Week 9

What is the difference between a community and an ecosystem?

A community is the set of organisms that live in a given place. A community together with the physical environment in which the organisms live constitutes an ecosystem.

The sequence of species that colonize a recently disturbed area through succession is unpredictable. True False

False

What is the difference between competitive exclusion and resource partitioning?

In competitive exclusion, there is ongoing competition between two species for a particular resource, leading one to change its niche in the presence of the other. In resource partitioning, species evolve to use different resources, so there is no longer competition for that particular resource. Over time, competitive exclusion can lead to resource partitioning.

In the example of the giant kelp forests on the Pacific coast, a rise in the otter population would have what effect on the kelp populations? Kelp populations would increase due to a decrease in sea urchins. Kelp populations would be totally unaffected by the otter population. Kelp populations would decrease due to an increase in sea urchins. Kelp populations would decrease due to increased predation by otters. Kelp populations would increase due to an increase in sea urchins.

Kelp populations would increase due to a decrease in sea urchins.

What is generally true about biomass and energy as we move from one trophic level to the next? Biomass increases but energy decreases. All of the energy stored initially in organic molecules by the primary producers will be available to the secondary consumers. Organisms at one trophic level always consume all of the resources from the level below them. They both increase. Not all energy is transferred to the next trophic level.

Not all energy is transferred to the next trophic level.

Recall that during the Paleozoic Era, atmospheric CO2 levels decreased. Why? New, extensive mountain ranges formed and chemical weathering decreased. Photosynthetic, woody plants first appeared during this period. Volcanism decreased during this period. Earth's plate tectonics changed dramatically, and subduction increased.

Photosynthetic, woody plants first appeared during this period.

A gardener treats his plants with pesticides, killing any aphids. Once the aphids die, what likely happens to the mutualistic bacteria inhabiting their digestive tracts? The bacteria would likely die without their mutualistic aphids, as this is an example of a facultative relationship. The bacteria would contribute to the decomposition of dead aphids. The bacteria would migrate outside of the digestive tract, and survive on the leaves of garden plants. The bacteria would likely die without their mutualistic aphids, as this is an example of an obligate relationship.

The bacteria would likely die without their mutualistic aphids, as this is an example of an obligate relationship.

Niches are dynamic, and are affected by interactions among species. False True

True

Symbiotic relationships are subject to natural selection. False True

True

The fact that diverse types of Anolis lizards inhabit (or hunt in) different levels of the tree canopy is the result of the effects of resource partitioning. False True

True

The long-term and short-term carbon cycles are connected by the fact that some of the carbon contained in C6H12O6 (or other organic molecules) in plants is incorporated into sedimentary rocks or oil; it is not immediately reintroduced back into the atmosphere. True False

True

While food chains show linear energy transfer between organisms, food webs depict more realistically what occurs in an ecosystem. True False

True

Which factors contribute MOST to intraspecific competition? predation and parasitism mutualistic relationships a species' rate of reproduction and the carrying capacity of the environment a species' fundamental niche and abiotic surroundings population size

a species' rate of reproduction and the carrying capacity of the environment

When two species compete for resources, the fitness of: only the poor competitor will decrease. both species will decline. only the better competitor will increase. both competitors will remain the same.

both species will decline.

A species that is involved in a facultative mutualism with another: should quickly develop adaptations in direct response to the other species. can only interact with that particular species. is reliant on the relationship for survival. can utilize a variety of different resources.

can utilize a variety of different resources. (opposite of obligate, one can survive without other)

When both participants in a species interaction develop adaptations in direct response to one another, in the long term this could progress into: extinction of one species. intraspecific competition. competitive exclusion. coevolution. resource partitioning.

coevolution

The sum total of the populations that live in a given area is called a(n): habitat. interaction. community. ecosystem.

community

Which of the following is a type of interaction in which BOTH parties are harmed?

competition

Benefits associated with symbiotic relationships might include all of the following EXCEPT: nutrients. shelter. protection. competitive exclusion. assistance in reproduction.

