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AP Biology 8.2: Energy Flow Through Ecosystems

Practise AP Biology 8.2 questions by linking energy strategies, trophic transfers, matter cycles and producer changes with ecosystem dynamics.

Syllabus
Effective Fall 2025
Course
AP Biology

Exam points

  • compare endothermic, ectothermic, autotrophic and heterotrophic strategies for acquiring and using energy
  • trace energy through trophic levels and matter through water, carbon, nitrogen and phosphorus cycles
  • predict how changes in energy availability, producers or environmental conditions alter populations and ecosystems

Covered syllabus points

8.2.A—Describe the strategies organisms use to acquire and use energy8.2.B—Explain how energy flows and matter cycles through trophic levels8.2.C—Explain how changes in energy availability affect populations, communities, and ecosystems8.2.D—Explain how the activities of autotrophs and heterotrophs enable the flow of energy within an ecosystem

8.2 Energy Flow Through Ecosystems question 1

[Maximum number: 1]

The internal temperature of different organisms was determined under various conditions, as shown in the table below.

Table for Question 8.2 Energy Flow Through Ecosystems question 1 — AP Biology

Predict the internal temperature (in °C) of a goose that is flying just above the treetops when the external temperature is 7°C. Give your answer to the nearest whole number.

Figure for Question 8.2 Energy Flow Through Ecosystems question 1 — AP Biology

8.2 Energy Flow Through Ecosystems question 2

[Maximum number: 1]

Which of the following best describes the process by which gas from the atmosphere is obtained by plants and used to build lipids?

A

Gas is fixed by plants as part of the sulfur cycle.

B

Gas is fixed by plants as part of the nitrogen cycle.

C

Gas is directly obtained by plants as part of the carbon cycle.

D

Gas is directly obtained by plants as part of the magnesium cycle.

8.2 Energy Flow Through Ecosystems question 3

[Maximum number: 1]

Questions 34-38 A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for seven additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1).

Figure 1. A tray of grass seed, grown under light for 14 days

Figure 1. A tray of grass seed, grown under light for 14 days

Figure 2. Modifications made to sections II and III on day 14

Figure 2. Modifications made to sections II and III on day 14

TABLE 1. MASS OF GRASS GROWN IN EACH SECTION

TABLE 1. MASS OF GRASS GROWN IN EACH SECTION

Based on the data, which of the following is the most likely effect of a period of increased volcanic activity that significantly decreases the amount of sunlight reaching a particular ecosystem for several years?

A

There will be a decrease in the population sizes of most species and a decrease in the number of trophic levels.

B

The population sizes of plant species will stay the same, but the average biomass of individual plants will increase.

C

There will be an increase in the population sizes of omnivores because they can eat other animals instead of the plants.

D

The biodiversity of the ecosystem will increase as new niches arise and become occupied by new species.

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