Mastering Bio: Biology Exam 2 Review

What interactions exist between a tick on a dog and the dog?

+/-

Deer are hosts of ticks but are not reservoirs of B. burgdorferi −− their immune systems detect and kill the bacterium. But a tick with a prior bacterial infection can consume a blood meal from a deer and then bite and infect a human. The fitness effects of a deer on B. burgdorferi can be summarized as:

- or + depending on whether the deer is the tick's last host.

Calculate the predicted genotypic frequency using the Hardy-Weinberg equation for the genotype ss. Enter to the 4th decimal place (worksheet #1)

0.0001 (with margin: 0.01)

What is the per capita rate of change for NYC in 2009? (To the third decimal place)

0.009 (with margin: 0.01)

Calculate the predicted genotypic frequency using the Hardy-Weinberg equation for the genotype Ss. Enter to the 3rd decimal place (worksheet #1)

0.018 (with margin: 0.01)

After several generations the actual genotype frequency for SCA in Nigeria is SS = 0.74, Ss = 0.24, and ss = 0.02. Calculate the frequency of allele "s" using the actual genotypic frequency for SCA in Nigeria. Enter to the 2nd decimal place. (Worksheet #5)

0.14 (with margin: 0.1)

What is the per capita rate of change in Valley Forge NHP (Worksheet question 2)

0.4 (with margin: 0.1)

In a hypothetical population of 1000 frogs there exists a gene with two alleles. 280 of the frogs are homozygous dominant (DD), and 220 are homozygous recessive (dd). What is the frequency of heterozygotes in the population?

0.5

Santa Cruz island is the largest of the six channel islands off of California's coast, and is entirely made up of conserved land and National Park administered land. The island is approximately 250 km^2 and is home to approximately 140 land bird, 11 mammal, 3 amphibian, and 5 reptile species. The next biggest island, Santa Rosa, is ~200km^2 and is home to approximately 100 bird, 3 mammal, 2 amphibian, and 3 reptile species.

0.54 (with margin: 0.01)

After several generations the actual genotype frequency for SCA in Nigeria is SS = 0.74, Ss = 0.24, and ss = 0.02. Calculate the frequency of allele "S" using the actual genotypic frequency for SCA in Nigeria. Enter to the 2nd decimal place. (Worksheet #5)

0.86 (with margin: 0.1)

A typical human population that historically has not been impacted by malaria has the following sickle cell anemia (SCA) allele frequency: S = non-mutated allele, s = sickle-cell allele. S = 0.991 and s = 0.009. Calculate the predicted genotypic frequency using the Hardy-Weinberg equation for the genotype SS. Enter to the 3rd decimal place. (Worksheet #1)

0.982 (with margin: 0.01)

Which size forest fragment would be most affected by habitat fragmentation over a given period of time?

1 hectare. The smallest fragments would be most affected by habitat fragmentation due to disturbances flowing into the fragment from the exterior.

Drag the labels to the diagram to identify the components of Shulte's experiment. Labels may be used once, more than once, or not at all.

1. Reef type is the independent variable. 2. Adult oyster density is a(n) dependent variable. 3. Spat density is a(n) dependent variable.

Biodiversity can be studied at three levels: genetic diversity, species diversity, and ecosystem diversity.

1. The number of habitat types increases when ecosystem diversity increases. 2. Low genetic diversity within a species increases the likelihood that the species may go extinct. 3. A human activity such as draining a wetland decreases ecosystem diversity. 4. Extinction decreases specific diversity. 5. High genetic diversity within a species increases the likelihood that the species can adapt to new environmental conditions.

Shulte's team collected oyster density data from all nine reef complexes and calculated mean densities for each reef type. The results are shown here:

1. The reef types used in Shulte's experiment are shown on the x axis. The mean density of oysters per squre meter is shown on the y axis. 2. Adult oysters are represented by yellow bars, spat are represented by blue bars, and the total of these groups is represented by red bars. 3. What is the total number of oysters growing on high-relief reefs? not shown in graph 4. What is the average number of oysters per square meter supported on high-relief reefs? 1,000 5. How many times greater is the total density of oysters on high-relief reefs compared to the total density on low-relief reefs? 4 6. How many times greater is the total density of oysters on high-relief reefs compared to the total density on the unrestored bay bottom? 170

Assume there are 200 MendAliens living on an island in my back yard. If my island has an area of 20 hectares, what is the population density of MendAliens in terms of MendAliens per hectare?

10 MendAliens per hectare. Population density is calculated as population size divided by area: 200 MendAliens / 20 hectares = 10 MendAliens per hectare.

What is the population density of NYC? (Worksheet Question # 3) Correct!

10,622 (with margin: 50)

A population is growing exponentially and its instantaneous growth rate (r) is 0.02. Would the number of individuals added to the population (rN) be greatest at a population size (N) of 20, 500 or 1000? See Section 51.3 (Page) .

1000. rN would be greatest at the highest N.

Suppose researchers marked 800 turtles and later were able to trap a total of 300 individuals in that population, of which 150 were marked. What is the estimate for total population size?

1600

What was the population density of foxes on Santa Cruz Island in 1999?

2.1 (with margin: 0.1)

Imagine five forest communities, each with one hundred individuals distributed among four different tree species (W, X, Y, and Z). Which forest community would be most diverse?

25W, 25X, 25Y, 25Z

The abundance of birds and other predators of borer beetles depends on how much natural forest is left within and around the coffee plantations. What is the approximate percentage increase in borer predators per hectare if forest cover is doubled from 15 to 30 percent?

