Unit 8 Review 𖦹⋆｡°✩

Question 1

Scientists are studying the two primary vocalizations made by Belding’s ground squirrels (Urocitellus beldingi). The trill call consists of a series of medium-pitched notes given rapidly, while the whistle call consists of a single high-pitched note. The objective of the experiment is to determine the function of each vocalization. Recordings of the calls were played to four different groups of squirrels, and the response of each individual squirrel was documented. The responses are summarized in Table 1. Which of the following correctly identifies the dependent variable and the independent variable for the experiment?

Answer 1

A. The independent variable is the percent of squirrels responding, and the dependent variable is the type of alarm call.

B. The independent variable is the percent of squirrels responding, and the dependent variable is the type of response.

C. The independent variable is the group of squirrels, and the dependent variable is the percent of squirrels responding.

D. The independent variable is the type of alarm, and the dependent variable is the percent of squirrels responding.

Question 2

✩CORRECT ANSWER FOR 8.1, 1✩

Answer 2

D

Question 3

A group of biologists were investigating the effects of light color on phototropism (growing toward the light source) in tomato plants. Four groups of tomato plants were grown in the same greenhouse under identical conditions. Each group was then placed in a different room, each room having a different color of light, exposed to that single color of light from different directions for one week at a time. After each week, the biologists counted the number of tomato plants in the groups that were showing evidence of phototropism. The results are summarized in Table 1. Which of the following correctly identifies the dependent and independent variables in this experiment?

Answer 3

A. The color of the light is the dependent variable, and the percentage of plants showing phototropism is the independent variable.

B. The percentage of plants showing phototropism is the dependent variable, and the color of the light is the independent variable.

C. The direction of the light is the dependent variable, and the percentage of plants showing phototropism is the independent variable.

D. The color of the light is the dependent variable, and the direction of the light is the independent variable.

Question 4

✩CORRECT ANSWER FOR 8.1, 2✩

Answer 4

B

Question 5

Quorum sensing is a form of cell-to-cell communication used by some bacterial species to regulate their behavior and population size. Staphylococcus aureus uses quorum sensing to activate its virulence genes once its population reaches a minimum size. Virulence refers to the ability of a pathogen to cause disease. S. aureus secretes autoinducing peptide (AIP), which binds to the AgrC receptor on the bacterial cell membrane. When the S. aureus population is sufficiently large and produces enough AIP, this concentration activates AgrC and stimulates a signal cascade resulting in the production of hemolysin, a toxin used to attack the host organism. In order to lessen the impact of the toxin produced by an S. aureus infection on patients, scientists created AIP mimics intended to act as competitive inhibitors of AIP-AgrC binding at the cell surface. Identify the experimental design that would determine which AIP mimic would most effectively inhibit the production of hemolysin toxin.

Answer 5

A. Grow S. aureus in separate culture media containing one AIP mimic each and measure the amount of AIP mimic transported into the cells. The most effective AIP mimic will be absorbed the fastest.

B. Grow S. aureus in separate culture media containing one AIP mimic each and measure the production of hemolysin toxin. The most effective AIP mimic will be in the culture producing the lowest amount of hemolysin.

C. Grow S. aureus in culture media containing hemolysin and measure the production of AIP
mimic in response to hemolysin intake. The most effective AIP mimic will be produced in the highest amount.

D. Grow S. aureus in separate culture media containing one AIP mimic each and measure the amount of live cells in each culture. The most effective AIP mimic will be the one that killed the most S. aureus.

Question 6

✩CORRECT ANSWER FOR 8.1, 3✩

Answer 6

B

Question 7

A population of 250 birds inhabit a canopy of a tropical rain forest that has a carrying capacity of 400 birds. What is the maximum population growth rate (rmax) if the population grows to 283 in one year?

