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Quizzes > Science

Ecosystem Interactions Quiz: Test Biotic and Abiotic Factors

Quick, free biotic and abiotic interactions quiz. Instant results.

Editorial: Review CompletedCreated By: Michaela ColteyUpdated Aug 26, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art leaves tree fish rock water waves on yellow background illustrating ecosystem interactions quiz

This ecosystem interactions quiz helps you check how living (biotic) and nonliving (abiotic) factors shape each other in a habitat. It covers the basics you need for class and gives instant feedback as you go. For more practice, try the species interactions quiz, explore the energy flow in ecosystems quiz, and review the biotic factors quiz.

What best describes an ecosystem?
A group of organisms of the same species living together
The interaction of living and non-living factors in a defined area
The genetic variation within a population
The chemical processes within an organism
An ecosystem encompasses both biotic (living) and abiotic (non-living) components interacting within a specific environment. It includes organisms, climate, soil, water, and nutrients working together as a system. This distinguishes ecosystems from isolated biological or chemical processes alone. For more details see .
Which term refers to the living components of an ecosystem?
Biotic
Abiotic
Heterotrophic
Autotrophic
Biotic factors are the living elements in an ecosystem, such as plants, animals, fungi, and microorganisms. They interact with each other and with abiotic factors like temperature and soil. Understanding biotic components helps explain food webs and energy flow. See .
Which of the following is an abiotic factor in an ecosystem?
Temperature
Predator population
Plant species diversity
Fungal decomposers
Abiotic factors are non-living physical and chemical elements, and temperature is a key abiotic influence on organism survival. It affects metabolic rates, distribution, and behavior of species. Other examples include sunlight, water, and soil minerals. Learn more at .
Which example represents a biotic factor influencing ecosystem dynamics?
Bacteria decomposing leaf litter
Soil pH level
Sunlight intensity
Wind speed
Biotic factors encompass living organisms and their interactions; bacteria breaking down organic matter is a prime example. This process returns nutrients to the soil for plant uptake. Biotic activities shape nutrient cycles and energy flow. See .
Which group of organisms is considered primary producers in most ecosystems?
Fungi
Green plants and algae
Bacteria
Herbivorous animals
Primary producers, such as green plants and algae, synthesize organic compounds from sunlight via photosynthesis. They form the base of food webs by converting solar energy into chemical energy. Without them, energy flow to consumers would cease. More at .
What role do decomposers play in an ecosystem?
They produce energy through photosynthesis
They fix atmospheric nitrogen
They break down dead organic matter, recycling nutrients
They consume primary producers
Decomposers, including bacteria and fungi, decompose dead material and release nutrients back into the soil and water. This recycling is critical for nutrient availability to producers. Without decomposers, ecosystems would accumulate waste and run out of vital elements. For details see .
Primary consumers in an ecosystem are also known as what?
Herbivores
Omnivores
Detritivores
Carnivores
Primary consumers feed directly on producers (plants or algae) and are known as herbivores. They transfer energy from producers to higher trophic levels. Examples include rabbits and caterpillars. More information at .
What does a food chain illustrate in an ecosystem?
The physical layout of habitats
A linear sequence of energy transfer through feeding relationships
The age structure of a population
The genetic relationships among species
A food chain shows how energy and nutrients flow from one organism to another through feeding interactions. It starts with producers and ends with top predators or decomposers. Food chains highlight the interconnectedness of species. See .
Which of the following is an example of a primary consumer?
Rabbit
Sunlight
Wolf
Grass
Rabbits feed on plants and are classified as primary consumers or herbivores. They occupy the second trophic level in a food chain. This role channels energy from producers up the chain. Learn more at .
Which organism is typically a secondary consumer in a terrestrial ecosystem?
Fox
Mushroom
Grasshopper
Oak tree
Secondary consumers prey on primary consumers; foxes often feed on herbivores like rabbits. They occupy the third trophic level, transferring energy further up the food web. Secondary consumers help control prey populations. See .
What is the main source of energy for most ecosystems?
Sunlight
Wind
Soil nutrients
Geothermal heat
Sunlight drives photosynthesis in primary producers, providing the base energy input for most ecosystems. This solar energy is converted into chemical energy stored in biomass. Other sources like geothermal energy are minor by comparison. More at .
Which organisms are most responsible for nitrogen recycling in soils?
Bacteria
Mycorrhizal fungi
Lichens
Earthworms
Soil bacteria perform nitrification and denitrification, converting nitrogen between different chemical forms. This microbial activity makes nitrogen available to plants and returns it to the atmosphere. Without bacteria, nitrogen cycling would halt. For more see .
What best defines an organism's habitat?
The genetic traits it possesses
Its role in the food web
The physical environment where it lives
Its reproductive behavior
A habitat is the natural environment where an organism lives, including biotic and abiotic factors. It provides shelter, resources, and conditions suitable for survival. Habitats range from microhabitats like a leaf surface to macrohabitats like a forest. More at .
What distinguishes an ecosystem from a biome?
Biomes are smaller than ecosystems
An ecosystem lacks living organisms; a biome includes them
Ecosystems are defined by climate alone
An ecosystem is a local community plus environment; a biome is a large region
Ecosystems are local interactions of organisms and their environment, while biomes are broad geographic categories defined by climate and vegetation. Multiple ecosystems (e.g., forest patches) can exist within one biome. Biomes include tundra, desert, and rainforest. See .
