Combo with Unit 6 Mastering Biology and 5 others

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Which of the following sensory receptors is incorrectly paired with its category?

rod-electromagnetic receptor
taste receptor-chemoreceptor
muscle spindle-mechanoreceptor
olfactory receptor-electromagnetic receptor
hair cell-mechanoreceptor

olfactory receptor-electromagnetic receptor

The middle ear converts

air pressure waves to fluid pressure waves.
fluid pressure waves to nerve impulses.
air pressure waves to nerve impulses.
fluid pressure waves to air pressure waves.
pressure waves to hair cell movements.

air pressure waves to fluid pressure waves.

During the contraction of a vertebrate skeletal muscle fiber, calcium ions

spread action potentials through the T tubules.
break cross-bridges by acting as a cofactor in the hydrolysis of ATP.
transmit action potentials from the motor neuron to the muscle fiber.
re-establish the polarization of the plasma membrane following an action potential.
bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed.

bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed.

Which sensory distinction is not encoded by a difference in neuron identity?

spicy and cool
red and green
salty and sweet
white and red
loud and faint

loud and faint

The transduction of sound waves into action potentials takes place

within the middle ear as the vibrations are amplified by the malleus, incus, and stapes.
as the basilar membrane vibrates at different frequencies in response to the varying volume of sounds.
as the basilar membrane becomes more permeable to sodium ions and depolarizes, initiating an action potential in a sensory neuron.
within the tectorial membrane as it is stimulated by the hair cells.
when hair cells are bent against the tectorial membrane, causing them to depolarize and release neurotransmitter that stimulates sensory neurons.

when hair cells are bent against the tectorial membrane, causing them to depolarize and release neurotransmitter that stimulates sensory neurons

Plasma membranes of adjacent cardiac muscle cells interlock at specialized regions called intercalated disks. What is the significance of this feature of cardiac muscles?

The intercalated disks play the same role as striations of skeletal muscle.
The intercalated disks generate action potentials within the heart muscle without nervous system input.
The intercalated disks allow coordinated contraction of the whole heart.

The intercalated disks allow coordinated contraction of the whole heart.

In mammals, the eardrum transmits sound waves to three small bones, which transmit the waves to fluid waves within the cochlea. Where are the three small bones located?

Middle ear
Outer ear
Inner ear

Middle ear

Identify the correct statement(s) about sensory receptors.
Select all that apply.

Mechanoreceptors detect sound.
Foods taste spicy when they activate the same sensory receptors that high temperatures activate.
Electromagnetic receptors detect pheromones.

Mechanoreceptors detect sound.
Foods taste spicy when they activate the same sensory receptors that high temperatures activate.

Sensory pathways have four basic functions: sensory reception, transduction, transmission, and perception. How do these functions differ between yourself and a star-nosed mole?
Select all that apply.
Select all that apply.
The perception of sensory input by humans and star-nosed moles differs.
The mechanism by which the energy of a sensory stimulus is transduced into a receptor potential differs between humans and star-nosed moles.
The number and type of sensory receptors in humans and star-nosed moles differ.

The perception of sensory input by humans and star-nosed moles differs.
The number and type of sensory receptors in humans and star-nosed moles differ.

Identify the role(s) of ATP in muscle contraction.
Select all that apply.

Provides the energy to convert myosin to a form that forms a cross-bridge with actin
Binds to myosin to break an actin-myosin cross-bridge
Binds to the troponin complex to expose myosin-binding sites

Provides the energy to convert myosin to a form that forms a cross-bridge with actin
Binds to myosin to break an actin-myosin cross-bridge

Which of the following is true of innate behaviors?

Their expression is only weakly influenced by genes.
They are expressed in most individuals in a population.
They occur in invertebrates and some vertebrates but not mammals.
They are limited to invertebrate animals.
They occur with or without environmental stimuli.

They are expressed in most individuals in a population

According to Hamilton's rule,

natural selection is more likely to favor altruistic behavior that benefits an offspring than altruistic behavior that benefits a sibling.
natural selection favors altruistic acts when the resulting benefit to the beneficiary, corrected for relatedness, exceeds the cost to the altruist.
natural selection does not favor altruistic behavior that causes the death of the altruist.
altruism is always reciprocal.
the effects of kin selection are larger than the effects of direct natural selection on individuals.

natural selection favors altruistic acts when the resulting benefit to the beneficiary, corrected for relatedness, exceeds the cost to the altruist.

Female spotted sandpipers aggressively court males and, after mating, leave the clutch of young for the male to incubate. This sequence may be repeated several times with different males until no available males remain, forcing the female to incubate her last clutch. Which of the following terms best describes this behavior?

promiscuity
certainty of paternity
monogamy
polyandry
polygyny

polyandry

A region of the canary forebrain shrinks during the nonbreeding season and enlarges when breeding season begins. This change is probably associated with the annual

renewal of mating and nest-building behaviors.
sensitive period in which canary parents imprint on new offspring.
addition of new syllables to a canary's song repertoire.
crystallization of subsong into adult songs.
elimination of the memorized template for songs sung the previous year.

addition of new syllables to a canary's song repertoire.

Although many chimpanzees live in environments containing oil palm nuts, members of only a few populations use stones to crack open the nuts. The likely explanation is that

members of different populations have different nutritional requirements.
the cultural tradition of using stones to crack nuts has arisen in only some populations.
members of different populations differ in manual dexterity.
the behavioral difference is caused by genetic differences between populations.
members of different populations differ in learning ability.

the cultural tradition of using stones to crack nuts has arisen in only some populations.

Which of the following is not required for a behavioral trait to evolve by natural selection?

An individual's reproductive success depends in part on how the behavior is performed.
In each individual, the form of the behavior is determined entirely by genes.
An individual's genotype influences its behavioral phenotype.
The behavior varies among individuals.
Some component of the behavior is genetically inherited.

In each individual, the form of the behavior is determined entirely by genes.

Graylag goslings imprint on a nearby object that moves away from them during a sensitive period in the first few hours after they hatch, and follow the object steadfastly from that time on. What is the adaptive value of this behavior?

