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Quizzes > Science

What Is True About Ecosystems? Quiz

Quick, free ecosystems quiz to test your knowledge. Instant results.

Editorial: Review CompletedCreated By: Oliwia SobasUpdated Aug 27, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art scene showing forest desert ocean and mountains representing ecosystems and biomes on dark blue background.

This quiz helps you check which statements are true about ecosystems and how they work. Review core ideas on species, resources, and energy flow across biomes, then keep learning with our ecosystem interactions quiz, energy flow in ecosystems quiz, and ecosystem vocabulary quiz. Great for quick study before class.

Which components make up an ecosystem?
Living organisms and their physical environment
Only living organisms
Climate and weather alone
Only non-living factors
An ecosystem includes both biotic (living) and abiotic (non-living) components interacting as a system. This interaction determines energy flow and nutrient cycling. Understanding both parts is fundamental to ecology. .
What is the primary role of producers in an ecosystem?
To decompose organic matter
To consume herbivores
To fix nitrogen
To convert solar energy into chemical energy
Producers, mainly plants and algae, use photosynthesis to convert sunlight into chemical energy stored in carbohydrates. They form the base of all food chains. Without producers, energy would not enter ecosystems. .
Which biome is known for having the highest biodiversity?
Tropical rainforest
Desert
Tundra
Temperate forest
Tropical rainforests have stable, warm temperatures and high precipitation year-round, fostering immense species richness. They cover only about 6% of Earth's surface yet contain over half of its terrestrial species. .
What is the average annual precipitation threshold below which a region is classified as a desert biome?
Less than 100 cm
Less than 10 cm
Less than 50 cm
Less than 25 cm
A desert is defined by receiving under 25 cm of annual precipitation, resulting in sparse vegetation. This low rainfall leads to specialized adaptations in flora and fauna. .
Which characteristic is typical of the tundra biome?
Permafrost layer
Year-round warm temperatures
High annual rainfall
High tree diversity
Tundra biomes are marked by a permanently frozen subsoil called permafrost. This restricts deep root growth and leads to low vegetation. It also influences carbon storage and soil ecology. .
Grassland biomes are primarily dominated by which type of vegetation?
Broadleaf deciduous trees
Cacti and succulents
Mosses and lichens
Grasses and herbaceous plants
Grasslands are characterized by dominant grasses and herbaceous plants, adapted to moderate rainfall and periodic fires. They support large grazing mammals and deep fertile soils. .
What typically initiates a food chain in an ecosystem?
Decomposers
Producers
Detritivores
Secondary consumers
Producers, like plants, initiate food chains by converting solar energy into biomass. Consumers then feed on producers or other consumers. Decomposers complete the cycle by breaking down organic matter. .
What role do decomposers play in an ecosystem?
They produce new biomass
They increase salinity
They consume primary producers
They recycle nutrients back into the soil
Decomposers such as bacteria and fungi break down dead organic material, releasing nutrients that plants can reuse. They maintain nutrient cycling and soil fertility. .
Which factor differentiates freshwater ecosystems from marine ecosystems?
Presence of fish
Salinity
Sunlight penetration
Oxygen availability
The primary difference is salinity: freshwater systems have under 0.5 ppt salinity, while marine exceed 30 ppt. Species adapt specifically to these salinity ranges. .
What process converts atmospheric nitrogen into forms usable by plants?
Nitrification
Ammonification
Nitrogen fixation
Denitrification
Nitrogen fixation by bacteria (free-living or symbiotic) converts N? to ammonia, a plant-usable form. This is key because most organisms cannot use atmospheric nitrogen directly. .
Primary succession typically begins on what kind of surface?
Previously forested soil
Abandoned agricultural field
Bare rock with no soil
Soil enriched with organic matter
Primary succession occurs where no soil exists, such as on bare rock after glacial retreat or lava flow. Pioneer species like lichens colonize first. They help create soil for later communities. .
What is a carbon sink in ecological terms?
A reservoir that absorbs more CO? than it releases
A volcanic vent
A factory producing carbon
A process that emits CO?
Carbon sinks like forests and oceans absorb CO? during photosynthesis or dissolution, storing it and reducing greenhouse gas levels. Understanding sinks is crucial for climate science. .
What layer forms the leafy overstory in a tropical rainforest?
Canopy
Forest floor
Understory
Emergent layer
The canopy is the dense layer of tree crowns forming the forest's roof. It intercepts light, houses diverse wildlife, and influences microclimates below. .
Estuaries are considered which type of ecological zone?
Eutrophic zone
Oligotrophic zone
Thermal vent
Ecotone
Estuaries are ecotones - transition areas between freshwater and marine ecosystems. They are nutrient-rich and highly productive. .
How do mangrove forests benefit coastal regions?
Stabilize shorelines and reduce erosion
Increase ocean acidity
Reduce oxygen levels
Prevent coral growth
Mangroves have dense root systems that trap sediment and reduce erosion. They also provide nursery habitat for many marine species and sequester carbon. .
