last of the last

In an experiment, scientists took plants and exposed them to different amounts of light and darkness to see if they would flower. Which of the following describes the significance of this experiment?

Angiosperms only flower at certain times of the year based solely on the amount of continuous darkness they receive.

Moskt and Honza (2000) studied the interrelationship between the cuckoo (parasite) and Great reed warbler (host). In their research, ninety nesting sites were observed. Of the data, 31 nests (34%) were unparasitized, 37 nests (41%) were parasitized only once, and 22 nests (24%) were parasitized numerous times. According to this research, several factors were identified as being most relevant in parasite behavior. Which of the following identifies the abiotic factor MOST responsible for repeated parasitism?

Host and parasite habitats that exhibit significant overlap (access)

In a hypothetical region of the southeastern United States, a species of mouse that feeds mainly on seeds and a species of snake that feeds mainly on mice are found. Given what you know about trophic structure, which of the following is likely to be TRUE?

An increase in the primary productivity levels in a particular habitat would lead to an initial increase in both mice and snake populations.

In the food web depicted above, an increase in the population of osprey would cause which of the following to occur?

An initial decrease in the sea duck population.

Some hawk moth (Sphingidae family) species have been found to produce ultrasonic clicks. A scientist hypothesizes that these clicks function to disrupt bat (a hawk moth predator) echolocation function. Which of the following is the BEST plan for testing the hypothesis?

Artificially reproduce the sound frequency used by the moths, and measure the impact the sound has on bats' ability to track non-moth targets

Evaporative cooling is one of several processes that contributes to homeostasis in endotherms. Which of the following describes the thermodynamic principle behind this process?

As a phase change, evaporation of water absorbs heat, drawing heat energy out of the body.

In Australia, farmers whose fields are located along the edges of streams or rivers are currently being paid to decrease the amount of farmable land by planting wide strips of trees between their fields and the streams and rivers that the fields abut. The hope is that the roots of the trees will provide a buffer zone that will absorb fertilizer nutrients which would otherwise end up in aquatic ecosystems. Which of the following phenomena are the farmers attempting to avoid?

Eutrophication.

As the human population in the United States has increased over time, more and more forest habitats have cleared, developed, and fragmented. Which of the following statements regarding forest fragmentation is CORRECT?

Fragmented forests support less biodiversity than non-fragmented forests.

Plant anatomy can have a significant impact on the conservation of water. Which of the following adaptations is the LEAST successful adaptation for reducing water loss?

Growth of many thin but broad leaves.

In a hypothetical situation, scientists studying the impacts of climate hypothesize that warmer temperatures in the arctic tundra should cause an increase in the population sizes of insects and herbivores. They chart changes in the average temperatures for the month of July over a period of fifty years, as well as the annual population sizes of a certain insect species and a certain herbivorous species. Based on the data collected, scientists can logically conclude that warmer temperatures impact which of the following?

Have differing impacts on different species in the arctic tundra.

A hypothetical species of antelope is host to a pathogenic species of bacteria that is spread through the air over short distances of 10 to 20 feet. Scientists have observed that in areas with a low population density, bacteria displaying lower virulence make up a greater presence than virulent strains. While in areas with a high population density, the reverse is true. Below is a graph showing the virulence of the bacterial pathogen compared to the density of the antelope population. Which of the following BEST explains the relationship shown in the graph?

In antelope populations with low density, less virulent strains of the bacteria are more successful because infected organisms stay healthy enough to move and spread the bacteria.

Switchgrass is a species of grass that is native to the Midwestern prairie ecosystem of the United States. When it is grazed by native buffalo, it responds by growing rapidly, flowering, and producing seeds. Additionally, the grazed plants change their root growth pattern and develop roots deeper into the soil than non-grazed plants. Which of the following terms would BEST describe the relationship between switchgrass and buffalo?

Mutualism.

Which of the following statements is true regarding the logistic growth equation shown below? dN/dt=rmaxN(K−N)/K

The growth rate is zero when N equals K.

When an endotherm's body temperature drops below normal, cold receptors send information to the hypothalamus. Which of the following is MOST likely to occur?

