Ecology Exam 4

In what way is the geometric growth model different from the exponential growth model?
a. The geometric growth model uses continuous time.
b. The geometric growth model uses regular time intervals.
c. The geometric growth model includes carrying capacity (K).
d. The exponential growth model includes carrying capacity (K).

b. The geometric growth model uses regular time intervals.

Which plot is consistent with an exponential growth model when r > 0?

a. I

b. II

c. III

d. IV

c. III

Which plot is consistent with a geometric growth model in which λ = 1?

a. I
b. II
c. III
d. IV

a. I

Which is likely to follow an exponential increase in population size?
I. a population of mice that has consumed most of the food in its habitat
II. A small population of rats recently introduced to an island with many resources
III. bacteria recently placed on a new petri dish with suitable growth medium
a. I only
b. II only
c. III only
d. I and II only
e. II and III only

e. II and III only

In a population growing according to the exponential growth model, population size is
a. limited by density-dependent factors.
b. limited by density-independent factors.
c. limited by both density-dependent and density-independent factors.
d. not limited.

d. not limited.

In the exponential growth model, which term indicates the intrinsic rate of increase?
a. N0
b. e
c. r
d. t

c. r

Consider a biologist studying a population of deer. At the beginning of the year, there are 100 adult deer in the population. Over the course of the year, 15 adult deer die, and an additional 25 deer are born. What can we conclude about λ for this year?
a. λ < 0
b. λ = 0
c. λ > 0
d. λ = 1
e. λ > 1

e. λ > 1

The intrinsic growth rate, r, is
a. the number of new individuals produced minus the number that die.
b. the highest possible per capita increase in population size under ideal conditions.
c. the time it takes for a population to double in size.
d. the maximum population size that can be supported by the environment

b. the highest possible per capita increase in population size under ideal conditions.

According to the exponential growth model, which would reduce a population's doubling time?
a. an increase in the initial population size
b. a decrease in the initial population size
c. an increase in the intrinsic growth rate
d. a decrease in the intrinsic growth rate

c. an increase in the intrinsic growth rate

According to an exponential growth population model, when the number of births is less than the number of deaths,
a. r < 0.
b. r = 0.
c. 0 ≤ r ≤ 1.
d. r > 1.

a. r < 0.

Negative density dependence occurs when the
a. per capita population growth rate increases as population becomes larger.
b. per capita population growth rate remains constant as population becomes larger.
c. per capita population growth rate decreases as population becomes larger.
d. population increases without limit.
e. population decreases until it becomes extinct.

c. per capita population growth rate decreases as population becomes larger.

Under positive density dependence, population growth rate
a. increases as populations become larger.
b. remains the same as populations become larger.
c. decreases as populations become larger.
d. is highest at intermediate population size and lowest when population is large or small.

a. increases as populations become larger.

Which reflects density-independent population regulation?
I. a winter storm that kills birds with equal probability regardless of bird abundance
II. a drought that kills a higher proportion of plants when there are many plants and a smaller proportion when there are fewer plants
III. a lethal disease that is more easily transmitted when animals are found in high abundance than in low abundance
a. I only
b. II only
c. III only
d. I and III
e. II and III

a. I only

Which reflects positive density-dependent population regulation?
I. Small populations of flowers produce fewer seeds per individual than large populations of flowers.
II. Large groups of birds are better able to detect and avoid predators than small groups of birds.
III. The probability that a squirrel will be killed by a forest predator does not depend on the size of the squirrel population.
a. I only
b. II only
c. III only
d. I and II
e. I and III

d. I and II

Which reflects negative density dependence?
I. A fungus infects and kills plants at a higher rate when they are abundant than when they are rare.
II. A group of birds has a higher per capita survival rate when it is large than when it is small.
III. A large population of deer exhausts local food supplies and has a high risk of death; a small population has plentiful food and low risk of death.
a. I only
b. II only
c. III only
d. I and II
e. I and III

e. I and III

A species of louse (an external parasite) infests salmon. Researchers have found that the lice have difficulty finding a mate when there are only a few lice on an individual fish. The lice find mates more easily and produce more offspring when there are many lice on an individual fish. This is an example of
a. the geometric growth model.
b. positive density-dependent population regulation.
c. negative density-dependent population regulation.
d. density-independent population regulation.

b. positive density-dependent population regulation.

