The Living World – Ecosystems

These flashcards cover key concepts of ecosystems, including species interactions, biomes, nutrient cycles, energy flow, productivity, and experimental design.

What is a predator-prey relationship?

A relationship where a predator hunts, kills, and eats a prey organism.

What does a predator-prey population graph look like?

A cyclical graph where prey population increases first, followed by predator population; predator increases cause prey to decrease, then predator declines.

What is symbiosis?

A close and long-term interaction between two different species.

What is mutualism?

A symbiotic relationship where both species benefit.

What is commensalism?

A symbiotic relationship where one species benefits and the other is unaffected.

What is parasitism?

A symbiotic relationship where one species benefits and the other is harmed.

What is competition?

When organisms compete for limited resources such as food, water, space, or mates.

What is an organism’s niche?

The role an organism plays in its ecosystem, including how it uses resources and interacts with other species.

What is resource partitioning?

When species divide resources by using them in different ways, places, or times to reduce competition.

What is an example of resource partitioning?

Birds feeding on different parts of the same tree or hunting at different times of day.

What is a biome?

A large community of plants and animals adapted to a specific climate.

What factors determine a biome?

Temperature, precipitation, soil type, latitude, and altitude.

What are the major terrestrial biomes?

Tundra, taiga, temperate rainforest, temperate deciduous forest, temperate grassland, shrubland, desert, savanna, tropical rainforest.

Which biome has the poorest soil and why?

Tropical rainforest, because heavy rainfall leaches nutrients from the soil.

Which biome has permafrost?

Tundra.

What is permafrost?

Permanently frozen soil that prevents deep root growth.

How will temperate seasonal forests shift with climate warming?

They will shift northward (toward the poles).

Why are biomes always changing?

Climate change, geological changes, and human activity alter temperature and precipitation patterns.

What are freshwater biomes?

Streams, rivers, ponds, and lakes.

What are marine biomes?

Oceans, intertidal zones, coral reefs, estuaries, and coastal wetlands.

What is an estuary?

A biome where freshwater and saltwater mix.

Why are phytoplankton most abundant near the surface?

Because sunlight needed for photosynthesis only penetrates the upper layers of water.

Why are marine algae important?

They produce large amounts of oxygen and remove CO₂ from the atmosphere.

What is the carbon cycle?

The movement of carbon between sources and sinks in the atmosphere, biosphere, hydrosphere, and geosphere.

What are the reactants of photosynthesis?

Carbon dioxide, water, and sunlight.

What are the products of photosynthesis?

Glucose and oxygen.

What are the reactants of cellular respiration?

Glucose and oxygen.

What are the products of cellular respiration?

Carbon dioxide, water, and energy (ATP).

What are long-term carbon reservoirs?

Fossil fuels, sedimentary rocks, and oceans.

What parts of the carbon cycle are anthropogenic?

Burning fossil fuels, deforestation, and cement production.

Where does most dissolved oxygen in the ocean come from?

Marine phytoplankton.

What is the nitrogen cycle?

The movement of nitrogen through the atmosphere, soil, water, and living organisms.

What is nitrogen fixation?

Conversion of atmospheric N₂ into ammonia by bacteria or lightning.

What is nitrification?

Conversion of ammonia into nitrite and then nitrate.

What is assimilation?

Uptake of nitrate or ammonia by plants to build proteins.

What is ammonification?

Conversion of organic nitrogen from waste or dead organisms into ammonia.

What is denitrification?

Conversion of nitrate back into atmospheric nitrogen by bacteria.

What is eutrophication?

Nutrient runoff causes excessive algae growth and oxygen depletion.

How do humans impact the nitrogen cycle?

Fertilizer use, fossil fuel burning, and wastewater runoff.

What is the largest nitrogen reservoir?

The atmosphere.

What is the phosphorus cycle?

The movement of phosphorus through rocks, soil, water, and organisms.

What is the major reservoir of phosphorus?

Rocks and sediments.

Why is phosphorus often a limiting nutrient?

It does not have a gaseous phase and is not easily dissolved.

How does phosphorus enter ecosystems?

Through weathering of rocks.

What are human sources of phosphorus?

Mining, fertilizer use, manure, and guano.

What is the hydrologic cycle?

The movement of water between Earth’s surface and atmosphere in different phases.

What powers the water cycle?

Solar energy.

What is evaporation?

Liquid water turning into water vapor.

What is condensation?

Water vapor cooling into liquid droplets.

What is precipitation?

Water falling as rain, snow, sleet, or hail.

What is transpiration?

Release of water vapor from plants.

What is runoff?

Water flowing over land into rivers and oceans.

What is seepage/percolation?

Water moving downward through soil to groundwater.

What are the main water reservoirs?

Oceans, ice caps, and groundwater.

How do humans impact the water cycle?

Dams, irrigation, urbanization, deforestation, and groundwater withdrawal.

What is primary productivity?

The rate at which producers convert sunlight into chemical energy.

What is gross primary productivity (GPP)?

Total energy captured through photosynthesis.

What is net primary productivity (NPP)?

Energy remaining after respiration (NPP = GPP − R).

Why are red organisms found deeper in the ocean?

Red light is absorbed near the surface; red organisms reflect red and absorb blue light.

Why do open oceans produce most of Earth’s biomass?

They cover the largest surface area, despite low productivity per unit area.

What is the 10% rule?

Only about 10% of energy is transferred to the next trophic level.

How does the 1st law of thermodynamics relate to energy flow?

Energy is conserved, not created or destroyed.

How does the 2nd law explain energy loss?

Energy becomes less usable as heat during transfers.

What is a food chain?

A linear path of energy transfer through feeding relationships.

What is a food web?

Interconnected food chains showing multiple energy pathways.

What organism always starts a food chain?

A producer.

Where does most energy in ecosystems originate?

The sun.

What direction do arrows point in food webs?

Toward the organism that consumes the energy.

What is an independent variable?

The variable that is manipulated.

What is a dependent variable?

The variable that is measured.

What are constants?

Factors kept the same throughout an experiment.

What is a control?

A baseline used for comparison.

Why do experiments need a control?

To compare results and account for normal conditions and random environmental factors.