The hypothalamus will send out signals that cause vasoconstriction (narrowing) of blood vessels.

Prairie dogs are burrowing rodents found in western North America. They are the keystone species, and their presence benefits over 100 species in the ecosystem. Based on the diagram, which of the following would be the MOST reasonable prediction if the prairie dog population experienced a sharp decline?

There would be an increase in shrub cover.

Cows are ruminants with four stomachs for digestion. In addition to having four stomachs, there are several species of gut bacteria that reside in the cow intestine and help cows digest food. Which of the following identifies the type of relationship that exists between cows and their bacteria?

This is a mutualistic relationship since the cows receive help from the bacteria in the digestion of food, and the bacteria receive food and habitat, so this is beneficial for both species.

Voters in a particular town in Massachusetts pass a law that bans the hunting of beavers. Additionally, under the new law beaver dams and lodges may not be removed or tampered with by people. Wildlife biologists track species diversity and distribution over the next ten years following the passage of the law. They conclude that beavers act as a keystone species in the area. Point X shows the enactment of the law. Point Y shows the repeal of the law. Which of the following graphs MOST accurately represents what might be seen if voters repeal the law and beavers are once again hunted and their dams and lodges removed?

X at level of B in Biodiversity Y at level of y in Biodiversity

The riparian zone includes a river or stream and the nearby habitat. A density-independent factor that might affect a riparian zone is

abiotic, including weather and climate.

The graph above illustrates the approximate number of species in each biome. The data only includes amphibians, birds, mammals, and reptiles. Endemic species are species that are only found in that particular biome. Based on the diagram, which of the following would be the MOST reasonable ecosystem to be sensitive to environmental stresses?

Tundra.

The following chart presents data for a biological community. Species Population A 100 100 B 200 200 C 150 150 Which of the following correctly represents the diversity index for this community?

0.642

The graph below shows the population growth of Atlantic Cod off the east coast of Newfoundland. Collapse of the cod fisheries by Lamiot (CC BY-SA 3.0) In what year did the population MOST likely exceed the resource availability of the area?

1966

A city identifies that it has a problem with Norwegian rats (Rattus norvegicus). A population ecologist is hired to study the situation. She determines that the current population of rats in the city is 4,000 individuals and has an annual birth rate of 0.03. A city-wide trapping program has increased the annual death rate to 0.01. Given this information, the population ecologist reports that in one year, the rat population will be

4,080 individuals

Limiting factors ​often have a positive impact on the environment and ensure biodiversity.

A limiting factor is a necessary resource or condition that is limited in a habitat. Which of the following is MOST accurate about limiting factors?

Acid mine drainage is due to the lack of reclamation of an area that has been mined for coal. This means that after an area has been mined for materials such as coal, it is returned to its original condition as best as possible. When this does not occur, the pyrite in the coal is exposed to the water and is oxidized creating sulfuric acid. This releases large amounts of hydrogen ions into the water. The release of these ions lowers the pH and acidifies the water. It also gives the water and rocks around it a characteristic red appearance, as seen in the image below. Which of the following statements BEST describes the effects of acid mine drainage on the aquatic life?

As the pH of the water lowers and becomes more acidic, fewer and fewer organisms will be able to live in the water due to the increased acidic environment. Consequently, there will be less and less life in the stream, completely decimating the ecosystem.

Population growth is regulated by many variables, including biotic and abiotic factors, as well as population size. Fecundity, commonly known as reproductive rate, in addition to mortality rate, are directly influenced by the size of a population. The graph below illustrates the results of a study focusing on the giant intestinal roundworm, Ascaris lumbricoides, a parasite of humans and other mammals. Which of the following is the likely conclusion BEST supported by the data?

Ascaris lumbricoides provide an example of density-dependent regulation because the data show that denser populations of the parasite exhibit lower fecundity.

Beavers are the largest rodent in North America and are widespread in North America. These mammals, often termed "nature's engineers", can significantly alter natural landscapes to their benefit. While research suggests that beavers can significantly and positively impact many other species, beavers have also been observed to harm other resident species. Regulation of this keystone species occurs through human trapping, predation, disease, and habitat quality. According to Van Horn (2011) the northern third of Wisconsin supports 48% of Wisconsin's breeding wood duck population and 38% of the mallard population. Given that these waterfowl survey regions overlap closely with Beaver Management Zones, which of the following infers the nature of the relationship between beaver activity and these wetland birds?