The Allee effect describes
a. density-independent population regulation.
b. negative density-dependent population regulation.
c. positive density-dependent population regulation.
d. logistic population growth.

c. positive density-dependent population regulation.

Which illustrates a negative relationship between population density and the average size of individuals over time?
a. an exponential growth curve
b. a J-shaped curve
c. a survivorship curve
d. a self-thinning curve

d. a self-thinning curve

The larvae of a carnivorous species of salamander inhabit ponds. When the pond contains few larvae, they mostly eat small invertebrates and have a high survival rate. When there are many salamander larvae in a pond, the larvae will also cannibalize each other and have a low survival rate. This is an example of
a. geometric growth.
b. positive density-dependent population regulation.
c. negative density-dependent population regulation.
d. density-independent population regulation.

c. negative density-dependent population regulation.

Alpine ibex are a type of wild goat that lives high in the mountains. During winters with heavy snow, Alpine ibex have high mortality rates, but when winters have little snow, Alpine ibex have low mortality rates. This is an example of
a. geometric growth.
b. positive density-dependent population regulation.
c. negative density-dependent population regulation.
d. density-independent population regulation.

d. density-independent population regulation.

The logistic growth model describes a maximum population size that is
a. limited by density-dependent factors.
b. limited by density-independent factors.
c. limited by both density-dependent and density-independent factors.
d. not limited by any factors

a. limited by density-dependent factors.

A biologist grew 10 groups of flowers in 1-square-meter plots of soil. In five plots, the biologist planted 20 flowers, and in the other five plots, the biologist planted 100 flowers. At the end of the summer, the biologist counted the seeds that each flower produced and found 100 seeds per plant in the plot with 20 plants and 500 seeds per plant in the plot with 100 plants. This is an example of
a. density-independent population regulation.
b. positive density-dependent population regulation.
c. negative density-dependent population regulation.
d. self-thinning curve.

b. positive density-dependent population regulation.

Which of the following is supported by the data?
a. The populations are growing exponentially.
b. The populations are regulated by density-independent processes.
c. The carrying capacity (K) is between 160 and 320 fish per pond.
d. The carrying capacity (K) is between 320 and 640 fish per pond.
e. The carrying capacity (K) is above 640 fish per pond.

c. The carrying capacity (K) is between 160 and 320 fish per pond.

Which describes the figure of logistic population growth shown in the graph?
a. r > 0; K > 300
b. r < 0; K > 300
c. r > 0; K < 300
d. r < 0; K < 300

c. r > 0; K < 300

In the logistic growth model, under which condition is the per capita rate of increase the highest?
a. N = K
b. N = K/2
c. N = (K )/4
d. N = K + r

c. N = (K )/4

In the logistic growth model, in which of the following conditions is the overall rate of increase the highest?
a. N = K
b. N = K/2
c. N = (K )/4
d. N = K + r

b. N = K/2

Which is the most accurate statement about the conservation biology of species with positive density-dependent population regulation?
a. If the population is small, it may not be able to increase.
b. The population will quickly exhaust all resources.
c. Species with positive density dependence are not at risk for extinction.
d. Population growth rate is highest when N > K.

a. If the population is small, it may not be able to increase

Which accurately describes the inflection point in the logistic growth model?
I. Population growth slows after the inflection point.
II. The inflection point is equal to the carrying capacity.
III. The highest growth rate occurs at the inflection point.
a. I only
b. II only
c. III only
d. I and II
e. I and III

e. I and III

Which form of population growth results in an S-shaped curve?
a. exponential growth
b. geometric growth
c. logistic growth
d. density-independent growth

c. logistic growth

Which factors could limit a species' carrying capacity?
I. the amount of food available
II. the number of eggs a female can produce
III. the number of nesting sites present
a. I only
b. II only
c. III only
d. I and II
e. I and III

