Ecology and Ecosystems Quiz

Grade 9 · Science · Quiz

Test your knowledge of ecosystems, food webs, trophic levels, and ecological relationships with 10 questions.

Questions

1. A hawk eats a snake that ate a frog that ate a grasshopper that ate grass. The hawk is a:

   1. Primary consumer
   2. Secondary consumer
   3. Tertiary consumer
   4. Quaternary consumer
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   Answer: Quaternary consumer

   Counting: grass (producer) → grasshopper (primary) → frog (secondary) → snake (tertiary) → hawk (quaternary). Each step adds one trophic level.

2. Decomposers are consumers because they obtain energy from other organisms.

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   Answer: True

   Decomposers are technically heterotrophs (consumers) — they obtain energy by breaking down organic matter. They are a special category that recycles nutrients rather than building biomass up the chain.

3. The variety of species in an ecosystem is called ___.

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   Answer: biodiversity

   Biodiversity encompasses the variety of species, genetic diversity within species, and ecosystem diversity. Higher biodiversity generally creates more stable, resilient ecosystems.

4. Which relationship best describes a tapeworm living inside a dog?

   1. Mutualism
   2. Commensalism
   3. Parasitism
   4. Predation
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   Answer: Parasitism

   The tapeworm benefits (food, shelter) while the dog is harmed (nutrient loss, illness). This is the definition of parasitism: one benefits, one is harmed.

5. What drives energy flow at the base of most food chains?

   1. Decomposition
   2. Photosynthesis
   3. Cellular respiration
   4. Chemosynthesis
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   Answer: Photosynthesis

   Plants capture solar energy through photosynthesis, converting it to glucose. This is the primary energy entry point into nearly all food chains on Earth.

6. Matter (like carbon and nitrogen) cycles through ecosystems, but energy flows in one direction.

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   Answer: True

   Matter (atoms) is neither created nor destroyed — it cycles through living and non-living components via biogeochemical cycles. Energy, however, enters as sunlight and exits as heat — it flows through but doesn't cycle.

7. If a population of wolves (top predator) is removed from an ecosystem, you would most likely expect:

   1. Producers to decrease
   2. Herbivore populations to increase
   3. More decomposers
   4. Biodiversity to increase
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   Answer: Herbivore populations to increase

   Removing top predators allows prey populations to boom (a trophic cascade). More herbivores can overgraze producers, destabilizing the entire ecosystem — as seen in Yellowstone before wolf reintroduction.

8. Organisms that make their own food using sunlight are called ___.

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   Answer: producers

   Producers (autotrophs) include plants, algae, and some bacteria. They convert inorganic energy (sunlight or chemicals) into organic matter that the rest of the ecosystem depends on.

9. Which ecological level includes ALL living and non-living components in an area?

   1. Population
   2. Community
   3. Ecosystem
   4. Organism
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   Answer: Ecosystem

   An ecosystem includes both the community (all living organisms) and the abiotic (non-living) factors — water, soil, temperature, light. It is the functional unit of ecology.

10. Why are food chains rarely longer than 4-5 levels?

    1. Predators become too large
    2. Too little energy remains at higher levels
    3. Producers run out of sunlight
    4. Decomposers disrupt longer chains
    Show answer

    Answer: Too little energy remains at higher levels

    The 10% rule means energy decreases dramatically at each level. By level 5, there is so little energy that sustaining a population of organisms becomes impossible.

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