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AP Environmental Science Practice Quiz: Food Chains and Food Webs

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 9 questions to check your progress.

Question 1 of 9

According to the provided text, what is the primary purpose of a food web model?

All Questions (9)

According to the provided text, what is the primary purpose of a food web model?

A) To illustrate the life cycle of a single keystone species.

B) To map the geographic distribution of organisms in an ecosystem.

C) To depict the flow of energy and nutrients among various organisms.

D) To quantify the total biomass at each trophic level.

Correct Answer: C

The provided content explicitly states that a food web is a model that 'depicts the flow of energy and nutrients in two or more food chains.'

How does the provided content distinguish a food web from a food chain?

A) A food web only includes producers, while a food chain includes consumers.

B) A food web is a model of an interlocking pattern of multiple food chains.

C) A food chain depicts nutrient flow, while a food web depicts energy flow.

D) A food web and a food chain are described as identical concepts.

Correct Answer: B

The text defines a food web as 'a model of an interlocking pattern of food chains,' indicating that a food web is a more complex representation that incorporates multiple food chains.

The provided text states that the members of food chains and food webs are organized by which of the following criteria?

A) Trophic level

B) Geographic location

C) Population size

D) Reproductive rate

Correct Answer: A

The first point of the content explicitly says to 'Describe food chains and food webs, and their constituent members by trophic level.'

Based on the principles described, what is the most direct and predictable consequence of adding a new, highly efficient predator to a stable food web?

A) The entire food web will remain unaffected due to its complexity.

B) The populations of the new predator's prey species are likely to decline.

C) All producer populations will immediately increase.

D) The new predator will form a separate food chain that does not interlock with the existing web.

Correct Answer: B

The content states that when a species is added, 'the rest of the food web can be affected.' The most direct effect of adding a predator is a decrease in the populations of the species it consumes (its prey).

A disease suddenly eliminates a species of primary consumer from an ecosystem. The population of its main predator declines, while the plant species it primarily fed on flourishes. This scenario best illustrates which concept from the text?

A) Food webs are static and resistant to change.

B) The removal of one species can affect the rest of the food web.

C) Positive feedback loops always stabilize an ecosystem.

D) Energy flows in a single, unbranching direction.

Correct Answer: B

This directly demonstrates the principle that 'When one species is removed from... a specific food web, the rest of the food web can be affected.' The effects are seen on both the trophic level above (predator) and below (producer).

The description of a food web as an 'interlocking pattern of food chains' emphasizes that...

A) most consumers feed on only one type of organism.

B) energy flows from consumers to producers.

C) ecosystems are composed of multiple, interconnected feeding relationships.

D) each trophic level has the same amount of energy.

Correct Answer: C

The term 'interlocking pattern' implies that species are not in simple, linear chains but are part of a complex network with multiple connections, where one organism may be prey for several predators and a predator may consume several types of prey.

In a marine food web, a decline in a small fish population causes its predator, the seal, to also decline. The seal's decline allows its own predator, the great white shark, to have less food, leading to a shark population decline. This chain of events, where a change at a lower trophic level causes a series of subsequent declines at higher levels, is an example of...

A) the interconnectedness and potential for cascading effects within a food web.

B) a negative feedback loop that quickly restores the fish population.

C) a positive feedback loop where the ecosystem becomes more stable.

D) the principle that trophic levels are independent of one another.

Correct Answer: A

This scenario highlights the core concepts that a food web is an 'interlocking pattern' and that removing or reducing one species 'can affect the rest of the food web.' The decline cascades up through the trophic levels, showing their interdependence.

Which of the following describes a negative feedback loop within a food web?

A) The removal of a keystone predator causes an explosion of its prey, which overgrazes vegetation, leading to a total ecosystem collapse.

B) An increase in a rabbit population provides more food for foxes, allowing the fox population to increase, which in turn reduces the rabbit population.

C) An invasive plant species outcompetes native plants, causing a decline in herbivores that cannot eat it, which further reduces predator populations.

D) A single producer species is removed, causing all dependent food chains to disappear permanently.

Correct Answer: B

The content mentions that negative feedback loops can play a role. A negative feedback loop is a stabilizing mechanism where the result of an action (an increased fox population) counteracts the initial change (the increased rabbit population), tending to bring the system back to a stable balance.

A warming climate allows a beetle to expand its range, killing a dominant tree species in a forest. The loss of the trees reduces the habitat for a specific bird, causing its population to decline. This is a clear example of how...

A) a change affecting one species can indirectly impact another through the food web.

B) food webs are solely determined by predator-prey relationships.

C) positive feedback loops always increase biodiversity.

D) energy flow in an ecosystem is a closed system.

Correct Answer: A

This illustrates the principle that 'the rest of the food web can be affected' when a change occurs. Although not a direct predator-prey interaction, the beetle's impact on the tree (a producer) alters the ecosystem structure, which then affects the bird population, demonstrating the interconnectedness of the web.