e. I and III

In the logistic growth model, which term determines the maximum number of individuals a population can sustain?
a. r
b. N
c. K
d. dN/dt

c. K

In the logistic growth model, which term determines how quickly a population will initially grow from low density?
a. r
b. N
c. K
d. dN/dt

a. r

Which of the following statements about the logistic growth model is accurate?
I. The per capita rate of population increase declines as population size increases.
II. The overall rate of population increase is highest at K/2.
III. The overall rate of population growth is negative when N is greater than K/2.
a. I only
b. II only
c. III only
d. I and II only
e. I and III only

d. I and II only

The figure shows the change in population size of Paramecium from Gause's experiment, raised in either high-food or low-food conditions. Based on this figure, how was the logistic growth model for Paramecium changed by adding food?
a. High food increased r.
b. High food decreased r.
c. High food increased K.
d. High food decreased K.

c. High food increased K.

The age structure of a population is often represented by a pyramid. What does an age structure pyramid with a broad base and a narrow top indicate about a population?
a. The population is declining.
b. The population is growing.
c. The population is stable.
d. The shape of the pyramid does not provide information on population growth.

b. The population is growing.

If a population has relatively few individuals in the young classes but many in the medium-aged and old classes, what can we conclude about population growth?
a. The population is declining.
b. The population is growing.
c. The population is stable.
d. The population is below carrying capacity.

a. The population is declining.

All cohort life tables
a. follow individuals born at the same time from birth to death.
b. quantify the survival and fecundity of all individuals at a single time interval.
c. have a stable age distribution.
d. describe a population at its carrying capacity.

a. follow individuals born at the same time from birth to death.

When a population has a stable age distribution,
a. the total number of individuals stays constant over time.
b. the proportion of individuals in each age class remains constant.
c. the net reproductive rate is less than one.
d. it is at its carrying capacity.

b. the proportion of individuals in each age class remains constant.

Which describes this population?
I. The population has a stable age distribution.
II. The population's growth is consistent with a geometric model.
III. The population's growth is consistent with a logistic model in which K = 1,900.
a. I only
b. II only
c. III only
d. I and II only
e. I and III only

d. I and II only

The geometric mean growth rate (λ) from year 1 to year 2 is
a. 0.33.
b. 3.
c. 24.
d. 81.

b. 3

A biologist is studying a population of raccoons that live in a park. The population contains 50 males and 50 females. The biologist determines that R0 = 2. How many female raccoons are expected to be in the park next year?
a. 25
b. 48
c. 50
d. 52
e. 100

e. 100

What is the generation time (T) of this species?
a. 4 years
b. 4.6 years
c. 5 years
d. 7.7 years

b. 4.6 years

What is the R0 for this species?
a. 30
b. 24
c. 1.664
d. 0.1152

c. 1.664

Which is consistent with the results of this experiment?
a. Goose populations are increasing in both populations but at different rates.
b. Goose populations are decreasing in both populations but at different rates.
c. Goose populations are increasing with coyotes and decreasing without coyotes.
d. Goose populations are decreasing with coyotes and increasing without coyotes.

d. Goose populations are decreasing with coyotes and increasing without coyotes.

Which is correct about the geese in these populations?
I. When coyotes are removed, goose R0 > 1.
II. When coyotes are removed, goose R0 < 1.
III. When coyotes are present, goose R0 > 1.
IV. When coyotes are present, goose R0 < 1.
a. I and III
b. I and IV
c. II and III
d. II and IV

d. II and IV

Which goose life stage is affected by predation from coyotes?
I. survival from egg to juvenile
II. survival from juvenile to adult
III. fecundity of adults
a. I only
b. II only
c. III only
d. I and II only
e. I and III only

a. I only

The rate at which solar or chemical energy is captured and converted to chemical bonds by photosynthesis or chemosynthesis is called
a. secondary productivity.
b. net primary productivity.
c. gross primary productivity.
d. primary productivity

d. primary productivity

What percentage of solar energy is captured by plants for photosynthesis?
a. 50 percent
b. 1 percent
c. 99 percent
d. 25 percent

b. 1 percent

The biomass of producers in a given area of an ecosystem at a particular moment is called
a. net primary production.
b. ecosystem mass.
c. the standing crop.
d. the standing harvest.

c. the standing crop.

