ecology

A population of deer is currently at 18,000 individuals. The carrying capacity of the forest is 15000. The rmax of the deer is 0.5. What is the population growth rate of this population?

-1800

A population of squirrels is currently at 600. Over the course of one year, there were 65 births and 30 deaths in the squirrel population. What is the per capita growth rate of this population over that one year?

.058

In the early 1970s, researchers hypothesized that carbon was the limiting nutrient in many aquatic ecosystems. To test this hypothesis, the researchers divided a small lake in two roughly equal halves with an impermeable curtain that was fastened and sealed to the bedrock of the lake. Beginning in 1971 the researchers treated one side of the lake with sucrose and the other side with both sucrose and phosphate. From 1971 to 1983 the researchers monitored the phytoplankton biomass in both parts of the lake. The results are shown in Figure 1. The average growth rate of the phytoplankton population from 1971 to 1975 in the side of the lake treated with sucrose and phosphate is closest to which of the following (in mg/m^3)?

1,500

Researchers performed an ecological survey in a particular region in Alaska. The researchers used the mark and recapture method to estimate the moose population to be approximately 32,000 in 2020. The moose are kept in check by a wolf population. The carrying capacity of this region allows for 50,000 deer. For this example, assume the rmax is1.0. With this information, answer/calculate the following: What is the population growth rate for 2020?

11,520

A population of beetles is kept under ideal conditions. With unlimited supply of food and space in the lab, the population is growing exponentially. The rmax of population is 1.5. The population size is currently 500. What will the population size be after one additional month?

1250

Researchers performed an ecological survey in a particular region in Alaska. The researchers used the mark and recapture method to estimate the moose population to be approximately 32,000 in 2020. The moose are kept in check by a wolf population. The carrying capacity of this region allows for 50,000 deer. For this example, assume the rmax is 1.0. With this information, answer/calculate the following: What will be the starting population size at the beginning of 2021?

43,520

In the early 1970s, researchers hypothesized that carbon was the limiting nutrient in many aquatic ecosystems. To test this hypothesis, the researchers divided a small lake in two roughly equal halves with an impermeable curtain that was fastened and sealed to the bedrock of the lake. Beginning in 1971 the researchers treated one side of the lake with sucrose and the other side with both sucrose and phosphate. From 1971 to 1983 the researchers monitored the phytoplankton biomass in both parts of the lake. The results are shown in Figure 1. Which of the following treatments would have been the best control treatment for the experiment?

An untreated section of the lake

Which of the following is an example of a density-independent limitation on a population?

At higher temperatures, more tomato plants in a population become infested with nematodes than at lower temperatures.

Producers within very deep regions of the ocean most likely introduce energy into ecosystems through which of the following processes?

Capturing electrons from inorganic molecules

Which of the following statements correctly describes a typical trend during the initial stages of succession in a terrestrial ecosystem?

Diversity of plant species increase.

Which of the following best explains why there are seldom more than five trophic levels in a food chain?

Energy is lost from each trophic level.

The population would be most likely to remain at the level shown at Q under which of the following conditions?

Environmental conditions do not fluctuate.

In some species of bats, adult females regurgitate (bring up food from the stomach) to feed their young. In addition, adult bats regurgitate to feed other adults that have not recently eaten. The adults receiving the food may be unrelated bats who have previously participated in food sharing and are members of the same social group. Scientists claim that sharing among unrelated adult bats increases the fitness of the species. Which of the following best supports the scientists' claim?

Food sharing increases the number of unrelated animals that cluster in one area, thus decreasing competition for food among members of the social group.

The California grunion (Leuresthes tenuis) is a small marine fish that lives in shallow waters near the ocean shore. Grunions swim as far onto the beach as possible to mate and lay their eggs (spawn). A researcher proposes that the spawning behavior takes place when the nighttime tides are highest during the month. Which of the following pieces of evidence would best support the researcher's claim?

