What is an ecosystem?

• Populations of organisms in their environment

• All the organisms of the same or closely-related species

• Two or more populations of organisms

Animals that hunt and kill others for food are ____?

• Consumers

• Predators

• Producers

In an ecosystem, there are always:

• the same number of predators as prey.

• more prey than predators.

• more predators than prey

What factor is threatening the survival of the Sonoran pronghorn, especially affecting vulnerable fawns?

• Increasing droughts

• Predation by mountain lions

• Habitat loss due to urbanization

• Competition with other herbivores

MATCHING: Identify an example of each type of ecosystem relationship.

• whitebird and greybird

• predator-prey

• rat and birds (eggs)

• mutualism

• whitebird and berry bush

• competition

1. Berry bushes need lots of rainfall. Which graph best predicts

what would happen to the populations on the North Island during a 10-year period of decreasing rain.

• 
• 
• 

The graph shows that the ​ (a)   population decreases by half. This is because

there aren’t as many ​ (b)   for them to eat and the ​ (c)   eat more bird eggs because there are fewer

berries available. The bird population doesn’t drop as much as the berry population, though, because they are also able to eat ​ (d)   . This causes the population of nut trees to decrease as well.

​ Since the rats need to eat berries or bird eggs, their population goes ​ (e)   as the berries drop and

the ones left will eat more bird eggs.

• whitebird
• rats
• berries
• nuts
• down
• up

If the Robins begin to disappear from this forest ecosystem, which other population would be likely to decrease?

• caterpillars

• hawks

• bass

• bears

What would likely happen to other populations in this food web if the algae began disappearing? Check all that apply.

• The population of minnows would decrease.

• The population of bass would increase.

• The population of bears would decrease.

• The population of robins would increase.

• The population of caterpillars would decrease.

SCENARIO 1 - Freshwater Lake Fish: Rainbow smelt are a freshwater fish that can survive in a wide range of lake environments. When rainbow smelt were introduced to Crystal Lake in northern Wisconsin, they quickly changed ecological interactions in the lake. For example, they ate up much of the food preferred by other fish. They have nearly eliminated the yellow perch, another type of fish.

Which graph best shows this scenario?

• 
• 
• 
• 
•