BIO 121 Exam 4

The symbols +, -, and o are to be used to show the results of interactions between individuals and groups of individuals in the examples that follow. The symbol + denotes a positive interaction, - denotes a negative interaction, and o denotes where individuals are not affected by interacting. The first symbol refers to the first organism mentioned. What interactions exist between a lion pride and a hyena pack? +/+ +/o +/- o/o -/-

-/-

Consider the food chain of grass → grasshopper → mouse → snake → hawk. About how much of the chemical energy fixed by photosynthesis of the grass (100 percent) is available to the hawk? 10% 1% 60% 0.1% 0.01%

0.01%

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

Batesian mimicry

Why does high species richness result in high productivity? Because more species results in higher consumption amounts Because species-rich communities have more mutualistic relationships Because richer species produce more Because of resource partitioning

Because of resource partitioning Correct! A greater proportion of resources should be uniquely used in high-diversity areas

Why is the 12 percent of land protected so far not enough to avert a mass extinction? Because a mass extinction is inevitable regardless of conservation effort Because the 12 percent does not consist primarily of biodiversity hot spots Because species inhabit more than 12 percent of the land Because the necessary amount of land to protect to avoid it is 55 percent

Because the 12 percent does not consist primarily of biodiversity hot spots Correct! Protection of key areas will protect a substantial number of species.

Which of the following levels of analysis is not typically used to measure biodiversity? Ecosystem Genetic Species Behavior

Behavior Correct! Behavior is not a typical measure of biodiversity

Which of the following statements about the movement of nutrients through an ecosystem is true? Nutrients in the soil can be eaten and used directly by animals. An organism transfers only its energy to the organism that eats it. Carbon cycles between the atmosphere and living biomass. A biogeochemical cycle is the path that an element takes as it moves from organism to organism.

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

How does carbon move from the biota to the atmosphere? Carbon is incorporated into sedimentary rocks. Carbon dioxide diffuses into the atmosphere. Carbon dioxide is released during cellular respiration. Carbon dioxide is released during photosynthesis.

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

How have humans altered the global carbon cycle? Deforestation has decreased carbon levels in the atmosphere. Carbon inputs into the atmosphere have risen. The amount of photosynthesis has increased. The burning of fossil fuels removes carbon from the global carbon cycle.

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

Regarding soil and organic matter in humus, which of the following statements is true? Eventually, the nutrients in soil organic matter are converted to organic form. Completely decayed soil organic matter is called humus. Soil organic matter is completely decayed. Humus is composed of inorganic nutrients, and organic matter is composed only of organic matter.

Completely decayed soil organic matter is called humus.

Why do populations grow more slowly as they approach their carrying capacity? Individuals voluntarily stop mating so that overcrowding does not occur. The incoming energy decreases in populations experiencing a high rate of increase. Density-independent factors lead to fewer births and increased mortality. Density-dependent factors lead to fewer births and increased mortality. Hormonal changes promote higher death rates in crowded populations.

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

Why does net productivity diminish with increasing trophic levels? There are fewer plants at higher trophic levels. Higher trophic level organisms have to work less to obtain food. Due to poor trophic transfer efficiency, most energy is lost at higher trophic levels. Energy is gained at each trophic level.

Due to poor trophic transfer efficiency, most energy is lost at higher trophic levels. Correct! Basal trophic levels have the highest productivity.

Elephants are not the most dominant species in African grasslands, yet they influence community structure. The grasslands contain scattered woody plants, but they are kept in check by the uprooting activities of the elephants. Take away the elephants, and the grasslands convert to forests or to shrublands. The newly growing forests support fewer species than the previous grasslands. Which of the following describes why elephants are the keystone species in this scenario? Elephants prevent drought in African grasslands. Grazing animals depend upon the elephants to convert forests to grassland. Elephants help other populations survive by keeping out many of the large African predators. Elephants are the biggest herbivore in this community. Elephants exhibit a disproportionate influence on the structure of the community relative to their abundance.

Elephants exhibit a disproportionate influence on the structure of the community relative to their abundance.

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

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

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

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

Which is the most efficient food source to consume in terms of bioenergetics? Cow Pig Chicken Fish

Fish Correct! Because these are ectotherms, they devote less energy to the maintenance of a constant body temperature.