What does 'trophic level' refer to in an ecosystem?
The overall biomass of an ecosystem
The pH level of the soil
The age structure of a population
An organism's position in a food chain
Trophic levels categorize organisms by their source of energy transfer, from producers at level one to top predators. Each level represents a step in the flow of energy and nutrients. Understanding trophic structure helps ecologists study ecosystem dynamics. More at .
Approximately what percentage of energy is transferred from one trophic level to the next?
10%
90%
50%
1%
The 10% rule states that roughly 10% of energy at one trophic level is converted to biomass at the next. The rest is lost as heat and metabolic processes. This low efficiency limits the number of trophic levels in a food web. See .
What is ecological succession?
The cycling of nutrients within an ecosystem
The process of photosynthesis in plants
The flow of energy through a food web
Gradual change in species composition over time
Ecological succession is the sequential replacement of species in an ecosystem following a disturbance or the creation of a new habitat. It can be primary (on bare substrate) or secondary (after disturbance with soil). Succession leads to community maturity or climax conditions. More at .
Which type of succession begins on bare rock with no soil?
Retrogressive succession
Secondary succession
Primary succession
Cyclic succession
Primary succession occurs in lifeless areas where soil has not yet formed, such as on lava flows or glacial retreats. Pioneer species like lichens colonize rock and slowly create soil. Over time, more complex plant and animal communities establish. See .
Which characteristic is typical of a climax community?
Constant large-scale disturbances
Rapid colonization by pioneer species
Bare substrate with no vegetation
A relatively stable ecosystem with dominant mature species
A climax community represents a stable endpoint of succession where the species composition remains relatively unchanged until a disturbance occurs. It features mature trees or long-lived plants. Stability comes from balanced energy flow and nutrient cycling. More at .
In a biomass pyramid, how does biomass change at higher trophic levels?
It fluctuates unpredictably
It increases
It remains constant
It decreases
Biomass pyramids typically show decreasing biomass at higher trophic levels due to energy loss at each step. Only a fraction of energy is converted into organism tissue by consumers, so less biomass accumulates. This pattern limits the number of trophic levels. See .
Which cycle includes processes like evaporation, condensation, and precipitation?
Water cycle
Carbon cycle
Nitrogen cycle
Phosphorus cycle
The water cycle describes the continuous movement of water on, above, and below Earth's surface. Key processes include evaporation, transpiration, condensation, and precipitation. It regulates climate and distributes fresh water. More at .
Which organisms take up the largest amount of atmospheric CO? during photosynthesis?
Fungi
Bacteria
Animals
Plants and algae
Plants and algae use photosynthesis to convert CO? into organic compounds, serving as the primary mechanism for carbon fixation in ecosystems. They drive the global carbon cycle and influence climate regulation. Other organisms rely on these producers for energy. See .
Which human activity is the major contributor to increased atmospheric CO? levels?
Recycling plastics
Burning fossil fuels
Planting trees
Organic farming
Combustion of coal, oil, and natural gas releases large amounts of CO?, driving the recent rise in atmospheric concentrations. Deforestation also contributes but to a lesser extent. This increase enhances the greenhouse effect and global warming. More at .
What is a keystone species?
A species with a disproportionately large effect on its ecosystem
An invasive species
The most abundant species in an ecosystem
A species found only in one geographic area
Keystone species play critical roles that disproportionately influence ecosystem structure and function relative to their abundance. Their removal can lead to significant changes or collapse of the community. Classic examples include sea otters and wolves. For more see .
Which of these is a primary decomposer in aquatic ecosystems?
Phytoplankton
Bacteria
Shark
Algae
In aquatic systems, bacteria are the main decomposers, breaking down organic matter and recycling nutrients. They operate in the water column and sediments. Other organisms like fungi also contribute but to a lesser degree. See .
What best defines an ecological niche?
The role and position of a species in its ecosystem
The number of individuals of a species
The physical location where a species lives
The total genetic variability in a population
An ecological niche describes how a species interacts with its environment, including its habitat, resource use, and role in nutrient and energy cycles. It encompasses both biotic and abiotic factors. Overlapping niches can lead to competition. More at .
What is biomagnification?
The spread of invasive species
The increasing concentration of toxins at higher trophic levels
The growth of biomass in primary producers
The breakdown of nutrients by decomposers
Biomagnification refers to the cumulative increase of persistent pollutants (like PCBs or mercury) in organisms at successive trophic levels. Predators ingest contaminated prey, leading to higher concentrations in their tissues. This poses health risks to top consumers. See .
Which biome is characterized by low precipitation and temperature extremes?
Wetland
Temperate deciduous forest
Tropical rainforest
Desert
Deserts receive less than 250 mm of rain per year and experience high temperature fluctuations between day and night. Vegetation is sparse, and organisms exhibit specialized adaptations. Desert ecosystems demonstrate unique survival strategies. More at .
Which microbial process converts nitrate back into atmospheric nitrogen?
Ammonification
Nitrogen fixation
Nitrification
Denitrification
Denitrification is carried out by anaerobic bacteria that convert nitrate (NO??) into nitrogen gas (N?), returning it to the atmosphere. This process completes the nitrogen cycle and reduces soil nitrate levels. Other steps include nitrification and fixation. For details see .
Which is an example of mutualism in an ecosystem?
Bees pollinating flowers
Wolves preying on deer
Fungi decomposing leaf litter
Barnacles on whale skin
