Ecology Mid Term

Which statement is false?

a) Biomes are determined according to similarities in the morphological responses of organisms to the physical environment.

b) The same biome can be found on different continents.

c) Biomes are characterized more by the plants that are found there than by the animals.

d) Determination of biomes incorporates taxonomic similarities among organisms.

Based on the climate diagram above, the location is most likely in a _______ at around _______ latitude.

Suppose that in order to grow a plant requires at least 3 mm of precipitation for every 1°C that the average monthly temperature is above freezing. Based on the climate diagram above, and assuming that the weather conforms to the long-term average, this plant should be able to grow for about _______ months of the year.

Which statement about hot deserts is true?

a) Succulent stems are not common in hot deserts.

b) They are usually located within 10° of the equator.

c) Low water availability is an important constraint on the abundance of desert plants.

d) Both a and c

Which factor most likely prevented the grasslands at the eastern edge of the Great Plains from becoming forest?

Midges of the genus Axarus, which live in the bottom of rivers and lakes, are examples of a(n) _______ species.

Which statement about estuaries is false?

a) They usually have high levels of nutrients.

b) Estuary is another name for salt marsh.

c) Many commercially important fish species inhabit estuaries during their juvenile stages.

d) Their salinity often varies according to the tides.

Corals are animals that are related to _______ and form close relationships with _______ in their colonies.

Compared with the zone below it, temperatures in the marine photic zone are generally _______ and water pressure is _______.

Suppose that in order to grow, a plant requires at least 40 mm of average monthly precipitation and an average monthly temperature above 5°C. Based on this climate diagram, and assuming that the weather conform to the long-term climatic average, this plant should be able to grow during _______ months of the year.

What is FALSE about green house effect?

a) In the absence of greenhouse gases, Earth would be about 33 Celcius cooler than it is now

b) It is not a natural phenomenon

c) There are other green house gases than carbon dioxide.

d) None of the above

Cool air is _______ dense than warm air; as air cools, it _______.

The greatest seasonal variation of temperature is most likely to be seen over,

a) land near oceans at low latitudes.

b) oceans at low latitudes.

c) land at low latitudes.

d) land in the middle of a continent at high latitudes.

Boston, Massachusetts, and Albany, New York, are at about the same latitude, but Albany is farther inland. Based on this, you would expect Albany to have _______ humidity and _______ variation in temperature than Boston.

The side of a mountain range that faces into the prevailing winds is called the _______ side. This usually receives _______ precipitation than the other side of the mountain.

a) leeward; more

b) starboard; less

c) leeward; less

d) windward; more

El Niño events are associated with,

a) flooding in Indonesia and parts of Australia.

b) much reduced or absent upwelling in the eastern Pacific Ocean.

c) droughts in the southeastern United States.

d) greatly increased upwelling in the eastern Pacific Ocean.

Which of the following is not associated with Milankovitch cycles?

a) Changes in the shape of Earth’s orbit

b) Changes in the degree of tilt of Earth’s axis

c) Changes in the intensity of solar radiation at high latitudes

d) Changes in the speed of continental drift

Suppose water sample A has a pH of 4.3. The pH of a sample of water that has 10 times a lower concentration of H+ ions as sample A would be,

In wetland sediments, the physiological functioning of organisms is most likely to be negatively affected by _______ conditions.

Over the last century, which cycle has had the greatest effect on cycles of salmon production in the North Pacific?

a) PDO

b)ENSO

c) Cycles in sunspot activity

d) Milankovitch cycles

Refer to the graph below based on Johnson’s experiment on the effects of trematode parasites on tadpoles.

Adding 16 parasites per tadpole to a group of tadpoles resulted in _______ in their survival.

a) No change

b) A 20% increase

c) A 10% decrease

d) A 20% decrease

Refer to the graph below based on Johnson’s experiment on the effects of trematode parasites on tadpoles.

Which statement about this experiment is false?

a) The experiment did not contain a control group.

b) As more parasites were added, the overall effect of each individual parasite on the tadpoles decreased.

c) As the number of parasites to which the tadpoles were exposed increased, the percentage of surviving tadpoles decreased.

d) As the number of parasites to which the tadpoles were exposed increased, the percentage of deformed frogs increased.

