AP Environmental Science Practice Quiz: Eutrophication
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Test your understanding with short quizzes. This quiz has 11 questions to check your progress.
Question 1 of 11
All Questions (11)
A) The process where microbes digest algae and consume oxygen.
B) A condition where a body of water is low in dissolved oxygen.
C) The enrichment of a body of water in nutrients.
D) A rapid increase in algae caused by agricultural runoff.
Correct Answer: C
The text explicitly states, 'Eutrophication occurs when a body of water is enriched in nutrients.' The other options describe steps or consequences of eutrophication, not the definition itself.
A) An immediate fish die-off.
B) A decrease in dissolved oxygen.
C) The water becomes hypoxic.
D) An algal bloom occurs.
Correct Answer: D
The text outlines a sequence of events: 'The increase in nutrients causes an algal bloom.' The other options are later consequences in the eutrophication process.
A) They are the primary producers in the algal bloom.
B) They digest dead algae and consume dissolved oxygen.
C) They release nutrients from wastewater into the ecosystem.
D) They are a food source for fish, preventing die-offs.
Correct Answer: B
The text specifies that 'When the bloom dies, microbes digest the algae and oxygen, leading to a decrease in dissolved oxygen levels.' This consumption of oxygen is their key role in creating hypoxic conditions.
A) Eutrophic
B) Anthropogenic
C) Hypoxic
D) Enriched
Correct Answer: C
The text provides a direct definition: 'Hypoxic waterways are those bodies of water that are low in dissolved oxygen.'
A) Algal blooms and microbial digestion.
B) Fish die-offs and oxygen depletion.
C) Natural nutrient decay and seasonal turnover.
D) Agricultural runoff and wastewater release.
Correct Answer: D
The text identifies human-caused sources directly: 'Anthropogenic causes of eutrophication are agricultural runoff and wastewater release.'
A) The algae release toxins that are poisonous to fish.
B) The decomposition of dead algae by microbes depletes the oxygen fish need to survive.
C) The excessive use of fertilizers in runoff is directly toxic to aquatic life.
D) The algal bloom blocks sunlight, causing the water temperature to drop rapidly.
Correct Answer: B
The text links the steps: microbes digest dead algae, which consumes oxygen. This leads to a decrease in dissolved oxygen, which in turn causes fish die-offs. The other options are not mentioned in the provided content.
A) Algal bloom -> Microbes digest algae -> Wastewater release -> Hypoxia
B) Hypoxia -> Fish die-off -> Algal bloom -> Nutrient enrichment
C) Agricultural runoff -> Nutrient enrichment -> Algal bloom -> Oxygen depletion
D) Microbes digest algae -> Oxygen depletion -> Nutrient enrichment -> Algal bloom
Correct Answer: C
This option correctly follows the causal chain described in the text: a human source (agricultural runoff) leads to nutrient enrichment, which causes an algal bloom, and the subsequent decomposition of that bloom leads to oxygen depletion (hypoxia).
A) Pesticides and herbicides
B) Fossil fuels and industrial chemicals
C) Fertilizers and detergents
D) Plastics and microfibers
Correct Answer: C
The first sentence of the content explicitly mentions 'the environmental effects of excessive use of fertilizers and detergents on aquatic ecosystems,' linking them directly to the problem.
A) As the bloom dies, it releases oxygen, causing dissolved oxygen levels to increase.
B) As the bloom dies, the microbes that decompose it consume oxygen, causing dissolved oxygen levels to decrease.
C) The death of the algal bloom has no direct effect on the dissolved oxygen level.
D) The dying algae physically prevent oxygen from the atmosphere from dissolving in the water.
Correct Answer: B
The text states that when the algal bloom dies, 'microbes digest the algae and oxygen, leading to a decrease in dissolved oxygen levels.' This shows a direct inverse relationship mediated by microbial activity.
A) Related to aquatic environments.
B) Caused by natural processes.
C) Beneficial to the ecosystem.
D) Originating from human activity.
Correct Answer: D
The text uses 'anthropogenic causes' in the context of 'agricultural runoff and wastewater release,' which are human activities. This implies that anthropogenic means human-caused.
A) Increased dissolved oxygen -> Increased fish populations -> Decreased algae
B) Runoff of nutrients -> Algal bloom -> Microbial decomposition -> Hypoxia
C) Wastewater release -> Decreased nutrients -> Algal bloom -> Fish die-off
D) Runoff of nutrients -> Immediate fish die-off -> Decreased microbial activity
Correct Answer: B
This question requires applying the entire eutrophication process to a specific scenario. The fertilizer runoff provides the nutrients, which causes the algal bloom. The death and decomposition of the bloom by microbes consumes oxygen, leading to hypoxic conditions.