CHAPTER 42 Flashcards

A 3-hectare lake in the American Midwest suddenly has succumbed to an algal bloom. What
is the likely cause of eutrophication in freshwater ecosystems, such as this one?
A) increased solar radiation
B) introduction of non-native tertiary consumer fish
C) nutrient-rich runoff
D) accidental introduction of a prolific culture of algae
E) iron dust blowing into the lake

Approximately how many kg of carnivore biomass can be supported by a field plot
containing 1,000 kg of plant material?
A) 10,000
B) 1,000
C) 100
D) 10
E) 1

The amount of chemical energy in a consumer's food that is converted to its own new
biomass during a given time period is known as which of the following?
A) biomass
B) standing crop
C) biomagnification
D) primary production
E) secondary production

What is secondary production?
A) energy converted by secondary consumers from primary consumers
B) solar energy that is converted to chemical energy by photosynthesis
C) food that is converted to new biomass by consumers
D) energy that is not used by consumers for growth and reproduction
E) growth that takes place during the second year of life in consumers

How does inefficient transfer of energy among trophic levels result in the typically high
endangerment status of many top-level predators?
A) Top-level predators are destined to have small populations that are sparsely distributed.
B) Predators have relatively large population sizes.
C) Predators are more disease-prone than animals at lower trophic levels.
D) Predators have short life spans and short reproductive periods.
E) Top-level predators are more likely to be stricken with parasites.

Trophic efficiency is
A) the ratio of net secondary production to assimilation of primary production.
B) the percentage of production transferred from one trophic level to the next.
C) a measure of how nutrients are cycled from one trophic level to the next.
D) usually greater than production efficiencies.
E) about 90% in most ecosystems.

Owls eat rats, mice, shrews, and small birds. Assume that, over a period of time, an owl
consumes 5,000 J of animal material. The owl loses 2,300 J in feces and owl pellets and uses
2,600 J for cellular respiration. What is the production efficiency of this owl?
A) 0.02%
B) 1%
C) 4%
D) 10%
E) 40%

Why does a vegetarian leave a smaller ecological footprint than an omnivore?
A) Fewer animals are slaughtered for human consumption.
B) There is an excess of plant biomass in all terrestrial ecosystems.
C) Vegetarians need to ingest less chemical energy than omnivores.
D) Vegetarians require less protein than do omnivores.
E) Eating meat is an inefficient way of acquiring photosynthetic productivity.

For most terrestrial ecosystems, pyramids composed of species abundances, biomass, and
energy are similar in that they have a broad base and a narrow top. The primary reason for this
pattern is that
A) secondary consumers and top carnivores require less energy than producers.
B) at each step, energy is lost from the system because of the second law of thermodynamics.
C) as matter passes through ecosystems, some of it is lost to the environment.
D) biomagnification of toxic materials limits the secondary consumers and top carnivores.
E) top carnivores and secondary consumers have a more general diet than primary producers.

Which of the following is primarily responsible for limiting the number of trophic levels in
most ecosystems?
A) Many primary and higher-order consumers are opportunistic feeders.
B) Decomposers compete with higher-order consumers for nutrients and energy.
C) Nutrient cycles involve both abiotic and biotic components of ecosystems.
D) Nutrient cycling rates tend to be limited by decomposition.
E) Energy transfer between trophic levels is almost always less than 20% efficient.

Which trophic level is most vulnerable to extinction?
A) producer level
B) primary consumer level
C) secondary consumer level
D) tertiary consumer level
E) decomposer level

Which statement best describes what ultimately happens to the chemical energy that is not
converted to new biomass in the process of energy transfer between trophic levels in an
ecosystem?
A) It is undigested and winds up in the feces and is not passed on to higher trophic levels.
B) It is used by organisms to maintain their life processes through the reactions of cellular
respiration.
C) Heat produced by cellular respiration is used by heterotrophs to thermoregulate.
D) It is eliminated as feces or is dissipated into space as heat in accordance with the second law
of thermodynamics.
E) It is recycled by decomposers to a form that is once again usable by primary producers.

Consider the food chain grass → grasshopper → mouse → snake → hawk. How much of the
chemical energy fixed by photosynthesis of the grass (100%) is available to the hawk?
A) 0.01%
B) 0.1%
C) 1%
D) 10%
E) 60%

If the flow of energy in an arctic ecosystem goes through a simple food chain, perhaps
involving humans, starting from phytoplankton to zooplankton to fish to seals to polar bears,
then which of the following could be true?
A) Polar bears can provide more food for humans than seals can.
B) The total biomass of the fish is lower than that of the seals.
C) Seal meat probably contains the highest concentrations of fat-soluble toxins.
D) Seal populations are larger than fish populations.
E) The fish can potentially provide more food for humans than the seal meat can.