Grunion spawning occurs when nighttime illumination levels are the lowest

( question with flowers light and dark graphs) After exposing the samples to light or dark for one hour, the students recorded the pH of the water in each beaker. Carbon dioxide dissolved in water will lower the pH of an aqueous solution. In the experiment, the students used changes in pH to monitor changes in the amount of carbon dioxide in the water. For each treatment group, the students calculated the mean pH and standard error, as documented in the table below. To investigate whether an organism in the study is capable of both photosynthesis and respiration, a comparison of which treatment groups is most appropriate?

I and II

Which of the following changes to the environment will most likely lead to more energy entering the meadow community represented above?

Increasing the light available to the plants

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.

Which of the following communities is likely to be most stable?

One with high species diversity

Which of the following claims is best supported by the data? In the early 1970s, researchers hypothesized that carbon was the limiting nutrient in many aquatic ecosystems. To test this hypothesis, the researchers divided a small lake in two roughly equal halves with an impermeable curtain that was fastened and sealed to the bedrock of the lake. Beginning in 1971 the researchers treated one side of the lake with sucrose and the other side with both sucrose and phosphate. From 1971 to 1983 the researchers monitored the phytoplankton biomass in both parts of the lake. The results are shown in Figure 1. Which of the following claims is best supported by the data?

Phosphate was a limiting factor for phytoplankton in the lake.

Which of the following would be most appropriate for identifying the species with the most even distribution of nests?

Standard deviation of the nearest-neighbor distances for each species

In a series of experiments, the researchers introduced a single snake into zone IV of the enclosure at 7:00 A.M. The researchers recorded the location of the snake at six time points throughout the day. In a related experiment, the researchers introduced two snakes, one of each species, into the enclosure at the same time and observed the location of each of the two snakes at the same six time points as before. The researchers repeated both the one-snake and two-snake experiments using different individual snakes of each species. The results are presented in the table. Based on the data in the table, which of the following best describes the habitat preference of T. atratus whenintroduced alone inside the meshed enclosure?

T. atratus exhibited a preference for the zones in or near water.

In the early 1970s, researchers hypothesized that carbon was the limiting nutrient in many aquatic ecosystems. To test this hypothesis, the researchers divided a small lake in two roughly equal halves with an impermeable curtain that was fastened and sealed to the bedrock of the lake. Beginning in 1971 the researchers treated one side of the lake with sucrose and the other side with both sucrose and phosphate. From 1971 to 1983 the researchers monitored the phytoplankton biomass in both parts of the lake. The results are shown in Figure 1. Which of the following was most likely a direct consequence of the addition of phosphate to the lake?

The amount of biomass in the second trophic level decreased.

A scientist is evaluating a proposal for raising large numbers of fish in ocean pens for human consumption. As part of the evaluation, the scientist is designing a plan for investigating how the fish in the ocean pens might affect nearby ecosystems. Which of the following is the most appropriate factor to use as the dependent variable in the experimental investigation?

The amount of metabolic wastes in the water where the fish are being raised

All of the following statements about the pyramid of biomass are correct EXCEPT:

The base of the pyramid generally represents primary consumers.

The following is a food web for a meadow habitat that occupies 25.6 km2. The primary producers' biomass is uniformly distributed throughout the habitat and totals 1,500 kg/km2 Developers have approved a project that will permanently reduce the primary producers' biomass by 50 percent and remove all rabbits and deer. Which of the following is the most likely result at the completion of the project?

The biomass of coyotes will be dramatically reduced.

They planted 20 pea and 20 melon seeds in each plot and watered each plot regularly.The studentsrecorded the number of seds that germinated,and as the plants grew,they recorded plant length,number and size of leaves, andgeneral health observations.The followingobservations were recorded.•In all treatments,morepea seeds germinated than melon seeds.•There was a week ofrainy weather atthree weeks.•Melon plantsdeveloped a fungalgrowth at four weeks.• Melon plantsgrew longer than pea plants, but many melon leaves showedsigns ofyellowing as the weeks passed.The students concluded that pea plantsgrew better incompost than did melon plants.Which of the followingbest addresses the validity of the conclusionmade by the students

The conclusion is invalid because other variables in the experiment (both biotic and abiotic) affected the results.

