Biology Term Exam Review: Experimental Design, Classification, Ecology, and Evolution

Comprehensive vocabulary flashcards covering the core concepts of experimental design, Linnaean taxonomy, ecological population dynamics, biogeochemical cycles, and evolutionary mechanisms.

Hypothesis

A proposed explanation for a narrow set of natural phenomena based on prior experience, background knowledge, and preliminary observations that can be tested.

The variable that is intentionally changed by the investigator in an experiment; also known as the independent variable.

Manipulated Variable

The variable that changes and is measured in response to the manipulated variable; also known as the dependent variable.

Responding Variable

The experimental group that is not changed, kept under baseline conditions for comparison purposes.

Control Group

The group in an experiment that receives the manipulated variable being tested so the resulting response can be measured.

Experimental Group

Conditions and factors that are kept identical across all groups in an experiment to prevent them from confounding the results.

Constant Variables

A broad, inferred explanation for natural phenomena that has been tested repeatedly, is strongly supported by evidence, and can be used to make predictions.

Theory

An experimental setup containing a manipulated variable, responding variable, constant variables, a control group, and experimental groups designed to limit human and experimental error.

Controlled Experiment

A hierarchical system for naming and classifying organisms, and the biological discipline that studies evolutionary and physical relatedness among organisms.

Taxonomy

A ranking level or classification group into which organisms are organized in Linnaeus' hierarchical system.

Taxon (Taxa)

A two-part naming system developed by Linnaeus consisting of the capitalized genus and the lowercase species, typically written in Latin and italicized.

Binomial Nomenclature

A taxonomic group consisting of closely related species; the first capitalized word in an organism's scientific binomial name.

Genus

A group of similar organisms capable of interbreeding and producing viable, fertile offspring that can also interbreed.

Species

An organism from which two or more different lineages or species historically descended and are related to.

Common Ancestor

A novel trait or characteristic that arises in an ancestral lineage and separates different groups of organisms on a phylogenetic tree.

Derived Character

A branching diagram illustrating evolutionary relationships and relatedness among different biological species or taxa based on shared traits.

Phylogenetic Tree

The organism or taxon that branches off earliest on a phylogenetic tree and is least closely related to the remaining organisms.

Outgroup

A single-celled organism that lacks a nucleus and membrane-bound organelles, characterized by a single, circular chromosome.

Prokaryote

A cell type possessing a membrane-enclosed nucleus, membrane-bound organelles, and multiple linear chromosomes.

Eukaryote

An organism capable of synthesizing its own organic energy molecules from inorganic substances.

Autotroph

A type of autotroph that converts light energy from the sun into chemical energy.

Photoautotroph

A type of autotroph that converts one kind of chemical energy into another to produce its own food.

Chemoautotroph

An organism that cannot synthesize its own energy and must obtain organic nutrients by consuming other organisms.

Heterotroph

A heterotroph that ingests or eats other organisms internally to obtain organic energy.

Ingestive Heterotroph

A heterotroph that secretes specialized chemicals to digest organic nutrients externally before absorbing them.

Absorptive Heterotroph

A measure of the fraction of solar radiation an object reflects on a scale from $0$ to $1$; lower reflectivity leads to increased absorption and higher temperatures.

Albedo Effect

A natural or artificial reservoir that absorbs and stores carbon-containing compounds over an extended period.

Carbon Sink

The maximum population size of a species that a specific environment can sustainably support.

Carrying Capacity

The total number of individuals of a single species living per unit of surface area or volume.

Population Density

A spatial dispersion pattern where individuals aggregate in social clusters, colonies, swarms, or around patchy resource pockets.

Clumped Distribution

A spatial dispersion pattern where individuals maintain regular, even spacing from one another due to territorial behavior or resource competition.

Uniform Distribution

A dispersion pattern where individuals show no predictable spatial pattern due to minimal social interaction or competitive pressure.

Random Distribution

An environmental limiting factor whose impact on population growth intensifies as population density increases (e.g., competition, predation, disease).

Density-Dependent Limiting Factor

An environmental limiting factor that affects a population identically regardless of its density (e.g., severe weather events, wildfires, volcanic eruptions).

Density-Independent Limiting Factor

Population growth that increases at a constant per capita rate over time, producing a J-shaped curve under ideal conditions.

Exponential Growth

Population growth that accelerates rapidly, slows as resources become limited, and eventually stabilizes at the carrying capacity.

Logistic Growth

The natural process where solar radiation penetrates Earth's atmosphere and is absorbed and reradiated in all directions by atmospheric gases, increasing planetary temperatures.

Greenhouse Effect

Atmospheric gases, such as carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons, that absorb infrared radiation and trap thermal energy.

Greenhouse Gases

A close, long-term biological interaction between individuals of two distinct species.

Symbiosis

The geographic boundaries and area in which a specific species naturally occurs, typically depicted on a map.

Range

The fundamental functional physical unit of heredity composed of DNA that controls a specific inherited trait.

Gene

One of two or more alternative versions or forms of a gene that occupy the same locus on a chromosome.

Allele

An observable physical or behavioral characteristic of an organism.

Trait

An inherited feature or trait that becomes prevalent in a population because it confers improved function or survival advantage.

Adaptation

The change in the allele or trait frequencies within a biological population across successive generations.

Evolution

The mechanism whereby individuals possessing advantageous inherited traits survive, reproduce at higher rates, and transmit those traits to offspring.

Natural Selection

The aggregate collection of all alleles present in all individuals comprising a specific population.

Gene Pool

A random shift in allele frequencies within a population resulting from chance occurrences or catastrophic natural disasters.

Genetic Drift

A sudden, drastic reduction in the genetic diversity and allele frequencies of a population following a severe decline in population size.

Bottleneck Effect

A change in allele frequencies that occurs when a small subgroup separates from a larger population to establish a new colony.

Founders Effect

An external factor in an environment that influences survival, causing individuals with specific traits to experience greater reproductive success.

Environmental Selective Pressure

The reproductive success of an organism, measured as its ability to survive, reproduce, and contribute viable offspring to the subsequent generation.

Fitness

A theoretical model describing a non-evolving population in which allele frequencies remain constant when five conditions are satisfied: very large population, no mutations, random mating, no migration, and no natural selection.

Hardy-Weinberg Equilibrium

A biological state in which the allele and genotype frequencies of a population remain stable and unchanged over generations.

Genetic Equilibrium

A heterotrophic organism that feeds exclusively or primarily on animal tissue (meat).

Carnivore

A heterotrophic organism that feeds exclusively or primarily on producers or plant matter.

Herbivore

A heterotrophic consumer whose diet routinely incorporates both plant material and animal meat.

Omnivore

A heterotrophic organism that obtains nutrients by consuming decomposing organic matter and dead remains.

Detritivore