competitive exclusion

Which group in a food web is responsible for returning inorganic compounds back to the environment? decomposers secondary consumers tertiary consumers primary producers primary consumers

decomposers

You decide to plant a garden in your backyard. You dig up a strip of grass in a sunny spot. When you have finished digging up the grass, but you haven't planted anything, you have created a(an) _____ in the lawn. new community ecological disturbance None of the answer options is correct. ecological disturbance and a new community

ecological disturbance

A(n) _____ is a community of organisms and the physical environment it occupies. ecosystem interaction community metapopulation population

ecosystem

Keystone species can have significant influences over several populations in a community through their: roles as prey species for predator populations in the community. avoidance of antagonistic interactions. ability to leave their environment relatively unchanged. effect on high amounts of biomass and energy transfer between populations. large body sizes.

effect on high amounts of biomass and energy transfer between populations.

Increased rate of photosynthesis is the most likely explanation as to why atmospheric CO2 levels appear lowest during glacial periods of Earth's history. False True

false

The rate of exchange of carbon between the atmosphere and the oceans represents a carbon: precipitation. biomass. sink. reservoir. flux.

flux

A _____ depicts the flow of carbon through an ecosystem, whereas a _____ depicts the transfer of energy. food web; niche niche; food web trophic pyramid, food web food web; trophic pyramid

food web; trophic pyramid

Imagine that a scientist takes a group of Anolis lizards and introduces them into an enclosure at a research facility in continental South America. He notes that the lizards thrive in this new environment. The fact that Anolis lizards could survive in habitats outside of the Caribbean is a reflection of their _____ niche; their _____ niche is determined by predation and resource availability.

fundamental; realized

A species that has a disproportionately large effect on a community is called a _____ species. central engineer producer linchpin keystone

keystone

The _____ cycle deals with geological processes and carbon reservoirs, some of which have been built up (or take place) over a period of millennia. In contrast, the _____ cycle involves biological processes that are carried out on a daily and/or seasonal basis. long-term carbon; intermediate carbon short-term carbon; rapid carbon long-term carbon; short-term carbon short-term carbon; long-term carbon

long-term carbon; short-term carbon

. A mutualism in which the survival of one or both participants is dependent on the other is: parasitic. competitive. facultative. obligate. antagonistic.

obligate

While biodiversity includes the number of species in a given area, it also includes: overall number of trophic levels in a food web. abiotic factors that define the community. amount of primary productivity. unique phylogenetic lineages.

phylogenetic lineages

Which of the following is a good predictor of biodiversity in terrestrial ecosystems? plant species in a community prey species in a community pollinator species in a community predator species in a community

plant species in a community

Measuring its costs and benefits in terms of energy spent and/or gained, which interaction(s) involve(s) one individual gaining and one individual losing?

predation

The broadest level in a trophic pyramid is primarily composed of: tertiary consumers. secondary consumers. primary consumers. primary producers.

primary producers

Organisms that take up inorganic nutrients and convert them to organic molecules such as carbohydrates and proteins are called: predators. herbivores. consumers. primary producers. heterotrophs.

primary producers.

The _____ of a species is usually the result of predation, competition, and other types of interaction between species. abiotic environment resource partitioning habitat realized niche fundamental niche

realized niche

Overlap of niches can be minimized through: reduction in the size of the fundamental niche. species evolving similar adaptations over time. increased population growth. an increase in the similarity of species occupying an area. resource partitioning.

resource partitioning

Which of the following is expected to reduce competition among individuals? resource partitioning destruction of habitat space a decrease in the carrying capacity of an environment the disappearance of a predator from an area a shortened mating season

resource partitioning

Measuring its costs and benefits in terms of energy spent and/or gained, mutualism: is a lose-lose interaction. None of the answer options is correct. results in a gain for one individual and neither a gain nor a loss for the other. results in gain for both individuals. results in a gain for one individual and a loss for the other.

results in gain for both individuals.

Following a disturbance, the process by which species replace each other over time is/are called: keystone species. succession. competition. ecosystem engineers. disturbances.

succession

Close interactions that have evolved over time between species are called: metapopulations. niches. symbioses. interspecific competition. resource partitioning.

symbioses

Energy flow through ecosystems can be depicted using a(n): ecosystem. trophic pyramid. food web. Calvin cycle. food chain

trophic pyramid