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20: Communities and Ecosystems
This activity contains 56 questions.
In the United States, _____ of all prescriptions contain substances derived from plants.
Genetic diversity refers to variation in __________.
numbers of certain nucleotide bases
numbers of chromosomes within a population
the quality of mutations
alleles within a population
numbers of genes
At the current rate of extinction, some scientists predict that _____ of all animal and plant species will be extinct by the year 2100.
Biodiversity includes genetic diversity, species diversity, and _____.
One of the major contributors to extinction of species today is __________.
thinning of the ozone layer
the greenhouse effect
Which of the following factors is most likely to lead to decreased biodiversity?
complex population interactions
the introduction of invasive species
a higher degree of habitat heterogeneity
increased energy availability
When goats were introduced to an island off the California coast, the goats lived in the same areas and ate the same plants as the native deer. The deer population dwindled and finally disappeared. This is an example of _____.
a food chain
The niche of an animal is __________.
its position in the food chain
the number of individuals of the species the environment will support
the way the animal fits into its environment
its den or nest
the same as its habitat
Two species of cuckoo doves live in a group of islands off the coast of New Guinea. Of 33 islands, 14 have one species, 6 have the other, 13 have neither, and none has both. What might best explain this? The two species of birds could __________.
have similar niches
be on different trophic levels
be keystone predators
have a mutualistic relationship
have different niches
If the niches of two species are very similar, which one of the following is true?
A mutualistic relationship will exist.
Competition between the two species will be severe.
The two species are mutually interdependent.
Carrying capacity will be exceeded for both.
Interspecific competition will be mild.
What type of population interaction benefits neither population?
Flounder look like the sea floor. This is an example of _____.
Which of the following is an example of mimicry?
A harmless frog resembles a poisonous frog.
The mottled pattern on a fish looks like dead leaves on the bottom of a pond.
An insect's bright colors warn a predator that it tastes bad.
Two species of mice live in the same area and eat the same kinds of seeds.
Both kangaroo rats and jackrabbits hop erratically when escaping from predators.
A tick has what type of relationship with a dog?
The bee fly resembles a honeybee, but the bee fly has no stinger. This is an example of _____.
A lichen is actually composed of two organisms: a fungus and an alga. They depend on each other for survival. The most specific term that describes their relationship is _____.
Certain species of acacia trees in Central and South America have hollow thorns that house stinging ants, which attack anything that touches the tree. The ants feed on nutrients produced by the acacias. This is an example of _____.
Why does biological magnification occur?
Because the amount of organic material in individual organisms decreases with increasing trophic level, their bodies contain a higher concentration of the toxin.
Because the amount of organic material of individual organisms increases with increasing trophic level, their bodies contain more of the toxin.
As the amount of organic material increases with increasing trophic level, the amount of toxin also increases.
Although the amount of organic material decreases with increasing trophic level, the amount of toxin remains the same.
As the amount of organic material decreases with increasing trophic level, the amount of toxin also decreases.
The main detritivores in an ecosystem are _____.
plants and animals
fungi and prokaryotes
prokaryotes and animals
prokaryotes and plants
plants and fungi
Herbivores are _____.
Which of the following is a producer?
When you eat an apple, you are a _____.
Consider this segment of a food web: Snails and grasshoppers eat pepper plants; spiders eat grasshoppers; shrews eat snails and spiders; owls eat shrews. The snail occupies the trophic level(s) of __________.
a tertiary consumer
primary and secondary consumers
a secondary consumer
a primary consumer
secondary and tertiary consumers
Which of the following must be considered to determine the species diversity of a community?
the number of each type of plant species in a community
both species richness and relative abundance
whether competitive exclusion has taken place
the number of different plant species found in a community
the time of year when a bird species mates and the location of their nests
Which of the following would be considered a "small-scale" disturbance?
a 100-year-old oak tree falling down
Which of the following best illustrates ecological succession?
Imported pheasants increase, while local quail disappear.
Decomposition in soil releases nitrogen that plants can use.
Overgrazing causes a loss of nutrients from soil.
A mouse eats seeds, and an owl eats the mouse.
Grass grows on a sand dune, then shrubs, and then trees.
In an ecosystem, almost all of the incoming energy will eventually be __________.
transferred to the decomposers
used in photosynthesis
transferred to producers
transferred from one trophic level to the next
radiated from Earth as heat energy
The biggest difference between the flow of energy and the flow of chemical nutrients in an ecosystem is that __________.
organisms always need nutrients, but they don't always need energy
nutrients are recycled, but energy is not
energy is recycled, but nutrients are not
the amount of energy is much greater than the amount of nutrients
organisms always need energy, but they don't always need nutrients
Most of the solar energy that reaches Earth __________.
is continually recycled by ecosystems
is used by plants for photosynthesis
is trapped by greenhouse gases
is not captured for use by living things
Which one of the following best describes the base of an energy pyramid?
It receives energy from the primary, secondary, and tertiary consumers.
It represents the energy available to secondary consumers.
It contains the energy left after the producers have died.
Its size depends on the energy available from detritivores.
It contains the energy captured by photosynthesis.
In any food chain, the top level of consumers is quaternary (fourth). Why are there almost never any fifth-level consumers?