Answer 7

A. 0.12
B. 0.13
C. 0.35
D. 0.39

Question 8

✩CORRECT ANSWER FOR 8.3, 1✩

Answer 8

C

Question 9

A fish population of 250 in a pond has a maximum annual rate of increase of 0.8. If the carrying capacity of the bond is 1500 for this species, what is the expected population size after one year?

Answer 9

A. 167
B. 417
C. 450
D. 500

Question 10

✩CORRECT ANSWER FOR 8.3, 2✩

Answer 10

B

Question 11

The population of Japanese sika deer in central Japan was determined each year from 2005 to 2014. The sika deer population underwent logistic growth starting at 26,000 deer in 2005 and stabilized at 58,000 deer between 2012 and 2014. Based on these data, the rmax for the population was determined to be 0.57. Central Japan contains a variety of habitats, including forests and grasslands. Sika deer benefit from the resources in grasslands more than forests; if deforestation occurred, producing more grasslands in the region, the carrying capacity for sika deer population would increase. What would the population size of sika deer be one year after the carrying capacity increased to 70,000 as a result of deforestation? Assume rmax does not change.

Answer 11

A. The population would grow to 70, 000 deer in a year, because they would occupy the entire environmental niche.
B. The population would grow to 91, 060 deer in a year, but then they would die off from a lack of resources.
C. The population would grow to 63, 667 deer in a year, and the growth rate would decrease the following year.
D. The population would remain at 58, 000 deer, since it had already stabilized

Question 12

✩CORRECT ANSWER FOR 8.3, 3✩

Answer 12

C

Question 13

✩WAITING ON 8.4 QUIZ RESULTS✩

Question 14

Researchers studied the diversity of macroscopic invertebrates in different areas of watershed ecosystems. They collected samples from 58 sites along 11 streams in the same geographical area. Their data were classified by stream type and can be found in Figure 1. The stream-type classifications range from the perennial stream type, which always has water, to the intermittent stream type, which is dry for more than nine months during the year. Figure 1. Diversity of macroscopic invertebrates in different stream types. Error bars represent a 95% confidence interval. Which of the stream types had a statistically lower macroscopic invertebrate species diversity than the seasonal streams?

Answer 14

A. Transitional streams only

B. Intermittent streams only

C. Perennial and intermittent streams only

D. Transitional and intermittent streams only

Question 15

✩CORRECT ANSWER FOR 8.5, 1✩

Answer 15

B

Question 16

Interactions among populations determine how they access resources within a community. In Costa Rica, two different species of mites, Rhinoseius colwelli and Rhinoseius richardsoni, exhibit a high degree of interspecies competition. Both mite species live within the flowers of plants, and adult male mites tend to kill mites if they belong to a different species. An experiment was carried out to determine whether these aggressive interactions have resulted in niche partitioning by R. colwelli and R. richardsoni, of different flower species, with each mite species living in different plant species. The results are summarized in Figure 1. Which of the following is an accurate interpretation of the data in Figure 1 ?

