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

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.

Explain the trend in atmospheric CO₂ since 1958. 

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

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.

Identify the independent variable for the experiment.

Explain why pH 8.2 is the control for the experiment.

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

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

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

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.

Justify or refute the claim made by the climate scientist.

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.

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

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

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.

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

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

Explain how an increase in CO₂ affects ocean pH. 

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

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

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

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.