Refer to the graphs below based on studies of the effects of pesticides on the tadpole immune system. In a laboratory experiment, wood frog (Rana sylvatica) tadpoles were exposed to low or high concentrations of a pesticide, and then Ribeiroia parasites. The tadpoles were then examined for (A) numbers of eosinophils and (B) numbers of Ribeiroia cysts. Error bars show one SE of the mean. Compared with the control group, the frogs exposed to low concentrations of pesticides had about _______ times as many parasite cysts.

a) 1.5

b) 3.0

c) 10

d) 4.5

How do connections in nature lead to unanticipated side effects in the case of amphibian deformities?

a) The increased pollution kills off the frogs’ prey and makes it more difficult for them to survive.

b) Increased pollution levels decrease predation which allows even deformed frogs to survive and reproduce.

c) Higher levels of pesticides increase the number of eosinophils in frogs.

d) Increased nutrients to ponds stimulate the growth of algae and provides the snails with a more abundant food source which also increases the number of Ribeiroia.

Which statement about environmental science is true?

a) All environmental scientists are activists.

b) It is an interdisciplinary field that incorporates concepts from the natural sciences, economics, and sociology.

c) It focuses on understanding the causes behind the distribution and abundances of organisms.

d) It is the same discipline as ecology.

Which of the following does not follow from the list of ecological maxims?

a) Whatever affects one organism can affect others as well.

b) Evolution took place in the past, but it is no longer occurring.

c) At some point, every population will experience checks on its growth and resource use.

d) Ecosystems change over space and time.

Many species live in the Quabbin Reservoir in Massachusetts, and these different species interact to varying degrees. This is an example of a(n)

a) Community

b) Population

c) Ecosystem

d) Biosphere

An association of individuals of the same species living in the same area is called a(n)

a) Population

b) Community

c) Ecoystem

d) Biosphere

Which of the following is an abiotic feature of the environment?

a) The number of days during which a predator is actively hunting

b)The average minimum temperature at night

c) The prevalence of parasites in the area

d) The density of plants in an area

Which statement about evolution by natural selection is true?

a) Individuals evolve by natural selection.

b) Adaptations are the result of evolution by natural selection.

c) Natural selection does not act on individuals.

d) Populations change only through natural selection.

Name at lease five biomes.

Despite being photosynthetic, mistletoe receives some of its energy from its host plant. Mistletoe is thus an example of a,

a) hemiparasite

b) hyperparasite

c) holoparasite

d) heterotroph

The nitrite that is oxidized by a bacterium in the process of chemosynthesis _______ electrons. The opposite of oxidation is _______.

The graph below shows the results of Bjorkman and colleagues’ studies of plant responses to different light levels. The plants were reared at three different levels of light: high (red line), medium (blue line), and low (green line). The acclimatized plants were then subjected to various light levels, and their ability to photosynthesize was measured. At the light intensity of 1,500 μmol/m2/s, which plants are light-limited?

a) Those acclimatized to high-intensity light.

b) None of the answers

c) Those acclimatized to medium-intensity light.

d) Those acclimatized to low-intensity light.

In the net reaction of photosynthesis, 24 carbon dioxide molecules are converted into _______ molecule(s) of glucose (a 6-carbon sugar) and _______ molecules of oxygen.

a) 4: 6

b) 1; 6

c) 4; 24

d) 1; 4

Refer to the graph below illustrating the effect of tissue temperature on photosynthetic rates in four different plant species. Which plant is most effective in photosynthesizing at tissue temperatures of 15°C?

The table below shows the oxygen and carbon dioxide concentrations of three different environments. In which environment would we expect photorespiration to be lowest?

a) Photorespiration rates should be roughly the same in all environments.

b) Environment 1

c) Environment 2

d) Environment 3

Which morphological difference is associated with C4 plants but not C3 plants?

a) Stomata in the lower epidermis

b) A waxy coating of the bundle sheath

c) Spongy mesophyll cells

d) Xylem

ome species in the genus Clusia start out as epiphytes but eventually can take on the tree form, a transformation that is facilitated by a property known as facultative CAM. This property allows them to

a) switch between C3 and CAM photosynthesis.

b) switch between C4 and CAM photosynthesis.

c) switch among C3, C4, and CAM photosynthesis.

d) switch between C3 and C4 photosynthesis.