Standing crop is determined by _____ productivity.
a. net primary
b. gross primary
c. net secondary
d. gross secondary

a. net primary

Net primary productivity is calculated as
a. GPP ÷ respiration.
b. GPP × respiration.
c. respiration − GPP.
d. GPP − respiration.

d. GPP − respiration.

What proportion of solar radiation captured by photosynthesis is used for plant growth and reproduction?
a. 60 percent
b. 80 percent
c. 50 percent
d. 40 percent

d. 40 percent

Which of the following factors is NOT used for quantifying primary productivity over time?
a. the change in consumer biomass
b. the change in producer biomass
c. the movement of carbon dioxide
d. the movement of oxygen

a. the change in consumer biomass

Measuring the change in biomass from the beginning to the end of the growing season gives an estimate of
a. herbivory.
b. standing crop.
c. gross primary productivity.
d. net primary productivity.

d. net primary productivity.

Which of the following is NOT used to measure primary production?
a. uptake and release of O2
b. net movement of 14C
c. release of CO2
d. changes in standing crop

c. release of CO2

Which technique allows measurement of conditions on Earth from a distant location?
a. remote sensing
b. remote monitoring
c. satellite sensing
d. satellite monitoring

a. remote sensing

When an animal eats fruit with hard seeds that cannot be digested and are excreted whole as a waste product, the seeds constitute _____ energy.
a. assimilated
b. egested
c. respired
d. kinetic

b. egested

Energy that an organism uses to add to its biomass is
a. egested.
b. respired.
c. assimilated.
d. secondary.

c. assimilated.

Which is the portion of energy that an organism uses to maintain its body temperature?
a. primary
b. secondary
c. egested
d. respired

d. respired

The rate of consumer biomass accumulation in a given area is called _____ productivity.
a. gross secondary
b. net secondary
c. gross primary
d. net primary

b. net secondary

Terrestrial secondary productivity is _____ correlated with primary productivity, and aquatic secondary productivity is _____ correlated with primary productivity.
a. positively; positively
b. positively; negatively
c. negatively; negatively
d. negatively; positively

a. positively; positively

What are the major drivers of NPP?
a. fertility and precipitation
b. temperature and pH
c. temperature and precipitation
d. fertility and temperature

c. temperature and precipitation

Between latitudes of 30° N and 30° S, NPP is primarily constrained by
a. temperature.
b. fertility.
c. pH.
d. precipitation

d. precipitation.

Experiments on how soil fertility limits terrestrial NPP demonstrate that _____ constrain(s) NPP.
a. nitrogen
b. phosphorus
c. nitrogen and phosphorus
d. micronutrients

c. nitrogen and phosphorus

In fertilization experiments in a lake in Ontario, which of the following nutrients were shown to have the greatest limitation on productivity?
a. nitrogen
b. carbon
c. phosphorus
d. All three nutrients equally limited productivity

c. phosphorus

Compilation of data from many experiments on nutrients and NPP in marine ecosystems shows that ecosystems with hard bottoms are generally limited by _____, while soft-bottomed ecosystems are generally limited by _____.
a. nitrogen; phosphorus
b. nitrogen; nitrogen and phosphorus
c. phosphorus; nitrogen
d. phosphorus; nitrogen and phosphorus

b. nitrogen; nitrogen and phosphorus

What accounts for the pyramid shape of the diagram that represents energy in trophic groups in an ecosystem?
a. Energy produced by consumers is greater than energy stored by producers.
b. Energy stored by consumers is greater than energy stored by producers.
c. Energy is gained as it moves from one trophic level to the next.
d. Energy is lost as it moves from one trophic level to the next.

d. Energy is lost as it moves from one trophic level to the next.