275 percent

You are doing a mark-recapture experiment to determine the population size of the MendAliens living on an island in my back yard. Initially, you catch and mark 130 MendAliens, which you then release. Next, you capture 90 MendAliens, of which 20 are marked. What is your estimate of the population size of MendAliens living on the island in my back yard?

585. To get the population size N, multiply the number marked in the first catch, M1, by the total number caught in the second catch, C, and divide that by the number of marked recaptures in the second catch, M2: N = (M1 x C) / M2 Or: (130 x 90) / 20 = 585.

Estimate total population size in a mark-recapture study in which 200 individuals were initially marked, and you recaptured 150 of which 50 were marked. See Section 51.1 (Page) .

600. Correct! This is a simple method for field biologists to determine rough population estimates.

What is the combination of resources used and conditions tolerated in the absence of competitors called? See Section 52.1 (Page) .

A fundamental niche. Correct. A fundamental niche is not influenced by competitors.

Which of the following food webs most accurately depicts the Santa Rosa Island community? (Dashed lines indicate this organism is rarely eaten by the consumer, but not usually)

A.

Assimilation is indicated by the letter(s) _____.

A. Assimilation is the uptake of nutrients into an organism.

The range of Burmese pythons in Florida is expanding rapidly. List abiotic factors and biotic factors that might limit the range of pythons. Sort these items into the proper categories.

Abiotic Factors: cold temperatures to the north occurrence of deep seawater (Atlantic Ocean and Gulf of Mexico) surrounding southern Florida Biotic Factors: competition for food spread of disease increased predation on eggs or juveniles occurrence of parasites

Which of the following is the best conclusion from this figure?

Acorn abundance is linked to the population of Lyme disease tick densities

Which of the following is the best conclusion from this figure?

Addition of acorns lead to a stabilization of the experimental mice population

In the accompanying figure, which of the lines represents exponential growth?

All of the lines represent exponential growth.

The reference map does not indicate the source of energy and nutrients for decomposers. What would be an appropriate linker to add to the map to make it more complete?

All trophic levels pass energy and nutrients to decomposers. Correct: A dead organism at any trophic level can pass energy and nutrients to decomposers.

Many of the linkers in the map say "pass SOME energy and nutrients to." Where did the rest of the energy go? Select the most appropriate linker to make the map more complete.

All trophic levels release some energy as heat. Correct: As energy fuels the activities of organisms at all trophic levels, some of the energy ultimately dissipates as heat.

White-footed mice occupy a broad ecological niche−−they occur in most communities regardless of habitat quality. Many other species, like the opossum, are absent from low-quality forest fragments. Based on this information and the graph, propose a hypothesis to explain the observed relationship between increased forest fragmentation and increased incidence of Lyme disease.

As forest fragmentation increases, species richness will decline. As species richness declines, white-footed mice will still be present in the population (due to the species' broad niche), but species like opossums will be absent (due to their narrow niches). Since mice are huge reservoirs of the Lyme bacterium and species like opossums are not, a greater percentage of animals present in forest fragments will host the Lyme bacterium. Thus, the incidence of Lyme disease will increase.

In the accompanying figure, what can be stated about species diversity and latitude?

As latitude increases, diversity decreases.

Which of the following statements about Hadley cells is true?

As warm air rises, air at the top of the atmosphere is pushed poleward and cools. This cool air causes the cooler climates away from the equator.

Foxes and skunks consume some of the same prey, although foxes are primarily diurnal and skunks are primarily nocturnal. Which graph best represents their respective niches?

B

Use the following diagram of a hypothetical food web to answer the question(s) below. The arrows represent the transfer of energy between the various trophic levels. Which letter represents an organism that could be a producer?

B

Nitrification is indicated by the letter(s) _____.

B. Nitrification is the conversion of organic nitrogen-containing compounds to nitrites and nitrates.

Which of the following choices would be the most logical third step in Connell's experimental procedure, permitting him to either accept or reject his hypothesis of competitive exclusion?

B. Remove Balanus from one half of each of the transplanted rocks. After transplanting rocks containing young Chthamalus from the upper to the lower intertidal zone and allowing Balanus larvae to colonize the rocks, Connell then removed the Balanus from one half of each transplanted rock. The experimental group: The half of each rock that contained both Balanus and Chthamalus was the experimental group. The experimental group tests to see if the presence of Balanus in some manner prevents Chthamalus from growing. The control group: The half of each rock that contained only Chthamalus was the control group, which was identical to the experimental group except that the competition between Balanus and Chthamalus was eliminated. This approach "controlled" for other factors that might have prevented Chthamalus from growing in the lower intertidal zone, such as interactions with organisms other than Balanus in the lower intertidal zone; interactions with the physical environment of the lower intertidal zone (e.g., temperature or time submerged); characteristics of individual rocks that might limit Chthamalus growth. Note that completely removing Balanus from some of the transplanted rocks would control for the first two factors, but not the third. Only removing Balanus from half of each transplanted rock controls for all three factors.

Which of the following student-drawn niche models most clearly shows two species of bacterium that are specialized to survive in environments of different pH?

B. Two Side by Side Graphs that overlap at the center.

While traveling in Texas, you stumble across a snake with red, yellow, and black bands. You somehow remember that this could be a poisonous coral snake or a harmless milk snake, but you forget how to differentiate them because they both have similar colors and banding patterns. You wisely decide not to pick up the snake. What you don't realize, is that it was the harmless milk snake. What defense of the snake was successful in preventing you from grabbing the snake?