Which one of the following is LEAST likely to be a hotspot for birds? East Africa Greenland Southwest China Amazon River basin

Greenland

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

I and II only

For a species to be called "invasive," it must _____. I) be introduced to a new area II) spread rapidly in this new area III) eliminate native species only I only II only III only II and III I, II, and III

I, II, and III

Which statement best describes the evolutionary significance of mutualism? Mutualistic interaction lessens competition in communities where it is present. Mutualism offers more biodiversity to a community. Individuals partaking in a mutualistic relationship are more resistant to parasites. Mutualistic relationships allow organisms to synthesize and use energy more efficiently. Interaction increases the survival and/or population growth rate(s) of mutualistic species.

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

Biologists study how nutrients and energy move among organisms and through water, soil, and air. Which level of ecological study is this? It is ecosystem ecology. It is population ecology. It is community ecology. It is organismal ecology.

It is ecosystem ecology. Correct. Ecosystem ecology is the study of movement of energy and nutrients within and between systems.

What conditions would lead to low decomposition rates in a marine environment? Lack of salt Lack of oxygen Lack of water Lack of sunlight

Lack of oxygen Correct! Stagnant water often has high organic carbon loads.

Which would you expect to see most reduced in a desert plant? Roots Flowers Leaves Seed coats

Leaves Correct! Because moisture is scarce, leaves are often very small to prevent water loss.

Why are food chains relatively short? Longer chains are less stable and energy transfer between trophic levels is inefficient. Top-level feeders tend to be more numerous than lower-trophic-level species. There are only so many organisms that are adapted to feed on other types of organisms. Top-level feeders tend to be small but are capable of conserving more energy. Food chain length is ultimately determined by the photosynthetic efficiency of producers.

Longer chains are less stable and energy transfer between trophic levels is inefficient.

How can human population size keep increasing in spite of decreased fertility rates? Population size will continue to increase as long as the average fertility is above the replacement rate. Decreases in fertility rate by definition mean the overall population size will decrease. Populations always increase exponentially. More resources are provided to each female.

Population size will continue to increase as long as the average fertility is above the replacement rate. Correct! Even with a decrease in fertility rates, populations can still grow at an exponential rate.

Which area is not one of the three major reservoirs of the global carbon cycle? Atmosphere. Terrestrial ecosystems. Oceans. Sedimentary rock.

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

In the hypothesis that C. stellatus (a species of barnacle) is competitively excluded from the lower intertidal zone by B. balanoides (another species of barnacle), what could be concluded about the two species? The fundamental and realized niches of B. balanoides and C. stellatus are different. The fundamental and realized niches of B. balanoides are different, but the fundamental and realized niches of C. stellatus are identical. The fundamental and realized niches of B. balanoides and C. stellatus are identical. The fundamental and realized niches of B. balanoides are identical, but the fundamental and realized niches of C. stellatus are different.

The fundamental and realized niches of B. balanoides are identical, but the fundamental and realized niches of C. stellatus are different.

As N approaches K for a certain population, which of the following is predicted by the logistic equation? The growth rate will approach zero. The carrying capacity of the environment will increase. The growth rate will not change. The population will increase exponentially. The population will show an Allee effect.

The growth rate will approach zero.

In general, NPP is much higher on land than in the oceans. Why? The leading hypothesis is that there is more light available on land than in the ocean. The leading hypothesis is that oceans have higher densities of herbivores, which quickly consume the producers. The leading hypothesis is that there are more available nutrients in water than on land. The leading hypothesis is that there are few photosynthetic organisms that can live in the ocean.

The leading hypothesis is that there is more light available on land than in the ocean. Correct. Water is a filter that absorbs and removes sunlight.

How are humans impacting the global water cycle when they pave, convert forest to agriculture, and irrigate that agriculture? The water table is rising on every continent. Precipitation is decreasing on every continent. Precipitation is increasing on every continent. The water table is dropping on every continent.

The water table is dropping on every continent. Correct. We are reducing the rate at which water penetrates the soil, and withdrawing more groundwater than is being replenished.

What is the primary limiting factor that determines why no female animal can produce a very large number of very large eggs? Temperature constraints will prevent females from carrying too many eggs. Time is limited. Male availability is limited. There are energy constraints. There will be an increase in predation pressure if the females carry too many large eggs.

There are energy constraints.

What are biodiversity hotspots? They are areas where biodiversity was first studied. They are regions that are extraordinarily rich in species diversity. They are the regions with the lowest species richness. They are areas that, due to lack of forestation, will be the most affected by global warming.