In terms of energy per unit mass, which of the following is the correct ordering, from highest to lowest, of amino acids, carbohydrates, and fats?

a) Fats > amino acids > carbohydrates

b) Carbohydrates > fats > amino acids

c) Amino acids > carbohydrates > fats

d) Fats > carbohydrates > amino acids

Characteristics of an animal’s digestive tract can impact the efficiency with which nutrients and energy can be absorbed from food. Which individual’s digestive system would probably be most efficient?

a) A rabbit with a narrower than average digestive system

b) An elephant with a longer than average digestive system

c) A buffalo with a wider than average digestive system

d) A cow with a shorter than average digestive system

Two tree species live in different environments yet share many similar characteristics. The most likely reason for these similarities is,

shared ancestry.

adaptive radiations.

genetic drift.

natural selection.

In the 1890s, the biologist Hermon Bumpus found that sparrows that had survived a Rhode Island storm were more likely to be of intermediate size than sparrows that had perished from the storm. This is most likely an example of,

disruptive selection.

gene flow.

genetic drift.

stabilizing selection.

The mutation rate of a gene involved in lactose metabolism is two mutations per million copies of the gene per generation. Suppose there are 15 million individuals in a population of a yeast, each with two copies of this gene (i.e., they are diploid). In this yeast population, how many new mutations would we expect at this gene each generation?

15

60

30

fewer than 1

Genetic drift tends to _______ genetic variation within small populations, and _______ genetic differences among populations.

decrease; increase

increase; decrease

increase; have no effect on

increase; increase

In the three panels below, simulations were performed in which it was assumed that the populations were subject to only genetic drift (no selection), and they were scored for the frequency of the B allele. All populations started with the frequency of 50% of the B allele. Each line represents a different replicate of the conditions. The three panels differ only in the population size. Which panel had populations with the largest population size?

C

B

A

A and B had roughly equal population sizes, and had larger populations than panel C.

Suppose that, following the experiments by Dodd, Drosophila pseudoobscura are raised on one of two diets (starch or maltose) for many generations. Once they have adapted to the new food sources, individual females from the starch treatment are given a choice between a male adapted to starch (a starch male), or a male adapted to maltose (a maltose male). When 50 females have chosen a mate, the experiment is repeated with females adapted to maltose. The results are in the table below.

What percentage of starch females chose maltose males?

56

38

12

24

Suppose a very remote island had several species in residence: 10 birds, 40 insects, and 2 lizards. Both the birds and the lizards rely on the insects for food. Now imagine an asteroid crashes into the island and triggers a mass extinction event of the species on the island. The impact does not change the long-term ecological conditions on the island. Based on what you know about mass extinctions, what do you think might happen over millions of years of evolution if all of the bird species and one of the two lizard species on the island were to become extinct?

Birds, lizards, and insects would all recover from the mass extinction event within a few years.

All of the island’s species would be at a disadvantage due to changes in long-term ecological conditions.

The insects would have fewer predators and would diversify due to genetic drift.

The mass extinction event would result in a decrease in the number of competitor bird species, and lizards would undergo adaptive radiation.

The population density of ground crickets at Oldmill Farm is about 15 per square meter. Assuming that the crickets are randomly distributed, about how many crickets would you expect to find in a rectangular section of land that is 6 meters × 2 meters?

120

180

15

12

The size of a population of beavers in a 5 × 5 kilometer area is 675. What is the population density (in individuals per square km)?

112

65

13

27

Some animals (e.g., whiptail lizards) and plants (e.g., strawberries) form clones of genetically identical, but physiologically independent (or potentially independent) and distinct, individuals. These independent members of a clone are called

ramets

obelia

gametes

genets

Which of the following is not a biotic feature of the environment that can limit an organism’s distribution or abundance?

competitors

parasites

rainfall

predators

What is the most likely reason that polar bears are found in the Arctic but not in Antarctica?