The fourth-level consumers are already occupying the best territories.
Quaternary consumers are too large and fierce to be prey for other animals.
There is not enough available energy to sustain a fifth level.
Consumers tend to eat a broad variety of prey, and so we have food webs rather than food chains.
The force of gravity prevents the evolution of such large animals.
In ecosystems, organisms at the highest trophic levels usually contain less collective biomass than the organisms at lower trophic levels because __________.
top-level predators use so much energy to catch their food
biomass shrinks as it rises
producers (for example, plants) tend to be heavier than consumers (for example, birds)
organisms are inefficient at converting the energy they consume to biomass
most of the solar energy hitting Earth is reflected or re-radiated into space
Why is a diagram of energy flow from trophic level to trophic level shaped like a pyramid?
Organisms at each level store most of the energy and pass little on.
Organisms eventually die as they get older.
There are more producers than primary consumers, and so on.
Most energy at each level is lost, leaving little for the next.
Secondary consumers are larger than primary consumers, and so on.
The relationship between biomass and primary productivity is that __________.
biomass is the rate of primary productivity
biomass is the inverse of primary productivity
primary productivity is the inverse of biomass
biomass is the natural log of primary productivity
primary productivity is the rate at which biomass is produced
In an ecosystem, the __________ is always greater than the __________.
number of producers ... number of primary consumers
biomass of producers ... biomass of primary consumers
biomass of secondary consumers ... biomass of producers
energy used by primary consumers ... energy used by secondary consumers
energy used by primary consumers ... energy used by producers
In general, the biomass in an ecosystem will be greatest at the trophic level comprising _____.
Phosphate pollution of lakes and rivers __________
is a symptom of global warming
occurs because of biological magnification
occurs due to human impact on the carbon cycle
can result in high growth rates of fish in lakes
can cause algal blooms that can kill most aerobic organisms in a lake
Local conditions such as heavy rainfall or the removal of plants may limit the amount of nitrogen, phosphorus, or calcium available to a particular ecosystem, but the amount of carbon available to the system is seldom a problem. Why?
Many nutrients come from the soil, but carbon comes from the air.
Plants can make their own carbon using water and sunlight.
Symbiotic bacteria help plants capture carbon.
Plants are much better at absorbing carbon from the soil.
Organisms do not need very much carbon.
Which of the following is a component of the carbon cycle?
return of CO
to the atmosphere by animal and plant respiration
the functioning of carbon-fixing bacteria in the soil
weathering of rocks to release mineral phosphate
precipitation and transpiration
assimilation of nitrates by plants
In the global carbon cycle, carbon flows from consumers to producers in the form of _____.
Which one of the following refers to the nitrogen cycle?
Atmospheric nitrogen is taken in by plants via diffusion.
Nitrates are converted to ammonium by nitrifying bacteria.
Nitrogen is found predominantly in abiotic reservoirs such as rocks.
It requires different types of bacteria at various stages.
Nitrogen is a component of all carbohydrates.
Bacteria are especially important in making _____ available to plants.
The major source of nitrogen for most nonagricultural plants is __________.
ammonium in the soil
gas in the air
nitrates in the soil
Atmospheric nitrogen (N
) is replenished through the process of _____ by _____.
decomposition ... fungi and bacteria
erosion ... water
denitrification ... bacteria
nitrogen fixation ... bacteria
nitrification ... bacteria
Nitrogen gas makes up nearly 80% of Earth's atmosphere, yet nitrogen is often a limiting factor for plant growth. Why?
The atmospheric form of nitrogen cannot be used by plants.
Plants use nitrogen faster than it can be recycled back into the atmosphere.
Plants must absorb nitrogen through their roots, which are not in contact with the atmosphere.
Atmospheric nitrogen dissolves readily in the soil but is washed out with every rainfall.
Nitrifying bacteria remove usable nitrogen from the soil more rapidly than plants can absorb it.
The phosphorus cycle lacks a(n) _____ component.
organic and gaseous
Species found in only one place on Earth are _____ species.
Of the lemurs found on Madagascar, _____ are endemic to the island.
Regions with high concentrations of species, especially species that are endangered or threatened, are referred to as _____.
biodiversity hot spots
Hot spots such as rain forests and dry shrublands, which make up less than _____ of Earth's land surface, are home to about _____ of all plant and vertebrate species.
15% ... 50%
1.5% ... 33%
5% ... 25%
10% ... 25%
10% ... 50%
An assemblage of interacting ecosystems makes up a _____.
Forest fragmentation __________.
results in a total loss of biodiversity
has no effect on biodiversity
is a good conservation biology strategy
Bioremediation is the __________.
use of biological agents for warfare
use of living organisms to clean a polluted environment
use of natural substances to cure diseases
increasing of fitness of certain organisms
greening of communities
Sustainable development __________.
is practiced in most industrial countries
is a top priority of most nations
is practiced in most industrial countries and is a top priority of most nations
places the emphasis on improving ecosystems and may be detrimental to human needs
focuses on the long-term prosperity of humans and the biosphere
Biophilia is __________.
the increasing of fitness of certain organisms
practiced in most industrial countries and is a top priority of most nations
the greening of communities
a love of life
the use of biological agents for warfare
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