They are regions that are extraordinarily rich in species diversity. Correct. It turns out that some regions of the world are much higher in species number and in endemism than other areas of the world.

How do greenhouse gases contribute to global warming? They prevent infrared light from leaving Earth's atmosphere. They allow excess radiant light to leave Earth's atmosphere. They block solar energy from reaching Earth's atmosphere. They prevent the oceans from absorbing shorter wavelengths of light.

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

What makes pioneering plant species successful? They are adapted for survival under all kinds of conditions. They are naturally selected for longevity. They rapidly colonize soil that is exposed and has few or no competitors already present. They can outcompete all other species.

They rapidly colonize soil that is exposed and has few or no competitors already present. Correct. Pioneering plant species excel in being able to survive in open habitat, even if the resource availability in such habitats is low.

Which of the following is a consequence of biological magnification (biomagnification)? Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers. The amount of biomass in the producer level of an ecosystem decreases if the producer turnover time increases. The biomass of producers in an ecosystem is generally higher than the biomass of primary consumers. Only a small portion of the energy captured by producers is transferred to consumers. Populations of top-level predators are generally smaller than populations of primary consumers.

Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers.

Which of the following is a widely supported explanation for the tendency of tropical communities to have greater species diversity than temperate or polar communities? More competitive dominant species have evolved in temperate and polar communities. Tropical communities are generally older than temperate and polar communities. Tropical communities are low in altitude, whereas temperate and polar communities are high in altitude. They are less likely to be affected by human disturbance. There are fewer parasites to negatively affect the health of tropical communities.

Tropical communities are generally older than temperate and polar communities.

Which biome is the most productive? Tropical dry forest Temperate forest Desert Tropical wet forest

Tropical wet forest

Why might one get mercury poisoning from eating tuna every day, but not from eating sardines from the same water? Sardines are able to excrete the mercury. Tuna biomagnify the mercury. Mercury is more readily available for uptake in tuna. Sardines do not uptake mercury.

Tuna biomagnify the mercury. Correct! Tuna eat many sardines and concentrate the mercury in their tissues.

Which of these is a starting point for primary succession? none of these is a starting point for primary succession a neglected yard a surface exposed by a retreating glacier abandoned farmland an abandoned city

a surface exposed by a retreating glacier Such a surface lacks any life and is thus a starting point for primary succession.

According to most conservation biologists, the single greatest threat to global biodiversity is _____. overexploitation of certain species chemical pollution of water and air alteration or destruction of the physical habitat stratospheric ozone depletion

alteration or destruction of the physical habitat

Which of the following locations is the main reservoir for nitrogen in the nitrogen cycle? fossilized plant and animal remains (coal, oil, and natural gas) plant and animal biomass sedimentary bedrock atmosphere soil

atmosphere

Some birds follow moving swarms of army ants in the tropics. As the ants march along the forest floor hunting insects and small vertebrates, birds follow and pick off any insects or small vertebrates that fly or jump out of the way of the ants. This situation is an example of what kind of species interaction between the birds and the ants? cooperation consumption parasitism commensalism mutualism

commensalism

Uniform spacing patterns in plants such as the creosote bush are most often associated with _____. the concentration of nutrients within the population's range chance competitive interaction between individuals of the same population patterns of high humidity the random distribution of seeds

competitive interaction between individuals of the same population

Which of the following examples would most accurately measure the density of the population being studied? counting the number of moss plants in one-square-meter quadrants counting the number of zebras from airplane census observations. counting the number of times a one-kilometer transect is intersected by tracks of red squirrels after a snowfall counting the number of prairie dog burrows per hectare counting the number of coyote droppings per hectare

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

An ecologist recorded twelve white-tailed deer, Odocoileus virginianus, per square kilometer in one woodlot and twenty per square kilometer in another woodlot. What was the ecologist comparing? cohorts carrying capacity dispersion density range

density

A study conducted at Hubbard Brook Experimental Forest watershed areas provided experimental evidence that _____. contamination in nearby areas passes into watersheds water levels become higher and more easily maintained as the number of nearby trees increases deforestation increases the rate of nutrient loss from ecosystems forest productivity is a function of number of trees and diversity of species present

deforestation increases the rate of nutrient loss from ecosystems Correct. Plant roots reduce nutrient losses.