Answer 16

A. R. richardsoni is found significantly more frequently on Species 4 compared to Species 3.

B. R. colwelli is found significantly more frequently on Species 1 compared to Species 2.

C. R. richardsoni is found significantly more frequently on Species 3 and Species 4 compared to Species 1 and Species 2.

D. R. colwelli is found significantly more frequently on Species 3 and Species 4 compared to Species 1 and Species 2.

Question 17

✩CORRECT ANSWER FOR 8.5, 2✩

Answer 17

C

Question 18

In the Florida Everglades, Burmese pythons are an invasive species. They were introduced into southern Florida in 1992. These pythons feed on many of the native Florida species, establishing the pythons as the top predator in the environment. By the year 2000, their population had increased dramatically. Figures 1 and 2 display data collected by ecologists studying the results of the Burmese python invasion. Figure 1 shows counts of animals collected from nighttime road surveys in southern Florida, which are used to estimate population size. Figure 2 shows data collected from mosquitoes captured from the wild. DNA sequencing was used to identify the species of blood that the mosquitoes had in their stomachs, identifying various hosts used by the mosquitoes. In 1996, the native Culex cedecei mosquitoes in southern Florida preferentially took blood meals from white-tailed deer and raccoons. It was predicted that changes in host population size would alter these host preferences. Additionally, it is known that cotton rats are often infected by the Everglades virus, which normally exists in animals, but is capable of infecting humans. Ecologists predict that increased feeding on cotton rats by C. cedecei may significantly increase the tendency of this virus to infect humans. Which of the following populations have significantly decreased in size between 1996 and 2011 ?

Answer 18

A. White-tailed deer only

B. Cotton rats and rabbits only

C. White-tailed deer and raccoons only

D. White-tailed deer, raccoons, and cotton rats

Question 19

✩CORRECT ANSWER FOR 8.5, 3✩

Answer 19

C

Question 20

Researchers were studying species diversity in a savanna rangeland community in southwest Queensland, Australia. Researchers counted the numbers of plants species in four different categories at two nearby sites within the savanna rangeland; one lightly grazed by herbivores and one heavily grazed by herbivores (Figure 1). Which of the following best predicts the results of a drought in the savanna research area with regards to community resilience to this environmental change?

Answer 20

A. The heavily grazed area is more likely to recover more quickly from the drought due to reduced competition between species.

B. The lightly grazed area is likely to recover more quickly from the drought due to greater biodiversity.

C. The lightly and heavily grazed areas are likely to recover at equal rates due to the overlapping categories of plant species.

D. The lightly and heavily grazed areas are likely to recover at equal rates due to the similar climates and locations.

Question 21

✩CORRECT ANSWER FOR 8.6, 1✩

Answer 21

B

Question 22

In the Florida Everglades, Burmese pythons are an invasive species. They were introduced into southern Florida in 1992. These pythons feed on many of the native Florida species, establishing the pythons as the top predator in the environment. By the year 2000, their population had increased dramatically. Figures 1 and 2 display data collected by ecologists studying the results of the Burmese python invasion. Figure 1 shows counts of animals collected from nighttime road surveys in southern Florida, which are used to estimate population size. Figure 2 shows data collected from mosquitoes captured from the wild. DNA sequencing was used to identify the species of blood that the mosquitoes had in their stomachs, identifying various hosts used by the mosquitoes. In 1996, the native Culex cedecei mosquitoes in southern Florida preferentially took blood meals from white-tailed deer and raccoons. It was predicted that changes in host population size would alter these host preferences. Additionally, it is known that cotton rats are often infected by the Everglades virus, which normally exists in animals, but is capable of infecting humans. Ecologists predict that increased feeding on cotton rats by C. cedecei may significantly increase the tendency of this virus to infect humans. Which of the following most accurately explains an impact of Burmese pythons on the Everglades community in southern Florida using the data provided?

Answer 22

A. Python parasitism has reduced the population of white-tailed deer and raccoons.

B. Python predation has caused a trophic cascade that changed the mosquitoes’ niche.

C. Pythons have a mutual symbiosis with cotton rats, allowing their population to increase.

D. Intraspecific competition for food between white-tailed deer and raccoons has increased due to pythons

Question 23

✩CORRECT ANSWER FOR 8.6, 2✩

Answer 23

B

Question 24

In the Florida Everglades, Burmese pythons are an invasive species. They were introduced into southern Florida in 1992. These pythons feed on many of the native Florida species, establishing the pythons as the top predator in the environment. By the year 2000, their population had increased dramatically. Figures 1 and 2 display data collected by ecologists studying the results of the Burmese python invasion. Figure 1 shows counts of animals collected from nighttime road surveys in southern Florida, which are used to estimate population size. Figure 2 shows data collected from mosquitoes captured from the wild. DNA sequencing was used to identify the species of blood that the mosquitoes had in their stomachs, identifying various hosts used by the mosquitoes. In 1996, the native Culex cedecei mosquitoes in southern Florida preferentially took blood meals from white-tailed deer and raccoons. It was predicted that changes in host population size would alter these host preferences. Additionally, it is known that cotton rats are often infected by the Everglades virus, which normally exists in animals, but is capable of infecting humans. Ecologists predict that increased feeding on cotton rats by C. cedecei may significantly increase the tendency of this virus to infect humans. Based on the data, which of the following most accurately matches a potential change with its predicted effects on the southern Florida ecosystem?