Polar bears, which were derived from brown bears that lived in the Northern Hemisphere, can migrate long distances, but they are either unable or unwilling to travel across tropical areas that lie between the Arctic and Antarctica.

Antarctica does not provide a suitable habitat for polar bears.

Polar bears, which were derived from brown bears that lived in the Northern Hemisphere, are unable to travel long distances.

Continental drift prevented the polar bears from going to Antarctica.

Which of the following would be most influential in causing a clumped dispersion pattern among Seychelles warblers?

Differences in territory quality

All the answers

Territory defense

Cooperative breeding

Which of the following often improves the accuracy of estimates of population size based on area-based counts?

Use of smaller quadrats

Using as many quadrats as possible

Using niche modeling to improve the accuracy of counts within a quadrat

Placing quadrats at nonrandom locations throughout the entire study area

Individuals of a plant species are counted in four transects that are each 2 × 3 meters. In each transect, respectively, 6, 15, 18, and 33 are found. What is the density per square meter of this species?

9

2

6

3

In a mark–recapture study to estimate the size of a rodent population, researchers catch and mark 30 individuals. Two days later, they again capture a number of rodents and find that 20% of the individuals are marked. Assuming no births, deaths, or migrations, what is the estimated size of the population?

150

15

300

30

According to the work of Estes and others, an increase in _______ would lead to an increase in the abundance of urchins.

orcas

anemones

otters

glades

Life tables can be based on the

All of these

sizes of organisms

ages of organisms

life cycle stages of organisms

Refer to the table below showing the survivorship, fecundity, and life expectancies for U.S. females of various ages as of 2005.



Approximately 1.5 million females were born in the United States as of 2005. Based on this fact and the life table data, how many of them should we expect to live to at least age 90?

149,000

376,000

654,000

305,000

Refer to the life table below for a hypothetical species of plant that reproduces once a year (in the spring).



Which survivorship curve best fits the data for this species?

Type I for newborns and Type III for older individuals

Type III

Type II

Type I

Refer to the life table below for a hypothetical species of plant that reproduces once a year (in the spring).



How many individuals should be in age class 0 next summer (assuming that the survival probabilities and fecundities stay the same, and rounding to the nearest integer)?

520

480

380

320

A population of rabbits reproduces in synchrony at discrete time periods each year. If the current population is 150 and its geometric population growth rate is 1.4 per year, the expected size of the population after two years will be

294

210

140

196

A continuously growing population of bears has a population size of 500 and its intrinsic rate of increase is r = 0.07 per year. Assuming that this rate of increase remains the same, about how long should it take for the population to reach 1,000? (Note: The natural logarithm of 2 is about 0.70.)

14 years

20 years

10 years

18 years

Davidson and Andrewartha’s studies of thrips (Thrips imaginis) showed that

annual fluctuations in population size were due primarily to density-dependent factors.

annual fluctuations in population size could be predicted based on rainfall and temperature data.

All of these answers

density-independent factors increase the size of populations when population size is low.

Which statement about density-dependent or density-independent growth is true?

Density-independent factors do not have large effects on population size.

A decrease in birth rate with increasing population size is a density-independent factor.

Only density-independent factors can regulate population size.

An increase in emigration rate with increasing population size is a density-dependent factor.

Which statement about Arcese and Smith’s studies of the effects of population density on song sparrows is false?

The number of eggs laid per female declined with increasing density.

At high density, the population size of the sparrows was likely regulated by food shortages.

The number of young per female that survived to become independent of their parents increased with increasing density.

Nesting pairs that were fed were found to produce many more young than did pairs in the control group.

Use the graph below to determine the point at which the population growth rate is maximized under the logistic model.

When N = K/2

When K is reached

When the population is extremely small

When K is surpassed

A population of rodents contained 703 individuals at the end of March. During the month of April, 47 died, 17 were born, 57 immigrated, and 16 emigrated. What was the population size after those events?

