CH37-COMMUNITY AND ECOSYSTEM ECOLOGY

A community is composed of A) potentially interacting populations of different kinds of organisms. B) one species of organism living in a specific environment on Earth. C) living organisms and their nonliving environment. D) the factors that constitute an organism's niche.

One reason it is important to understand community ecology is A) to understand the life cycle of fish, such as cichlids. B) for identification of stomach microbes. C) to aid in conservation of endangered species. D) to provide an enriched habitat for humans.

When a crocodile eats a fish, the interspecific interaction between the two could be expressed as ________ for the crocodile and ________ for the fish. A) . . . B) + . . . + C) + . . . D) . . . +

The feeding relationships among the species of a community is the community's A) niche. B) diversity. C) density. D) richness. E) trophic structure.

If an overlap develops between the ranges of two closely related species, and if the species occupy the same niche in the zone of overlap, what will probably happen in the zone of overlap? A) A new species will arise by hybridization. B) Both species will coexist, provided the environment in the zone of overlap is different from that in either individual range. C) Both species will coexist, provided the environment in the zone of overlap is similar to that of one of the individual ranges. D) The species will partition the zone so that half of it is added to the range of each species and there is no overlap. E) One species will take over most or all of the zone of overlap.

According to the competitive exclusion principle, two species cannot continue to occupy the same A) environmental habitat. B) ecological niche. C) territory. D) range. E) biome.

If an overlap develops between the ranges of two closely related species, and if the species occupy the same niche in the zone of overlap, what will probably happen in the zone of overlap? A) A new species will arise by hybridization. B) Both species will coexist, provided the environment in the zone of overlap is different from that in either individual range. C) Both species will coexist, provided the environment in the zone of overlap is similar to that of one of the individual ranges. D) One species will take over most or all of the zone of overlap

Dinoflagellates are important to coral and coral-dwelling animals because they A) produce energy that is used by coral animals through photosynthesis. B) provide shelter for the fast-growing seaweeds associated with coral. C) produce CO2 and nitrogen for coral. D) are toxic to species that prey on reef-dwelling fish.

The differentiation of niches that enables similar species to coexist in a community is called A) resource partitioning. B) the competitive exclusion principle. C) interspecific competition. D) niche competition. E) resource reduction.

We expect that a keystone species that is a predator will A) maintain the species diversity in a community. B) harvest prey species down to extinction. C) help many of its prey reproduce. D) be a parasite. E) More than one of the choices is correct

Some herbivore-plant interactions evolved through a series of reciprocal evolutionary adaptations in both species. The process is called A) herbivory. B) coevolution. C) selection. D) trophism.

Most plants have a variety of chemicals, spines, and thorns because the plants A) cannot run away from herbivores. B) feed on the organisms that try to eat them. C) are camouflaged into their surroundings. D) are adapted to attract herbivores. E) are relying upon Batesian mimicry.

The relationship between cattle and the birds that eat insects stirred up by grazing cattle is an example of A) predation. B) parasitism. C) mutualism. D) commensalism. E) interspecific competition.

When a New England farm is abandoned, its formerly plowed fields first become weedy meadows, then shrubby areas, and finally forest. This sequence of plant communities is an example of A) evolution. B) a phylogenetic trend. C) a trophic chain. D) secondary succession. E) genetic drift.

During ecological succession, the species composition of a plant community generally A) changes from a diverse community in which many plants are common to one in which a few species are numerically dominant. B) simplifies until most of the plants originally present have disappeared. C) remains stable as long as major environmental factors (climate, human interference) remain constant. D) changes gradually because each species responds differently to the changing environment. E) changes until climax forest is established and a single species remains.

Which one of the following statements is false? A) Small-scale disturbances rarely have positive effects. B) Storms, fire, freezing, glacial advance and retreat, and volcanic eruptions are types of disturbances. C) Primary succession occurs when a community arises in a virtually lifeless area with no soil. D) Secondary succession occurs where a disturbance has destroyed an existing community but left the soil intact. E) The transition in species composition in a community is called ecological succession.

If left under otherwise natural conditions, which of the following ecosystems would quickly change into a different type if fire was suppressed? A) deciduous forest B) desert C) tallgrass prairie D) freshwater marsh E) None of the choices would change significantly.

In a hypothetical food chain consisting of grass, grasshoppers, sparrows, and hawks, the grasshoppers are A) primary consumers. B) primary producers. C) secondary consumers. D) secondary producers. E) detritivores.

A hypothetical community on a barren mid-Atlantic island consists of two fish-eating seabirds (the booby and the noddy), fungi and microorganisms that live on the birds' dung, a tick that feeds on these two birds, a cactus, a moth that feeds on cast-off feathers, a beetle that lives on dung organisms, and spiders that eat the other arthropods. There are no plants and no lichens. Which of the following choices incorrectly pairs a member of this assemblage with its position in the trophic structure? A) spiders, secondary consumer B) booby and noddy birds, primary consumers C) fungi, detritivores D) moths, detritivores E) the cactus is a producer

In a food chain consisting of phytoplankton → zooplankton → fish → fishermen, the fishermen are A) primary consumers. B) secondary consumers. C) tertiary consumers. D) primary producers. E) secondary producers.

The primary decomposers of a community are called A) primary consumers. B) detritivores. C) primary producers. D) protozoa. E) herbivores.

