Biodiversity

Question 1

Which sentence best defines biodiversity?

Accepted Answer

Biodiversity is the variety of different species that live together in an ecosystem.

Answer

Biodiversity is the total number of animals that live in a forest.

Answer

Biodiversity is the amount of water and sunlight an ecosystem receives.

Answer

Biodiversity is the number of food chains that exist in an ecosystem.

Question 2

Scientists reintroduce wolves to a forest where a large elk population has been eating most of the young willow and aspen trees. Which of the following chains of effects is most likely to happen over the next few years?

Accepted Answer

Wolves eat many elk, so elk numbers drop; fewer elk browse the young trees, allowing the willows and aspens to grow into mature trees; the taller trees provide more shade and food for birds and insects, improving overall forest health.

Answer

Wolves eat many elk, so elk numbers drop; with fewer elk, wolves soon run out of food and their numbers quickly decline, leaving the elk population unchanged and the forest still overgrazed.

Answer

Wolves eat many elk, so elk numbers drop; the loss of elk lets grass grow taller, which attracts more deer that then overgraze the forest even more than the elk did.

Answer

Wolves eat many elk, so elk numbers drop; the reduction in elk means fewer predators for small mammals, causing a rabbit boom that eats the new tree seedlings and stops forest recovery.

Question 3

A park has two ponds. Pond A is home to many different plants, insects, and fish, while Pond B has only a few kinds of each. After a heavy rain, extra nutrients flow into both ponds, causing algae to grow quickly. Which statement best explains why Pond A is more likely to stay healthy and keep its water clear?

Accepted Answer

Because the many species in Pond A can perform similar jobs, the pond can more easily recover from the nutrient surge, keeping the water clean and the ecosystem stable.

Answer

Pond A will stay healthy because its many fish can be caught for food, providing more food for the park’s visitors.

Answer

Pond B will stay healthy because having fewer species means there is less competition, so the algae will not grow as fast.

Answer

The amount of sunlight hitting the water is the only factor that determines water clarity, so biodiversity does not matter.

Try three questions

Which sentence best defines biodiversity?

Scientists reintroduce wolves to a forest where a large elk population has been eating most of the young willow and aspen trees. Which of the following chains of effects is most likely to happen over the next few years?

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