Ecosystems and Biogeochemical Cycles - Practice Flashcards

A comprehensive set of Q&A style flashcards covering ecosystem concepts, biomes, aquatic systems, and major biogeochemical cycles based on the lecture notes.

What is an ecosystem?

All living and nonliving things in an area and their interactions within a system.

What is a biome?

The plants and animals found in a region, determined by climate (annual temperature and precipitation).

Define Population.

A group of individuals of the same species living in a particular area (e.g., an elk herd).

Define Community.

All living organisms in a given area.

Define Ecosystem.

All living and nonliving things in an area (air, water, soil, rocks, etc.) and their interactions.

Define Biome in terms of climate.

A region’s plant and animal communities determined by climate (temperature and precipitation).

What is resource partitioning?

Using resources in different ways, places, or times to reduce competition.

Name the types of symbiosis.

Mutualism, commensalism, and parasitism.

What is mutualism?

A close interaction between species where both benefit.

What is commensalism?

A relationship in which one species benefits and the other is not affected.

What is parasitism?

A relationship where one benefits at the expense of the other, often without killing the host.

What is predation?

An interaction where a predator eats prey for energy.

What is competition in ecosystems?

Fighting for limited resources, which can limit population size unless resources are partitioned.

What is temporal partitioning?

Using resources at different times to reduce competition.

What is spatial partitioning?

Using different areas of a habitat to reduce competition.

What is morphological partitioning?

Using different resources based on evolved body features.

Define mutualism in a sentence.

Mutualism is a symbiotic relationship in which both species benefit.

What is a lichen?

A composite organism of fungi and algae living together, where algae provide sugars and fungi provide nutrients.

Give an example of coral-algae mutualism.

Coral provides housing and CO2 to algae; algae provide sugars to coral.

What is a mangrove ecosystem known for?

Tropical/coastal forests with specialized root systems; protects coastlines and serves as a fish nursery; threatened by shrimp farming and sea-level rise.

What is an estuary?

Area where rivers mix with seawater; highly productive with nutrient-rich sediments.

What role do mangrove roots play?

Stand partly above water to facilitate oxygen uptake and provide habitat for many species.

Describe coral reef mutualism.

Coral and algae exchange energy and CO2; both rely on each other for survival.

What are intertidal zones?

Coastline area between high and low tide where organisms must withstand waves and desiccation.

What is open ocean characterized by?

Low productivity over vast areas; photic zone supports photosynthesis; aphotic zone is deep and dark.

What defines the nutrient dynamics in tropical rainforests vs. boreal forests?

Both have nutrient-poor soils; decomposition rates and temperature influence nutrient availability.

What factors define terrestrial biomes?

Annual average temperature and precipitation (climate) determine biome distribution.

Why do biomes shift with climate change?

Global climate changes alter temperature and precipitation patterns, shifting biome boundaries.

What are the main freshwater biomes?

Rivers, lakes, wetlands, streams; rivers have high oxygen and carry nutrients; lakes store fresh water.

What are estuaries known for?

High nutrient input from rivers creating high productivity and diverse life.

What is the mangrove ecosystem’s ecological importance?

Coastal protection, shoreline stabilization, nursery habitat for many species, high biodiversity.

What is a coral reef’s key mutualism?

Coral and algae exchange energy and CO2; both depend on the other for survival.

What defines an intertidal zone’s adaptations?

Organisms must withstand waves and exposure to sunlight and air during low tide.

What are pelagic vs benthic zones in oceans?

Pelagic refers to open water; benthic refers to the ocean floor with nutrient-rich sediments.

What is photosynthesis’ role in the carbon cycle?

Plants convert CO2 and water into glucose and oxygen, acting as a carbon sink.

What is respiration’s role in the carbon cycle?

Living organisms use glucose and oxygen to release energy, emitting CO2 back to the atmosphere.

What is a carbon sink?

A reservoir that absorbs more carbon than it releases (e.g., oceans, plants, soil).

What is a carbon source?

A reservoir that releases more carbon than it absorbs (e.g., fossil fuels, deforestation).

Explain direct exchange in the carbon cycle.

CO2 moves between atmosphere and ocean by dissolving in surface water and out, influencing ocean acidity.

What is burial in the carbon cycle?

Long-term storage of carbon in sediments or fossil fuels; releases take place during extraction and combustion.

What is nitrogen fixation?

Process converting atmospheric N2 into ammonia (NH3) or nitrates usable by plants; done by bacteria or synthetic fixation.

What is the atmosphere’s role in the nitrogen cycle?

Atmosphere is the major reservoir of nitrogen (N2 gas), largely unusable by plants without fixation.

Name a key nitrogen cycle process.

Nitrification: NH4+ to NO2- to NO3- by soil bacteria; Ammonification: decomposers release NH3; Denitrification: NO3- to N2O/N2 gas.

What is eutrophication?

Excess nutrients (N and P) cause algal blooms, killing aquatic life by reducing oxygen through decomposition.

Why is phosphorus considered a limiting nutrient?

There is no atmospheric component; weathering of rocks releases phosphate slowly, so availability often limits growth.

What are major phosphorus sources?

Weathering of phosphate minerals; synthetic fertilizers; detergents; animal/plant waste runoff.

What is the hydrologic cycle’s primary driver?

Solar energy drives evaporation, condensation, precipitation, runoff, and groundwater processes.

What are the two main water cycle processes that move water from land back to the atmosphere?

Evaporation and evapotranspiration (transpiration plus evaporation from surfaces).

Define net primary productivity (NPP).

NPP = GPP minus plant respiration; the amount of energy stored as biomass available to consumers.

What does the 10% rule state?

On average, only about 10% of the energy at one trophic level is transferred to the next level; the rest is lost as heat or used for metabolism.

What is a food web?

An interlocking network of two or more food chains showing energy and nutrient flow through an ecosystem.

What is a trophic cascade?

A top-down effect where changes in a predator population ripple through lower trophic levels, altering ecosystem structure.

How do energy and matter flow differ in an ecosystem?

Energy flows through the system (one-way, decreasing at higher levels); matter cycles within the system through biogeochemical cycles.