The number of species in a community is called the A) species diversity. B) species richness. C) species population. D) species index.

We expect that a keystone species that is a predator will A) maintain the species diversity in a community. B) harvest prey species down to extinction. C) help many of its prey reproduce. D) reduce the diversity of the community.

Non-native species that are introduced in new environments, spread far beyond the original point of introduction, and cause damage are called A) destructive species. B) enemy species. C) invasive species. D) proprietary species.

The flow of ________ into ecosystems occurs in one direction only, while ________ are recycled within the ecosystem itself. A) minerals . . . energy compounds B) genetic information . . . genotypes C) organic compounds . . . minerals D) energy . . . chemicals

A hypothetical grassland community has the following five trophic levels: (1) grasses and other plants; (2) herbivores, such as aphids, rodents, and antelope; (3) carnivores, such as ladybugs and weasels, that feed mainly on herbivores; (4) carnivores, such as wolves and hawks, that feed on level (3) carnivores as well as on herbivores; and (5) detritivores, such as vultures, fungi, and bacteria. If a drought occurred, which of the consumer levels would most likely be affected first? (Assume that adequate drinking water remains available.) A) 2 B) 3 C) 4 D) 5 E) 3 and 4

A biology teacher takes fish, algae, pond weed, invertebrates, and bottom muck from a local pond and establishes them in an aquarium. When the system is stable, the teacher seals it into a large, airtight glass box and leaves the box in a sunny location. After 3 months, the organisms in the aquarium appear alive and healthy. Which of the following statements about the experiment is false? A) No energy has entered or left the glass box during the 3 months. B) Some of the energy in the system has moved from one organism to another during the 3 months. C) Some atoms from water molecules have become parts of organic molecules. D) The air in the glass box contains carbon dioxide. E) During the 3 months, the biomass of plant life was greater than the biomass of animal life

For a given area and time period, the amount of solar energy converted to chemical energy is called A) primary succession. B) secondary succession. C) primary production. D) secondary production. E) primary photosynthesis.

In a certain ecosystem, field mice are preyed on by snakes and hawks. The entry of wild dogs into the system adds another predator of the mice. Of the following, the most likely short-term result of this addition is A) an increase in snake population. B) a tendency for hawks to prey on the dogs. C) a reduction in numbers of mice. D) migration of the hawks to another ecosystem.

You want to do all that you can to safeguard the environment by preserving energy. One simple thing that you can do is to eat a diet consisting only of organisms that are A) producers. B) primary consumers. C) secondary consumers. D) a mix of producers and consumers.

In an average ecosystem, about how much energy is present in the organisms at a given trophic level compared to the organisms at the next higher trophic level? A) a tenth as much B) half as much C) twice as much D) ten times as much E) It is impossible to say without knowing which trophic levels are involved.

Which of the following substances is not cycled between organic matter and abiotic reservoirs? A) water B) carbon C) nitrogen D) phosphorus E) All of the choices are cycled between biotic and abiotic reservoirs

Which of the following frequently cycles through the environment, bypassing biotic components and relying completely on geological processes? A) carbon B) nitrogen C) water D) nitrogen and carbon E) carbon and nitrogen

Given that CO2 is produced by respiration, why does the amount of CO2 in the atmosphere remain relatively constant? (When answering this question, exclude the impact of human activities on atmospheric CO2 .) A) CO2 is converted in photosynthesis to carbohydrates. B) CO2 is split apart during photosynthesis. C) CO2 mostly forms carbonate rocks. D) CO2 is trapped in dead organisms' bodies. E) CO2 is a buffer.

Which of the following represents a step in the nitrogen cycle? A) nitrogen-fixing bacteria convert atmospheric nitrogen to nitrates B) nitrites bind to soil particles C) nitrogen-fixing bacteria convert atmospheric nitrogen to ammonium D) denitrifiers convert ammonium to atmospheric nitrogen

Which of the following is not true of the nitrogen cycle? A) It requires different types of bacteria. B) Nitrogen gas is converted to nitrates in plant leaves. C) Nitrogen is cycled through living organisms. D) When plants and animals die, their nitrogen is recycled. E) Nitrogen is a component of all proteins.

Denitrifying bacteria convert ________ to ________. A) ammonium . . . nitrates B) nitrates . . . nitrogen gas C) nitrogen gas . . . nitrates D) nitrogen gas . . . nitrites

Which one of the following statements about the phosphorus cycle is false? A) Consumers obtain phosphorus in organic form from plants. B) Phosphorus has its main abiotic reservoir in water. C) Plants absorb dissolved phosphorus ions in the soil. D) Phosphorus that drains from soils into the sea becomes part of new rock and will not cycle back into living organisms until geologic processes lift the rock up and expose it to weathering. E) Phosphates are a major component of sewage.

Which of the following statements about the phosphorus cycle is true? A) Phosphorus has its main abiotic reservoir in water. B) Plants release dissolved phosphorus ions in the soil. C) Phosphorus that drains from soils into the sea becomes part of new rock and will cycle back into living organisms. D) Guano can be used by farmers to add phosphorus to the soil.

One of the most worrisome results of the large-scale clearing and cultivation of land is A) erosion and soil degradation. B) the inability to supply fresh water. C) the inability fo supply enough food for growing populations. D) hurricanes.