CourseCourseConceptConceptDocumentDocument

AP Biology 8.2 Energy Flow Through Ecosystems Questions

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

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 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 1 — AP Biology

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.

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.

Question 4

[Maximum number: 1]

Questions 12-17

Certain reef-building corals contain photosynthetic, symbiotic algae that have the ability to make dimethylsulphoniopropionate (DMSP), a chemical involved in the marine sulfur cycle. DMSP is released into the surrounding water, where it is converted to the gas dimethyl sulfide (DMS) by microorganisms and enters the atmosphere. Once in the atmosphere, it triggers the formation of sulfate aerosols, which induce cloud formation and block sunlight from heating up the water. The symbiotic algae produce DMSP when they are stressed by a high water temperature. If water temperature is too high, corals will expel the symbiotic algae that produce DMSP.

Researchers measured the amount of DMSP produced by juvenile and adult coral and their symbionts under normal and thermally stressed conditions. The data are shown in the graphs in Figure 1.

Figure 1: DMSP concentration in juvenile and adult corals and their symbionts in normal and thermally-stressed conditions. Error bars represent \(\pm 2 \mathrm{SE}_{x}\)

Figure 1: DMSP concentration in juvenile and adult corals and their symbionts in normal and thermally-stressed conditions. Error bars represent \(\pm 2 \mathrm{SE}_{x}\)

The researchers also measured the density of the symbiont as well as the photosynthetic yield in adult corals at the two temperatures. Photosynthetic yield is an index measure of energy output compared to sunlight energy input in which larger photosynthetic yield values represent photosynthetic organisms producing more energy.

Figure 2: Variation in symbiont density and photosynthetic yield in adult corals grown in normal and thermally-stressed conditions. Error bars represent \(\pm 2 \mathrm{SE}_{x}\)

Figure 2: Variation in symbiont density and photosynthetic yield in adult corals grown in normal and thermally-stressed conditions. Error bars represent \(\pm 2 \mathrm{SE}_{x}\)

Which of the following best explains the result of adult corals being exposed to elevated temperatures for extended periods?

A

They are able to obtain more energy from their symbionts because the algae are receiving more light.

B

They are able to obtain more energy from their symbionts because the efficiency increases slightly over time.

C

They are able to obtain less energy from their symbionts because the algae have been expelled.

D

They are able to obtain less energy from their symbionts because more DMSP is being produced at lower temperatures.

All question bank results loaded