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Test Prep for AP<sup>®</sup> Courses
35.
Producers and consumers are necessary for ecosystem function and for energy to pass through an ecosystem. What might happen in an aquatic system with excess producers relative to consumers?
  1. Oxygen depletion would result in dieoff.
  2. There would be no basal energy source.
  3. Carbon cannot be sequestered.
  4. There would be more undigestable animal parts.
36.
Energy is a fundamental component in an ecosystem and is contributed by the primary producers. Describe how light energy can, in turn, support the consumers of an ecosystem.
  1. Light energy is converted to chemical energy by primary producers and primary consumers. Consumers belonging to higher trophic levels feed on them to gain energy.
  2. Primary producers can only obtain energy from sunlight to chemical energy using photosynthesis and gain energy by feeding on them or other consumers which have consumed these producers.
  3. Primary producers convert light energy by photosynthesis and consumers gain energy by feeding on them or other consumers which have consumed these producers.
  4. Primary producers convert light energy through chemosynthesis and consumers gain energy by feeding on them or other consumers which have consumed these producers.
37.
In a microcosm experiment using fish tanks to mimic a lake environment, an increase in the number of stickleback species would increase the dissolved organic carbon particle size. How could this affect primary producers in the ecosystem?
  1. enhance growth rate
  2. increase abundance
  3. decrease abundance
  4. maintain growth rate
38.
Studies on stickleback fish revealed that the presence of two species of stickleback reduced the amount of algal blooms relative to the presence of one species of stickleback in a microcosm experiment. How does this occur?
  1. This occurred as the presence of two species caused an increase in dissolved organic carbon molecule size, which blocked the penetration of light in water and prevented algal photosynthesis.
  2. This occurred because two stickleback species consumed all the nutrients which prevented algae from being able to grow.
  3. This occurred because dissolved organic carbon molecule size increased in the presence of one fish species which increased the amount of algal blooms.
  4. This occurred as algae are consumed in greater amounts in the presence of two stickleback species.
39.

This figure depicts energy exchange through trophic levels. Which level represents the primary producers?

A pyramid chart is broken into four categories labeled A through D, from top, which smallest, to bottom, which is largest.

  1. A
  2. B
  3. C
  4. D
40.
Using the flow chart showing carbon flow in a grassland ecosystem, how much carbon, in grams per meter squared, is released into the atmosphere as a result of the metabolic activity of herbivores? Give your answer to the nearest whole number.
A flow chart is titled Carbon Flow in a Grassland Ecosystem. At the bottom, a box labeled Soil-Decomposers has an arrow extending to the right labeled Respiration 336 grams per meter squared. There are three other boxes above it that all have allowed pointing to the box labeled Soil-Decomposers. On the left, there is a box labeled Grass that has two arrows pointing to the Soil-Decomposers box. One arrow reads 250 grams per meter squared, roots, and the other arrow reads 125 grams per meter squared, litter. Another arrow from the Grass box points to a box labeled Herbivores in the middle and is labeled 125 grams per meter squared. The Herbivore box has an upward-pointing arrow labeled Respiration, and arrow to the Soil-Decomposers box that reads 60 grams per meter squared, and an arrow to a Predators box to the right labeled 5 grams per meter squared. The Predators box has an upward-pointing arrow labeled Respiration and 4 grams per meter squared, as well as an arrow pointing to the Soil-Decomposers box labeled 1 gram per meter squared.
 
  1. 125 g/m2
  2. 65 g/m2
  3. 60 g/m2
  4. 5 g/m2
41.

The food web for a meadow habitat occupies 25.6 km2. The primary producers’ biomass is uniformly distributed throughout the habitat and totals 1,500 kg/km2. This figure shows a food web with Meadow grasses at the bottom with three arrows extending upward. The first arrow points to Deer, then there is an arrow from Deer to Coyote. The second arrow points to Rabbit, which has an arrow to Coyote and an arrow to Hawk. The third arrow points to Vole, which has an arrow pointing to Hawk.

Developers have approved a project that will permanently reduce the primary producers’ biomass by 50 percent and remove all rabbits and deer. What is the most likely result at the completion of the project?

  1. The biomass of coyotes will be 6 kg, and the biomass of hawks will be 0.5 kg.
  2. The biomass of coyotes will be dramatically reduced.
  3. The coyotes will switch prey preferences and outcompete the hawks.
  4. There will be 50 percent fewer voles and 90 percent fewer hawks.

42.

This figure shows a food web of an ecosystem.