Nitrogen is available to plants mostly in the form of
A) N2 in the atmosphere.
B) nitrite ions in the soil.
C) uric acid from animal excretions.
D) nucleic acids from decomposing plants and animals.
E) nitrate and ammonium ions in the soil.

Which of the following locations is the main reservoir for nitrogen in Earth’s nitrogen cycle?
A) atmosphere
B) sedimentary bedrock
C) fossilized plant and animal remains (coal, oil, and natural gas)
D) plant and animal biomass
E) soil

Which of the following locations is the reservoir for carbon in the carbon cycle?
A) atmosphere
B) sediments and sedimentary rocks
C) fossilized plant and animal remains (coal, oil, and natural gas)
D) plant and animal biomass
E) all of the above

In the nitrogen cycle, the bacteria that replenish the atmosphere with N2 are
A) Rhizobium bacteria.
B) nitrifying bacteria.
C) denitrifying bacteria.
D) methanogenic protozoans.
E) nitrogen-fixing bacteria.

How does phosphorus normally enter ecosystems?
A) cellular respiration
B) photosynthesis
C) rock weathering
D) vulcanism
E) atmospheric phosphorous gas

Which of the following statements is correct about biogeochemical cycling?
A) The phosphorus cycle involves the recycling of atmospheric phosphorus.
B) The phosphorus cycle involves the weathering of rocks.
C) The carbon cycle is a localized cycle that primarily involves the burning of fossil fuels.
D) The carbon cycle has maintained a constant atmospheric concentration of CO2 for the past
million years.
E) The nitrogen cycle involves movement of diatomic nitrogen between the biotic and abiotic
components of the ecosystem.

Why do logged tropical rain forest soils typically have nutrient-poor soils?
A) Tropical bedrock contains little phosphorous.
B) Logging results in soil temperatures that are lethal to nitrogen-fixing bacteria.
C) Most of the nutrients in the ecosystem are removed in the harvested timber.
D) The cation exchange capacity of the soil is reversed as a result of logging.
E) Nutrients evaporate easily into the atmosphere in the post-logged forest.

What is the first step in ecosystem restoration?
A) to restore the physical structure
B) to restore native species that have been extirpated due to disturbance
C) to remove competitive invasive species
D) to identify the limiting factors of the producers
E) to remove toxic pollutants

What is the goal of restoration ecology?
A) to replace a ruined ecosystem with a more suitable ecosystem for that area
B) to speed up the restoration of a degraded ecosystem
C) to completely restore a disturbed ecosystem to its former undisturbed state
D) to prevent further degradation by protecting an area with park status
E) to manage competition between species in human-altered ecosystems

Which of the following relies upon existing biodiversity for the decontamination of polluted
ecosystems?
A) Some types of bacteria naturally convert toxins to less hazardous forms.
B) Sawdust from lumber mills can be used to soak up chemicals that have saturated natural
ecosystems.
C) Species in contaminated areas may evolve into forms that can survive in contaminated soils.
D) After centuries of agricultural production, soils depleted of nitrogen can be replenished by
promoting the growth of nitrogen-fixing organisms.

Which of the following would be considered an example of bioremediation?
A) using a bulldozer to reshape the land around an abandoned strip mine to change erosion
patterns
B) dredging a river bottom to remove contaminated sediments
C) reconfiguring the channel of a river to increase the flow of water down a river
D) raising chromium-accumulating plants to extract chromium from contaminated soil
E) selectively harvesting younger trees in a forest to leave older trees for woodpecker nesting
habitat

To selectively remove soil toxins from regions affected by Hurricane Katrina, some residents
have raised sunflowers and other plants in their yards. Then, the mature plants are pulled up and
safely stored with other contaminated wastes. This is an example of
A) biological augmentation.
B) reducing primary production.
C) lowering production efficiency.
D) bioremediation.
E) arresting nutrient cycling.

Corn production in many states of the Midwest is limited by nitrogen levels in the soil. Some
farmers reduce the need to apply expensive anhydrous ammonia to their fields by rotating corn
crops with nitrogen-fixing soybean crops. Using soybeans to add nitrogen to soils is an example
of
A) biological augmentation.
B) the biomass pyramid.
C) promoting leaching efficiency.
D) bioremediation.
E) trophic efficiency.