AP Biology 8.2.C: Energy Availability and Ecosystems

Practise AP Biology 8.2.C questions by predicting how changes in sunlight, producers and energy resources affect trophic levels and ecosystems.

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

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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8.2.C—Explain how changes in energy availability affect populations, communities, and ecosystems question 1