Batesian mimicry

Which letter represents an organism that could only be a primary consumer?

C

Which of the following niche models suggests the most competition between two species?

C. Graphs on top of each other, tiny graph inside, big graph outside.

Which of the following statements about the movement of nutrients through an ecosystem is true?

Carbon cycles between the atmosphere and living biomass. This statement is true; carbon flows from carbon dioxide in the atmosphere to living biomass.

How does carbon move from the biota to the atmosphere?

Carbon dioxide is released during cellular respiration. Carbon dioxide is indeed released into the atmosphere during cellular respiration by living organisms.

How have humans altered the global carbon cycle?

Carbon inputs into the atmosphere have risen. Human activities such as deforestation and the burning of fossil fuels have increased the amount of carbon in the atmosphere.

Why does it take 10 times more energy to grow a kilogram of beef than a kilogram of wheat?

Cattle only integrate 10 percent of their food into biomass.

Which of the following student models does the clearest job of showing the flow of energy and nutrients in this partial food web?

Clover and Blue Grass --> Rabbit --> Fox

Researchers hypothesize that the severe winter of 2010 caused the decline in the number of pythons encountered that year. Is cold weather typically a density-dependent factor or a density-independent factor? Explain the difference.

Cold weather is typically a density-independent factor because it affects the pythons the same way no matter whether there are few or many pythons. A density-dependent factor, such as competition for food, increases with increasing python density.

Which of the communities in the figure has the lowest species richness?

Community 3

Based on the background text, what kind of interspecific interactions are occurring between skunks and foxes?

Competition

Nitrogen-fixing bacteria is(are) indicated by the letter(s) _____.

D and E. Both of these pointers are indicating nitrogen-fixing bacteria. Nitrogen fixation is the conversion of nitrogen to a form that plants can use.

Returning foxes to their pre-Eagle introduction population levels would have what effect on primary consumer populations?

Decrease

Denitrifying bacteria convert _____ to _____.

Denitrifying bacteria convert nitrates to nitrogen gas.

Why do populations grow more slowly as they approach their carrying capacity?

Density-dependent factors lead to fewer births and increased mortality.

Why has the growth of the fox population on Santa Cruz Island started to level off during the last few years of available data?

Density-dependent factors lead to fewer births and increased mortality.

What are rain shadows?

Dry regions on the leeward side of mountain ranges. Rain shadows are dry regions on the leeward side of mountain ranges that result when an air mass releases its moisture on the windward side of the range and then is carried by winds to the leeward side.

Which location on Earth receives the most solar radiation per unit area?

Equator. The equator receives the most solar radiation per unit area because sunlight arrives almost perpendicular to Earth's surface there.

Which of the following statements is consistent with the principle of competitive exclusion?

Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of two competing species

Which of the following statements is consistent with the principle of competitive exclusion?

Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of two competing species.

Which of the following statements best summarizes evolution by natural selection as it is viewed today?

Evolution by natural selection is the differential survival and reproduction of the most-fit phenotypes.

The equilibrium theory of island biogeography predicts that large islands close to the mainland will have more species than small islands that are distant from the mainland.

Evolution occurs more rapidly on large islands, thereby increasing species diversity.

True or false? Weather is defined as the prevailing long-term atmospheric conditions in a particular region.

False. Climate is defined as the prevailing long-term weather conditions in a particular region; weather is defined as the short-term atmospheric conditions of temperature, sunlight, moisture, and wind.

True or false? Local biogeochemical cycles are isolated within their particular ecosystem and all ions and molecules remain in that ecosystem permanently.

False. Local biogeochemical cycles are linked into one global system by the movement of ions and molecules from one ecosystem to another.

True or false? In the global carbon cycle, rivers link the terrestrial and marine reservoirs of carbon, whereas carbon exchange between the atmosphere and the ocean is achieved by active transport.

False. Rivers do indeed link the terrestrial and marine reservoirs of carbon on Earth, but carbon is exchanged between the atmosphere and the ocean by diffusion, which depends on the concentration gradient between the two reservoirs.

Researchers have measured a positive correlation between forest fragmentation and incidence of Lyme disease. According to the theory of island biogeography, how do you predict fragmentation will affect species richness?

Forest fragmentation will subdivide large areas of habitat into many small islands of habitat, causing species richness to decline.

Lionfish are usually found in full-salinity seawater (35 parts per thousand). However, lab studies show that lionfish can tolerate salinities as low as 4 parts per thousand for several days, suggesting that the low-salinity water of estuaries (such as at the mouth of the Amazon River) may not be a barrier to lionfish dispersal along the coasts. Complete a niche model predicting lionfish abundance as a function of salinity.

Freshwater is bottom left, Seawater is top right. Salinity is x-axis and y-axis is number of individuals.

How might genotype frequencies of alleles for body size change under directional selection? See Section 23.3 (Page) .

Genotypes that represent larger individuals become more prevalent. Directional selection is changing genotypes in a particular direction.

The symbols +, - , and 0 are to be used to show the results of interactions between individuals and groups of individuals in the examples that follow. The symbol + denotes a positive interaction, denotes a negative interaction, and 0 denotes where individuals are not affected by interacting. The first symbol refers to the first organism mentioned. Match the organismal interaction with the appropriate symbols.

