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AP®Environmental ScienceCollege BoardExam QuestionsUnit 8: Aquatic & Terrestrial PollutionPersistent Organic Pollutants (POPs)

Persistent Organic Pollutants (POPs) (College Board AP® Environmental Science): Exam Questions

7 mins7 questions
11 mark

Which of the following best describes how persistent organic pollutants (POPs) behave in the environment?

  • They rapidly decompose, preventing accumulation in ecosystems.

  • They readily evaporate into the atmosphere, reducing their concentration in the environment.

  • They are synthetic, carbon-based compounds that are highly stable and resist natural degradation, allowing them to persist and accumulate.

  • They transform into harmless byproducts when exposed to natural sunlight.

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21 mark

How do persistent organic pollutants (POPs) become toxic to organisms?

  • They dissolve in water and are rapidly excreted by organisms.

  • They are immediately broken down by metabolic processes.

  • They only affect plants and do not pose a risk to animals.

  • They accumulate in fatty tissues because they are fat-soluble.

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31 mark

Which of the following is an example of a persistent organic pollutant (POP)?

  • Carbon dioxide (CO₂)

  • Lead (Pb)

  • DDT (Dichlorodiphenyltrichloroethane)

  • Ozone (O₃)

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41 mark

How do persistent organic pollutants (POPs) spread over long distances?

  • They are broken down quickly before they can travel.

  • They dissolve in soil and remain in one location.

  • They are carried by wind and water before being redeposited in new areas.

  • They can only move through direct contact with organisms.

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51 mark

Which of the following describes is a major concern regarding the long-distance transport of persistent organic pollutants (POPs)?

  • They remain in one location and do not affect other ecosystems.

  • They are beneficial to ecosystems by providing nutrients.

  • They only affect the immediate area where they are released.

  • They can accumulate in remote regions, including the Arctic, far from their original source.

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61 mark

Persistent Organic Pollutants

Top-level predators, such as polar bears, orcas, and eagles, often accumulate significantly higher levels of persistent organic pollutants (POPs) than their prey due to a process known as biomagnification. These toxic chemicals, including DDT and PCBs, are fat-soluble and do not easily break down in the environment, allowing them to accumulate in the fatty tissues of organisms over time.

“Predators at the top of the food chain can have POP concentrations millions of times higher than the surrounding environment,” says Dr. Lisa Thompson, an environmental toxicologist at the University of California. A 2022 study published in Environmental Science & Technology that studied the impact of persistent organic pollutants in polar regions found that polar bears in the Arctic had PCB levels up to 100 times higher than the seals they consume.

This occurs because POPs are passed up the food chain with each level of predation. Small fish absorb pollutants from water, larger fish eat them, and top predators consume these contaminated species, leading to dangerous concentrations in their bodies. “This accumulation can cause immune suppression, reproductive issues, and developmental disorders,” explains Dr. Mark Reynolds, a wildlife biologist.

Scientists warn that unless POP emissions are controlled, apex predators and even humans will continue to face toxic exposure, with long-term consequences for health and biodiversity.

Which of the following identifies the author's main claim in the article about persistent organic pollutants (POPs) in top-level predators?

  • Top-level predators accumulate higher levels of POPs due to biomagnification, which poses risks to their health and ecosystems.

  • POPs break down quickly in the environment and do not pose a significant threat to wildlife.

  • Lower-level organisms are more affected by POPs than top predators because they are directly exposed to pollutants.

  • Scientists have found no evidence that POPs harm predators or disrupt ecosystems.

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71 mark

Persistent Organic Pollutants

Top-level predators, such as polar bears, orcas, and eagles, often accumulate significantly higher levels of persistent organic pollutants (POPs) than their prey due to a process known as biomagnification. These toxic chemicals, including DDT and PCBs, are fat-soluble and do not easily break down in the environment, allowing them to accumulate in the fatty tissues of organisms over time.

“Predators at the top of the food chain can have POP concentrations millions of times higher than the surrounding environment,” says Dr. Lisa Thompson, an environmental toxicologist at the University of California. A 2022 study published in Environmental Science & Technology that studied the impact of persistent organic pollutants in polar regions found that polar bears in the Arctic had PCB levels up to 100 times higher than the seals they consume.

This occurs because POPs are passed up the food chain with each level of predation. Small fish absorb pollutants from water, larger fish eat them, and top predators consume these contaminated species, leading to dangerous concentrations in their bodies. “This accumulation can cause immune suppression, reproductive issues, and developmental disorders,” explains Dr. Mark Reynolds, a wildlife biologist.

Scientists warn that unless POP emissions are controlled, apex predators and even humans will continue to face toxic exposure, with long-term consequences for health and biodiversity.

Which of the following evidence is used to support the author’s claim that top-level predators accumulate higher levels of persistent organic pollutants (POPs)?

  • Scientists have determined that POPs break down quickly and do not accumulate in organisms.

  • Research shows that only small fish absorb pollutants, while predators remain unaffected.

  • A study found that polar bears in the Arctic had PCB levels up to 100 times higher than the seals they consume.

  • Scientists warn that the ecosystems closest to the equator will be most impacted by persistent organic pollutants. 

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