Ecology

Competitive exclusion is most likely to occur between two

. closely related species occupying the same niche

If the experiment was continued for an additional 500 days, the population density of T. castaneum with the parasite would most likely stabilize at a value closest to which of the following?

10 beetles/culture dish

In a population at equilibrium, thousands of eggs and hundreds of tadpoles are produced by a single pair of frogs. About how many offspring will live to maturity and reproduce?

2

Which of the following predictions about the community is most likely true?

A decrease in the wolf population will lead to a decrease in the mean aspen height.

In an experiment on birds learning to sing, young male chicks were exposed only to the songs sung by another species. Later, as they approached maturity, songs of their own species were played to them. When the birds reached maturity, they were able to sing neither the typical song of their species nor the full song of the second species. Which of the following accounts for this result?

Birds pass through a critical period early in life when learning their species-typical song is possible

Scientists have found that the existing populations of a certain species of amphibian are small in number, lacking in genetic diversity, and separated from each other by wide areas of dry land. Which of the following human actions is most likely to improve the long-term survival of the amphibians?

Building ponds in the areas of dry land to promote interbreeding between the separated populations

Which of the following is the best explanation for the pattern of change in mass of the organisms over time?

Cellular respiration

Thrips are insects that feed on rose pollen. Scientists noted that the thrips population increased in the spring and decreased dramatically during the summer. The researchers hypothesized that food abundance was the limiting factor for the population. Which of the following types of data would be most useful for the scientists to collect at regular intervals on a designated test plot of rose plants?

Density of rose pollen produced (g/m2)

Which of the following levels of organization includes all of the others?

Ecosystem

Based on the data, which of the following behaviors in elk could account for the differences between the percent of aspens browsed by herbivores and the height of aspen trees in riparian and upland environments?

Elk tend to avoid riparian areas where the steep, wooded riverbanks make it difficult to escape predators.

Prior to 1960, Lake Washington was highly polluted and underwater visibility was limited to one or two meters. In the late 1960s, a large cleanup effort reduced pollution, resulting in visibility that increased to six to seven meters by 1976. Which of the following best explains how the change in underwater visibility affected armor plating in Lake Washington sticklebacks between 1957 and 1976 ?

Higher visibility made the sticklebacks more susceptible to large-toothed predators in the lakes, giving complete armor a selective advantage.

Chytridiomycosis is a potentially lethal fungal infection that adversely affects some frog populations. The incidence and severity of the fungal infection can vary over time. Which of the following statements best describes the changes in the frog population that are depicted in the model above?

Infected individuals gradually died out, and genetically resistant individuals became more common. The frog population recovered because of the increased frequency of resistant individuals.

What can be inferred from the data in the graph about the loss of calcium in the deforested watershed?

It appears to be correlated wit the seasons

The pesticide DDT was widely used in the 1940s as a method of insect control. In the late 1950s the first DDT-resistant mosquitoes were discovered, and eventually DDT-resistant mosquitoes were found globally. When DDT is used now, the development of DDT resistance in mosquito populations occurs in months rather than years. Which of the following best explains the observations concerning DDT resistance in mosquitoes?

Natural selection favors DDT-resistant mosquitoes that are already present in a population when DDT exposure occurs.

To refine their model of deep-sea biological communities, the researchers investigated areas of the seafloor that are distant from any active hydrothermal vents. Which of the following is the best interpretation of the observation that some octopus species are only found near active hydrothermal vents?

Octopuses depend indirectly on inorganic compounds in the seawater surrounding hydrothermal vents.

What most likely causes the trends in oxygen concentration shown in the graph above?

Photosynthesis produces more oxygen than is consumed by respiration during the day.

Water in a pond contaminated with the weed killer atrazine is suspected of inhibiting metamorphosis in northern leopard frogs. A team of scientists collected fertilized northern leopard frog eggs from a different pond that is not contaminated. Which of the following is the best experimental design to determine whether atrazine is responsible for inhibiting metamorphosis in northern leopard frogs?

Place half of the fertilized eggs in a pool of water with the same concentration of atrazine as the contaminated pond and place the other half of the fertilized eggs in a pool of water that has no atrazine. Monitor the development of the embryos through metamorphosis into adulthood.

Based on the data, which of the following is the best explanation for the changes in the elk population size between 2000 and 2005 ?

Predation by wolves was higher than before 1995

On the basis of the food web, which of the following members of a deep-sea biological community is most likely to also have a symbiotic relationship with chemosynthetic organisms?

Shrimp

Toads in a particular population vary in size. A scientist observes that in this population, large males mate with females significantly more often than small males do. All of the following are plausible hypotheses to explain this observation EXCEPT:

Small females are more likely to mate with small males and large females are more likely to mate with large males

Based on an analysis of the food web, an observation that deep-sea bacteria consume molecular hydrogen ( H2 ) is most relevant to resolving which of the following apparent contradictions?

Some deep-sea organisms appear to be primary consumers, but no plants live near the hydrothermal vents.

Which of the following best explains how biological communities near deep-sea hydrothermal vents can exist in a habitat lacking sunlight?