An earthworm that feeds on the remains of plants and animals is acting as a _____. secondary consumer producer tertiary consumer primary consumer detritivore

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

Biomes are major groupings of plant and animal communities that are defined by _____. net primary productivity altitude weather dominant vegetation type

dominant vegetation type Correct. Biomes are defined by vegetation.

Which of the following levels of ecological organization is arranged in the correct sequence from most to least inclusive? ecosystem, community, population, organism organism, community, population, ecosystem population, ecosystem, organism, community organism, population, community, ecosystem community, ecosystem, organism, population

ecosystem, community, population, organism

If two species are close competitors, and one species is experimentally removed from the community, the remaining species would be expected to _____. change its fundamental niche expand its realized niche become the target of specialized parasites decline in abundance eventually become competitively superior to the other species

expand its realized niche

Which of the following is the greatest threat to biodiversity? disruption of trophic relationships as more and more prey species become extinct pollution of Earth's air, water, and soil overharvesting of commercially important species introduced species that compete with native species habitat alteration, fragmentation, and destruction

habitat alteration, fragmentation, and destruction

When biologists refer to community stability, resilience is a measure of _____. how quickly a community recovers following a disturbance how community members work together (cohesion) to maintain stability how many members of a community there are total how many members of a community succumb to a disease, blight, or parasite

how quickly a community recovers following a disturbance Correct. Resilience is the ability of the community to "rebound."

Populations grow due to births and _____. emigration survivorship deaths immigration

immigration Correct. Immigration is the entry of new individuals moving from other populations.

In a particular case of secondary succession, three species of wild grass all invaded a field. By the second season, a single species dominated the field. A possible factor in this secondary succession was _____. facilitation parasitism equilibrium inhibition immigration

inhibition

The competitive exclusion principle states that _____. two species with the same niche will constantly be competing for resources it is not possible for two species with the same niche to coexist in the same region two species with different niches will not compete for the same resources it is not possible for two species to compete for the same resources

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

Different types of research have all concluded that global climate change is _____. making climates more extreme increasing annual temperatures everywhere making storms more frequent increasing annual precipitation everywhere

making climates more extreme Correct. One of the responses of our planet to global warming is to increase the magnitude of climate fluxes.

There are more species in tropical areas than in places more distant from the equator. This is probably a result of _____. more intense annual solar radiation fewer agents of disease fewer predators more frequent ecological disturbances

more intense annual solar radiation

Bees visiting flowers to harvest nectar and pollen would be considered examples of _____. competition commensalism mutualism parasitism

mutualism Correct. Both the bee and the flower benefit from the interaction.

According to the competitive exclusion principle, two species cannot continue to occupy the same _____. range niche territory habitat biome

niche

Ecosystem services include processes that increase the quality of the abiotic environment. Which of the following processes would fall under this category? I) Keystone predators have a marked effect on species diversity. II) Green plants produce the oxygen we breathe. III) The presence of land plants builds soil. IV) The presence of diverse wetlands helps in flood control. only I, II, and IV only II and IV only I, II, and III only II, III, and IV only I and III

only II, III, and IV

Approximately how many species have we described out of the species alive today? We have described _____. almost all of the species on Earth. about one-eighth of the species on Earth. only a small fraction of the species on Earth. about half of the species on Earth. about one-quarter of the species on Earth.

only a small fraction of the species on Earth.

What is the dominant conservation problem faced by marine species? invasive species (introduced competitors, diseases, or predators) habitat destruction pollution overexploitation

overexploitation Correct. Overexploitation is the unsustainable harvest of animals for human use.

What is net primary productivity (NPP)? solar energy consumed by non-photosynthetic organisms minerals and nitrogen that can be fixed water maintained in the soil plant biomass or organic material that can be consumed

plant biomass or organic material that can be consumed Correct. NPP measures the amount of plant material that is available for consumption after plants have used their component of GPP.

You own three hundred acres of patchy temperate forest. Which one of the following actions would increase the net primary productivity of the area the most? adding fertilizer to the entire area relocating all of the deer found in the area introducing one hundred rabbits into the area planting five hundred new trees

planting five hundred new trees

An example of an age-structure influence on human population size is that _____. populations dominated by juveniles should experience rapid growth populations with equal numbers in each age class are more likely to go extinct populations with equal numbers in each age class grow fastest populations dominated by juveniles are more likely to go extinct

populations dominated by juveniles should experience rapid growth Correct. Juveniles are about to enter a period of fecundity with low mortality rates, so the population will grow rapidly.