Answer 24

A. Introduction of a new top predator species that preys solely on Burmese pythons would cause an increase in the raccoon population.

B. If the population of Burmese pythons were to decrease, then the cotton rat population would increase.

C. If more Burmese pythons are introduced in the Everglades, then mosquitoes will begin feeding on white-tailed deer frequently again.

D. Introduction of a new snake species that competes with the Burmese python for food would lead to an increase in the white-tailed deer population.

Question 25

✩CORRECT ANSWER FOR 8.6, 3✩

Answer 25

A

Question 26

Phytoplankton (dashed line) are important because they occupy the bottom of the food web absorbing CO2, functioning as a carbon sink. A scientist suggests that an El Niño event in early 1998 caused a significant decrease in the abundance of phytoplankton that year in the equatorial Pacific Ocean. Which of the following observations would best support this alternative hypothesis?

Answer 26

A. Previous dips in plankton abundance coincided with other El Niño events.

B. Primary consumers also experienced a dip in abundance in early 1998.

C. After mid-1998, there is no correlation between phytoplankton and zooplankton abundance.

D. CO2 levels in surface waters increased significantly in this region during 1998.

Question 27

✩CORRECT ANSWER FOR 8.7, 1✩

Answer 27

A

Question 28

Fur color is a genetically controlled trait in mice. A population of a species of mouse that typically lives in habitats with light-colored soil was studied for several generations. The background color of the habitat of this population became darker after the second generation due to human activity. A researcher sampled approximately 120 mice in each generation and recorded the fur color phenotypes as shown in Figure 1. The researcher claims that there is no selective advantage to fur color, so light and dark fur color phenotypes are present in similar frequencies in the fourth generation of this mouse population. Based on the data in Figure 1, which of the following best evaluates this null hypothesis?

Answer 28

A. The null hypothesis is rejected, because the change to a darker background color led to an increase in the dark-colored fur phenotype.

B. The null hypothesis is rejected, because there is no significant difference between the frequencies of the two phenotypes right after the human-caused change to the habitat in the third generation.

C. The null hypothesis cannot be rejected, because there is no significant difference between the frequencies of the two phenotypes right after the human-caused change to the habitat in the third generation.

D. The null hypothesis cannot be rejected, because the darker background color caused by the human-caused change to the habitat led to a decrease in the light fur color phenotype.

Question 29

✩CORRECT ANSWER FOR 8.7, 2✩

Answer 29

A

Question 30

Zebra mussels are an invasive species that has become widely established throughout the United States. Figure 1 shows the percent change in the population sizes of selected groups of organisms in the Hudson River since the introduction of zebra mussels. In this study chlorophyll-containing bacteria are considered phytoplankton and all other bacteria are considered bacterioplankton. Which of the following hypotheses about the effect of zebra mussels on the Hudson River community is best supported by the data in Figure 1 ?

