Ecology and Life Sciences Comprehensive Course Review

Practice vocabulary flashcards covering biogeochemical nutrient cycles, scientific theory and experimental design, ecosystem energetics, and community biodiversity dynamics.

Essential Plant Nutrients

The mineral elements required by plants for healthy growth, categorized into primary nutrients ($N$, $P$, $K$), secondary nutrients ($Ca$, $Mg$, $S$), and micronutrients ($Fe$, $Mn$, $Zn$, $Cu$, $Mo$, $B$, $Cl$), alongside carbon and water.

Global Carbon Cycle

The biogeochemical cycle detailing carbon movement and storage across reservoirs, including the atmosphere ($800$), soil carbon ($2{,}300$), fossil carbon ($10{,}000$), deep ocean ($37{,}000$), plant biomass ($550$), and annual human emissions ($9$).

Phosphorus Cycle

A mineral biogeochemical cycle where phosphate ($PO_4$) is released through rock weathering, taken up by plants, leached into aquatic reserves and sediments, and recycled by geological uplift, lacking any significant gaseous atmospheric reservoir.

Nitrogen Fixation

The conversion of atmospheric dinitrogen ($N_2$) into ammonia ($NH_3$) through free-living or symbiotic nitrogen-fixing bacteria (associated with legumes), lightning, or industrial processes.

Nitrification

The two-step biological oxidation of ammonia ($NH_3$) into nitrite ($NO_2$) and subsequently into nitrate ($NO_3$).

Assimilation (Nitrogen Cycle)

The uptake of dissolved nitrate ($NO_3$) through plant roots and its incorporation into essential biological molecules such as proteins, DNA, and RNA.

Ammonification

The process by which decomposers convert biological forms of nitrogen contained in organic waste and dead tissues back into ammonia ($NH_3$).

Denitrification

The microbial reduction of nitrate ($NO_3$), and to a lesser extent other nitrogen forms, back into inert gaseous dinitrogen ($N_2$).

Leaching

The physical process where dissolved nutrients are transported out of an ecosystem by percolating groundwater or surface runoff.

Ecology

The study of relationships between living organisms, including humans, and their physical environment, seeking to understand connections between plants, animals, and the world around them.

Pollination

The mechanical transfer of pollen for plant reproduction, mediated by abiotic forces or biotic strategies such as animal pollinators.

Null Hypothesis

The foundational scientific assumption stating that no significant relationship or effect exists between the investigated variables, which scientists always assume at the outset of research.

Independent Variable

The variable manipulated or systematically altered by an experimenter to determine its effect on a measured outcome.

Dependent Variable

The variable observed and measured in an experiment that responds to changes in the independent variable.

Random Error

Unintentional mistakes made by investigators during research, such as measurement inaccuracies, species misidentifications, or data entry errors, which cannot be fixed by redesigning the experiment.

Bias (Systematic Error)

A systematic inaccuracy where an experiment fails to fully explain variable relationships, often caused by unmeasured confounding variables, that can be corrected by modifying the experimental design.

Continuous Variable

A quantitative variable that can take on an infinite continuum of values along an unbroken numerical measurement scale.

Discrete Variable

A numeric variable that can only assume distinct, separate, countable values.

Ordinal Variable

A categorical variable whose values exhibit a natural ranking, relative progression, or orderly sequence.

Nominal Variable

A categorical variable consisting of named groups or categories that possess no inherent ranking or order.

First Law of Thermodynamics (Ecological Version)

The fundamental principle stating that energy cannot be created nor destroyed, meaning all energy must be fully accounted for on both sides of any ecological transformation.

Second Law of Thermodynamics (Ecological Version)

The principle stating that no energy transformation is $100\%$ efficient, meaning disorder in a closed system increases unless an external source of energy is added.

Energy Flow Through an Ecosystem

The one-way transfer of energy starting with solar energy captured by autotrophic producers and passing upward to primary consumers, secondary consumers, and decomposers.

Trophic Level 1 (Producer)

The base ecological energy tier consisting of autotrophs whose feeding pattern relies on green plants fixing energy via photosynthesis.

Consumer Trophic Levels

The successive tiers of heterotrophs, categorized into level $2$ primary consumers (herbivores), level $3$ secondary consumers (carnivores), and level $4$ third level consumers (carnivores).

Apex Predator

A top-level consumer in a community or food web that is not preyed upon or consumed by any other species.

Bioaccumulation

The sequential increase and concentration of non-metabolized substances or contaminants in organisms across higher trophic levels of a food web.

10% Rule

The energetic principle stating that only roughly $10\%$ of energy is passed to the next trophic level, driven by metabolic costs of foraging, uneaten tissues, and unassimilated waste.

Gross Primary Productivity (GPP)

The total mass of carbon fixed or overall organic biomass generated by autotrophs through photosynthesis within a given ecosystem.

Net Primary Productivity (NPP)

The total mass of carbon (biomass) fixed through photosynthesis minus the carbon released or utilized by autotrophs during respiration.

Inverted Pyramid of Biomass

An aquatic biomass pattern where steady-state phytoplankton biomass is small due to intense grazing by zooplankton, yet supports large consumer populations due to an extremely high turnover and reproduction rate.

Diversity

The total count of species inhabiting a defined geographic area, taking into account the relative balance of species abundances and variations across time and space.

Taxonomic Species Diversity

The proportional distribution of documented life on Earth, where insects represent the majority of all cataloged species, vastly outnumbering non-insect animals, plants, fungi, protists, and monerans.

Alpha-diversity (Simple Diversity)

The species richness within a single site or localized habitat patch, measured as the number of distinct populations in a community (e.g., mammals of the Lake Romeyn Woodlands).

Gamma-diversity

The total regional species richness spanning multiple ecosystems across a broad landscape network (e.g., mammals of Massachusetts).

Shannon-Wiener Diversity

A diversity measurement index that balances simple species richness with the equitability and evenness of individual distributions among species.

Species-Area Curve

A graphical and mathematical relationship demonstrating how detected species richness increases with surveyed land area, used to calculate projected diversity.

Island Biogeography

The theory stating that island species richness balances colonization and extinction rates, where extinction depends on land area and colonization depends on isolation from the mainland.

Metapopulation

A regional network of spatially separated subpopulations occupying habitat patches without a central mainland, persisting through dispersal and recolonization among connected patches.

Keystone Species

A species that exerts a disproportionately powerful structuring influence on community diversity and ecosystem stability relative to its actual numerical abundance or biomass.

Trophic Cascade

The widespread restructuring of community composition and reduction in biodiversity that propagates down through lower trophic levels following the loss of apex predators.

Green World Hypothesis

The concept that predators exert top-down control on herbivore populations, keeping them low enough to prevent the overgrazing and destruction of terrestrial plant biomass.

Top-Down Control

The regulation of ecosystem structure and productivity primarily driven by higher-level predators limiting the abundance of intermediate consumers and primary producers.

Bottom-Up Control

The limitation of ecosystem community structure and trophic biomass primarily by abiotic resources, soil fertility, climate, and primary producer productivity.