Golden Eagle/Fox: +/- Fox/Skunk: 0/0 Golden Eagle/Skunk: 0/+

Match each description with the appropriate graph. Remember that Knight's predictions were: Fish →→ Low dragonfly population →→ High insect population →→ High St. John's wort population No fish →→ High dragonfly population →→ Low insect population →→ Low St. John's wort population

Graph 1 most closely resembles the results from Knight's experiment. (Rather than directly measuring individuals of each species, Knight took other indirect measurements of population size.). She found that the numbers of dragonflies, insects, and St. John's wort all trended in the direction she predicted. Her results indicate that trophic cascades are strong and do operate across ecosystems.

How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria?

He evaluated blood samples for malaria parasites and the presence of sickle cells. He expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected. Dr. Allison gathered blood samples from more than 5,000 children in East Africa. He analyzed the samples to identify malaria parasites and sickle cells. He found that children carrying the sickle cell character (or trait) had a lower parasite count, as if they were partially protected against malaria.

In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?

He hypothesized that there was a connection between malaria and sickle cell disease. On the basis of this hypothesis, Dr. Allison predicted high frequencies of sickle cell disease only in areas where malaria is common.

How does inbreeding alter genotype and allele frequencies? See Section 23.2 (Page) .

Homozygotes increase in frequency in the population over generations. Inbreeding increases homozygosity.

A population is correctly defined as having which of the following characteristics? I. inhabiting the same general area II. belonging to the same species III. possessing a constant and uniform density and dispersion

I and II only

Which of the following would be most significant in understanding the structure of an ecological community? I. determining how many species are present overall II. determining which particular species are present III. determining the kinds of interactions that occur among organisms of different species IV. determining the relative abundance of species

I, II, III, and IV

Looking at the data in the accompanying figure from the hare/lynx experiment, what conclusion can you draw? I. Food is a factor in controlling hare population size. II. Excluding lynx is a factor in controlling hare population size. III. The effect of excluding predators and adding food in the same experiment is greater than the sum of excluding lynx alone plus adding food alone.

I, II, and III

How does Dr. Allison's work provide an example of natural selection in humans?

In areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease. In areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles. In different environments, natural selection favors different characteristics. In areas with malaria, the reproductive advantages of having one sickle cell allele (and some protection from malaria) kept the allele at high frequencies in the population. In areas without malaria, the reproductive disadvantages from sickle cell disease reduced the allele in populations.

Will this population of lizards stay the same, increase, or decrease over time? See Section 51.6 (Page) .

Increase, since R0 >1

How might climate change alter the figure arrows?

Increased evaporation from the ocean

In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?

Individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population. People with one sickle cell allele are protected from malaria, but do not have sickle cell disease. Protection from malaria comes at the cost of more sickle cell disease in the population.

Which statement best describes the evolutionary significance of mutualism?

Interaction increases the survival and/or population growth rate(s) of mutualistic species.

How might genetic drift be important in a small population. See Section 23.4 (Page) .

It decreases genetic diversity via sampling error during mating. Genetic drift is of large concern with populations of a small size because you are more likely to have mating between close relatives.

Evaluate this statement: Leaving some natural forest in and around coffee plantations is a "win−−win" situation−−a win for ecosystems and a win for farmers.

It does look like a win−−win situation. Leaving more natural forests increases the biodiversity at the genetic, species, and ecosystems level, increasing the chance of resilience and ecosystem function. Leaving some of the natural forests is a win for farmers because the forest provides ecosystem services.

How might gene flow be important in managing an endangered population? See Section 23.5 (Page) .

It increases genetic diversity by introducing alleles from one population into another. Gene flow is the movement of alleles between populations.

Which statement best describes what ultimately happens to the chemical energy that is NOT converted to new biomass in the process of energy transfer between trophic levels in an ecosystem?

It is eliminated as feces or is dissipated into space as heat, consistent with the second law of thermodynamics.

Look at the graph above. Why did the researchers bother to collect data from the coffee shrubs before the nets were added to treatment plots to exclude birds?

It was important for the researchers to demonstrate that there was no difference between control and treatment plots at the start of the experiment so that they could be sure that any change seen was due to the exclusion of birds and not some other factor, such as a difference in shade, water availability, abundance of beetles, and so on.

How would the species richness curves on an island be affected if mainland habitats were wiped out by urbanization? See Section 52.4 (Page) .

It would lower the rate of immigration and increase the rate of extinction. Correct! In effect, the island would become more remote.

Marine reserves are protected areas in the ocean where harvesting fish and invertebrates is limited or prohibited. Generally, these reserves protect a coral reef ecosystem, a kelp forest ecosystem, or an area near a particular shoreline, rather than a single species. The following graphs represent changes typical after the establishment of some well-planned marine reserves. Interpret the graphs and determine which of the following statements are true.

Kelp forest recovery in marine reserves is likely due to an increase in predators. An increase in the number of predators in a community correlates with a decrease in the number of grazers (sea urchins in this case). Species diversity generally increases in marine reserves. Organism size increased by about 30% after the establishment of this reserve.

Interpret the model.

Kelp is the primary producer in this food web. True The arrows should point down instead of up. False Sea otters are the primary consumers in this food web. False Some of the energy and nutrients in the orca came from the kelp. True This food web shows all of the species interactions in this ecological community. False

Drag the pink labels to indicate which type of interaction occurs between each pair of species. Based on those interactions, drag the blue labels to indicate the population changes Knight predicted for each species in the two different treatments. Labels can be used once, more than once, or not at all.

