allopatric Speciation

Speciation that occurs when populations become isolated by an extrinsic physical geographic barrier during divergence.

Sympatric Speciation

Speciation occurring within populations in the same geographic location without any extrinsic physical barriers.

Parapatric Speciation

Speciation occurring in adjacent, continuously distributed populations where divergence occurs across a partial extrinsic barrier.

Coevolution

Simultaneous reciprocal phenotypic changes occurring between ecologically interacting community members as each exerts strong selection pressures on the other.