PrepGo

AP Environmental Science Practice Quiz: The Nitrogen Cycle

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

Test your understanding with short quizzes. This quiz has 11 questions to check your progress.

Question 1 of 11

According to the provided text, what is the major reservoir of nitrogen?

All Questions (11)

According to the provided text, what is the major reservoir of nitrogen?

A) Plants

B) The atmosphere

C) Ammonia

D) Sinks

Correct Answer: B

The content explicitly states, 'The atmosphere is the major reservoir of nitrogen.'

What is the primary purpose of nitrogen fixation as described in the text?

A) To return nitrogen compounds to the atmosphere.

B) To move nitrogen between various sources and sinks.

C) To convert atmospheric nitrogen into a form usable by plants.

D) To ensure nitrogen is stored in reservoirs for long periods.

Correct Answer: C

The text defines nitrogen fixation as the process that converts atmospheric nitrogen into a form, primarily ammonia, 'that is available for uptake by plants.'

The nitrogen cycle is best defined as the movement of nitrogen-containing atoms and molecules between which two components?

A) The atmosphere and plants

B) Ammonia and the atmosphere

C) Reservoirs and the atmosphere

D) Sources and sinks

Correct Answer: D

The text directly defines the nitrogen cycle as 'the movement of atoms and molecules containing the element nitrogen between sources and sinks.'

Which statement accurately describes the residence time of nitrogen compounds in most reservoirs?

A) They are held for relatively short periods of time.

B) They are held for extremely long geological timescales.

C) The residence time is longest in plant reservoirs.

D) The residence time is constant across all reservoirs.

Correct Answer: A

The provided content states, 'Most of the reservoirs in which nitrogen compounds occur hold those compounds for relatively short periods of time.'

The process of nitrogen fixation involves the conversion of nitrogen from which major reservoir?

A) Plant biomass

B) Soil sinks

C) The atmosphere

D) Ammonia sources

Correct Answer: C

The text specifies that nitrogen fixation is the process where 'atmospheric nitrogen is converted.' It also identifies the atmosphere as the 'major reservoir of nitrogen,' linking the process directly to the reservoir.

What is the primary chemical product of nitrogen fixation mentioned in the text?

A) Nitrogen gas

B) Plant protein

C) Ammonia

D) Nitrogen atoms

Correct Answer: C

The text states that atmospheric nitrogen is converted into a form '(primarily ammonia)'.

Based on the text, which of the following represents a key interaction between reservoirs in the nitrogen cycle?

A) Nitrogen is held for long periods in sinks before being released to sources.

B) Plants directly absorb nitrogen from the atmosphere, its largest reservoir.

C) Nitrogen moves from the atmospheric reservoir to be made available for plant uptake through fixation.

D) Ammonia is converted back into atmospheric nitrogen to complete the cycle.

Correct Answer: C

This statement correctly synthesizes multiple points from the text: the atmosphere is the major reservoir, and fixation converts this atmospheric nitrogen into a form that plants can take up.

The text implies that atmospheric nitrogen is not directly available to plants because...

A) it is held in reservoirs for too short a time.

B) the atmosphere is a sink, not a source.

C) it must first be converted through nitrogen fixation.

D) it is the smallest reservoir of nitrogen.

Correct Answer: C

The text states that nitrogen fixation converts atmospheric nitrogen into a form 'that is available for uptake by plants.' This implies the original atmospheric form is not available and requires this conversion process.

Which of the following is a key characteristic of the nitrogen cycle, as opposed to some other biogeochemical cycles?

A) Its primary reservoir is in sedimentary rock.

B) The element is not essential for living organisms.

C) Compounds are held in most reservoirs for relatively short periods.

D) It does not involve the atmosphere in any step.

Correct Answer: C

The text explicitly mentions that 'Most of the reservoirs in which nitrogen compounds occur hold those compounds for relatively short periods of time,' which is a distinguishing feature.

Combining the information provided, the atmosphere can be best described as a major...

A) sink for plant-available nitrogen.

B) source of nitrogen for the fixation process.

C) reservoir where nitrogen is held briefly before conversion.

D) product of the movement between sources and sinks.

Correct Answer: B

The text identifies the atmosphere as the major reservoir and states that nitrogen fixation converts 'atmospheric nitrogen.' Therefore, the atmosphere acts as the primary source for this crucial step in the cycle.

A student claims that the nitrogen cycle primarily involves the long-term storage of nitrogen in various reservoirs. Which piece of evidence from the text contradicts this claim?

A) The atmosphere is the major reservoir of nitrogen.

B) Nitrogen fixation converts atmospheric nitrogen into ammonia.

C) The cycle involves movement between sources and sinks.

D) Nitrogen compounds are held in most reservoirs for relatively short periods.

Correct Answer: D

The student's claim of 'long-term storage' is directly contradicted by the statement: 'Most of the reservoirs in which nitrogen compounds occur hold those compounds for relatively short periods of time.'