In aquatic ecosystems, trophic pyramids of biomass are inverted because
a. most biomass is found in the producers.
b. the standing biomass of algae is lower than the standing biomass of consumers.
c. the lifespan of producers is very long compared to that of consumers.
d. consumers do not rapidly consume producers.

b. the standing biomass of algae is lower than the standing biomass of consumers.

What is at the top level of a four-level terrestrial trophic pyramid?
a. quaternary consumers
b. tertiary consumers
c. secondary consumers
d. producers

b. tertiary consumers

The percentage of energy or biomass in a trophic level that is consumed by the next higher trophic level is called _____ efficiency.
a. consumption
b. predation
c. assimilation
d. net production

a. consumption

Consumption efficiency is calculated as
a. consumed energy times net production energy of the next lower trophic level.
b. net production energy of the next lower trophic level divided by consumed energy.
c. consumed energy divided by net production energy of the next higher trophic level.
d. consumed energy divided by net production energy of the next lower trophic level.

d. consumed energy divided by net production energy of the next lower trophic level

Assimilation energy is the percentage of consumed energy that is
a. used for reproduction.
b. digested and absorbed.
c. used for growth.
d. consumed by the next higher trophic level.

b. digested and absorbed.

Net production energy divided by assimilation energy is _____ efficiency.
a. consumption
b. assimilation
c. net assimilation
d. net production

d. net production

Ecological efficiency is also called _____ efficiency.
a. trophic pyramid
b. food chain
c. assimilation
d. net production

b. food chain

Food chain efficiency is the percentage of _____ from one trophic level compared to the next_____ trophic level.
a. net production; higher
b. net production; lower
b. consumed energy; higher
c. consumed energy; lower

b. net production; lower

As a rule of thumb, ecologists use _____ as a value for food chain efficiency.
a. 10 percent
b. 25 percent
c. 15 percent
d. 20 percent

a. 10 percent

Aquatic ecosystems typically have _____ trophic levels, while terrestrial ecosystems typically have _____ trophic levels.
a. two; three
b. four; five
c. three or four; six
d. five; three or four

d. five; three or four

The _____ the residence time, the _____ amount of biomass in the trophic level.
a. shorter
b. longer
c. longer
d. shorter

c. longer

The average energy residence time is calculated as
a. energy in a trophic level times net productivity.
b. net productivity times energy in a trophic level.
c. energy in a trophic level divided by net productivity.
d. net productivity divided by energy present in a trophic level.

c. energy in a trophic level divided by net productivity.

Biomass residence time is the length of time that
a. biomass takes to move through the food chain.
b. energy takes to move through the food chain.
c. energy spends in a given trophic level.
d. biomass spends in a given trophic level.

c. energy spends in a given trophic level.

In which ecosystem does leaf litter have the shortest residence time?
a. humid tropical forest
b. temperate forest
c. dry tropical forest
d. boreal forest

a. humid tropical forest

In the hydrologic cycle, infiltration refers to
a. water evaporating from the environment and condensing into water vapor.
b. plants taking up water from the soil.
c. the change of water from a liquid to a gas.
d. the change of water from a gas to a liquid.
e. water from precipitation becoming part of the groundwater.

e. water from precipitation becoming part of the groundwater.

Which statement is TRUE about the global hydrologic cycle?
a. Precipitation is greater than evaporation in terrestrial ecosystems.
b. Evaporation is greater than precipitation in terrestrial ecosystems.
c. Precipitation and evaporation are about equal in terrestrial ecosystems.
d. Precipitation exceeds evaporation in aquatic ecosystems.
e. Precipitation and evaporation are about equal in aquatic ecosystems.

c. Precipitation and evaporation are about equal in terrestrial ecosystems.

What is the ultimate destination of water in the hydrologic cycle?
a. deep aquifers
b. oceans
c. lakes, rivers, and streams
d. the atmosphere

b. oceans

When terrestrial ecosystems are paved over, for example to construct a parking lot, how is the hydrologic cycle affected?
a. Infiltration is decreased and runoff is increased.
b. Infiltration is increased and runoff is decreased.
c. Evapotranspiration is increased and runoff is decreased.
d. Evapotranspiration is increased and precipitation is decreased.

a. Infiltration is decreased and runoff is increased.