Beaver-related wetlands provide necessary habitat for wood ducks, mallard ducks, and other waterfowl.

Executives for a resort on Lake Superior are attempting to temper the effect of algal blooms in order to improve water clarity. Their reasoning is that by clarifying water, it will be less of a burden for fishermen to navigate the lake and will also provide fewer false-positive readings for sonar-related fishing techniques. In order to accomplish this goal, they consult with a private landscaping firm known for their use of non-selective chemical herbicides and pesticides in order to achieve various cosmetic feats. The firm's plan is to utilize an aquatic organic phosphate compound that is selective in its ability to destroy certain species of plants and algae while touting a minimal effect to desirable algal species and on animal life. Which of the following arguments would be the MOST effective for convincing the Lake Superior executives to take a different course of action with respect to maintaining a diversity of fish upon which their entire industry is based?

By eliminating various species of algae, the overall producer biodiversity is reduced. In order to maintain a functioning food web in the lake, the needs of all organisms must be taken into consideration. By limiting the biodiversity of producers, they run the risk of eliminating the biodiversity of the animal life which depend on them.

The rate of increase in the biomass of a heterotroph depends on the metabolic needs of the organism. Which of the following types of organism would be a more efficient secondary consumer and why?

Ectotherm because it spends less energy maintaining body temperature.

Humans have lived alongside honey bees for thousands of years. Eighty percent of global agriculture pollination services can be attributed to the European honey bee, Apis mellifera. Apiculture, the maintenance of honey bee colonies by humans, has faced a number of challenges in recent years. In the US, the number of honey bee colonies dropped 61% between 1947 and 2008. In Europe, colony numbers decreased from over 21 million in 1970 to about 15.5 million in 2007. Various pests, diseases, parasites, predators, and their interactions have been blamed for part of this decline. Furthermore, use of pesticides by human managers, weather, climate, and international trade have also been suggested to contribute to this phenomenon. In order to better understand the model of honey bee health and colony productivity, researchers selected 31 colonies throughout Denmark (Figure 1) and fitted each with a hive scale connected to a central database for monitoring. Weight records were collected every two hours beginning at 06:00 (AM) and ending at 22:00 (PM). The field study was conducted from 2010 to 2013. Which of the following is a plausible limitation to either the design or execution of this experiment?

Colonies were selected based on landscape type (urban, agriculture, and mixed variety).

Migratory birds must balance their energy with the need to remain light and aerodynamic. Besides fat and protein, maintaining a proper ratio of water is essential to overcome the extreme effort of long-distance migration. Water imbalance may also limit a bird's flight range (Carmi et al., 1992). Which of the following is the MOST appropriate adaptation used by migratory birds to conserve water over long-distance flight?

Convert toxic ammonia into uric acid (solid, white powder).

In the landmark Meselson and Stahl experiment, E. coli bacteria were grown for several generations in media containing nitrogen-15. Later, they transferred the E. coli to media containing nitrogen-14. They analyzed the DNA after separating the DNA by mass using a centrifuge. The results that they found were shown in the diagram below. Which of the following was illustrated in the experiment by Meselson and Stahl?

DNA copies itself such that each strand is half old and half newly constructed.

The graph above illustrates the approximate number of species in each biome. The data only includes amphibians, birds, mammals, and reptiles. Endemic species are species that are only found in that particular biome. Based on the diagram, which of the following would be the MOST reasonable ecosystem to survive a sudden environmental change?

Deserts and xeric shrublands.

A species of mosquito that carries West Nile Virus inhabits a New England forest in which live two species of birds: crows and blue jays. Crows are highly susceptible to West Nile Virus, but blue jays are not. A third species living in the same forest, the little brown bat, primarily feeds on mosquitos. In recent years, the population of little brown bats has declined rapidly. Which of the following is MOST likely to occur in response to the decline in the bat population over the next 10 years?