Coral reefs are built primarily by:
Coral polyps secreting calcium carbonate
Sea grasses
Sponge skeletons
Algae
Coral polyps secrete calcium carbonate skeletons that accumulate over time to form reefs. These structures host diverse marine life. .
What defines a keystone species in an ecosystem?
The fastest reproducing species
A species with a disproportionately large effect on its environment
The most abundant species
The largest predator
A keystone species has an impact on ecosystem structure and function far greater than its abundance suggests. Removal often leads to significant shifts in community composition. .
Biomagnification refers to:
Accumulation of toxins in bodies of apex predators
Rapid recycling of nutrients
Decrease of toxin concentration at higher trophic levels
Improved water quality
Biomagnification is the increasing concentration of pollutants like heavy metals or pesticides in organisms at higher trophic levels. This poses risks to top predators. .
Carrying capacity is best described as:
A population's growth rate at low density
Number of species in a community
The minimum viable population
The maximum population size an environment can sustain
Carrying capacity (K) is the maximum number of individuals an environment can support indefinitely given resource limits. Populations fluctuate around K with density-dependent factors. .
Species richness refers to:
Total number of species in a community
Distribution of individuals among species
Total biomass of an ecosystem
Genetic variability within a species
Species richness is simply the count of different species present in a given area. It's one measure of biodiversity, distinct from evenness. .
An invasive species typically:
Disrupts native ecosystems and outcompetes local species
Occurs only in its native range
Has no ecological impact
Enhances native biodiversity
Invasive species introduced outside their native range can outcompete or prey on native species, altering ecosystem function and biodiversity. .
Riparian zones are important because they:
Act as buffer strips filtering pollutants into waterways
Increase salinity of rivers
Reduce biodiversity
Prevent photosynthesis
Riparian zones along riverbanks filter runoff, stabilize soil, and provide habitat corridors. They improve water quality and ecosystem health. .
Which ecosystem service is provided by wetlands?
Reduction of soil nutrients
Increased desertification
Flood control through water storage
Permanent freshwater shortage
Wetlands store excess rainfall and slow runoff, reducing flood peaks. They also filter pollutants and recharge groundwater. .
Chaparral ecosystems are adapted to:
Year-round inundation
Frequent, low-intensity fires
High salinity soils
Permafrost conditions
Chaparral biomes in Mediterranean climates experience periodic fires that trigger seed germination and maintain shrub dominance. Fire adaptation is key to their regeneration. .
Savanna biomes are characterized by:
Permafrost
Heavy snowfall
No dry season
Distinct wet and dry seasons
Savannas have pronounced wet and dry seasons. During dry periods, fires are common and grasses dominate, while trees are more prevalent in wetter times. .
Boreal forests (taiga) are primarily dominated by:
Cacti and succulents
Deciduous oaks
Coniferous trees like pines and spruces
Tropical palms
Boreal forests consist largely of cold-tolerant conifers such as pines, spruces, and firs. They occupy northern latitudes with long winters. .
Oligotrophic lakes are characterized by:
Low nutrient concentrations and clear water
High nutrient levels and frequent algal blooms
Saline conditions
Permanent ice cover
Oligotrophic lakes have low concentrations of nutrients like phosphorus and nitrogen, resulting in low productivity but high water clarity. .
Eutrophication typically results from:
Enrichment of water by excess nutrients
Decreased agricultural runoff
Increased salinity
Introduction of invasive fish
Eutrophication is caused by excess nutrients, often from fertilizers, leading to algal blooms, hypoxia, and loss of aquatic life. .
An example of mutualism in ecosystems is:
Birds eating fruit
Bees pollinating flowers
Barnacles on whale skin
Tapeworm in a host
Bees collect nectar while transferring pollen between flowers, benefiting both species. This is a classic mutualistic relationship enhancing plant reproduction and bee nutrition. .
Which cycle has no significant gaseous phase?
Nitrogen cycle
Water cycle
Phosphorus cycle
Carbon cycle
The phosphorus cycle lacks a gaseous phase; phosphorus moves through rocks, water, soil, and organisms. Its scarcity often limits productivity. .
An ecotone is defined as:
Uniform habitat with little change
A type of deep ocean trench
An area devoid of life
A boundary area between two ecosystems
An ecotone is a transition zone between two ecological communities, often showing high species diversity. It combines species from both adjacent ecosystems. .
Which ecosystems exhibit the highest net primary productivity (NPP) per unit area?
Deserts and tundra
Tropical rainforests and coral reefs
Temperate grasslands
Deep ocean benthic zones
Tropical rainforests and coral reefs have abundant sunlight, warm temperatures, and nutrient availability, yielding very high NPP. They support dense, diverse life. .
Secondary productivity in an ecosystem is measured as:
Increase in consumer biomass over time
Rate of decomposition
Biomass produced by autotrophs
Total solar energy input
Secondary productivity refers to the rate at which heterotrophs convert consumed organic matter into new biomass. It depends on consumption efficiency. .
What is the 'edge effect' in ecology?