The graph above represents the proportions of hatchlings of certain types of reptiles that are male at different egg incubation temperatures. Which of the following claims is best supported by the data?

The expression of sex-determination genes in certain reptiles is influenced by temperature

As depicted in the diagram, honeybees communicate the location of flower patches to members of their hives with waggle dances that give information about the direction and distance to the flowers. Which of the following statements about how honeybees communicate the position of flower patches is most consistent with the model?

The farther the target flowers from the hive, the longer the waggle phase.

Decades of seal hunting eliminated many fur seal breeding colonies. Since that time, fur seals have recolonized several islands in the Pacific Ocean. Scientists studying the populations of fur seals on three recently colonized islands observed different population growth rates among the three populations. Which of the following best explains the different population growth rates on the recently colonized islands?

The islands differed in the amount of available prey, resulting in a higher population growth rate on the islands with fewer prey.

Which of the following observations provides the best evidence that photosynthesis occurred in treatment group I?

The mean pH of the samples increased after one hour.

Figure 1 represents the feeding relationships between selected organisms in the Chesapeake Bay. Decades of overharvesting have reduced the populations of both blue crabs and rockfish. However, recent efforts have increased the number of rockfish in the bay. Based on Figure 1, what is the most likely result of the increase in rockfish?

The population of blue crabs will decrease because predation by rockfish will increase

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.

Beaked whales feed at various depths, but they defecate at the ocean's surface. Nitrogen-rich whale feces deposited in surface waters supply nutrients for algae that are eaten by surface dwelling fish. Which of the following best predicts what would happen if the whale population decreased?

The surface fish populations would decline due to reduced populations of algae.

There is strong evidence that two species of cliff-dwelling birds have nested in the same environment and fed in the same water for thousands of years, with each having stable population sizes. Based on this information, which of the following statements is the best conclusion?

The two birds have different ecological niches that allow coexistence.

Prairie dogs are small mammals that live in large colonies in burrows in the ground. Prairie dogs that are near their own relatives when a predator approaches are much more likely to issue a warning bark than those that are near unrelated prairie dogs. The prairie dogs that hear a warning bark are more likely to hide in their burrows than to remain above ground. However, the prairie dog that gives the warning bark is putting itself at increased risk of being identified and killed by the predator. Which of the following presents the most likely evolutionary explanation for the behaviors described?

The warning bark changes the behavior of the related prairie dogs nearby, allowing the prairie dog's family to have increased survival and reproductive success.

Which of the following best describes opportunistic, or r-strategy, organisms?

They reach sexual maturity rapidly.

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.

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 the year 2000, specimens of Caulerpa taxifolia,a green alga used in tropical aquariums, were found off the coast of California. Native to the Indian Ocean, C. taxifolia is known for aggressive growth and an ability to compete with sea grasses.It is currently on an international list of invasive species. Which of the following best predicts the consequences of the introduction of C. taxifolia to the California coast?

Without natural herbivores or competitors,C. taxifolia will grow rapidly and crowd out native species ofproducers.

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

In short-day (long-night) plants, the critical environmental factor that induces flowering is the

duration of uninterrupted dark only

The graph below shows changes in a population of wild sheep that were introduced to the island of Tasmania in the early 1800's. The type of population growth represented by that portion of the graph line enclosed in the bracket is most accurately termed

exponential

An experiment to measure the rate of respiration in crickets and mice at 10oC and 25oC was performed using a respirometer, an apparatus that measures changes in gas volume. Respiration was measured in mL of O2 consumed per gram of organism over several five-minute trials and the following data were obtained. According to the data, the crickets at 25oC have greater oxygen consumption per gram of tissue than do the crickets at 10oC. This trend in oxygen consumption is the opposite of that in the mice. The difference in trends in oxygen consumption among crickets and mice is due to their

mode of internal temperature regulation

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