This behavior is not adaptive because goslings may imprint on objects other than their parents.
This behavior is likely to increase gosling survival.
This behavior is genetic.

This behavior is likely to increase gosling survival.

A female zebra finch reared by a father with a red feather taped to his head will select a mate with a similar ornament over an unornamented male. What are plausible ultimate explanations for this behavior?
Select all that apply.

A female zebra finch that chooses a mate that resembles her father is more likely to choose a mate from her own species.
A female zebra finch learns to recognize suitable mates by observing her father.
Zebra finches are able to perceive ornamentation on other birds.

A female zebra finch that chooses a mate that resembles her father is more likely to choose a mate from her own species.

Select the correct statement(s) about the genetics of behavior.
Select all that apply.

Behaviors with a genetic component can evolve through natural selection.
Learned behaviors are not subject to genetic influence.
Most behavioral traits are determined by a single gene.

Behaviors with a genetic component can evolve through natural selection.

The majority of young, inexperienced Western garter snakes born in the laboratory from mothers captured in coastal areas of California readily eat pieces of slug. What are plausible proximate explanations for this behavior?
Select all that apply.

Coastal snakes can detect odor molecules produced by banana slugs.
Coastal snakes have a genetically acquired taste for banana slugs.
Coastal snakes that readily eat banana slugs gain most of their calories from this prey species.

Coastal snakes can detect odor molecules produced by banana slugs.
Coastal snakes have a genetically acquired taste for banana slugs.

In cross-fostering studies, the young of one species are placed in the care of adults from another species. In broad terms, what do researchers learn from such studies?
Select all that apply.

Changes in the behavior of cross-fostered young provide information about how the social and physical environment influences behavior.
Cross-fostering studies provide information about the relative importance of nature and nurture in the development of a trait.
Cross-fostering studies provide information about the evolutionary relationship between the two species.

Changes in the behavior of cross-fostered young provide information about how the social and physical environment influences behavior.
Cross-fostering studies provide information about the relative importance of nature and nurture in the development of a trait.

Which of the following areas of study focuses on the exchange of energy, organisms, and materials between ecosystems?

population ecology
organismal ecology
landscape ecology
community ecology
ecosystem ecology

landscape ecology

Which lake zone would be absent in a very shallow lake?

aphotic zone
pelagic zone
limnetic zone
littoral zone
benthic zone

aphotic zone

Which of the following is true with respect to oligotrophic lakes and eutrophic lakes?

Sediments in oligotrophic lakes contain larger amounts of decomposable organic matter.
Eutrophic lake water contains lower concentrations of nutrients.
Rates of photosynthesis are lower in eutrophic lakes.
Eutrophic lakes are richer in nutrients.
Oligotrophic lakes are more subject to oxygen depletion.

Eutrophic lakes are richer in nutrients.

Which of the following biomes is correctly paired with the description of its climate?

temperate broadleaf forest-relatively short growing season, mild winters
tundra-long summers, mild winters
temperate grasslands-relatively warm winters, most rainfall in summer
savanna-low temperature, precipitation uniform during the year
tropical forests-nearly constant day length and temperature

tropical forests-nearly constant day length and temperature

Which of the following is characteristic of most terrestrial biomes?

clear boundaries between adjacent biomes
a distribution predicted almost entirely by rock and soil patterns
annual average rainfall in excess of 250 cm
vegetation demonstrating vertical layering
cold winter months

vegetation demonstrating vertical layering

The oceans affect the biosphere in all of the following ways except

producing a substantial amount of the biosphere's oxygen.
moderating the climate of terrestrial biomes.
removing carbon dioxide from the atmosphere.
regulating the pH of freshwater biomes and terrestrial groundwater.
being the source of most of Earth's rainfall.

regulating the pH of freshwater biomes and terrestrial groundwater.

Which statement about dispersal is false?

Dispersal occurs only on an evolutionary time scale.
Colonization of devastated areas after floods or volcanic eruptions depends on dispersal.
Seeds are important dispersal stages in the life cycles of most flowering plants.
Dispersal is a common component of the life cycles of plants and animals.
The ability to disperse can expand the geographic distribution of a species.

Dispersal occurs only on an evolutionary time scale.

When climbing a mountain, we can observe transitions in biological communities that are analogous to the changes

in a community through different seasons.
in biomes at different latitudes.
in an ecosystem as it evolves over time.
at different depths in the ocean.
across the United States from east to west.

in biomes at different latitudes.

Suppose that the number of bird species is determined mainly by the number of vertical strata found in the environment. If so, in which of the following biomes would you find the greatest number of bird species?

savanna
tropical rain forest
temperate grassland
desert
temperate broadleaf forest

tropical rain forest

WHAT IF? If the direction of Earth's rotation reversed, the most predictable effect would be

winds blowing from west to east along the equator.
a loss of seasonal variation at high latitudes.
no more night and day.
a big change in the length of the year.
the elimination of ocean currents.

winds blowing from west to east along the equator.

In ecological terms, disturbance is an event such as a storm, fire, or human activity that changes a community, removing organisms and altering resource availability. Which of the following statements about the effects of disturbance is correct?

A healthy community is in an equilibrium state of balance, with few disturbances.
The effects of disturbance on a community are almost always negative.
Disturbances can create patches of different habitats in a community.

Disturbances can create patches of different habitats in a community.

Which statement accurately describes the potential effects of disturbance on species diversity?

Moderate levels of disturbance generally act to reduce species diversity within a community.
In many biomes, periodic disturbances may eliminate the dominant plants.
Many species are well adapted to survive periodic disturbances.

Many species are well adapted to survive periodic disturbances.

In Australia, researchers tested the hypothesis that sea urchin abundance limits kelp distribution. Select the evidence that offers the best support for this hypothesis.

There is an inverse relationship between the abundance of sea urchins and the abundance of kelp.
When sea urchins were removed from experimental plots, kelp cover increased.
Sea urchins graze on kelp.

When sea urchins were removed from experimental plots, kelp cover increased.