Answer 30

A. Shoreline fish have replaced open water fish as top predators in a stable community.

B. Zebra mussels have integrated into the existing community with little effect on the community stability.

C. The reduction in primary productivity has resulted in an unstable community that will eventually collapse.

D. Bacterioplankton have replaced phytoplankton as the energy harvesters in the community.

Question 31

✩CORRECT ANSWER FOR 8.7, 3✩

Answer 31

C

Question 32

Potatoes as a food crop originated in South America. There are over 4,000 variations of potato grown there. Potatoes were brought to Europe by Spanish colonists in the late 1500s. One variety became the chief crop grown in much of Ireland by the early 1800s. Table 1 summarizes the spread of potatoes as a food crop. The Irish Lumper variety of potato was introduced into Ireland in the early 1800s. The Lumper soon became the only variety of potato grown in much of Ireland. The potato blight destroyed most of the Lumper crop between 1845 and 1852 resulting in the death of about 1 million Irish from starvation. A researcher suggests that the Irish monoculture (growing a single crop) of the Lumper potato did not significantly change the overall resistance of the potato crop in Ireland to diseases. Which of the following observations best refutes this null hypothesis?

Answer 32

A. Before the arrival of the potato blight, there were already two other potato plant diseases in Ireland.

B. The number of fatalities from the Irish potato famine was greater than the rest of the European countries combined.

C. During the early nineteenth century, the vast majority of people in Ireland depended on the Lumper potato for food.

D. Growing more varieties of potatoes increases competition for available resources, which may yield fewer potatoes.

Question 33

✩CORRECT ANSWER FOR 8.7, 4✩

Answer 33

B

Question 34

In the Florida Everglades, Burmese pythons are an invasive species. They were introduced into southern Florida in 1992. These pythons feed on many of the native Florida species, establishing the pythons as the top predator in the environment. By the year 2000, their population had increased dramatically. Figures 1 and 2 display data collected by ecologists studying the results of the Burmese python invasion. Figure 1 shows counts of animals collected from nighttime road surveys in southern Florida, which are used to estimate population size. Figure 2 shows data collected from mosquitoes captured from the wild. DNA sequencing was used to identify the species of blood that the mosquitoes had in their stomachs, identifying various hosts used by the mosquitoes. In 1996, the native Culex cedecei mosquitoes in southern Florida preferentially took blood meals from white-tailed deer and raccoons. It was predicted that changes in host population size would alter these host preferences. Additionally, it is known that cotton rats are often infected by the Everglades virus, which normally exists in animals, but is capable of infecting humans. Ecologists predict that increased feeding on cotton rats by C. cedecei may significantly increase the tendency of this virus to infect humans. Scientists hypothesize that the invasive Burmese pythons are responsible for recent increases in human Everglades virus infections. Evaluate this alternate hypothesis using the data provided.

Answer 34

A. The alternate hypothesis is supported because invasive Burmese pythons caused an increase in the mosquito population. This enabled them to transmit the Everglades virus at a higher frequency if they were infected.

B. The alternate hypothesis is supported because the invasive Burmese pythons caused mosquitoes to switch to feeding on cotton rats. This means that mosquitoes are more likely to carry the Everglades virus when they bite humans.

C. The alternate hypothesis is refuted because humans are used as hosts for only a small percentage of mosquito feedings. Humans therefore will not have an increase in Everglades virus infection.

D. The alternate hypothesis is refuted by the data because the population of cotton rats increased. Since there are more cotton rats, they will contain the Everglades virus and prevent it from infecting humans.

Question 35

✩CORRECT ANSWER FOR 8.7, 5✩

Answer 35

B

Question 36

Figure 1 shows the changing pattern of human population sizes in rural and urban areas from 1960 to 2016 with regard to the global population. A scientist interested in investigating how human population trends might affect local animal species’ richness stipulates a null hypothesis that animal biodiversity in rural areas will be unaffected in the future by the human population trends shown in Figure 1. Which of the following would best refute this null hypothesis?

Answer 36

A. More rural areas will become available for animal habitats over time.

B. Urbanization causes habitat fragmentation.

C. Urbanization decreases the per person fossil fuel use in urban areas.

D. Water in urban areas is treated before it is released into the rivers that flow into rural areas.

Question 37

✩CORRECT ANSWER FOR 8.7, 6✩

Answer 37

B