Questions About Ecosystems
Multiple-Choice Questions: Ecosystems
1. What is an ecosystem?
A) A population of organisms of the same species
B) A community of organisms interacting with each other
C) The total area covered by a forest
D) A biological community and its physical environment
E) A group of species living separately
2. Which of the following is a biotic component of an ecosystem?
A) Soil
B) Water
C) Sunlight
D) Bacteria
E) Temperature
3. Which of the following is an abiotic factor?
A) Fungi
B) Grass
C) Carbon dioxide
D) Insects
E) Algae
4. What role do producers play in an ecosystem?
A) Break down dead organisms
B) Feed on other animals
C) Convert sunlight into chemical energy
D) Eat only plants
E) Feed on detritus
5. Which organisms are primary consumers?
A) Herbivores
B) Carnivores
C) Decomposers
D) Omnivores
E) Producers
6. What is the main function of decomposers in an ecosystem?
A) Produce oxygen
B) Recycle nutrients back into the soil
C) Consume primary consumers
D) Store water
E) Control predators
7. The trophic level of an organism refers to:
A) Its habitat
B) Its evolutionary stage
C) Its energy source
D) Its position in the food chain
E) Its population size
8. Which of the following represents a correct energy flow in an ecosystem?
A) Consumer → Producer → Decomposer
B) Sun → Producer → Consumer → Decomposer
C) Producer → Decomposer → Consumer
D) Decomposer → Producer → Sun
E) Sun → Consumer → Producer
9. Energy in an ecosystem primarily enters through:
A) Decomposers
B) Water
C) The soil
D) The sun
E) Wind
10. What is a food web?
A) A single path of energy flow
B) A collection of abiotic components
C) A series of connected food chains
D) A predator-prey relationship
E) A group of producers
11. Which of the following ecosystems has the highest biodiversity?
A) Desert
B) Tundra
C) Tropical rainforest
D) Temperate grassland
E) Polar ice cap
12. What is biomass in an ecosystem?
A) The total number of organisms
B) The total energy in the ecosystem
C) The total mass of living organisms
D) The amount of water stored
E) The number of species
13. A keystone species is:
A) The species with the largest population
B) The most dangerous predator
C) A species that has a disproportionate effect on its ecosystem
D) A decomposer that recycles nutrients
E) Always a plant
14. Which of the following is an example of an aquatic ecosystem?
A) Savanna
B) Coral reef
C) Desert
D) Temperate forest
E) Prairie
15. The carbon cycle involves:
A) Movement of nitrogen in the air
B) Storage of solar energy
C) Transfer of carbon between organisms and the environment
D) Decomposition of minerals
E) Water evaporation and condensation
16. Which of the following human activities can disrupt ecosystems?
A) Recycling
B) Deforestation
C) Wildlife conservation
D) Organic farming
E) Reforestation
17. In ecological succession, what typically occurs first in a primary succession?
A) Forest growth
B) Appearance of grasses
C) Soil development
D) Growth of mosses and lichens
E) Insect colonization
18. What term describes the final stable stage of ecological succession?
A) Dominant stage
B) Primary stage
C) Growth stage
D) Climax community
E) Transitional state
19. Which organisms are at the base of an energy pyramid?
A) Tertiary consumers
B) Primary consumers
C) Decomposers
D) Producers
E) Secondary consumers
20. Which of the following best explains why energy decreases at higher trophic levels?
A) Organisms at higher levels are smaller
B) Energy is created at each level
C) Energy is lost as heat and through metabolic processes
D) Producers absorb all the energy
E) Consumers do not eat enough
Answer Key with Explanations
1. D – An ecosystem is made up of living organisms and their physical (non-living) environment interacting together.
2. D – Bacteria are living components and thus biotic.
3. C – Carbon dioxide is a non-living factor affecting ecosystems, so it's abiotic.
4. C – Producers (like plants) use photosynthesis to turn sunlight into chemical energy.
5. A – Primary consumers are herbivores that feed on producers.
6. B – Decomposers break down dead matter and recycle nutrients back to the ecosystem.
7. D – Trophic levels indicate an organism’s position in the food chain (e.g., producer, consumer).
8. B – Energy flows from the sun to producers to consumers and finally decomposers.
9. D – The sun is the ultimate energy source for most ecosystems.
10. C – A food web is made up of interconnected food chains, showing complex feeding relationships.
11. C – Tropical rainforests have the greatest species diversity.
12. C – Biomass refers to the total mass of living organisms in a given area.
13. C – Keystone species have an unusually large impact on ecosystem structure and function.
14. B – Coral reefs are aquatic ecosystems found in marine environments.
15. C – The carbon cycle includes photosynthesis, respiration, and decomposition, moving carbon through systems.
16. B – Deforestation removes trees, disrupting habitats and nutrient cycles.
17. D – Mosses and lichens are pioneer species in primary succession, breaking down rock into soil.
18. D – The climax community is the final, stable ecosystem after succession.
19. D – Producers form the base of energy pyramids because they harness energy directly from the sun.
20. C – As energy moves up trophic levels, much is lost as heat through respiration and metabolism.
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