This graph shows the effect of removal of urchins and limpets (alone and together) on seaweed cover. Select the statement that accurately describes the results shown in this graph.

Sea urchins have a much greater effect than limpets in limiting seaweed cover.
Removing only limpets increased seaweed cover dramatically.
The lack of change over time in the control plots (with urchins and limpets present) shows that limpets and urchins have no effect on seaweed cover.

Sea urchins have a much greater effect than limpets in limiting seaweed cover.

Examine the climograph for some major North American biomes. Which two factors influence the distribution of organisms, as shown in this climograph?

The presence of tundra and presence of forested land
Annual mean temperature and annual mean precipitation
The presence of broadleaf and presence of coniferous forest

Annual mean temperature and annual mean precipitation

Population ecologists follow the fate of same-age cohorts to

determine if a population is regulated by density-dependent processes.
determine if a population's growth is cyclic.
determine the factors that regulate the size of a population.
determine the birth rate and death rate of each group in a population.
determine a population's carrying capacity.

determine the birth rate and death rate of each group in a population.

A population's carrying capacity

increases as the per capita growth rate (r) decreases.
generally remains constant over time.
can be accurately calculated using the logistic growth model.
may change as environmental conditions change.
can never be exceeded.

may change as environmental conditions change.

Scientific study of the population cycles of the snowshoe hare and its predator, the lynx, has revealed that

the hare population is r-selected and the lynx population is K-selected.
the prey population is controlled by predators alone.
both hare and lynx populations are regulated mainly by abiotic factors.
hares and lynx are so mutually dependent that each species cannot survive without the other.
multiple biotic and abiotic factors contribute to the cycling of the hare and lynx populations.

multiple biotic and abiotic factors contribute to the cycling of the hare and lynx populations

Based on current growth rates, Earth's human population in 2012 will be closest to

10 billion.
2 million.
7 billion.
3 billion.
4 billion.

7 billion.

A recent study of ecological footprints concluded that

it is not possible for technological improvements to increase Earth's carrying capacity for humans.
the ecological footprint of the United States is large because per capita resource use is high.
Earth's carrying capacity would increase if per capita meat consumption increased.
current demand by industrialized countries for resources is much smaller than the ecological footprint of those countries.
Earth's carrying capacity for humans is about 10 billion.

the ecological footprint of the United States is large because per capita resource use is high.

The observation that members of a population are uniformly distributed suggests that

the members of the population are competing for access to a resource.
the size of the area occupied by the population is increasing.
resources are distributed unevenly.
the members of the population are neither attracted to nor repelled by one another.
the density of the population is low.

the members of the population are competing for access to a resource.

According to the logistic growth equation

the birth rate (b) approaches zero as N approaches K.
the population grows exponentially when K is small.
population growth is zero when N equals K.
the number of individuals added per unit time is greatest when N is close to zero.
the per capita growth rate (r) increases as N approaches K.

population growth is zero when N equals K.

Which pair of terms most accurately describes life history traits for a stable population of wolves?

semelparous; r-selected
iteroparous; r-selected
iteroparous; K-selected
iteroparous; N-selected
semelparous; K-selected

iteroparous; K-selected

During exponential growth, a population always

quickly reaches its carrying capacity.
cycles through time.
grows at its maximum per capita rate.
loses some individuals to emigration.
grows by thousands of individuals.

grows at its maximum per capita rate.

Which of the following statements about human population in industrialized countries is incorrect?

The survivorship curve is Type I.
Average family size is relatively small.
Age distribution is relatively uniform.
The population has undergone the demographic transition.
Life history is r-selected.

Life history is r-selected.

Consider a population whose growth over a given time period can be described by the exponential model: dN/dt = rN. Select the correct statement about this population.

A population with an r of 0 will have no births or deaths during the time period under consideration.
A population with a positive value of r will grow exponentially.
A population with an r of 0.1 will decrease over time.

A population with a positive value of r will grow exponentially.

Consider a population whose growth can be described by the logistic growth model: dN/dt = rmaxN[(K − N)/K]. Which of the following statements about this population is true?

rmax declines as N increases.
At low values of N, the logistic growth and exponential growth (dN/dt = rN) models predict similar population growth.
K is a constant value.

At low values of N, the logistic growth and exponential growth (dN/dt = rN) models predict similar population growth.

The graph shows the growth of a laboratory culture of Paramecium aurelia. After 15 days, the researcher removed ~400 paramecia from the culture. How will the population growth rate (dN/dt) change as a result of this action?

The growth rate of the Paramecium population will decrease.
The growth rate of the Paramecium population will increase.
The growth rate of the Paramecium population will not change.

The growth rate of the Paramecium population will increase.

Select the correct statement about the global carrying capacity for the human population.

The global carrying capacity for the human population is limitless because technological advances allow food supply to keep up with global population growth.
Estimates of the global carrying capacity for the human population depend on resource use per capita.
It is impossible to calculate the global carrying capacity for the human population.

Estimates of the global carrying capacity for the human population depend on resource use per capita.

Select the correct statement about the factors that limit the growth of a population.

Density-dependent factors are biotic; density-independent factors are abiotic.
The most important factor limiting population growth is the scarcest factor in that area.
If a factor limits population growth, increasing its availability will increase population growth.

If a factor limits population growth, increasing its availability will increase population growth.

The feeding relationships among the species in a community determine the community's

species richness.
secondary succession.
trophic structure.
species-area curve.
ecological niche.

trophic structure

The principle of competitive exclusion states that

two species cannot coexist in the same habitat.
two species that have exactly the same niche cannot coexist in a community.
competition between two species always causes extinction or emigration of one species.
competition in a population promotes survival of the best-adapted individuals.
two species will stop reproducing until one species leaves the habitat.

two species that have exactly the same niche cannot coexist in a community.

Based on the intermediate disturbance hypothesis, a community's species diversity is increased by

frequent massive disturbance.
intensive disturbance by humans.
stable conditions with no disturbance.
human intervention to eliminate disturbance.
moderate levels of disturbance.

moderate levels of disturbance.