What are the six types of transformations in the carbon cycle?
a. photosynthesis, respiration, combustion, infiltration, sedimentation, burial
b. combustion, precipitation, respiration, aeration, photosynthesis, exchange
c. respiration, aeration, condensation, photosynthesis, exchange, extraction
d. extraction, exchange, respiration, photosynthesis, sedimentation and burial, combustion
e. sedimentation and burial, photosynthesis, respiration, exchange, mineralization, combustion

d. extraction, exchange, respiration, photosynthesis, sedimentation and burial, combustion

The carbon cycle in ecosystems mostly follows the same paths as the movement of
a. water.
b. nitrogen.
c. phosphorus.
d. energy.
e. heat.

d. energy.

In waterlogged conditions, anaerobic metabolism of carbon compounds can cause the production of the greenhouse gas
a. hydrogen sulfide (H2S).
b. methane (CH4).
c. ozone (O3).
d. nitrous oxide (N2O).
e. carbon dioxide (CO2).

b. methane (CH4).

From 1958 to 2012, atmospheric carbon dioxide measurements at Mauna Loa have risen approximately
a. 35 percent.
b. 10 percent.
c. 15 percent.
d. 25 percent.
e. 55 percent.

d. 25 percent.

The chemical process NH4+ → NO2− → NO3−, is known as
a. assimilation.
b. mineralization.
c. nitrification.
d. nitrogen fixation.
e. ammonification.

c. nitrification.

Nitrogen mineralization is the process by which
a. producers take up soil nitrogen and incorporate it into their tissues.
b. primary consumers ingest producers in the soil and absorb or excrete nitrogen from their tissues.
c. soil microbes produce organic nitrogen compounds from inorganic soil nitrogen.
d. soil microbes break down organic nitrogen into inorganic nitrogen.
e. nitrogen waste products in the soil are converted to atmospheric nitrogen by soil microbes.

d. soil microbes break down organic nitrogen into inorganic nitrogen.

Denitrification is described by
a. NO → N2O → N2.
b. N2O → NO → N2.
c. NO → N2 → N2O.
d. N2 → NO → N2O.
e. N2 → N2O → NO.

a. NO → N2O → N2.

Denitrification occurs under _____ conditions.
a. aerobic
b. anaerobic
c. both aerobic and anaerobic
d. neither aerobic nor anaerobi

b. anaerobic

Nitrogen fixation in the soil is carried out by
a. anaerobic bacteria.
b. aerobic bacteria.
c. mycorrhizal fungi.
d. cyanobacteria.
e. archaebacteria.

d. cyanobacteria.

Nitrogen mineralization in the soil is primarily carried out by
a. producers.
b. consumers.
c. decomposers.
d. cyanobacteria.
e. nitrogen-fixing plants.

c. decomposers.

The burning of fossil fuels affects the nitrogen cycle by increasing atmospheric
a. nitrous oxide.
b. nitric oxide.
c. nitrate.
d. ammonia.
e. nitrite.

b. nitric oxide.

Where does phosphorus originate in the phosphorus cycle?
a. the atmosphere
b. ocean sediments
c. wastewater
d. rocks containing phosphate
e. aqueous phosphate

d. rocks containing phosphate

Which of the following is NOT a critical phosphorus-containing structure for organisms?
a. bones
b. nucleic acids
c. ATP
d. lipids
e. teeth

d. lipids

Dead zones are formed when rivers that empty into oceans carry excess phosphorus and nitrate runoff. These dead zones are caused by
a. precipitates of nitrate and phosphorus forming in the water.
b. bacterial blooms.
c. algal blooms.
d. nitrate and phosphorus poisoning.
e. increased acidity due to nitrates and phosphorus.

c. algal blooms.

Weathering is important to the input of
a. nitrogen.
b. carbon.
c. phosphorus.
d. water.

c. phosphorus.