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Ecosystems and Biodiversity Practice Tests

These Grade 9 Biology practice tests explore how biodiversity supports ecosystem structure, function, and resilience. Questions cover genetic, species, and ecosystem diversity; keystone species; ecosystem services; habitat loss; invasive species; pollution; climate change; restoration; and conservation.

Skills covered

  • Distinguishing genetic, species, and ecosystem biodiversity and explaining resilience and resistance
  • Analyzing keystone species, indicator species, trophic cascades, decomposers, and ecosystem services
  • Evaluating habitat loss, fragmentation, edge effects, invasive species, eutrophication, plastic pollution, and climate change
  • Connecting ecological footprints, sustainability, protected areas, corridors, restoration, and native species
  • Interpreting population, food-web, biodiversity, and ecosystem-health evidence for conservation decisions

How to use these practice tests

First identify the ecological level or biodiversity type. Then trace the direct and indirect effects of a disturbance and consider which evidence would support a conservation decision. Review the explanations to strengthen environmental science vocabulary and systems thinking.

For more Grade 9 Science practice, return to the Grade 9 Science category.

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Grade 9 Ecosystems and Biodiversity Practice Tests

Practice Grade 9 Science questions about biodiversity, ecosystem structure, keystone species, ecosystem services, habitat loss, pollution, climate change, and conservation.

Choose the best answer. Identify the level of biodiversity or ecosystem process involved, trace direct and indirect effects, and evaluate conservation choices.

10 Questions
0/10 Questions0 %
Correct 0
Incorrect 0
Unanswered 10
1. QuestionMultiple choice

Why can a food web be used to predict effects of species loss?

Please select an answer first.

Correct answer: A

The correct answer is It shows how species are connected through feeding relationships..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Food-web connections help scientists predict direct and indirect effects when a species increases, declines, or disappears.
  3. Check the answer: The correct answer is It shows how species are connected through feeding relationships..

Food-web connections help scientists predict direct and indirect effects when a species increases, declines, or disappears.

2. QuestionMultiple choice

What happens when a population exceeds its carrying capacity for a long time?

Please select an answer first.

Correct answer: B

The correct answer is Limited resources can increase competition, disease, and mortality, causing the population to decline..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Overshoot can deplete resources and increase limiting factors, leading to a population decrease.
  3. Check the answer: The correct answer is Limited resources can increase competition, disease, and mortality, causing the population to decline..

Overshoot can deplete resources and increase limiting factors, leading to a population decrease.

3. QuestionMultiple choice

Why can genetic diversity help a species survive a new disease?

Please select an answer first.

Correct answer: C

The correct answer is Some individuals may carry alleles that provide resistance or reduce disease effects..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Variation increases the chance that some individuals can survive and reproduce when a new pathogen appears.
  3. Check the answer: The correct answer is Some individuals may carry alleles that provide resistance or reduce disease effects..

Variation increases the chance that some individuals can survive and reproduce when a new pathogen appears.

4. QuestionMultiple choice

What is a limiting resource?

Please select an answer first.

Correct answer: D

The correct answer is A resource that is insufficient for all organisms that need it..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Food, water, space, light, and nutrients can limit growth when demand exceeds availability.
  3. Check the answer: The correct answer is A resource that is insufficient for all organisms that need it..

Food, water, space, light, and nutrients can limit growth when demand exceeds availability.

5. QuestionMultiple choice

Why can an ecosystem with few species be more vulnerable to disturbance?

Please select an answer first.

Correct answer: A

The correct answer is It may have fewer alternative species to perform important ecological functions..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Low diversity can reduce functional redundancy and make the system more dependent on particular species.
  3. Check the answer: The correct answer is It may have fewer alternative species to perform important ecological functions..

Low diversity can reduce functional redundancy and make the system more dependent on particular species.

6. QuestionMultiple choice

Which observation would best indicate that a lake is becoming eutrophic?

Please select an answer first.

Correct answer: B

The correct answer is A large algal bloom followed by low dissolved oxygen and fish deaths..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Nutrient enrichment can trigger algal blooms; decomposition consumes oxygen and may cause fish kills.
  3. Check the answer: The correct answer is A large algal bloom followed by low dissolved oxygen and fish deaths..

Nutrient enrichment can trigger algal blooms; decomposition consumes oxygen and may cause fish kills.

7. QuestionMultiple choice

Why can removing a wetland increase flooding downstream?

Please select an answer first.

Correct answer: C

The correct answer is The lost wetland can no longer store and slowly release as much water..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Wetlands act like natural storage areas and can reduce peak water flow during heavy rain.
  3. Check the answer: The correct answer is The lost wetland can no longer store and slowly release as much water..

Wetlands act like natural storage areas and can reduce peak water flow during heavy rain.

8. QuestionMultiple choice

What is a likely benefit of reforesting a degraded watershed?

Please select an answer first.

Correct answer: D

The correct answer is More roots and soil structure can reduce erosion and improve water regulation..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Trees and other vegetation stabilize soil, absorb water, provide habitat, and store carbon.
  3. Check the answer: The correct answer is More roots and soil structure can reduce erosion and improve water regulation..

Trees and other vegetation stabilize soil, absorb water, provide habitat, and store carbon.

9. QuestionMultiple choice

Why should conservation plans consider local communities?

Please select an answer first.

Correct answer: A

The correct answer is Human cooperation and livelihoods influence whether conservation actions are practical and lasting..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Effective conservation often combines ecological goals with fair, workable solutions for people living in or near habitats.
  3. Check the answer: The correct answer is Human cooperation and livelihoods influence whether conservation actions are practical and lasting..

Effective conservation often combines ecological goals with fair, workable solutions for people living in or near habitats.

10. QuestionMultiple choice

What is the strongest reason to use several indicators when assessing ecosystem health?

Please select an answer first.

Correct answer: B

The correct answer is Different indicators reveal different parts of ecosystem structure and function..

  1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
  2. Apply the ecological principle: Combining species abundance, water quality, habitat structure, and other data gives a more complete assessment.
  3. Check the answer: The correct answer is Different indicators reveal different parts of ecosystem structure and function..

Combining species abundance, water quality, habitat structure, and other data gives a more complete assessment.

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