Knight had a complex prediction. Ultimately, ponds with fish should have a higher abundance of St. John's wort than ponds without fish, due to a trophic cascade. In the case of ponds with fish, the fish eat dragonfly larvae. When there are fewer dragonflies, fewer insects are eaten, and the insect populations increase. When there are more insects that can pollinate St. John's wort, the population of St. John's wort increases. In the case of ponds without fish, there are no fish to eat the dragonfly larvae. When there are many dragonflies, they eat many insects, and the insect populations decline. When there are fewer insects to pollinate St. John's wort, the population of St. John's wort declines.

Looking at the data in the accompanying figure, what can be said about survival and clutch size?

Large clutch size correlates with low survival.

Drag the images of the left half of the rock (white) and right half of the rock (blue) to indicate which barnacle species (if any) would be present at the end of the summer if niche differentiation had occurred between Chthamalus and Balanus.

Left half- Balanus only. Right half- No barnacles. If Connell had observed these results from his experiment, he would have had to reject his hypothesis of competitive exclusion. In this hypothetical experiment, because Chthamalus did not survive in the lower intertidal zone even when Balanus were removed, that means that competition with Balanus could not explain why Chthamalus do not inhabit the lower intertidal zone. Given these results, Connell would have had to conclude that Chthamalus do not survive in the lower intertidal zone because of physical limitations. This would be an example of niche differentiation in which each species would be limited to its respective niche by physical factors rather than biological interactions (competition). Only Balanus would survive in the lower intertidal zone, and only Chthamalus would survive in the upper intertidal zone. Note that competition between species can lead to niche differentiation. Because natural selection favors individuals that do not compete, niche overlap, and thus competition, may be reduced or eliminated over time. Once niche differentiation is complete, it is only physical factors that limit the niches of the two previously competing species.

Which of the following is the most important assumption for the mark-recapture method to estimate the size of wildlife populations?

Marked individuals have the same probability of being recaptured as unmarked individuals during the recapture phase

Which of the following is the most important assumption for the mark-recapture method to estimate the size of wildlife populations?

Marked individuals have the same probability of being recaptured as unmarked individuals during the recapture phase.

Which of the following models presents a species relationship as it would typically be drawn within a food web?

Milk-Weed --> Monarch Butterfly

Which of these models shows the highest evenness?

Most balanced

Which of these models shows the highest species richness?

Most diverse

Which one of these is a nitrite?

NO2-.

Which one of these is a nitrate?

NO3-.

Which evolutionary mechanism results in adaptation? See Section 23.2 (Page) .

Natural selection. Correct. Adaptation is the ability to reproduce and produce viable offspring in a particular environment. Natural selection is the evolutionary mechanism that produces adaptation.

What is the term used to describe the process shown in the panels in the accompanying figure, assuming Time 2 follows Time 1?

Niche differentiation

Nitrifying bacteria convert _____ to _____.

Nitrifying bacteria convert ammonium to nitrites.

The Chesapeake Bay is a delicate system of interacting organisms, including marine animals, plankton, and microbes. In recent decades, nutrient pollution has posed a major threat to this system, resulting in dead zones where oxygen levels drop too low to support life. This process is known as eutrophication.If reef restoration efforts based on Shulte's experiment are implemented throughout the bay, increased oyster populations may help to restore the ecosystem. The flowchart below shows how oysters can affect other components of the Chesapeake Bay ecosystem.

Nitrogen and phosphorus flowing into the bay have drastically increased phytoplankton populations. A healthy oyster population can keep bay waters clear by filtering nutrients and phytoplankton from bay waters, but in many areas the decline in oyster populations has enabled nutrient overenrichment, elevated growth of phytoplankton, and subsequent ecosystem degradation.

_____ removes nitrogen from the atmosphere.

Nitrogen fixation. Nitrogen fixation is the conversion of nitrogen gas to a form that can be used by plants (and other organisms).

Which assumption must be correct for a population to be in Hardy-Weinberg equilibrium for a specific gene? See Section 23.1 (Page) .

No genetic drift can affect allele frequencies for the gene. Correct. Any condition that changes allele frequencies in the population represents a violation of the Hardy-Weinberg principle and means that the population will not be in Hardy-Weinberg equilibrium.

For a gene suspected of causing hypertension in humans, you observe the following genotype frequencies: A1A1 0.574; A1A2 0.339; A2A2 0.087. Is this gene in Hardy-Weinberg equilibrium? Why or why not? (Assume that a difference of three percent or more in any of the observed versus expected frequencies is statistically significant.) See Section 23.1 (Page) .

No. The expected genotype frequencies are A1A1 0.553; A1A2 0.381; A2A2 0.066. Correct. The expected genotype frequencies are significantly different from those expected from the Hardy-Weinberg Principle.

A student has drawn a model to compare two forest communities in Borneo. Interpret her model.

Oil palms do not occur in the native community. True The oil palm community has higher evenness. False The species richness of the native community is twice as high as the oil palm community. True The native community has higher species diversity than the oil palm community due to its higher evenness and species richness. True Species F is the most abundant species in the native community. True

List the five main levels of ecological study, and write a question about the ecology of lionfish that you could research at each level. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

Organismal: What range of salinities can lionfish tolerate? Global: How will climate change and ocean acidification affect the invasive behavior of lionfish? Community: How are the lionfish affecting other species in the coral reef? Ecosystem: How do lionfish affect the net primary productivity of the coral reef ? Population: What is the growth rate of the lionfish number?

