Free Response Questions (College Board AP® Environmental Science): Exam Questions

30 mins3 questions
1a
1 mark

The International Union for Conservation of Nature (IUCN) is composed of scientists that compile a list of the most threatened species that is a critical indicator of the health of the world’s biodiversity. The chart below shows the percent of species that are endangered in four different taxonomic groups.

Identify the taxonomic group with the greatest number of species threatened with extinction.

1b
1 mark

Most reptile species are r-selected species. Describe the characteristics of an r-selected species.

1c
1 mark

Identify an ecological benefit provided by high biodiversity.

1d
1 mark

Explain how a loss of genetic diversity could make a population more vulnerable to extinction.

1e
1 mark

Describe how habitat fragmentation can lead to loss of species.

1f
1 mark

A team of researchers is studying the impact of habitat fragmentation on an endangered reptile species. They want to determine how the size and isolation of habitat patches affect the population density of the reptiles.

Habitat Patch Size (sq km)

Isolation Distance (km)

Population Density (reptiles/sq km)

50

0

120

50

10

85

25

0

95

25

10

60

10

0

75

10

10

40

5

0

50

5

10

20

Identify a hypothesis for the experiment

1g
1 mark

Identify an independent variable for the experiment.

1h
1 mark

Justify a claim about a conclusion based on the results of the experiment.

1i
1 mark

Destruction of habitat for mining mineral resources also poses a threat to reptile species. The waste from the mining process is stored in piles next to the mining site. 

Identify the term for the piles of mining waste.

1j
1 mark

Explain how mining waste could threaten reptile biodiversity.

2a
1 mark

Scientists at the National Oceanic and Atmospheric Association have been studying atmosphere and ocean water at the Mauna Loa Station in Hawaii since the late 1950’s. The graph below represents the results of decades of monitoring.

Identify the highest atmospheric CO2 concentration in 2024.

2b
1 mark

Explain the trend in atmospheric CO2 since 1958. 

2c
1 mark

Describe the relationship between ALOHA seawater CO2 and ALOHA seawater pH.

2d
1 mark

A group of researchers conducted an experiment to determine the impact of pH on the weight and thickness of marine organism shells. They placed one each of identical marine snails in tanks with seawater at different pH levels (8.2, 7.8, 7.5, and 7.2) for six months. At the end of the experiment, they measured the shell weight and thickness of each snail for each pH level.

pH

Shell Weight (g)

Shell Thickness (mm)

8.2 (control)

12.4

2.8

7.8

10.8

2.5

7.5

9.2

2.1

7.2

7.5

1.6

Identify the independent variable for the experiment.

2e
1 mark

Explain why pH 8.2 is the control for the experiment.

2f
1 mark

Describe how the experiment could be modified to improve the validity of the results.

2g
1 mark

Describe how the results of the experiment would change if CO2 was pumped into the tanks.

2h
1 mark

Explain how a decrease in pH can affect shelled marine organisms.

2i
1 mark

In addition to impacting ocean pH, carbon dioxide functions as a greenhouse gas. A local climate scientist claims that methane (CH4) , also a greenhouse gas, poses a greater threat to climate change than CO2.  

Identify an anthropogenic source of methane.

2j
1 mark

Justify or refute the claim made by the climate scientist.

3a
1 mark

The carbon cycle is the natural process through which carbon is exchanged between the Earth's atmosphere, oceans, soil, and living organisms.

Identify a process shown in the diagram that removes carbon to the atmosphere.

3b
1 mark

Identify one anthropogenic activity shown in the diagram that adds carbon to the atmosphere. 

3c
1 mark

Explain why oil and gas are carbon sinks that store carbon for millions of years. 

3d
1 mark

The ocean serves as a carbon sink, capturing and storing carbon in multiple forms. 

Describe how calcium carbonate accumulates and is stored in marine sediments.

3e
1 mark

Describe the role of carbon dioxide CO₂ in regulating Earth's climate.

3f
1 mark

Carbon is also stored in oceans as dissolved carbon dioxide gas.

Explain how an increase in CO2 affects ocean pH. 

3g
1 mark

Explain how this change in pH effects shelled marine organisms like clams and mussels

3h
1 mark

Identify one solution to reduce the impact of CO2 dissolving in ocean water.

3i
1 mark

Describe an additional advantage of the strategy you described in (h) 

3j
1 mark

Another approach to reducing the impacts of CO₂ involves enhancing the ocean’s ability to absorb and store carbon by introducing substances that help neutralize its chemistry.

Identify a substance that could be used to solve this problem.