1. The _______ is the dependent variable and the ________is the independent variable.
a. latitude; species number
b. species number; latitude
c. land; ocean
d. ocean; land

2. At what latitude do the largest number of species occur?
a. 0o
b. 20o
c. 30o
d. 40o
e. 60o

3. Passenger pigeons became extinct because of:
a. large population size.
b. restricted geographic range.
c. extensive geographic range.
d. narrow habitat tolerance.
e. broad habitat tolerance.

4. Which ecosystem disturbance is not reversible?
a. Volcanic eruption
b. Forest fire
c. Flooding
d. Earthquake
e. One involving species loss

5. How can invasive species outcompete native species?
a. Invasive species may be better adapted to the environment.
b. Invasive species and native species evolved in similar ecosystems.
c. Invasive species may have no natural pathogens.
d. Invasive species may have no natural predators.
e. Both c. and d.

6. Which of the following is a “greenhouse gas”?
a. Sulfur dioxide
b. Nitrogen dioxide
c. Carbon dioxide
d. Hydrogen
e. Oxygen

7. The presence or absence of amphibians (frogs) in an ecosystem is a sign of its health. Therefore, amphibians would be categorized as a(n):
a. flagship species.
b. umbrella species.
c. keystone species.
d. indicator species.

8. How does deforestation increase the rate of global warming?
a. Deforestation = less CO2 is removed from the atmosphere
b. More CO2 released into the atmosphere as forests are cleared and burned
c. Deforestation changes solar absorption/reflection in an area
d. All of the above.

9. Which state listed below has the most acidic precipitation?
a. Florida
b. California
c. Texas
d. Pennsylvania
e. Kansas

10. How did human activity lead to the extinction of the passenger pigeon?
a. Habitat destruction
b. Overexploitation
c. Introduction of exotic species
d. Both a. and b.
e. All of the above.