According to the equilibrium model of island biogeography, species richness would be greatest on an island that is

environmentally homogeneous.
small and remote.
large and close to a mainland.
small and close to a mainland.
large and remote.

large and close to a mainland.

Keystone predators can maintain species diversity in a community if they

prey on the community's dominant species.
allow immigration of other predators.
reduce the number of disruptions in the community.
prey only on the least abundant species in the community.
competitively exclude other predators.

prey on the community's dominant species.

Food chains are sometimes short because

most producers are inedible.
most of the energy in a trophic level is lost as it passes to the next higher level.
predator species tend to be less diverse and less abundant than prey species.
local extinction of a species causes extinction of the other species in its food chain.
only a single species of herbivore feeds on each plant species.

most of the energy in a trophic level is lost as it passes to the next higher level.

Which of the following could qualify as a top-down control on a grassland community?

limitation of plant biomass by rainfall amount
effect of humidity on plant growth rates
effect of grazing intensity by bison on plant species diversity
influence of temperature on competition among plants
influence of soil nutrients on the abundance of grasses versus wildflowers

effect of grazing intensity by bison on plant species diversity

The most plausible hypothesis to explain why species richness is higher in tropical than in temperate regions is that

tropical communities are younger.
tropical regions have very high rates of immigration and very low rates of extinction.
diversity increases as evapotranspiration decreases.
higher temperatures cause more rapid speciation.
tropical regions generally have more available water and higher levels of solar radiation.

tropical regions generally have more available water and higher levels of solar radiation.

Select the correct statement(s) about a terrestrial food chain.
Select all that apply.

The total biomass of the top trophic level is greatest because the top consumers are large.
About 1% of the energy stored in producers is converted to organic matter at the secondary consumer level.
Energy is transferred from decomposers to plants to herbivores to carnivores.

About 1% of the energy stored in producers is converted to organic matter at the secondary consumer level.

Gray wolves, once the top predators in Yellowstone National Park, were hunted to extinction there in 1926. In 1995, 15 wolves were brought to Yellowstone from Alberta. The wolf population has now grown to 300.
The forest community in Yellowstone National Park can be described by a top-down model of community organization. Wolves hunt and eat elk. Elk are herbivores that prefer riparian vegetation (plants growing next to streams and lakes). Ravens, bears, and eagles feed on elk carcasses.
How would you expect the return of the wolves to Yellowstone to affect the other species there?
Select all that apply.

Riparian vegetation would decline.
Elk populations would decline.
Bear populations would decline.

Elk populations would decline.

What is a likely outcome of a moderate disturbance, such as a severe thunderstorm?
Select all that apply.

Reduced species diversity within a community
Patches of different habitats within the landscape
Loss of an equilibrium state of balance, leading to a less healthy community

Patches of different habitats within the landscape

Select the correct statement(s) about the transfer of food energy up the trophic levels from its source in autotrophs.
Select all that apply.

Few plants have adaptations to reduce feeding by herbivores.
The length of a food chain is limited by the inefficiency of energy transfer along the chain.
An organism feeds at only one trophic level.

The length of a food chain is limited by the inefficiency of energy transfer along the chain

Which of the following may result from resource partitioning?
Select all that apply.

A population's fundamental niche may be smaller than its realized niche.
A population may have a smaller realized niche when it coexists with a competitor.
Competing species may partition time, feeding at different times of day.

A population may have a smaller realized niche when it coexists with a competitor.
Competing species may partition time, feeding at different times of day.

Which of the following organisms is incorrectly paired with its trophic level?

eagle-tertiary consumer
fungus-detritivore
cyanobacterium-primary producer
zooplankton-primary producer
grasshopper-primary consumer

zooplankton-primary producer

Which of these ecosystems has the lowest net primary production per square meter?

a tropical rain forest
a salt marsh
an open ocean
a grassland
a coral reef

an open ocean

The discipline that applies ecological principles to returning degraded ecosystems to a more natural state is known as

conservation ecology.
population viability analysis.
restoration ecology.
resource conservation.
landscape ecology.

restoration ecology.

Nitrifying bacteria participate in the nitrogen cycle mainly by

incorporating nitrogen into amino acids and organic compounds.
converting ammonia to nitrogen gas, which returns to the atmosphere.
converting nitrogen gas to ammonia.
converting ammonium to nitrate, which plants absorb.
releasing ammonium from organic compounds, thus returning it to the soil.

converting ammonium to nitrate, which plants absorb.

Which of the following has the greatest effect on the rate of chemical cycling in an ecosystem?

the production efficiency of the ecosystem's consumers
the trophic efficiency of the ecosystem
the location of the nutrient reservoirs in the ecosystem
the rate of decomposition in the ecosystem
the ecosystem's rate of primary production

the rate of decomposition in the ecosystem

The Hubbard Brook watershed deforestation experiment yielded all of the following results except:

Calcium levels remained high in the soil of deforested areas.
The flow of minerals out of a natural watershed was offset by minerals flowing in.
Deforestation increased water runoff.
Most minerals were recycled within a forest ecosystem.
The nitrate concentration in waters draining the deforested area became dangerously high.

Calcium levels remained high in the soil of deforested areas.

Which of the following would be considered an example of bioremediation?

reconfiguring the channel of a river
using a bulldozer to regrade a strip mine
adding seeds of a chromium-accumulating plant to soil contaminated by chromium
dredging a river bottom to remove contaminated sediments
adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability

adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability

If you applied a fungicide to a cornfield, what would you expect to happen to the rate of decomposition and net ecosystem production (NEP)?

Decomposition rate would decrease and NEP would increase.
Decomposition rate would increase and NEP would decrease.
Neither would change.
Both decomposition rate and NEP would increase.
Both decomposition rate and NEP would decrease.

Decomposition rate would decrease and NEP would increase.

How do pyramids of net production and pyramids of biomass differ?

Pyramids of net production include fewer trophic levels than pyramids of biomass.
Unlike pyramids of biomass, pyramids of net production are based on measurements per unit time.
Unlike pyramids of net production, the shape of a pyramid of biomass varies with the size of the organisms in the ecosystem.