What about the life history traits of pigs allowed them to thrive on the Channel Islands? (Select all that apply)

Pigs produce a large number of young per litter. Adult pigs are too large to generally be eaten by Golden Eagles

Which of the following is the best conclusion from this figure?

Removal of mice lead to an increase in gypsy moth larvae successfully changing into adults.

What does the graph in the accompanying figure tell you about the definition of a keystone species?

Removing a keystone species from the community drastically reduces diversity.

What is the take-home message?

Removing just a few lionfish does not help much; many of the invasive fish must be removed to help native fish recover.

Which desert is caused by a Hadley cell?

Sahara Desert in Africa. The Sahara Desert is caused by a Hadley cell; it is not the result of topography, since there are no extensive North-South mountain ranges in Africa.

Use the accompanying diagram of Channel Islands, as well as MacArthur and Wilson's island biogeography principles, to answer the question(s) below: Which island would likely have the greatest species diversity?

Santa Cruz

Which area is not one of the three major reservoirs of the global carbon cycle?

Sedimentary rock. Sedimentary rock is the source of fossil fuels, but it is not one of the three reservoirs of the global carbon cycle.

Compare sickle cell disease and malaria.

Sickle cell disease and malaria are both potentially lethal diseases. Though malaria is an infectious disease and sickle cell disease is inherited, both can cause life-threatening conditions.

Pythons are generalist predators, consuming a wide variety of prey including birds, mammals ranging from rodents to deer, and alligators. A road survey showed a 99 percent decrease in the frequency of raccoon and opossum observations within python areas from 2003 to 2011. Rabbits and foxes have also disappeared from the area. Do you think food availability limits, or could limit, the carrying capacity of Burmese pythons in the Everglades?

Since pythons are generalists, it would seem that food availability would not be a primary factor in determining the carrying capacity. However, the dramatic disappearance of raccoons and opossums indicates that predation rates are very high and at least some food sources are disappearing. In the long run, the size of the python population will be food-limited (the population cannot increase exponentially forever).

Which aspects of a region's climate have the most impact on plants and animals?

Temperature and moisture. Temperature and moisture are the aspects of a region's climate that have the most impact on plants and animals.

Consider this niche model of rainbow trout at different temperatures.

Temperature is the independent variable. True The number or proportion of trout is the dependent variable. True Temperature should be labeled on the y-axis. False The model indicates that rainbow trout are more sensitive to changes in cooler temperatures than to warmer temperatures. True Rainbow trout are most abundant at a temperature of about 15 C. True

Foxes that escaped Golden Eagle predation tended to be more active at night compared to other foxes. If, under this selective pressure, island foxes become nocturnal what would this suggest about that trait?

That there is an heritable trait associated with time of activity.

DNA studies suggest that the lionfish invasion began with just a few females released off the coast of Florida, probably from a fish tank. Based on your knowledge of ocean currents, predict the direction in which the lionfish dispersed most quickly.

The North Atlantic Gyre flows in a clockwise direction, so the prevailing current on the Florida coast would be south to north, and it would disperse lionfish up the coast.

Suppose you trap some fish in a lake, mark them, and release them. Every month for a year you re-trap a similar number of the fish and release them. You notice each month that the proportion of marked fish trapped is declining. Which of the following is a reasonable explanation for this observation? See Section 51.2 (Page) .

The fish do not have long lifespans so some of the marked fish are dying each month. This would be a reasonable explanation.

How would the addition of a plant in which nitrogen fixation occurs alter succession? See Section 52.3 (Page) .

The following community would change drastically. With nutrients more readily available, the species of plants would be much different than before.

Your classmate sketched four niche models but forgot to label them. Identify which two represent predicted niches for a mountain goat and which two represent predicted niches for the Caribbean reef octopus.

The graphs showing predicted mountain goat niches are 3 and 1. The graphs showing predicted Caribbean reef octopus niches are 2 and 4.

Conservation biologists are scrambling to put measures in place to contain the spread of lionfish. For example, Stephanie Green and colleagues measured how quickly the number of native fish would recover if varying numbers of lionfish were removed from reefs in the Bahamas. They randomly assigned 24 reefs to one of four groups and plotted the proportional change in the number native fish at six-month intervals after different amounts of lionfish (0%%, 25%%, 75%%, or 95%%) were removed. (In the graph that follows, values above 1 on the y-axis represent amounts that exceed those at the start of the study in 2009, while values below 1 indicate declines.) Compare the percentage of native fish observed in June 2011 after 25 percent versus 95 percent of lionfish were removed.

The green data point at June 2011 shows a proportional change of about 1.7, which means that the native fish population increased by about 70 percent when 95 percent of the lionfish was removed. In contrast, the orange data point at June 2011 shows a proportional change of about 0.5, which means that the native fish population decreased by about 50 percent when only a quarter of the lionfish were removed.

As N approaches K for a certain population, which of the following is predicted by the logistic equation?

The growth rate will approach zero.

Interpret this niche model for three species of birds.

The independent variable is branch height. True Species B builds nests in the widest variety of branch heights. False Species A and Species B both build the most nests in branches about 4.5 m high. True All three species build nests in branches that are 6 m high. True Competition for nest space will increase the fitness of Species B but decrease the fitness of Species A. False More competition for branch space occurs between Species A and B than between Species B and C. True

Which of the following statements about the effects of forest fragmentation on plant biomass and species diversity is true?

