AP Environmental Science Practice Quiz: Primary Productivity

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

Test your understanding with short quizzes. This quiz has 12 questions to check your progress.

Question 1 of 12

What is the definition of primary productivity?

A)The rate at which solar energy is converted into organic compounds via photosynthesis.B)The total mass of living organisms in a given area.C)The energy transferred from producers to consumers.D)The rate at which decomposers break down organic matter.

All Questions (12)

What is the definition of primary productivity?

A) The rate at which solar energy is converted into organic compounds via photosynthesis.

B) The total mass of living organisms in a given area.

C) The energy transferred from producers to consumers.

D) The rate at which decomposers break down organic matter.

Correct Answer: A

Based on the provided content, 'Primary productivity is the rate at which solar energy (sunlight) is converted into organic compounds via photosynthesis over a unit of time.'

Which term describes the total rate of photosynthesis in a given area, before accounting for the energy used by the producers themselves?

A) Net primary productivity

B) Gross primary productivity

C) Secondary productivity

D) Trophic level efficiency

Correct Answer: B

The content defines Gross primary productivity as 'the total rate of photosynthesis in a given area.' This is the total energy captured before any is used for respiration.

Net primary productivity (NPP) is best described as the rate of energy that is:

A) captured by photosynthesis plus the energy lost to respiration.

B) transferred from consumers to decomposers.

C) stored by photosynthesizers after subtracting the energy lost to their own respiration.

D) reflected back into the atmosphere by producers.

Correct Answer: C

The provided text states that Net primary productivity is 'the rate of energy storage by photosynthesizers in a given area, after subtracting the energy lost to respiration.'

If the gross primary productivity of an ecosystem is 2,500 kcal/m²/yr and the energy lost to respiration by producers is 1,500 kcal/m²/yr, what is the net primary productivity (NPP)?

A) 4,000 kcal/m²/yr

B) 2,500 kcal/m²/yr

C) 1,500 kcal/m²/yr

D) 1,000 kcal/m²/yr

Correct Answer: D

Net primary productivity is calculated by subtracting the energy lost to respiration (R) from the gross primary productivity (GPP). Therefore, NPP = GPP - R = 2,500 - 1,500 = 1,000 kcal/m²/yr.

Which of the following represents a correct unit for measuring primary productivity?

A) grams per meter

B) kilocalories per square meter per year

C) degrees Celsius per day

D) joules

Correct Answer: B

The content specifies that 'Productivity is measured in units of energy per unit area per unit time (e.g., kcal/m²/yr).'

In a deep aquatic ecosystem, a lack of visible light in lower depths directly limits which of the following?

A) The rate of decomposition

B) The rate of photosynthesis

C) The total number of consumers

D) The water temperature

Correct Answer: B

The provided text explains that 'The absorption of light in water affects photosynthesis in aquatic ecosystems.' A lack of light directly inhibits the process of photosynthesis.

The fundamental process by which living organisms acquire solar energy and convert it into organic compounds is known as:

A) Respiration

B) Photosynthesis

C) Decomposition

D) Chemosynthesis

Correct Answer: B

Content point 2 explicitly states that solar energy is converted into organic compounds 'via photosynthesis'.

What does the value of net primary productivity (NPP) represent for the higher trophic levels in an ecosystem?

A) The total solar energy input into the ecosystem.

B) The energy lost as heat by producers.

C) The energy available for consumption by herbivores.

D) The rate of nutrient recycling.

Correct Answer: C

NPP is the 'rate of energy storage by photosynthesizers.' This stored energy, in the form of biomass, is what becomes available to the next trophic level (herbivores) when they consume the producers.

The difference between Gross Primary Productivity (GPP) and Net Primary Productivity (NPP) is accounted for by:

A) Energy consumed by herbivores.

B) Energy lost to decomposition.

C) Energy lost to metabolic processes like respiration by producers.

D) Energy reflected from the producers' surfaces.

Correct Answer: C

NPP is defined as GPP minus the 'energy lost to respiration.' This respiratory loss represents the producers' own metabolic energy needs.

Aquatic photosynthesizers have developed adaptations to cope with what specific challenge mentioned in the text?

A) High levels of water pollution

B) Fluctuations in water temperature

C) The lack of visible light at certain depths

D) The high pressure in deep water

Correct Answer: C

The content states that 'photosynthesizers have adapted mechanisms to address the lack of visible light' due to the absorption of light in water.

A scientist measures the total amount of carbon fixed into organic molecules by phytoplankton in a specific volume of ocean water over a day. This measurement represents the:

A) Net primary productivity (NPP)

B) Gross primary productivity (GPP)

C) Standing crop of phytoplankton

D) Rate of cellular respiration

Correct Answer: B

Measuring the *total* amount of carbon fixed or organic compounds produced by photosynthesis, before accounting for what the phytoplankton use for their own life processes, is a measure of the Gross Primary Productivity (GPP).

Primary productivity is a measure of a rate, meaning it must be measured over a unit of:

A) Mass

B) Volume

C) Time

D) Distance

Correct Answer: C

The definition of primary productivity is the 'rate at which solar energy... is converted... over a unit of time.' The example unit, kcal/m²/yr, also includes a unit of time (yr).