Mutualism is a symbiotic relationship where both species benefit, as bees obtain nectar while pollinating flowers, aiding plant reproduction. Predation and decomposition are different interactions. Mutualistic partnerships are critical for ecosystem functions. See .
Which category of ecosystem services includes flood control by wetlands?
Provisioning services
Supporting services
Cultural services
Regulating services
Regulating services are benefits obtained from ecosystem processes that regulate climate, disease, or water flow; wetlands buffer floods by absorbing excess water. Provisioning relates to products like food, while supporting underpin all services. Learn more at .
What term describes species diversity between different habitats in a region?
Alpha diversity
Delta diversity
Beta diversity
Gamma diversity
Beta diversity measures the change in species composition between habitats or ecosystems in a region. Alpha diversity is the diversity within a single habitat, and gamma diversity is at the landscape scale. These metrics help assess biodiversity patterns. More at .
Which vegetation typically follows pioneer species in primary succession on bare rock?
Grasses and small shrubs
Mature trees
Large mammals
Algae
After pioneers like lichens and mosses create initial soil, grasses and small shrubs colonize to further stabilize and enrich the substrate. Over time, these species pave the way for larger plants. This sequential colonization defines primary succession stages. See .
Which factor is the primary determinant of biome distribution worldwide?
Species competition
Climate
Soil type
Human activity
Temperature and precipitation patterns primarily shape biome types, influencing vegetation structure and species adaptations. While soil and biotic interactions matter locally, climate sets broad global distributions. Human activity modifies biomes but does not define natural categories. More at .
What is the 'edge effect' in ecology?
Increased soil fertility at ecosystem centers
Different conditions at the boundary between ecosystems
Primary productivity in open areas
Symbiotic interactions between species
The edge effect refers to the greater diversity or abundance of species at the interface between two habitats due to mixed conditions and resources. Edges often support both interior and exterior species. Fragmentation increases edge areas. See .
Which carbon reservoir holds the largest amount of carbon in the long term?
Atmosphere
Oceans
Sedimentary rock
Living biomass
Most Earth's carbon is stored in sedimentary rocks such as limestone and shale over geological timescales. While oceans and biomass are active reservoirs, their storage is small compared to rocks. This long-term reservoir is key to the global carbon cycle. See .
What does 'allelopathy' refer to in plant ecology?
Chemical inhibition of one plant by another
Seed dispersal by animals
Mutualistic root associations
Physical competition for light
Allelopathy is when a plant releases biochemicals that inhibit the growth of neighboring species, reducing competition. These chemicals can affect germination, growth, and survival. It shapes plant community structure. More at .
Which ecological pyramid can be inverted depending on the ecosystem?
Pyramid of numbers
Pyramid of energy
Pyramid of biomass
Pyramid of productivity
Pyramids of numbers show the count of organisms at each trophic level; in some systems, such as a tree (one producer) supporting many insects, the pyramid appears inverted. Biomass and energy pyramids are rarely inverted due to energy loss rules. See .
Which is an example of a density-dependent factor affecting population size?
Natural disasters
Seasonal temperature changes
Competition for resources
Soil pH
Density-dependent factors, such as competition, predation, and disease, intensify as population density increases, limiting growth. Density-independent factors affect populations regardless of density. Understanding these helps in population management. More at .
What is an indicator species?
A top-level predator
A species whose presence reflects a specific environmental condition
A highly abundant species
A species found only in one country
Indicator species are sensitive to environmental changes and signal ecosystem health or degradation. Their presence or absence reflects water quality, pollution levels, or habitat integrity. Amphibians often serve as indicators. See .
What is the primary ecological consequence of widespread deforestation?
Increased oxygen production
Enhanced soil fertility
Loss of biodiversity
Reduced CO? levels
Deforestation destroys habitats, reducing species richness and disrupting ecosystem functions. It also contributes to soil erosion and carbon release. Biodiversity loss affects ecological resilience. More at .
Which term describes the rate at which an ecosystem returns to equilibrium after disturbance?
Resilience
Inertia
Elasticity
Resistance
Ecological resilience refers to the capacity of an ecosystem to recover its structure and function after perturbation. Resistance denotes the ability to withstand disturbance without change. Understanding resilience helps in ecosystem management. More at .
Which modeling approach treats ecosystems as interconnected pools exchanging matter and energy?
Box model
Markov chain
Cellular automata
Agent-based model
Box models represent ecosystems as compartments (boxes) with defined inputs, outputs, and internal transfers of energy or nutrients. They simplify complex interactions for quantitative analysis. They are widely used in biogeochemical cycling. See .
Removal of which keystone species in kelp forests leads to sea urchin population explosions and ecosystem collapse?
Kelp crab
Barnacle
Sea star
Sea otter
Sea otters prey on sea urchins, controlling their populations and allowing kelp forests to thrive. Without otters, urchins overgraze kelp, creating urchin barrens. This classic trophic cascade highlights keystone species roles. Learn more at .
What process describes the formation and development of soil from parent material over geological time?
Pedogenesis
Sedimentation
Evapotranspiration
Lithification
Pedogenesis encompasses physical, chemical, and biological processes that transform parent rock into soil. It involves weathering, organic matter accumulation, and horizon formation. Soil development influences vegetation patterns and ecosystem productivity. More at .
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Study Outcomes