In what populations does exponential growth tend to occur? populations that experience high rates of predation populations that have surpassed their carrying capacity populations that colonize new habitats populations that experience intense competition

populations that colonize new habitats

Which of the following are important biotic factors that can affect the structure and organization of biological communities? light intensity, seasonality predation, competition temperature, water precipitation, wind nutrient availability, soil pH

predation, competition

Keystone predators can maintain species diversity in a community if they _____. competitively exclude other predators allow immigration of other predators prey only on the least abundant species in the community reduce the number of disruptions in the community prey on the community's dominant species

prey on the community's dominant species

A cow eating grass is an example of a _____. primary consumer producer secondary consumer tertiary consumer detritivore

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

In an ecosystem, phytoplankton are _____. secondary consumers tertiary consumers producers detritivores primary consumers

producers Autotrophs, such as phytoplankton, are producers.

What is the most effective way to preserve species diversity? genetic restoration protect an entire area from exploitation seed banks wildlife corridors

protect an entire area from exploitation Correct. This is the most effective technique for protecting diversity.

Carbon dioxide functions as a greenhouse gas because it _____. reflects heat radiated from the Earth back toward the Earth the way the glass of a greenhouse reflects heat creates moist, humid environments similar to a greenhouse makes tropical plants grow more rapidly than normal just like in a greenhouse (eventually) makes plants grow year-round just like in a greenhouse

reflects heat radiated from the Earth back toward the Earth the way the glass of a greenhouse reflects heat Correct. Carbon dioxide allows visible light to pass but partially blocks heat.

When a human eats a steak, the human is acting as a _____. secondary consumer primary consumer producer detritivore tertiary consumer

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

A human who just ate a hamburger is eaten by a shark while swimming. The shark is acting as a _____. producer detritivore tertiary consumer secondary consumer primary consumer

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

What pattern do ecologists describe when referring to the latitudinal gradient? the frequent trend for there to be more species in communities at higher latitudes niche separation versus niche overlap the frequent trend for there to be more species in communities at lower latitudes the productivity of a community in kilograms of biomass per hectare

the frequent trend for there to be more species in communities at lower latitudes Correct. Birds, mammals, fish, reptiles, many invertebrates, and trees show this trend.

What best explains hare and lynx population cycles? natural variation in the number of lynxes born the population density of hares the seasonal trends in food availability the interaction of food availability and predation intensity

the interaction of food availability and predation intensity Correct. Predation limits hare population growth, but food availability is also important.

Carrying capacity is _____. seldom reached by marine producers and consumers because of the vast resources of the ocean the term used to describe the stress a population undergoes due to limited resources fixed for most species over most of their range most of the time determined by density and dispersion data the maximum population size that a particular environment can support

the maximum population size that a particular environment can support

Succession in an ecological context refers to _______. the predictable sequence of changes in species composition over time within the community after a disturbance what happens to the evolution of species as a result of the coevolutionary arms race the sequence of changes that a species goes through during its occupancy within a community the predictable series of changes in a community as species evolve and become extinct

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

Succession in an ecological context refers to _______. what happens to the evolution of species as a result of the coevolutionary arms race the sequence of changes that a species goes through during its occupancy within a community the predictable series of changes in a community as species evolve and become extinct the predictable sequence of changes in species composition over time within the community after a disturbance

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

Although extinction is a natural process, current extinctions are of concern to environmentalists because _____. the rate of extinction is higher than background extinction rates more animals than ever before are going extinct current extinction is primarily affecting plant diversity most current extinctions are caused by introduced species

the rate of extinction is higher than background extinction rates

Which habitats are the most productive? the combined boreal and temperate forests the tropical rain forests and coral reefs the combination of wetlands, estuaries, and deserts the open ocean

the tropical rain forests and coral reefs Correct. Productivity declines with increasing latitude.

The feeding relationships among the species in a community determine the community's _____. species richness secondary succession ecological niche species-area curve trophic structure

trophic structure

The main goal of sustainable development is to _____. involve more countries in conservation efforts use only natural resources in the construction of new buildings use natural resources such that they do not decline over time reevaluating and re-implementing management plans over time

use natural resources such that they do not decline over time