Increased mortality rates in the crow population.

There are a number of factors that play a role in fluctuations in the size of a mountain hare population so as to allow the population to exist at a maximum load. Which of the following observations BEST supports the model that population size is decreasing due to changes in the availability of free energy in the hare population?

It is winter, and food resources are diminished.

In a small, freshwater pond, a community ecologist found and recorded 14 species of macroinvertebrates. A year after the elimination of a particular species of fish from the pond due to over-fishing by humans, the community ecologist found and recorded just four of the original 14 species of macroinvertebrates. Which of the following MOST likely indicates what the eliminated fish species was?

Keystone species.

The Malacosteid family of deep-sea fishes has a unique "night vision" ability, a phenomenon known as bioluminescence. These fish emit a rare red light in contrast to the more common blue-green light emitted by the majority of marine organisms. Blue light has a relatively short wavelength and is able to travel further through the ocean water than red light, which has a longer wavelength. Most marine organisms lack the visual pigments needed to "see" longer wavelengths, but Malacosteid species have the ability to detect their own red light and, thus, "see" their immediate surroundings. The eyes and lower jaw of a fresh specimen of Malacosteus showing the position of the whitish postorbital/accessory (p-o) and the intense red fluorescence of the suborbital photophore (s-o). Malacosteus niger cam by Filip_em (CC BY-SA 3.0) Which of the following is the BEST reasoning that supports the unique "night-vision" ability in the Malacosteid species of fishes?

Malacosteid fishes can better view nearby prey without being detected, and this adaptation gives them an advantage in their deep-sea environment.

Variola major, the infectious agent that causes smallpox, is arguably the most deadly disease in all of human history. Symptoms often include a gradually increasing fever, aching muscles, headache, fatigue, and vomiting. As the disease progresses, pustules appear on the face, limbs, and trunk of the body. The fluid within these pustules is laden with viral particles that are highly infectious even when removed from a human body for a period of time. In the 1500s, Spanish conquistadores introduced smallpox to members of the Aztec empire. The devastation caused by the virus is depicted in the image above. Which of the following is the likely reason why the Aztecs were decimated by smallpox, while the Spanish conquistadores remained largely unaffected?

Many of the Spanish either already had and recovered from smallpox or had genetic immunity. This disease was new to the Aztecs, so they did not have any form of immunity (either acquired or genetic).

Male zebra finches have been observed to produce subtle yet discernable changes in their courtship song depending on whether they are singing alone (undirected) or directly to a female. It has been theorized that the undirected singing amounted to practice. To test female finch preference for a directed or undirected song, two- or three compartment-choice chambers are available for use. Diagram of the two-choice behavior assay by Sarah C. Woolley and Allison J. Doupe (CC BY 4.0) Which of the following experimental designs would be the most appropriate to test if female zebra finches have a preference for directed versus undirected songs?

Place females in a three-compartment choice chamber, play in alternating fashion each type of song from opposite ends, and monitor the females' preferences.

The interspecific relationship witnessed between clownfish and sea anemones has proven a vivid example of symbiosis in tropic waters. Scientists have adjusted their view of the relationship after years of observance. The venomous sea anemone undoubtedly provides a refuge for the mucus-coated clownfish, impervious to cnidarian harm. Larger predatory fish do not disturb the clownfish amidst the stinging tentacles. However, it appears not only do the anemones most likely feed on the detritus (decaying tissue remains) of the clownfish's meal, but the swimming patterns of the fish presumably improve circulation for its partner, increasing oxygen supply. Which of the following types of symbiosis was once identified between the sea anemone and clownfish, and which is currently accurate with the described interaction?

Previous: commensalism. Current: mutualism.

Determining the energy transfer from producer to primary consumer provides an estimate of secondary productivity. Other than the direct addition of mass to the organism, which of the following processes contributes positively to the biomass of an individual?

Production of offspring.

Below is a graph tracking the monthly levels of atmospheric carbon dioxide at the Mauna Loa observatory in Hawaii from 1991 to 2007. Which of the following provides the BEST explanation for the pattern shown in the graph?