Unlike pyramids of biomass, pyramids of net production are based on measurements per unit time.

Some aquatic ecosystems have inverted biomass pyramids, in which primary consumers outweigh the producers. Why is it that a pyramid of biomass, but not a pyramid of net production, may be inverted?

A pyramid of biomass may be inverted because it is based on biomass at one point in time. Pyramids of net production are based on productivity per unit time.
A pyramid of biomass may be inverted when the producers (e.g., phytoplankton) are much more plentiful than the consumers (e.g., zooplankton). Producers are always outnumbered by consumers, so pyramids of net production are never inverted.
A pyramid of biomass may be inverted when the producers (e.g., phytoplankton) are much smaller than the consumers (e.g., zooplankton). Producers always have higher productivity than consumers, so pyramids of net production are never inverted.

A pyramid of biomass may be inverted because it is based on biomass at one point in time. Pyramids of net production are based on productivity per unit time.

Why is it that nitrogen is often a limiting plant nutrient, despite the fact that the atmosphere is 80% nitrogen gas (N2)?

Because plants cannot assimilate nitrogen-containing compounds
Because N2 easily leaches away from soil
Because plants cannot fix N2

Because plants cannot fix N2

Select the correct statement describing the nitrogen cycle.

Nitrogen-fixing microbes provide energy for carbon fixation.
Denitrifying bacteria reduce ammonia (NH3 +) to molecular nitrogen (N2).
Bacteria obtain energy from nitrification.

Bacteria obtain energy from nitrification.

Your textbook states, "Like organisms, ecosystems are open systems." Which of the following provide a legitimate example to illustrate this statement?
Select all that apply.

A population of reef fishes with a high reproductive rate in a mangrove ecosystem may be a source of recruits for a population in an adjacent coral reef ecosystem with a lower reproductive rate.
Detritivores in soil consume nonliving organic matter and make the nutrients available to plants.
Earth's atmosphere is bombarded by about 1022 joules of solar radiation each day.

A population of reef fishes with a high reproductive rate in a mangrove ecosystem may be a source of recruits for a population in an adjacent coral reef ecosystem with a lower reproductive rate.
Earth's atmosphere is bombarded by about 1022 joules of solar radiation each day.

Unlike an earthworm's metanephridia, a mammalian nephron

functions in both osmoregulation and excretion.
is intimately associated with a capillary network.
forms urine by changing fluid composition inside a tubule.
has a transport epithelium.
receives filtrate from blood instead of coelomic fluid.

receives filtrate from blood instead of coelomic fluid.

Which process in the nephron is least selective?

secretion
salt pumping by the loop of Henle
reabsorption
active transport
filtration

filtration

which of the following animals generally has the lowest volume of urine production?

a shark inhabiting freshwater Lake Nicaragua
a marine bony fish
a freshwater bony fish
a vampire bat
a salmon in fresh water

a marine bony fish

The high osmolarity of the renal medulla is maintained by all of the following except

diffusion of salt from the descending limb of the loop of Henle.
the spatial arrangement of juxtamedullary nephrons.
diffusion of salt from the thin segment of the ascending limb of the loop of Henle.
active transport of salt from the upper region of the ascending limb.
diffusion of urea from the collecting duct.

diffusion of salt from the descending limb of the loop of Henle.

Natural selection should favor the highest proportion of juxtamedullary nephrons in which of the following species?

a beaver
a river otter
a mouse species living in a desert
a mouse species living in a temperate broadleaf forest
a mouse species living in a tropical rain forest

a mouse species living in a desert

African lungfish, which are often found in small stagnant pools of fresh water, produce urea as a nitrogenous waste. What is the advantage of this adaptation?

The highly toxic urea makes the pool uninhabitable to potential competitors.
Urea takes less energy to synthesize than ammonia.
Urea forms an insoluble precipitate.
Urea makes lungfish tissue hypoosmotic to the pool.
Small stagnant pools do not provide enough water to dilute the toxic ammonia.

Small stagnant pools do not provide enough water to dilute the toxic ammonia.

Which of the following is not an accurate statement?

Hormones of the same chemical class usually have the same function.
Hormones are chemical messengers that travel to target cells through the circulatory system.
Hormones are often regulated through feedback loops.
Hormones are secreted by specialized cells usually located in endocrine glands.
Hormones often regulate homeostasis through antagonistic functions.

Hormones of the same chemical class usually have the same function.

An example of antagonistic hormones controlling homeostasis is

epinephrine and norepinephrine in fight-or-flight responses.
progestins and estrogens in sexual differentiation.
oxytocin and prolactin in milk production.
thyroxine and parathyroid hormone in calcium balance.
insulin and glucagon in glucose metabolism.

insulin and glucagon in glucose metabolism.

Growth factors are local regulators that

bind to cell-surface receptors and stimulate growth and development of target cells.
are modified fatty acids that stimulate bone and cartilage growth.
are produced by the anterior pituitary.
convey messages between nerve cells.
are found on the surface of cancer cells and stimulate abnormal cell division.

bind to cell-surface receptors and stimulate growth and development of target cells.

Which hormone is incorrectly paired with its action?

ACTH-stimulates the release of glucocorticoids by the adrenal cortex
melatonin-affects biological rhythms, seasonal reproduction
insulin-stimulates glycogen breakdown in the liver
oxytocin-stimulates uterine contractions during childbirth
thyroxine-stimulates metabolic processes

insulin-stimulates glycogen breakdown in the liver

Steroid and peptide hormones typically have in common

the location of their receptors.
their requirement for travel through the bloodstream.
their reliance on signal transduction in the cell.
their solubility in cell membranes.
the building blocks from which they are synthesized.

their requirement for travel through the bloodstream.

Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal?

a decrease in the thyroid secretion of calcitonin
hypersecretion of TSH
hypersecretion of MSH
hyposecretion of TSH
greater production of T3 than of T4

hyposecretion of TSH

Shortly after ingesting a big plate of carbohydrate-rich pasta, you measure your blood's hormone levels. What results would you expect, compared to before the meal?

low insulin, low glucagon
high insulin, low glucagon
low insulin, high glucagon
high insulin, high glucagon
low insulin, no change in glucagon

high insulin, low glucagon

The relationship between the insect hormones ecdysteroid and PTTH is an example of

competitive inhibition of a hormone receptor.
how peptide-derived hormones have more widespread effects than steroid hormones.
an interaction of the endocrine and nervous systems.
homeostasis achieved by positive feedback.
homeostasis maintained by antagonistic hormones.

an interaction of the endocrine and nervous systems.

Which of the following characterizes parthenogenesis?

Specialized groups of cells grow into new individuals.
Both mates have male and female reproductive organs.
An egg develops without being fertilized.
An organism is first a male and then a female.
An individual may change its sex during its lifetime.

An egg develops without being fertilized.

In male mammals, excretory and reproductive systems share

the urethra.
the testes.
the vas deferens.
the seminal vesicle.
the prostate.

the urethra

Which of the following is not properly paired?

vas deferens-oviduct
seminiferous tubule-cervix
scrotum-labia majora
testosterone-estradiol
Sertoli cells-follicle cells

seminiferous tubule-cervix

Peaks of LH and FSH production occur during

the end of the luteal phase of the ovarian cycle.
the menstrual flow phase of the uterine cycle.
the beginning of the follicular phase of the ovarian cycle.
the secretory phase of the menstrual cycle.
the period just before ovulation.

the period just before ovulation.

During human gestation, rudiments of all organs develop

in the second trimester.
while the embryo is in the oviduct.
in the third trimester.
during the blastocyst stage.
in the first trimester.

in the first trimester.

Which of the following is a true statement?

The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles.
All mammals have menstrual cycles.
Ovulation occurs before the endometrium thickens in estrous cycles.
Estrous cycles are not controlled by hormones.
Estrous cycles are more frequent than menstrual cycles.

The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles.

For which of the following is the number the same in spermatogenesis and oogenesis?

gametes produced in a given time period
functional gametes produced by meiosis
interruptions in meiotic divisions
different cell types produced by meiosis
meiotic divisions required to produce each gamete

meiotic divisions required to produce each gamete

Which statement about human reproduction is false?

An oocyte completes meiosis after a sperm penetrates it.
Spermatogenesis and oogenesis require different temperatures.
Effective hormonal contraceptives are currently available only for females.
Fertilization occurs in the oviduct.
The earliest stages of spermatogenesis occur closest to the lumen of the seminiferous tubules.

The earliest stages of spermatogenesis occur closest to the lumen of the seminiferous tubules.

The cortical reaction of sea urchin eggs functions directly in

the generation of an electrical impulse by the egg.
the production of a fast block to polyspermy.
the release of hydrolytic enzymes from the sperm.
the formation of a fertilization envelope.
the fusion of egg and sperm nuclei.

the formation of a fertilization envelope.

Which of the following is common to the development of both birds and mammals?

epiblast and hypoblast
trophoblast
yolk plug
holoblastic cleavage
gray crescent

epiblast and hypoblast

The archenteron develops into

the mesoderm.
the blastocoel.
the lumen of the digestive tract.
the endoderm.
the placenta.

the lumen of the digestive tract.

What structural adaptation in chickens allows them to lay their eggs in arid environments rather than in water?

development of the brain from ectoderm
cleavage
gastrulation
extraembryonic membranes
yolk

extraembryonic membranes

In an egg cell treated with EDTA, a chemical that binds calcium and magnesium ions,

the fusion of sperm and egg nuclei would be blocked.
the acrosomal reaction would be blocked.
the fast block to polyspermy would not occur.
the fertilization envelope would not form.
the zygote would not contain maternal and paternal chromosomes.

the fertilization envelope would not form.

In humans, identical twins are possible because

early blastomeres can form a complete embryo if isolated.
cytoplasmic determinants are distributed unevenly in unfertilized eggs.
convergent extension occurs.
extraembryonic cells interact with the zygote nucleus.
the gray crescent divides the dorsal-ventral axis into new cells.

early blastomeres can form a complete embryo if isolated.

Cells transplanted from the neural tube of a frog embryo to the ventral part of another embryo develop into nervous system tissues. This result indicates that the transplanted cells were

mesenchymal.
determined.
apoptotic.
differentiated.
totipotent.

determined.

In an embryonic vertebrate, the apical ectodermal ridge (AER) is a thickened area at the tip of the bud. The cells of the AER secrete protein signals that promote limb-bud outgrowth, and removing the AER blocks growth of the limb along the proximal-distal axis. How would the forelimb of an embryo develop if the AER was removed early or late in limb development?

Early removal of the AER would prevent the formation of many distal structures, whereas late removal of the AER would prevent the formation of a few distal structures.
Early or late removal of the AER would have the same result: the embryo would not develop a forelimb.
Early removal of the AER would prevent the development of a forelimb, whereas late removal of the AER would not have any effect.

Early removal of the AER would prevent the formation of many distal structures, whereas late removal of the AER would prevent the formation of a few distal structures.

Select the correct statement about embryonic development in a frog.

Development from zygote to blastula involves mitotic division, cell movement, and cell growth.
The blastocoel of a developing frog embryo develops into the digestive tract.
The reorganization of cell layers during gastrulation allows the layers to interact with each other in new ways.

The reorganization of cell layers during gastrulation allows the layers to interact with each other in new ways.

The allantois stores nitrogenous wastes in a reptile egg. What is the function of the allantois in human development?

The allantois does not play any role in human development, because the placenta mediates the transfer of nitrogenous wastes from embryonic to maternal circulation.
The allantois helps form the umbilical cord in human development.
The allantois cushions the human embryo in a private "pond" during development.

The allantois helps form the umbilical cord in human development.

Identify the correct statement(s) about Spemann's organizer.
Select all that apply.

Spemann's organizer is the dorsal lip of the blastopore in frog gastrulation.
Spemann's organizer initiates a chain of inductive interactions in frog development.
Spemann's organizer is made up of totipotent cells.