  1. Understand Ecosystem Interactions -

    Learn how living organisms and non-living elements work together to form a balanced ecosystem.

  2. Analyze Energy Flow -

    Examine the pathways by which energy moves through producers, consumers, and decomposers in an ecosystem.

  3. Identify Biotic and Abiotic Factors -

    Distinguish between living (biotic) and non-living (abiotic) components and their roles in ecosystem dynamics.

  4. Evaluate Species Relationships -

    Assess how interactions such as predation, competition, and symbiosis shape community structure.

  5. Apply Ecosystem Definitions -

    Use precise terminology to define what constitutes an ecosystem and test your understanding through targeted quiz questions.

Cheat Sheet

  1. Fundamental Definition -

    When facing ecosystem definition questions or a what is an ecosystem quiz, remember that an ecosystem is best described as the interaction of living organisms (plants, animals, microbes) and their non-living surroundings (soil, water, climate) functioning as a cohesive unit. For example, in a forest ecosystem, trees convert sunlight into energy while depending on rainfall and mineral-rich soil. (Source: Britannica)

  2. Energy Flow and the 10% Rule -

    In many ecosystem quizzes, you'll see food chains and be asked to apply the 10% rule, which states only about 10% of energy transfers from one trophic level to the next. Use the mnemonic "Energy FIZZles FAST" to recall that if plants capture 1,000 kcal, herbivores get ~100 kcal, and carnivores just ~10 kcal. (Source: U.S. Geological Survey)

  3. Biogeochemical Cycles -

    Questions in an ecosystem interaction quiz often focus on cycles like carbon and nitrogen, where bacteria-driven steps - nitrogen fixation, nitrification, assimilation, denitrification - recycle essential elements. Remember the photosynthesis formula 6CO2 + 6H2O → C6H12O6 + 6O2 to visualize how the carbon cycle balances atmospheric CO2. (Source: NASA Earth Observatory)

  4. Species Interactions -

    For an ecosystem quiz on species relationships, distinguish mutualism (bee - flower pollination), commensalism (barnacles on whales), and parasitism (ticks on mammals) using the mnemonic "My Cat Purrs." Understanding these interactions reveals how organisms co-evolve and impact ecosystem stability. (Source: Smithsonian National Museum of Natural History)

  5. Abiotic Factors Influence -

    Expect to see environmental factors like temperature, pH, and precipitation in a what is an ecosystem quiz, as they determine nutrient availability and species distribution. For instance, aquatic ecosystems thrive in pH 6.5 - 8.5, while soil pH affects root nutrient uptake in plants. (Source: NOAA)

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