Changes in population dynamics near habitat edges
Increased biodiversity at the interface of two habitats
Total isolation of edge communities
Reduction in species at habitat boundaries
The edge effect describes greater species diversity and biological activity at the boundary of two ecosystems, due to resource overlap. This can also increase vulnerability to disturbances. .
How does albedo affect climate in polar regions?
High albedo leads to more heat absorption
Low albedo leads to reflection of solar radiation
High albedo reflects solar radiation, cooling the surface
Albedo has no effect on climate
Albedo is surface reflectivity. Snow and ice have high albedo, reflecting sunlight and helping maintain low temperatures. Melting reduces albedo, accelerating warming. .
How is net primary production (NPP) calculated?
GPP × respiration
GPP + respiration
GPP - respiration
Respiration - GPP
NPP is the gross primary production (GPP) minus the energy plants use for respiration (R). It represents biomass available to consumers. .
What causes the rainshadow effect?
Cold air descending in valleys
Moist air rising over mountains, cooling and precipitating on windward side
Ocean currents warming coastal areas
High albedo of mountain peaks
The rainshadow effect occurs when moist air ascends a mountain range, cools, and drops precipitation on the windward side, leaving dry air to descend leeward. .
In soil science, percolation refers to:
Absorption by plant roots
Vertical movement of water through soil pores
Surface runoff only
Loss of water to evaporation
Percolation is the downward flow of water through soil and rock layers due to gravity, important for groundwater recharge. .
Which soil horizon is richest in organic material?
O horizon
C horizon
B horizon
A horizon
The O horizon is composed of organic matter such as leaf litter and decomposed material. It sits at the soil surface. .
Climate change boundary shifts of biomes are best evidenced by:
Expansion of tundra equatorward
Poleward migration of vegetation zones
Stable biome boundaries over decades
Increased permafrost extent
Warming climates cause biomes like forests to shift poleward or to higher elevations. Vegetation surveys document these boundary migrations. .
Which is NOT one of the four major categories of ecosystem services?
Economic services
Supporting services
Provisioning services
Regulating services
The four categories are provisioning, regulating, supporting, and cultural services. 'Economic services' is not an official category. .
A trophic cascade occurs when:
Predator removal leads to population changes at multiple trophic levels
Abiotic factors dominate control
Nutrient cycling stops
Primary producers increase without herbivores
A trophic cascade is triggered when top predators are removed or added, causing ripple effects down the food web. This alters ecosystem structure and function. .
Ecosystem homeostasis refers to:
Complete lack of disturbance
Stability and self-regulation over time
Rapid change without return
No nutrient cycling
Homeostasis in ecology means the ability of an ecosystem to maintain internal stability through feedback mechanisms, despite external changes. .
Landscape ecology primarily studies:
Atmospheric chemistry only
Molecular interactions in soil
Individual organism behavior
Spatial patterns and ecological processes across heterogeneous areas
Landscape ecology focuses on how spatial arrangement of ecosystems and land uses affects ecological processes and biodiversity. .
Which speciation mechanism is associated with geographic isolation?
Parapatric speciation
Peripatric speciation
Allopatric speciation
Sympatric speciation
Allopatric speciation occurs when populations are geographically isolated, preventing gene flow and leading to divergence. This is the most common speciation type. .
The island biogeography equilibrium model was developed by:
G. Evelyn Hutchinson and David Tilman
Charles Darwin and Alfred Wallace
Robert MacArthur and E.O. Wilson
Robert Paine and John Krebs
MacArthur and Wilson formulated the equilibrium theory of island biogeography, predicting species richness based on colonization and extinction rates. .
In acid deposition studies, the critical load concept refers to:
Maximum pollutant input ecosystem can assimilate without damage
Tipping point for climate change
Maximum carbon sequestration rate
Load capacity of atmosphere
Critical load is the threshold of pollutant deposition below which no harmful ecological effects occur. It guides environmental regulation. .
Functional redundancy in ecosystems means:
Complete collapse if one species is lost
Multiple species perform similar ecological functions
All species perform unique roles
No overlap in ecosystem services
Functional redundancy refers to different species contributing similarly to ecosystem processes. It enhances resilience since loss of one species can be compensated by others. .
The term 'anthrome' refers to:
Isolated island ecosystems
Pristine natural biomes
Human-altered ecological patterns on a global scale
Undisturbed wilderness areas
Anthromes (anthropogenic biomes) classify global ecosystems shaped by long-term human interactions, such as croplands and urban areas. .
Metapopulation dynamics describe:
A set of spatially separated populations connected by dispersal
Genetic equilibrium in isolated groups
Always stable population sizes
A single, continuous population
A metapopulation consists of local populations in habitat patches with extinction and recolonization processes, affecting overall species persistence. .
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Study Outcomes