The loss of plant biomass has a domino effect on other species that live in the forest fragment. This phenomenon exacerbates the edge effects seen in forest fragments and causes a more rapid loss of species diversity in the fragment.

Why can't a female lizard have both high fecundity and high survival?

The more energy the female devotes to offspring, the less that can be devoted to her survival.

If a person has two normal copies of the hemoglobin allele, which statements are true?

The person is homozygous at the hemoglobin locus. The person is susceptible to malaria. A person with two copies of any allele is homozygous. A person with two normal copies of the hemoglobin allele is more susceptible to malaria than someone with a sickle cell hemoglobin allele.

What conclusion can you draw from the accompanying figure?

The relationship between the populations cannot be determined only from this graph.

In this experiment, Balanus was removed from the habitat shown on the left. Which of the following statements is a valid conclusion of this experiment?

The removal of Balanus shows that the realized niche of Chthamalus is smaller than its fundamental niche.

Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.

The sickle cell allele will decrease in frequency. Without malaria, selection for the sickle cell allele decreases. As a result, the frequency will likely decrease.

Which of the following is TRUE of species interactions?

They can act as agents of natural selection

Which of the following is TRUE of species interactions?

They can act as agents of natural selection.

How do greenhouse gases contribute to global warming?

They prevent infrared light from leaving Earth's atmosphere. Greenhouse gases prevent infrared light, or radiant heat, from leaving Earth's atmosphere, leading to global warming.

How do early successional species alter the environment in ways that make growing conditions more difficult for their own species? See Section 52.3 (Page) .

They reduce the disturbed nature of the soil, making it harder for their seeds to become established. Their seeds tend to do well in the disturbed soils.

Why are species like the lionfish considered "invasive"?

They spread aggressively and displace native species.

In the following diagram, label the fundamental and realized niches for Chthamalus. Note that one target should be left blank.

Top is Realized Niche, Both are Fundamental Niches. Connell's experiment supported his hypothesis that Chthamalus are competitively excluded from the lower intertidal zone. Chthamalus are able to live in both the upper and lower intertidal zones in the absence of competition with Balanus. Thus the entire intertidal zone is Chthamalus' fundamental niche. In the presence of Balanus, however, Chthamalus are limited to the upper intertidal zone -- their realized niche -- because of interspecific competition. The situation for Balanus is quite different, as Connell discovered in further experiments. Balanus are excluded from the upper intertidal zone only by physical factors -- the inability to tolerate the higher temperatures and greater desiccation that occur during the more lengthy exposure to air in the upper intertidal zone. Therefore, there is no realized niche for Balanus because there is no competition that limits their niche. Balanus' fundamental niche is the lower intertidal zone.

True or false? Biologists studied the effects of forest fragmentation by calculating the difference between the amount of plant biomass in the edges of forest fragments and the interiors of unfragmented forest.

True. Through these studies, biologists found that the edge plots lost about 14 percent of their biomass every two years, starting at two years after the fragmentation occurred.

Given the data in the table, which survivorship curve does Lacerta viviparta best resemble? See Section 51.2 (Page) .

Type II. There is a steady decline in survivorship over time.

Which of these sampling protocols would you use to obtain the most representative data of oyster growth on the three reef types?

Use a random sampling approach to select sites on different reef types from several of the reef complexes. Shulte's team sampled 85 one-square-meter plots allocated randomly across the three reef types in all nine reef complexes. By taking a random sample from each reef complex, they ensured that sampling was representative of the entire area.

Which action influences the abiotic components of an organism's environment?

Water pollution. Water pollution influences the abiotic components of an organism's environment.

Based on what you learned from Knight's study, which of the following would be reasonable explanations for why your pond has abundant St. John's wort and your neighbor's pond does not? Select the four best answers.

Your neighbor's pond has a plant that competes with St. John's wort. You have a bird house with dragonfly-eating birds near your pond. Your neighbor has been using herbicides to manage vegetation near his pond. Your pond has 100 fish, and your neighbor's pond has 50 fish. Submit

Refer to the paragraph on dark-eyed junco birds. The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of males from nearby mountain populations averaged 40—45% white. If this observed trait difference were due to a difference in the original colonizing population, it would most likely be due to __________.

a founder effect

Newly hatched ticks do not harbor B. burgdorferi. Rather, they pick it up from certain hosts that are reservoirs of the bacterium. When a larval tick crawls onto a host, it may get groomed off and killed by the host, or it may feed successfully, in which case it may or may not then become infected with B. burgdorferi. Felicia Keesing and others measured the rate of tick feeding and infection on different hosts. What percentage of ticks on mice were infected with B. burgdorferi?

about 45 percent

What percentage of ticks on opossums were groomed off and killed?

about 95 percent

Which sequence of organisms represents a primary producer -> primary consumer -> secondary consumer -> tertiary consumer in a food chain?

algae -> snail -> otter -> shark. Correct: Algae are the primary producers in this example, consumed by snails, which are consumed by otters, which are consumed by sharks.

Evolution in a population of island iguanas can be caused by the following agent(s):

all of the above

In the accompanying figure, which of the arrows represents the carrying capacity?

arrow C

In what form does energy pass through the trophic levels shown on the map?

chemical potential energy. Correct: Energy is stored in the covalent bonds of the macromolecules of organisms.