Rates of carbon fixation by terrestrial photosynthesizers increase and decrease significantly with the summer and winter seasons.

Plants in a certain community have been found to use different forms of nitrogen. For example, Plant Species 1 will use nitrate, Plant Species 2 will use ammonium, and Plant Species 3 will use nitrite. Which of the following is the BEST explanation for this behavior?

Reducing interspecific competition allows the plant species to survive together.

As the Pacific Ocean gets warmer, it absorbs greater concentrations of carbon dioxide and becomes increasingly acidic. Which of the following predicts the abiotic or biotic factor that is MOST directly affected in the ocean by this change?

Salinity.

Brood parasites are organisms that rely on others to raise their young. There is increasing evidence to suggest that this strategy is non-random. Brood parasitism is costly to hosts and, as a result, a number of anti-parasite defense mechanisms have evolved. In a study of anti-parasite strategies employed by barn swallows (Hirundo rustica), five geographic locations were observed: three located in Europe and two sites in China. Both varieties have been observed to breed outdoors; however, the European variety nests almost exclusively indoors in barns and other built structures. It has been noted that common cuckoos are rare in villages, towns, and cities where human populations are high. When presented with model cuckoo eggs by researchers, only the Chinese swallows rejected them. The European variety rejected no parasite eggs, whereas the Chinese birds rejected the impostor eggs 15% and 42% of the time in the two respective sites. Which of the following is the LEAST likely explanation for the differences observed between the European and Chinese barn swallows?

Suitable European hosts are better able to visually identify the parasitic egg than those living in China.

Scientists studied the effects of different temperatures and amounts of food on the emergence of black-spotted frogs, Pelophylax nigromaculatus, from hibernation. They set up mesocosms, or outdoor experimental systems meant to examine the natural environment under controlled conditions. Groups were either exposed to ambient temperatures or temperatures that were 2% higher than the ambient temperature. Groups were also exposed to normal amounts of food or 13 the amount of food. The results are shown in the graph below. Which of the following conclusions is MOST consistent with the data?

Temperature affects when P. nigromaculatus emerges from hibernation.

In 1975, volunteers from a birding organization begin monitoring the populations of Cardinalis cardinalis and Molothrus ater in a certain forest. Molothrus ater, also know as the Brown-headed Cow Bird, is a species that lays its eggs in the nests of other birds. The volunteers collect data for ten years. The following graph shows their data. Created for Albert. All rights reserved. The results shown in the graph above BEST support which of the following statements?

The ability of Cardinalis cardinalis to reproduce is reduced in the presence of Molothrus ater.

An ecologist is studying a community park ecosystem over a ten-year period. Native wildflower species populations are estimated at the beginning and end of the study. The data is presented below. Species Year 1 Year 10 A 100 150 B 70 100 C 5 150 D 20 50 Which of the following explanations is consistent with the data?

The diversity index of native wildflowers increased from 0.59 to 0.72 over time due to initiatives to irradicate invasive species.

Prior to 1940, the island of Guam had never hosted any species of snakes. With the construction of a United States air force base on the island in 1940, the brown tree snake was accidentally introduced to the island. Classified as an invasive species in Guam, which of the following BEST predicts what the snakes have caused?

The drastic decline of the populations of most of the island's native bird species.

The energy required to maintain the metabolic rate of a small field mouse is inversely related to its size. Based on this information, which of the following is MOST accurate?

The field mouse consumes more food per unit of body mass than a horse.

Bioluminescent organisms have the ability to produce light that allows them to camouflage themselves and attract mates. Bioluminescence occurs widely among many animals, especially marine organisms, including fish, jellyfish, mollusks, and plankton. The light emitted is frequently produced from bacteria that grow in certain tissues of their bioluminescent animal hosts, which provides the bacteria with an environmental niche to survive and reproduce. Squid komodo by Nhobgood (CC BY-SA 3.0) Which of the following statements BEST explains the relationship between light-emitting bacteria and their animal hosts?

The interaction between light-emitting bacteria and their host animals is an example of a mutually symbiotic relationship that is biotic in nature.