673

714

688

724

Which of the following provides a clear demonstration of logistic growth?

Cattle egrets in Florida

Most natural populations of lemmings

Sheep introduced to Tasmania

Blowflies in which the adults are given unlimited supplies of liver but maggots are given a limited supply

Which pattern of population dynamics best describes that exhibited by collared lemmings in Greenland?

Population cycles

Logistic growth

Exponential growth

Outbreaks

A population that experiences delayed density dependence will exhibit particular patterns of population dynamics depending upon rτ (the population growth rate under ideal conditions × the time lag in the effects of density dependence). At low levels of this interaction, the population should exhibit _______; at intermediate levels, it should display _______; and at still higher levels, it should exhibit _______.

logistic growth; dampened oscillations; stable limit cycles

demographic stochasticity; stable limit cycles; genetic drift

logistic growth; stable limit cycles; dampened oscillations

exponential growth; stable limit cycles; demographic stochasticity

A population of blowflies experiences logistic growth with delayed density dependence. Suppose that this population has an initial size of 4,295 and follows the standard equation for delayed density dependence with a 10-week delay and an intrinsic growth rate of 0.2 per week. If these conditions remain constant and the population is tracked for a long time, what type of population dynamics should it display? (The cutoff rτ value for dampened oscillations is 0.368, and the cutoff for a stable limit cycle is 1.57.)

Exponential growth

A stable limit cycle

Logistic growth

Dampened oscillations

In Nicholson’s experiments with blowflies, population cycles most often occurred when

adults and maggots both had an unlimited food supply.

adults and maggots both had a limited food supply.

adults had an unlimited food supply and maggots had a limited food supply.

adults had a limited food supply and maggots had an unlimited food supply.

Due to their low density, females of a species of turtles have difficulty finding mates. As a result, the population’s growth rate has been low, despite ample resources. This is an example of

environmental stochasticity.

genetic drift.

isolation by distance.

an Allee effect.

In a population of three asexual lizards, each lizard has a 40% probability of not producing any offspring. What is the probability that all three lizards will produce no offspring, thus ensuring the population’s extinction?

21.6%

1%

23.0%

6.4%

Ecologists have been monitoring three metapopulations of sawflies. Population A has a patch colonization rate of 0.08 and a patch extinction rate of 0.11. Population B has a patch colonization rate of 0.05 and a patch extinction rate of 0.04. Population C has a patch colonization rate of 0.10 and a patch extinction rate of 0.08. According to Levins’s metapopulation model, which of these populations would be expected to persist for a long time?

Population B only

Population C only

Populations B and C

Population A only

Which of the following can help protect local populations from extinction?

Demographic stochasticity

Inbreeding

Allee effects

Immigration

Which of the following cannot be a resource for an organism?

Another organism

All of these can be resources.

Light

Physical space

Two species of birds actively fight over berries. Injuries have been observed, and the presence of one species limits the survival and reproduction of the other. What type of competition is this?

Logistic

Allelopathy

Exploitative

Interference

Brown and Davidson’s study of a desert community showed that,

exclusion of rodents leads to a decrease of ant colonies.

there is substantial overlap in the seeds eaten by ants and rodents.

exclusion of both ants and rodents has little effect on the availability of seeds.

All of the answers

The results of Connell’s experiments with intertidal barnacles support which of the following principles of competition?

Both competition and physical factors can limit the local distribution of species.

Exploitative competition is the most common form of competition in nature.

Periodic disturbances that remove a superior competitor can allow inferior competitors to persist.

Evolution by natural selection can alter the outcome of competition.

Two species of flour beetles, Tribolium castaneum and Tribolium confuum, are competing according to the Lotka–Volterra equations. If the α of T. confuum on T. castaneum is 0.4, one can assume that the addition of 200 T. confuumi individuals would depress the population growth of T. castaneum by the same amount as the addition of _______ T. castaneum individuals would.

200

0

40

80

Which of the following would most likely contribute to the long-term persistence of a fugitive species?