  1. Understand Ecosystem Dynamics -

    Describe how energy flows and matter cycles through producers, consumers, and decomposers in terrestrial and aquatic ecosystems.

  2. Analyze Ecosystem Statements -

    Evaluate which of the following statements about ecosystems are true by applying scientific reasoning and evidence.

  3. Identify Biome Characteristics -

    Recognize key features such as climate, flora, and fauna that distinguish major biomes like tundra, rainforest, and grassland.

  4. Distinguish Biotic and Abiotic Factors -

    Classify the living and nonliving components that shape ecosystem structure and influence organism interactions.

  5. Evaluate Ecosystem Relationships -

    Assess symbiotic, competitive, and predatory interactions to understand how species interdependence affects ecosystem stability.

  6. Apply NGSS Concepts -

    Use Next Generation Science Standards principles to interpret real-world ecosystem scenarios and justify your answers with scientific data.

Cheat Sheet

  1. Energy Flow & Trophic Levels -

    Understand that energy moves in one direction through an ecosystem, from primary producers (plants) to consumers and decomposers. Remember Lindeman's 10% rule: only about 10% of usable energy transfers to the next trophic level. Practice drawing an energy pyramid to solidify which statements about ecosystems are true regarding energy loss.

  2. Biotic vs. Abiotic Factors -

    Differentiate living (biotic) components like plants, animals, and microbes from nonliving (abiotic) elements such as sunlight, temperature, and soil. Use the mnemonic "SWANS" (Sunlight, Water, Air, Nutrients, Soil) to recall key abiotic factors. This helps you ace questions on an ecosystems and biomes quiz about ecosystem interactions.

  3. Nutrient Cycling -

    Master the major biogeochemical cycles - carbon, nitrogen, and water - by mapping each step: photosynthesis, respiration, nitrification, denitrification, and evaporation. A handy phrase is "Can Newts Wiggle?" (Carbon, Nitrogen, Water) to recall the order of cycles studied. Recognizing true statements about ecosystems often hinges on knowing which cycle drives plant growth.

  4. Ecosystem Succession & Stability -

    Learn the difference between primary succession (bare rock to climax community) and secondary succession (soil-based recovery after disturbance). The acronym "PSR" (Primary, Secondary, Resilience) helps you recall that resilience measures an ecosystem's ability to return after change. This concept frequently appears in questions asking which of the following statements about ecosystems are true.

  5. Biome Classification by Climate -

    Familiarize yourself with Whittaker's biome diagram, which plots biomes by average temperature and precipitation - tundra at low temperature/low rainfall, tropical rainforest at high/high. When reviewing for an ecosystems and biomes quiz, practice identifying biomes from climate graphs. This ensures you correctly select true statements about ecosystems' global distribution.

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