In the Rocky Mountains of Colorado, two species of bumblebees, Bombus appositus and Bombus bifaryus, feed on the nectar of flowers. Careful measurements of the proboscis (mouthpiece used to siphon nectar) show the two species having significantly different lengths that, interestingly, allow each species to access distinct populations of flowers. How might this relationship impact interspecies dynamics?

The interaction will maintain species diversity.

When determining energy transfer efficiency from a producer, such as Brussels sprouts, and a primary consumer, such as butterfly larvae, the amount of energy contained in a gram of biomass is less for the producer (4.35 kcal/g) than it is for the consumer (5.5 kcal/g). Which of the following BEST explains this phenomenon?

The larger ratio of fat to carbohydrates found in the consumer compared to the producer.

Scientists believe that the Hawaiian island chain as it currently exists was formed as sea-floor spreading caused the Earth's crust to slowly move over a stationary point of volcanic activity in the mantle of the Earth. While above the area of activity, volcanic eruptions formed the islands, and as sea-floor spreading moved the newly formed island off the area of activity, other new islands formed leading to the seven islands that now exist. The largest island in the chain is the only one that is currently volcanically active, suggesting that it is still above the active region in the mantel. If this is true, which of the following should be observed?

The largest island should have less biodiversity than the other islands.

Only a small portion of chemical energy in an apple is transferred to an organism that eats it. Which of the following occurs to the majority of the chemical energy stored in the apple when another organism eats it?

The majority of the energy is lost as heat energy to the surrounding environment.

To measure the rate of organismal respiration, a 1000 mL respirometer was constructed. These measure relative volume as oxygen is consumed by respiring organisms. However, as oxygen gas is consumed during aerobic respiration, it is replaced by CO2 gas at a ratio of one molecule of CO2 for each molecule of O2. As such, in the following protocol, the CO2 produced is removed by a small piece of cotton treated with potassium hydroxide (KOH). KOH reacts with CO2 to form the solid potassium carbonate (K2CO3). Over the course of 20 minutes, changes in the volume were measured by following the distance of a red soap bubble placed on the end of a 40 μL capillary tube at t=0. Due to the larger sized respirometer, relatively larger sized organisms were used for the setup. An external temperature of 10∘C was used in one experimental setup. Another experiment had a temperature of 30∘C. Both experiments used a respirometer with an equal volume of glass beads to represent a control group. External pressure was constant in all cases. Which of the following would the results from these experiments show?

The mouse would show a slight increase in respiration rate in 10∘C but not radically different from the 30∘C temperature while the snake would show a low rate in 10∘C and a higher rate of respiration at the warmer temperature.

Euglena gracilis is a protist that has animal and plant-like characteristics. Because of its eyespot, Euglena exhibit phototaxis. In an experiment, a culture of Euglena is placed in a petri dish, and a piece of cardboard with a circle cut out of its center is placed over the petri dish, allowing light to enter only the center of the petri dish. After 30 minutes, the cardboard is removed, and the culture is observed. Which of the following BEST describes the appearance of the Euglena culture after the 30 minutes?

The petri dish has a concentrated dark green area where the circle was, indicating that the Euglena culture moved toward the light source.

Brood parasites are organisms that rely on others to raise their young. For example, the cuckoo will lay its eggs in nests belonging to the Reed warbler seemingly with the intent for the warbler to hatch and feed the cuckoo hatchling. Scientists have wondered how the parasitic cuckoo chick gets fed because other studies have shown that it takes stimulation of multiple open beaks—either sight or sound—to compel a mother warbler to provide food. Researchers observed that the parasitic chicks have bright yellow patches on the ends of their wings, and they make those patches quiver when the host parent returns to the nest. Researchers hypothesized that the bright yellow patches on the ends of the cuckoo's wings were related to stimulating the feeding process. Which of the following procedures is NOT consistent with their hypothesis?

The researchers tested the hypothesis by masking the yellow patches with additional, differently colored paint and adding additional patches of UV pigments. When they did that, the parasitic chicks got more food.