Apparent competition

Competitive exclusion

Character displacement

Periodic disturbances

Two species of Drosophila have been competing in the lab for a long time. A researcher notes that over the course of time, the competition coefficients of these species have become smaller. What is the most likely explanation of this change?

Competitive exclusion

Character displacement

Allelopathy

Periodic disturbances

Which observation would be the strongest evidence that character displacement is occurring?

The outcome of competition reverses after a period of time.

Competing species are more morphologically similar when apart than they are when they are together.

Within species, individuals that resemble their competitors the most have a selective advantage.

Within species, individuals that resemble their competitors the most have a selective disadvantage.

Which conclusion can be drawn from Brewer’s experiments on pitcher plants?

Competition for nitrogen is an important factor in their competition with noncarnivorous neighbors.

All the given answers

Competition for light is an important factor in their competition with noncarnivorous neighbors.

The plants were at a particular disadvantage when noncarnivorous neighbors were left intact and the pitchers were starved.

The limiting factor of Tilman's diatom experiments was,

Nitrogen

Silica

Phosphorous

Light

How do predation and herbivory differ from parasitism and parasitoidism?

Parasitism and parasitoidism are not exploitative relationships.

Most parasites and parasitoids spend their entire lives consuming a single individual, whereas herbivores and predators usually eat at least several different individuals.

Parasitism never results in the death of the organism, while predation and herbivory usually do cause the death of the organisms they eat.

Unlike parasitoids and parasites, predators and herbivores usually do not exert strong selective pressures on their food organisms.

The graphs below show different relationships between the proportion of prey that are tubificids and the proportion that are eaten by predators (guppies). Based on research by Murdoch et al., which graph best represents the foraging habits of guppies?

Graph C

Graph A

Graph D

Graph B

Which statement about predators and herbivores is true?

Herbivores tend to be generalist and usually forage on many different types of plants.

A broad diet is more typical of a predator than of an herbivore.

Only herbivores eat seeds more than any other plant part.

There are few herbivorous insects.

Which statement about the effects of herbivory on tobacco is false?

Tobacco produces secondary compounds that directly deter herbivores.

Tobacco plants respond to herbivory by growing thornier stems.

Tobacco produces secondary compounds that deter herbivores indirectly by attracting predators of the herbivores.

None of the secondary compounds produced by tobacco are induced defenses.

Which statement about garter snakes and TTX is true?

Some garter snakes produce TTX.

Some garter snakes are resistant to TTX due to TTX-resistant sodium channels in their neurons.

Snakes that are resistant to TTX cannot eat newts.

Snakes that are resistant to TTX move more quickly than other snakes.

Based on Schoener and Spiller’s studies of spider densities in the Bahamas, what is the correct ranking (from highest to lowest) of the probability of spiders going extinct according to three different conditions: islands on which lizards are absent from the islands, islands on which lizards have been introduced to the islands, and islands on which lizards are present naturally?

Lizards introduced > lizards absent > lizards natural

Lizards absent > lizards natural > lizards introduced

Lizards introduced > lizards natural > lizards absent

Lizards absent > lizards introduced > lizards natural

In Huffaker’s studies of an herbivorous mite and its mite predator, which variable was critical in determining whether the populations of predator and prey would go extinct quickly or persist?

Whether natural selection was operating to influence the population cycles

Whether the predators were “sit-and-wait” or active

The nature of the prey’s stress response

The complexity of the habitat

The population cycles of collared lemmings are driven by

Predators and food organisms of lemmings

predators of lemmings

decompoers

food organisms of lemmings

Hairston and colleagues found that the best explanation for the observed patterns of population dynamics of rotifers and their algal prey was that,

algae evolve in response to predation.

the accumulation of toxins alters algal physiology.

high levels of nitrogen increase algal nutritional quality.

rotifer egg viability increases with prey density.

Which factor most likely explains the synchrony of the hare population cycles in geographically distant areas?

Movement of hares

Movement of lynx and similarity of climate

Movement of lynx

Similarity of climate in these geographically distant areas

what is the current global human population?

influence on size population

Chance Events or the "Devil's Quarlet"

two (or more) parties can divide up the resources

one part can win the competition the other will die out