Spemann's organizer is the dorsal lip of the blastopore in frog gastrulation.
Spemann's organizer initiates a chain of inductive interactions in frog development.

In an embryonic vertebrate, the zone of polarizing activity (ZPA) is a block of tissue located on the posterior side of a limb bud. The ZPA provides information about the anterior-posterior axis of the limb. Cells nearest the ZPA form the most posterior of digits (like our little finger); cells farthest from the ZPA form the most anterior digits (like our thumb).

How would a vertebrate forelimb bud develop if it had two zones of polarizing activities, one on the posterior side and one on the anterior side of the bud?

The forelimb bud would develop into a hind limb.
The embryo wouldn't develop a forelimb.
The forelimb bud would develop with extra digits, in a mirror image arrangement to the normal digits.

The forelimb bud would develop with extra digits, in a mirror image arrangement to the normal digits.

What happens when a resting neuron's membrane depolarizes?

There is a net diffusion of Na+ out of the cell.
The equilibrium potential for K+ (E K) becomes more positive.
The neuron's membrane voltage becomes more positive.
The cell's inside is more negative than the outside.
The neuron is less likely to generate an action potential.

The neuron's membrane voltage becomes more positive.

A common feature of action potentials is that they

cause the membrane to hyperpolarize and then depolarize.
move at the same speed along all axons.
are triggered by a depolarization that reaches the threshold.
require the diffusion of and through ligand-gated channels to propagate.
can undergo temporal and spatial summation.

are triggered by a depolarization that reaches the threshold.

Where are neurotransmitter receptors located?

synaptic vesicle membranes
the postsynaptic membrane
the nuclear membrane
the myelin sheath
the nodes of Ranvier

the postsynaptic membrane

Temporal summation always involves

inputs that are not simultaneous.
synapses at more than one site.
both inhibitory and excitatory inputs.
multiple inputs at a single synapse.
electrical synapses.

multiple inputs at a single synapse.

Why are action potentials usually conducted in one direction?

Voltage-gated channels for both Na+ and K+ open in only one direction.
The brief refractory period prevents reopening of voltage-gated Na+ channels.
Ions can flow along the axon in only one direction.
The axon hillock has a higher membrane potential than the terminals of the axon.
The nodes of Ranvier conduct potentials in one direction.

The brief refractory period prevents reopening of voltage-gated Na+ channels.

Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal?

An EPSP or IPSP is generated in the postsynaptic cell.
The postsynaptic cell produces an action potential.
Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft.
Synaptic vesicles fuse with the membrane.
Voltage-gated calcium channels in the membrane open.

Voltage-gated calcium channels in the membrane open.

Why is an action potential an all-or-none response to stimuli?

Because a typical neuron receives signals through multiple dendrites but transmits signals through a single axon
Because neurons contain gated ion channels that are either open or closed
Because voltage-gated ion channels open when membrane potential passes a particular level

Because voltage-gated ion channels open when membrane potential passes a particular level

What causes the falling phase of the action potential? Select the best answer.

The opening of voltage-gated sodium channels
Inactivation of voltage-gated sodium channels and the opening of voltage-gated potassium channels
The opening of voltage-gated potassium channels

Inactivation of voltage-gated sodium channels and the opening of voltage-gated potassium channels

If the membrane potential of a neuron decreases, the membrane potential _____.

remains unchanged.
becomes more negative.
becomes more positive.

becomes more positive.

The plasma membrane of a neuron has voltage-gated sodium and potassium channels. What is the effect of membrane depolarization on these channels?

Membrane depolarization opens sodium and potassium channels at the same time.
Membrane depolarization first opens sodium channels and then opens potassium channels.
Membrane depolarization opens sodium channels but closes potassium channels.

Membrane depolarization first opens sodium channels and then opens potassium channels.

Identify the correct statement(s) about the resting membrane potential of a cell.
Select all that apply.

Potassium (K+) and sodium (Na+) gradients are maintained by active transport in a resting mammalian neuron.
Neurons are the only cells that have a charge difference across their membranes.
Concentration gradients of potassium (K+) and sodium (Na+) across the plasma membrane represent potential energy.

Potassium (K+) and sodium (Na+) gradients are maintained by active transport in a resting mammalian neuron.
Concentration gradients of potassium (K+) and sodium (Na+) across the plasma membrane represent potential energy.

Wakefulness is regulated by the reticular formation, which is present in the

spinal cord.
limbic system.
basal nuclei.
cerebral cortex.
brainstem.

brainstem.

Which of the following structures or regions is incorrectly paired with its function?

corpus callosum-communication between the left and right cerebral cortices
amygdala-emotional memory
limbic system-motor control of speech
medulla oblongata-homeostatic control
cerebellum-coordination of movement and balance

limbic system-motor control of speech

Patients with damage to Wernicke's area have difficulty

coordinating limb movement.
generating speech.
experiencing emotion.
understanding language.
recognizing faces.

understanding language.

The cerebral cortex plays a major role in all of the following except

foot-tapping rhythm.
long-term memory.
circadian rhythm.
short-term memory.
breath holding.

circadian rhythm.

After suffering a stroke, a patient can see objects anywhere in front of him but pays attention only to objects in his right field of vision. When asked to describe these objects, he has difficulty judging their size and distance. What part of the brain was likely damaged by the stroke?

the corpus callosum
the left parietal lobe
the right frontal lobe
the left frontal lobe
the right parietal lobe

the right parietal lobe

Injury localized to the hypothalamus would most likely disrupt

executive functions, such as decision making.
short-term memory.
coordination during locomotion.
regulation of body temperature.
sorting of sensory information.

regulation of body temperature.

Identify the role(s) of glia in the vertebrate brain.
Select all that apply.

Glia release neurotransmitters.
Glia protect the nervous system from pathogens.
Glia guide neuron migration during development of the CNS

Glia release neurotransmitters.
Glia protect the nervous system from pathogens.
Glia guide neuron migration during development of the CNS

Which examples correctly illustrate the cooperation between the motor and nervous systems to maintain homeostasis in a vertebrate body?
Select all that apply.