Brood parasites are organisms that rely on others to raise their young. The strategy appears among a wide variety of animals, including insects, fishes, and birds. A common strategy of the brood parasite is to trick a host parent to raise the parasite's young as if it belonged to the host. Cuckoo Eggs Mimicking Reed Warbler Eggs by Chiswick Chap (CC BY-SA 3.0) For example, the cuckoo will lay its egg in nests belonging to the reed warbler seemingly with the intent for the warbler to hatch and feed the cuckoo hatchling. Which of the following is the MOST plausible benefit for the parasite?

The resources required by the reed warbler in order to raise the cuckoo young will negatively impact the reed warbler offspring leading to a competitive advantage the cuckoo population.

Ecologically speaking, a typical keystone species is a small predator that prevents a particular herbivorous species from eliminating dominant plant species. Jaguars, a classic keystone species, inhabit wide habitats in Central and South America and consume more than 80 different herbivorous species including tapirs, capybaras, and monkeys. Which of the following predicts the MOST likely effect of a decrease in the Jaguar population?

The tapir population will increase.

Examine the food web below for a freshwater shoreline habitat with an area of 2.5 square kilometers. Assume that the 121 kilogram/square kilometer of biomass of the vegetation is uniformly distributed throughout the area of the habitat and between the primary consumers in the food web. A mid-summer drought reduces the total shoreline of the pond by 50%. All the mute swans and geese migrate to a different pond with a larger shoreline. Which of the following BEST describes the results of these changes after one growth season?

The total biomass of the wading birds in the pond will decrease significantly.

Beavers are the largest rodent in North America and are widespread in North America. These mammals, often termed "nature's engineers", can significantly alter natural landscapes to their benefit. While research suggests that beavers can significantly and positively impact many other species, beavers have also been observed to harm other resident species. Regulation of this keystone species occurs through human trapping, predation, disease, and habitat quality. Beaver and/or beaver ponds are associated with various microorganisms including bacteria (Francisella tularemia), intestinal parasite (Giardia lamblia) and fungi (Blastomyces dermatitidis). Both F. tularemia and G. Lambia, but not B. dermatitidis, impact beavers whereas humans and dogs are parasitized by all three organisms. F. tularemia has caused mass beaver mortalities. Notably, Wisconsin trappers reported 290 dead beavers from 83 colonies, and Giardia affected beavers in 1953. Which of the following predicts the MOST likely effect of this significant beaver population decrease from 1953-1954?

The total incidence of G. lamblia infection will decrease.

In a hypothetical scenario, scientists discover that the saliva of a species of Pacific Island bat called a P. scapulatus (flying fox) contains chemicals that possess anti-aging properties. In nature, these animals drink the nectar from the flowers of many local trees. Adult pairs raise one offspring each year. In response to the discovery, humans inadvertently hunt the flying fox to extinction. Which of the following BEST explains why the extinction of this one species could threaten the future of many of the tree species?

The trees have lost their primary pollinator and can no longer effectively reproduce sexually.

Chemosynthesizers can convert chemicals into biomass, and many types of chemosynthetic organisms congregate near hydrothermal vents where chemicals are abundant. Which of the following predicts why there would be higher biomass and greater primary production of organisms living in the hydrothermal vent areas in contrast to the areas outside the vent areas?

The vents release an abundance of chemicals the organisms living there can use in the production of energy molecules.

Beavers are the largest rodent in North America and are widespread in North America. These mammals, often termed "nature's engineers", can significantly alter natural landscapes to their benefit. While research suggests that beavers can significantly and positively impact many other species, beavers have also been observed to harm other resident species. Regulation of this keystone species occurs through human trapping, predation, disease, and habitat quality. Aspen, an early successional species, is highly utilized for beaver habitat and food but has declined across northern Wisconsin. Beavers tend to overharvest these pioneer tree species that, in turn, tends to stimulate the growth of climax tree species (e.g., dogwoods) that are not preferred by beavers. Which of the following explains the nature of the relationship between the aspen and beaver population?

This represents negative feedback because the more aspen trees that are consumed by beavers, the fewer beavers will be able to survive in the region.

