CRM 3.2 Changes in Population

Guam is an island in the Pacific Ocean covered in tropical forests. During WWII (1940’s) the green tree snake was accidentally released on the island. Of the 12 species of native birds on the island 10 are extinct and the last two are extinct in the wild. Historically the birds have had little to no natural predators. The large populations of birds would eat the fruit and spread the seeds over large parts of the forest. The snakes’ diet consists completely on birds. With the birds gone many populations of trees are beginning to fall. Which of the following best explains what is happening on Guam?

• A. Immigration

• B. Emmigration

• C. Invasive Species

• D. Natural Selection

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Wildlife bridges are pathways that wildlife can use to avoid crossing a highway. A scientist wants to determine if wildlife bridges could help the endangered Florida panther. In 2017 there were an estimated 120-230 adult panthers in the wild. In 2019 27 panthers were killed by collision with vehicles. Wildlife bridges like the one shown below are being considered in an effort to protect the Florida Panther. How could a scientist best monitor if more wildlife bridges should be built to protect the panther?

• A. Count the population after a wildlife bridge is built

• B. Use a camera to see if panthers use the wildlife bridge to avoid roads

• C. Count the total panther population before and after a wildlife bridge is built

• D. Look at the total number of panther deaths before and after a wildlife bridge is built

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Scientists are researching the relationship between two species of fish. They count the number of individuals in an isolated population of each fish and the number of individuals in an area where both fish are found together.

Species Avg. Isolated Population Avg. Population When

Found Together

Fish A 120 120

Fish B 45 230

Using the data from the table which type of relationship do these two fish have?

• A. Mutualism

• B. Parasitism

• C. Predator/Prey

• D. Commensalism

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DDT was a highly successful pesticide used in 1940’s until its ban in 1972. While highly effective against insects, populations of birds began to decline because of thinning eggshells. On top of that there were concerns about human health. How does the story of DDT show the importance of continued monitoring of ecosystems?

• A. Monitoring is important to make sure a product is effective

• B. Monitoring is not important as long as a product is thoroughly tested before being released

• C. Monitoring is not important because any unintended damage can be fixed when discovered

• D. Monitoring is important to ensure a product does not have unintended consequences on an ecosystem

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A community has had an increase of 5% in their population within the last year. As a result, city officials have planned to build a new commerce center that includes clothing stores, supermarkets, and restaurants. What is the most important consideration the local government should have about the environmental effects of this project prior to approving the plan?

• A. If the builder has considered how to spend leftover money to help the environment

• B. There should be no environmental considerations as long as the project makes money

• C. If the builder has checked the area for endangered species prior to submitting a plan

• D. If the builder has an evaluation of the overall impact on biodiversity in the area after the shops are built

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It is a relationship in which both organisms benefit.

• Mutualism

• Parasitism

• Commensalism

• Competition

It is an interaction in which one organism kills and eats another.

• Mutualism

• Predation

• Competition

• Commensalism

It is a relationship in which one organism benefits & the other is harmed, like tapeworms and humans.

• mutualism

• parasitism

• predation

• competition

It is the struggle between organisms to survive in a habitat with limited resources in the same place at the same time

• Competition

• Parasitism

• Mutualism

• Commensalism