This figure shows a food web. At the bottom, labeled D, is a photo of Diatoms. Two arrows extend from Diatoms to level C, one to a photo of Zebra/Quagga mussels and the other to a photo of Chironomids. Two arrows extend from the Zebra/Quagga mussels level B, one to a photo of Lake Whitefish and one to a photo of Round Goby. Two arrows extend from Chironomids to level B, one to a photo of Round Goby and one to a photo of Slimy Sculpin. One arrow extends from Lake Whitefish to a photo of a Sea Lamprey at level A. Three arrows from the Round Goby and from the Slimy Sclupin extend to photos of Sea Lamprey, Burbot, and Lake Trout at level A. Both Burbot and Lake Trout have arrows pointing to Sea Lamprey.
 
What would happen to the food web if all of the species of the entire row B was wiped out by a natural disaster such as an oil spill? Why?
  1. The producers may die out, causing the food web to collapse.
  2. The food web would not be affected as the secondary and tertiary consumers would become primary and secondary consumers, respectively.
  3. The tertiary consumers would die out due to lack of food and this could potentially lead to collapse of the entire food web.
  4. The food web might suffer from loss of primary producers for a while which would then recover quickly, thus, reviving the ecosystem.
43.
Humans are very active in modifying ecosystems worldwide. If a new set of buildings on the edge of a forest blocks sunlight from reaching the majority of one part of the forest, what might happen to that part of the forest?
  1. Herbivores would occur in high abundance.
  2. Plants would occur in high abundance.
  3. Everything would remain the same.
  4. Herbivores would occur in low abundance.
44.
If you examined predator-prey relationships within an ecosystem and noticed that the removal of predators also resulted in the die-off of herbivores, what would you suspect occurred?
  1. Removal of predators would directly lower the number of herbivores.
  2. The lack of predators could mean that too much primary production occurred.
  3. Herbivores from another region may have entered the ecosystem and consumed the primary producers, causing death of the original herbivores species.
  4. Overeating by herbivores could have caused depletion of the primary producers, leaving the herbivores without enough food.
45.
Although producers are essential for energy to flow into an ecosystem, consumers also have important roles. What might happen in an aquatic system with excess consumers relative to producers?
  1. Oxygen depletion would result in dieoff.
  2. There would be an excess of the basal energy source.
  3. Consumers would deplete the abundance of producers.
  4. There would be more undigestable animal parts.
46.
The following is the equation for trophic level transfer efficiency: (production at present trophic level/production at past trophic level)×100. If primary producers produce 1600 kcal/m2, and primary consumers have 800 kcal/m2, what is the trophic level transfer efficiency?
  1. 50
  2. 200
  3. 800
  4. 1600
47.
There are four trophic levels in a food chain and the amount of energy at the trophic level of the primary producer is 33,000 kcal/m2. Which of the following represents the amount of energy of the tertiary consumer?
  1. 75 kcal/m2
  2. 500 kcal/m2
  3. 11,000 kcal/m2
  4. 33,000 kcal/m2
48.

Why does this figure show a higher value of gross productivity for the decomposers than the tertiary consumers?

The figure shows a flow chart. At the top of the chart, there is a circle labeled Sunlight 1,700,000 kcal per meter squared per year with an arrow pointing to the primary producers. The box labeled Primary producers shows that they have a gross productivity of 20,810 calories per meter squared per year and a net productivity of 7,618. An arrow extends from the Primary producers to a box labeled Primary consumers that box shows a gross productivity of 3,368 and a net productivity of 1,103. An arrow extends from the Primary consumers to a box labeled Secondary consumers that shows a gross productivity of 383 and a net productivity of 111. An arrow extends from the Secondary consumers to a box labeled Tertiary consumers that shows a gross productivity of 21 and a net productivity of 5. An arrow extends from the Tertiary consumers to a box labeled Decomposers tat shows a gross productivity of 5,060. Lines extend from each box, not the circle representing the sun, to a line running along the left side of the figure labeled respiration plus heat that ends in an arrow to a box at the bottom of the figure labeled Total heat and respiration 20,810. Lines extend from each box to a line running along the left side of the figure, with the bottom line representing an arrow to the Decomposers box.

  1. Due to the difference in conversion efficiencies of decomposers and tertiary consumers.
  2. Because large animals are tertiary consumers whereas small microorganisms are decomposers.
  3. Because tertiary consumers only consume secondary consumers whereas decomposers consume dead components of each trophic level.
  4. Because tertiary consumers only consume primary consumers whereas decomposers consume dead components of each trophic level.
49.
One of the key concerns about global climate change is excess amounts of carbon being released into the atmosphere. There are, however, some ways in which carbon can be sequestered from the atmosphere. Which of the following is a natural process that promotes carbon sequestration?
  1. burning fossil fuels
  2. methane from cattle
  3. photosynthesis by plants
  4. volcanic eruption