Examine the graph depicting survivorship curves below. Survivorship Curves by Ray Husthwaite (CC BY 3.0) In many developing countries with poor nutrition, limited access to medical treatment, and a lack of access to clean water, infant mortality rates are very high. However, as children get older their likelihood of surviving increases. In such populations, the death rate decreases as the population ages. Which of the following types of curve(s) BEST represents the growth patterns observed in developing countries?

Type III.

In their given environments, bacteria will exhibit a behavior known as chemotaxis, or movement either toward or away from a given stimulus. This action is depicted in the diagram above. While observations regarding bacterial movement have been well-documented, there may be various physiological reasons why bacteria respond in such a manner to each given stimulus. Which of the following offers the BEST explanation as to why bacteria exhibit positive chemotaxis?

Various chemicals act as signal transducers, thereby inducing bacterial flagella to align in such a manner to allow them to move toward the stimulus.

The gram-negative oceanic bacteria Vibrio fischeri constantly synthesize and secrete a signal molecule known as AHL (N-acylhomoserine lactone). The AHL diffuses out of the cells and into the environment. If AHL accumulates in high enough concentrations, it will diffuse back into the bacterium. When the chemical is reabsorbed, it will activate genes that lead to bioluminescence, giving the bacterium the ability to glow. This uptake is an example of quorum sensing in nature using auto-inducers. Based on this information, which of the following is correct?

Vibrio fischeri living in colonies are bioluminescent

Humans have lived alongside honey bees for thousands of years. Eighty percent of global agriculture pollination services can be attributed to the European honey bee, Apis mellifera. Apiculture, the maintenance of honey bee colonies by humans, has faced a number of challenges in recent years. In the US, the number of honey bee colonies dropped 61% between 1947 and 2008. In Europe, colony numbers decreased from over 21 million in 1970 to about 15.5 million in 2007. Various pests, diseases, parasites, predators and their interactions have been blamed for part of this decline. Furthermore, use of pesticides by human managers, weather, climate and international trade have also been suggested to contribute to this phenomenon. In order to better understand the model of honey bee health and colony productivity, researchers selected 31 colonies throughout Denmark (Figure 1) and fitted each with a hive scale connected to a central database for monitoring. Weight records were collected every two hours beginning at 06:00 (AM) and ending at 22:00 (PM). The field study was conducted from 2010 to 2013. Each of the following conclusions are supported by the data (Figures 3, 4 and 5) EXCEPT

colonies suffered an average weight loss in June 2013 and a shorter productive summer period overall.

Humans have lived alongside honey bees for thousands of years. Eighty percent of global agriculture pollination services can be attributed to the European honey bee, Apis mellifera. Apiculture, the maintenance of honey bee colonies by humans, has faced a number of challenges in recent years. In the US, the number of honey bee colonies dropped 61% between 1947 and 2008. In Europe, colony numbers decreased from over 21 million in 1970 to about 15.5 million in 2007. Various pests, diseases, parasites, predators and their interactions have been blamed for part of this decline. Furthermore, use of pesticides by human managers, weather, climate and international trade have also been suggested to contribute to this phenomenon. In order to better understand the model of honey bee health and colony productivity, researchers selected 31 colonies throughout Denmark (Figure 1) and fitted each with a hive scale connected to a central database for monitoring. Weight records were collected every two hours beginning at 06:00 (AM) and ending at 22:00 (PM). The field study was conducted from 2010 to 2013. Researchers categorized and grouped the 71 annual recordings of Danish honey bee hive weights into 47 agricultural landscapes (typically home to a single cash crop such as Danish oilseed rape, Brassica napus), 14 urban landscapes (featuring gardens, parks and landscape flora), and 10 mixed landscapes (a mix of the first two types) at a radius of 1km around each hive. Agricultural: More than 50% of the surrounding landscape composes of agricultural areas. Urban: More than 50% of the surrounding 1km landscape composed of urban areas. Mixed: A combination of landscape types surrounding the apiary with no single habitat type representing more than 50% of the total landscape. Each of the following conclusions are supported by the data (Figures 3, 4 and 5) EXCEPT

in the year 2012, the productivity was significantly lower than in the other years. This difference could partly be explained by environmental variables such as temperature and rainfall levels.