A drop in body temperature leads to shivering and constriction of surface blood vessels.
In response to a sudden fright, the body responds by increasing heart rate, inhibiting digestion, and increasing blood glucose.
If you put your hand on a hot burner, a reflex pulls your hand back before you sense pain.

A drop in body temperature leads to shivering and constriction of surface blood vessels.

Which of these observations illustrate the developmental plasticity of the human nervous system?
Select all that apply.

When activity at a synapse correlates with the activity of other synapses, that synaptic connection is reinforced.
A person suffering from phantom limb pain following amputation may stop feeling pain after viewing a reflection of the remaining limb in a mirrored box.
The brain may ignore certain stimuli and actively process other stimuli.

When activity at a synapse correlates with the activity of other synapses, that synaptic connection is reinforced.
A person suffering from phantom limb pain following amputation may stop feeling pain after viewing a reflection of the remaining limb in a mirrored box.

Identify the correct statement(s) about glial cells and their functions.
Select all that apply.

Oligodendrocytes act as stem cells, producing neurons and glia.
Schwann cells myelinate dendrites in the PNS.
Astrocytes induce the formation of the blood-brain barrier.

Astrocytes induce the formation of the blood-brain barrier.

Which of these observations illustrate regional specialization in the human nervous system?
Select all that apply.

Reading a printed word out loud and then thinking of a related word involves the visual cortex, Broca's area, and the frontal and temporal lobes.
Sensory information may be processed in the occipital lobe or the temporal lobe.
When the activity of a synapse fails to correlate with that of other synapses, the synaptic connection may become weaker.

Reading a printed word out loud and then thinking of a related word involves the visual cortex, Broca's area, and the frontal and temporal lobes.
Sensory information may be processed in the occipital lobe or the temporal lobe.

Vertebrates and tunicates share

a notochord and a dorsal, hollow nerve cord.
an endoskeleton that includes a skull.
jaws adapted for feeding.
the formation of structures from the neural crest.
a high degree of cephalization.

a notochord and a dorsal, hollow nerve cord.

Some animals that lived 530 million years ago resembled lancelets but had a brain and a skull. These animals may represent

marsupials.
a "missing link" between urochordates and cephalochordates.
the first chordates.
nontetrapod gnathostomes.
early craniates.

early craniates.

Which of the following could be considered the most recent common ancestor of living tetrapods?

an early ray-finned fish that developed bony skeletal supports in its paired fins
a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates
an early terrestrial caecilian whose legless condition had evolved secondarily
an armored, jawed placoderm with two pairs of appendages
a salamander that had legs supported by a bony skeleton but moved with the side-to-side bending typical of fishes

a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates

Unlike eutherians, both monotremes and marsupials

lay eggs.
lack nipples.
have some embryonic development outside the uterus.
include only insectivores and herbivores.
are found in Australia and Africa.

have some embryonic development outside the uterus.

Which clade does not include humans?

synapsids
diapsids
craniates
lobe-fins
osteichthyans

diapsids

As hominins diverged from other primates, which of the following appeared first?

language
reduced jawbones
the making of stone tools
an enlarged brain
bipedal locomotion

bipedal locomotion

The body tissue that consists largely of material located outside of cells is

skeletal muscle.
nervous tissue.
smooth muscle.
connective tissue.
epithelial tissue.

connective tissue.

Which of the following would increase the rate of heat exchange between an animal and its environment?

feathers or fur
wind blowing across the body surface
blubber or fat layer
vasoconstriction
countercurrent heat exchanger

wind blowing across the body surface

Consider the energy budgets for a human, an elephant, a penguin, a mouse, and a snake. The __________ would have the highest total annual energy expenditure, and the __________ would have the highest energy expenditure per unit mass.

elephant; mouse
elephant; human
penguin; mouse
mouse; snake
human; penguin

elephant; mouse

Compared with a smaller cell, a larger cell of the same shape has

less surface area.
the same surface-to-volume ratio.
a smaller average distance between its mitochondria and the external source of oxygen.
a smaller cytoplasm-to-nucleus ratio.
less surface area per unit of volume.

less surface area per unit of volume.

An animal's inputs of energy and materials would exceed its outputs

if the animal is an endotherm, which must always take in more energy because of its high metabolic rate.
if it is hibernating.
never; homeostasis makes these energy and material budgets always balance.
if it is actively foraging for food.
if it is growing and increasing its mass.

if it is growing and increasing its mass.

You are studying a large tropical reptile that has a high and relatively stable body temperature. How would you determine whether this animal is an endotherm or an ectotherm?

You know from its high and stable body temperature that it must be an endotherm.
You note that its environment has a high and stable temperature. Because its body temperature matches the environmental temperature, you conclude that it is an ectotherm.
You measure the metabolic rate of the reptile, and because it is higher than that of a related species that lives in temperate forests, you conclude that this reptile is an endotherm and its relative is an ectotherm.
You know that it is an ectotherm because it is not a bird or mammal.
You subject this reptile to various temperatures in the lab and find that its body temperature and metabolic rate change with the ambient temperature. You conclude that it is an ectotherm.

You subject this reptile to various temperatures in the lab and find that its body temperature and metabolic rate change with the ambient temperature. You conclude that it is an ectotherm.

Which of the following animals uses the largest percentage of its energy budget for homeostatic regulation?

a desert bird
a hydra
a desert insect
a snake in a temperate forest
a marine jelly (an invertebrate)

a desert bird

Which of the following animals is incorrectly paired with its feeding mechanism?

aphid-fluid feeder
lion-substrate feeder
baleen whale-suspension feeder
clam-suspension feeder
snake-bulk feeder

lion-substrate feeder

The mammalian trachea and esophagus both connect to the

stomach.
rectum.
pharynx.
large intestine.
epiglottis.

pharynx.

Which of the following organs is incorrectly paired with its function?

small intestine-nutrient absorption
oral cavity-starch digestion
large intestine-bile production
stomach-protein digestion
pancreas-enzyme production

large intestine-bile production

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