1. An indirect effect in an ecosystem occurs when one population influences another...
- A. through a shared, non-living resource.
- B. by directly competing for territory.
- C. via an intermediary population.
- D. through a symbiotic relationship like mutualism.
2. In a simple food chain, owls eat snakes and snakes eat mice. If a disease were to wipe out most of the owl population, what would be the most likely indirect effect on the mouse population?
- A. The mouse population would decrease.
- B. The mouse population would increase.
- C. The mouse population would not change.
- D. The mice would be eaten by a new predator.
3. A marine food chain consists of sharks that prey on seals, which in turn eat fish. If a disease significantly reduces the shark population, what is the expected indirect impact on the fish population?
- A. The fish population will decrease because there will be more seals to eat them.
- B. The fish population will increase because the seals will have fewer predators.
- C. The fish population will remain unchanged because sharks do not eat fish directly.
- D. The seal population will also decrease, causing the fish population to increase.
4. Consider the food chain: Grass -> Grasshoppers -> Shrews -> Hawks. Which organism acts as the intermediary that allows a change in the hawk population to indirectly affect the grasshopper population?
- A. Grass
- B. Hawks
- C. Shrews
- D. Sunlight
5. In a forest ecosystem, a sudden increase in the population of foxes (predators) occurs. Foxes primarily eat rabbits, and rabbits primarily eat clover. What is the most probable chain reaction on the clover population?
- A. The clover population will increase.
- B. The clover population will decrease.
- C. The clover population will be unaffected.
- D. The foxes will begin to eat the clover.
6. In a simple food chain, owls eat snakes, and snakes eat mice. If a new disease significantly reduces the owl population, what is a likely indirect effect?
- A. The snake population will decrease.
- B. The mouse population will increase.
- C. The mouse population will decrease.
- D. The owl population will quickly recover.
7. Consider the food chain: Grass -> Grasshoppers -> Shrews -> Hawks. A change in which population would cause an indirect effect on the hawk population?
- A. The shrew population
- B. The grass population
- C. The coyote population, which also preys on shrews
- D. The hawk population itself
8. Which scenario is NOT an example of an indirect effect?
- A. A decrease in wolves leads to more elk, which leads to fewer aspen trees.
- B. A decline in plankton leads to fewer small fish, which leads to starving sea birds.
- C. A drought reduces grass growth, leading to a smaller zebra population.
- D. The reintroduction of a top predator causes a deer population to move to a new area, allowing a riverbank's vegetation to recover.
9. Which statement best describes an indirect effect within a food web?
- A. A predator's population size directly limiting the population of its immediate prey.
- B. A change in one population causing a change in another population that it does not directly eat or get eaten by.
- C. Two species competing for the exact same, limited food source in the same location.
- D. Decomposers breaking down a dead organism and returning its nutrients to the soil for plants.
10. A lake ecosystem includes algae, small fish that eat algae, and large fish that eat small fish. If a non-native plant is introduced and outcompetes the algae for sunlight, what is a probable indirect effect?
- A. The population of small fish will decrease.
- B. The population of large fish will decrease.
- C. The amount of algae will increase.
- D. The water will become more nutrient-rich.