Some organisms rely on energy captured from inorganic compounds to drive basic biological processes.

The data over the duration of the experiment provide the strongest support for which of the following conclusions regarding the effect of the parasite on Tribolium populations?

T. castaneum is adversely affected by the parasite, while T. confusum is not

Under which of the following conditions is the observed number of beetles per culture dish the greatest?

T. castaneum with parasite at 100 days

In the experiment, the researchers determined the relative abundance of two bacterial species found in the rumen of cattle. The rumen is a part of the stomach that acts as a fermentation chamber in cattle and other ruminants. Shown in the table are the results from before and after an abrupt change in the cattle's diet. Based on the results, which of the following best explains why the initial hypothesis should be revised?

The abundance of one of the bacterial species increased in response to the change in diet

Based on the graph, which of the following best describes why losses of calcium did not occur immediately in the deforested watershed?

The deforestation occurred during the winter when runoff was low

the difference between the two curves can best be attributed to which of the following?

The natural variation among populations

All of the following statements concerning characteristics of predator-prey relationships are correct EXCEPT:

The population of predators most often eliminates the population of prey

Which of the following is best supported by the data?

The presence or absence of plants greatly affects the loss of calcium from the soil

Assume there are 50,000 joules (J) of energy available in trophic level II in the figure. According to the conventional model of energy flow in ecosystems, which of the following statements correctly describes the flow of energy in the system?

Trophic level IV has approximately 500 J of available energy.

To estimate the total amount of calcium lost annually by each of the two watersheds, it would be most useful to measure which of the following variables?

Volume of water flowing out of each watershed each day

Researchers are investigating the evolutionary relationships among organisms found near deep-sea hydrothermal vents and similar organisms found closer to the ocean surface. Which of the following scientific questions is most relevant to the investigation?

What are the nucleotide sequences of ribosomal RNA genes that are found in the genomes of the different species?

The lionfish is a venomous fish found primarily in the Red Sea and the Indian Ocean. In the 1990s, lionfish were accidentally released into the Atlantic Ocean, where they found abundant resources and favorable environmental conditions. Which of the following scenarios is most likely to result in the lionfish having a major impact on the communities into which they were introduced?

With no natural predators, the lionfish population will become very large

In traveling from a forest ecosystem to a grassland, one notes that the trees gradually give way to prairie grasses. The critical factor governing this shift is usually the:

availability of water

Competition for food would probably be most severe between two

closely related species in similar niches

If the larvae of a particular species of mosquito are to survive to the adult stage, the eggs must be laid in the trapped pool of water of the northern pitcher plant. The mosquito larvae provide no apparent benefit or harm to the pitcher plant. This type of interaction is an example of:

commensalism

A study of the metabolic rate in a terrestrial community shows that the energy released by respiration exceeds the energy captured in photosynthesis. Which of the following situations is occurring?

community biomass is decreasing

A colony of termites was exposed to an atmosphere of 100 percent oxygen for three days. The insects were not immediately harmed by the treatment, but the protozoa that lived in the termites' guts were eliminated. The treated termites continued to behave normally and to eat wood, but they began to starve after a short time. When the treated termites were instead fed wood contaminated with the feces of untreated termites, the treated termites regained the ability to digest wood and no longer starved. The best analysis of the results of the experiment is that

cooperative interactions between the termites and the protozoa allow termites to extract energy from wood to survive

In the food pyramid above, which of the following organism are herbivores?

copepods

The LEAST effective means of controlling pest species such as rats or roaches over a long period of time is generally to (2002-5)

distribute pesticides throughout the habitat

A species of malaria-carrying mosquito lives in a forest in which two species of monkeys, A and B, coexist. Species A is immune to malaria but species B is not. The malaria-carrying mosquito is the chief food for a particular kind of bird in the forest. If all of these birds are eliminated suddenly by hunters, which of the following would be the immediate observable consequence?

increased mortality in monkey species B

Ducklings and goslings begin to follow and congregate around whatever moving animate or inanimate object is presented to them within a few hours after hatching. This type of behavior is called

insight

Species that utilize the same source of nutrition within a food web can best be described as

occupying the same trohpic level

A response of an organism to seasonal change is

photolysis

The divergence between the two populations of Rhagoletis must have occurred very rapidly because

the apple tree was imported into North America with European settlement approximately 200 years ago

In the Arctic Ocean, the predominant primary producers are phytoplankton. Phytoplankton are consumed by zooplankton, which in turn are eaten by codfish. In years when there is more open water (less ice coverage), there are more zooplankton and fish than in years with less open water (more ice coverage). Based on the graph above, the difference is most likely because

the ice blocks the light, so in years with more ice coverage, there is less photosynthesis by the phytoplankton

Which of the following factors affecting the hydrologic cycle would have the LEAST impact on calcium loss from the disturbed watershed?

transpiration

Which of the following types of behavior describes the way that mice find their way through mazes?

trial and error

All of the following are density-dependent factors that limit animal populations EXCEPT

weather