Epiphytic orchids grow harmlessly on their host trees, and derive their resources from the air and from rain, rather than from their host plant. Which of the following is the best description of this species interaction?

commensalism

An egret eats insects stirred up by grazing animals. Which of these terms applies to the relationship between the egret and the grazing animal?

commensalism. In commensalism, one member of the species pair benefits and the other is unaffected; in this case the egret is getting a meal and the grazing animals are unaffected.

Humans and sharks both eat fish. Which of these terms applies to the relationship between the human and the shark?

competition. The human and the shark are both competing for a resource (fish).

In this experiment, Balanus was removed from the habitat shown on the left. Connell conducted this experiment to learn more about ________.

competitive exclusion and distribution of barnacle species.

Which species interaction depends on prey density and effectiveness of prey defenses to determine the impact on the prey population?

consumption

Which of the following examples would most accurately measure the density of the population being studied?

counting the number of moss plants in 1-square-meter quadrants

Cows eat grass. If you added up all the biomass of a population of cows and the biomass of all the grass that those cows eat over their lifetimes, which would be higher?

cow biomass < grass biomass. Correct: It would take about 100 kg of grass to produce every 10 kg of cow.

Cystic fibrosis is a genetic disorder in homozygous recessive (ff) humans that typically significantly reduces life expectancy. Over time, we would expect the f allele frequency to ________ for this trait.

decrease

Which of the following is the most predictable outcome of increased gene flow between two populations?

decreased genetic difference between the two populations

An ecologist recorded 12 white-tailed deer, Odocoileus virginianus, per square kilometer in one woodlot and 20 per square kilometer in another woodlot. What was the ecologist comparing?

density

An earthworm that feeds on the remains of plants and animals is acting as a _____.

detritivore. The earthworm is feeding on the remains of dead organisms.

In relation to humans, B. burgdorferi is a/an ______ and the tick is a/an ______.

endoparasite/ectoparasite

Burmese pythons were first found in the wetlands of Everglades National Park in the 1980s, but only rarely. The graph shows what happened next. Most of the data are derived from chance encounters of pythons on roads (pythons are notoriously difficult to find). How would you describe the type of population growth in pythons from 2000 to 2008?

exponential

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the HardyWeinberg model?

f(A1) = 0.9700, f(A2) = 0.0300

Three types of threats to biodiversity are: habitat loss and fragmentation the introduction of exotic, or non-native, species overexploitation, or overharvesting Determine the type of threat that each of the following statements describes.

habitat loss and fragmentation: A wetland is drained to make room for ahousing development. Some fishing netsdamage the seafloor. Small rainforest remnantshave less diversity thanlarger rainforest remnants. Florida panthers weregeographically cut off from otherpanthers about 100 years ago. exotic species: South American rodents called nutria eat wetland plants and cause bankerosion in the United States. Melaleuca trees from Australia displace native wetland vegetation in Florida. overexploitation: Wild American ginseng populations have declined as a result of increased demand for the roots. Cod are caught fasterthan they can reproduce.

The recessive allele that causes sickle cell anemia is harmful to homozygous individuals. What maintains the presence of this allele in a population's gene pool?

heterozygote advantage

Grass contains carbon. When a cow eats grass, where does the carbon from the grass end up?

in the biomass of the cow and in the atmosphere as CO2. Correct: Some of the carbon will end up in the biomass of the cow, but some of the grass biomass will be processed by cell respiration and released into the atmosphere as CO2.

Mutation is the only evolutionary mechanism that ________.

is the ultimate source of variation in natural populations

The competitive exclusion principle states that ________.

it is not possible for two species with the same niche to coexist in the same region

In a tide pool, 15 species of invertebrates were reduced to 8 after one species was removed. The species removed was likely a(n) ________.

keystone species

Genetic variation ________.

must be present in a population before natural selection can act upon the population

Humans who have pets tend to be healthier than humans who do not have pets. Which of these terms applies to the relationship between a human and a pet?

mutualism. In mutualism, both members of the species pair benefit; in this case the human is healthier and the pet is getting room and board.

What is the term used to describe the process shown in the panels in the accompanying figure, assuming Time 2 follows Time 1?

niche differentiation

For biologists studying a large flatworm population in the lab, which HardyWeinberg condition is most difficult to meet?

no mutation

Which of these terms applies to the relationship between a dog and a blood-sucking tick?

parasitism. The tick benefits at the expense of the dog; the dog is the host and the tick is the parasite.

A human eats a deer. Which of these terms applies to the relationship between the human and the deer?

predation. The human is the predator and the deer is the prey.

What is the main advantage of controlled burnings of forested areas? Controlled burnings _____.

prevent the overgrowth of the underbrush

A cow eating grass is an example of a _____.

primary consumer. By feeding on a producer, the cow is acting as a primary consumer.

In an ecosystem, phytoplankton are _____.

producers. Autotrophs, such as phytoplankton, are producers.

When a human eats a steak, the human is acting as a _____.

secondary consumer. By feeding on a primary consumer, the human is acting as a secondary consumer.

The mark-recapture method would be best for sampling a population of _____.

sharks. The mark-recapture method works best for active species whose individuals tend to be highly mobile.

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation?

stabilizing selection

A human who just ate a hamburger is eaten by a shark while swimming. The shark is acting as a _____.

tertiary consumer. The shark that ate the human that ate the cow that ate the grass is the tertiary consumer.

Carrying capacity is _____.

the maximum population size that a particular environment can support

Succession in an ecological context refers to _______. See Section 52.3 (Page) .

the sequence of changes in species composition over time within the community after a disturbance. Correct. Succession is the description of how a community changes through time.