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Environmental Science Unit 3 Exam

Terms in this set (25)

Which definition best describes a biome?
a large geographical area identifiable by its climate and the organisms living there

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What conditions must be present for an ecosystem to exist?

Select all that apply.
variety of different organisms

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multiple interactions among organisms

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physical environment

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What are some biotic factors that can be found in any environment?

Select all that apply.
plants

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predators

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bacteria

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What abiotic factors are common to terrestrial, freshwater and marine ecosystems?

Select all that apply.
sunlight

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nutrients

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temperature

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Which factors will cause a change within an ecosystem?

Select all that apply.
entrance of a foreign organism

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lava flow from a volcanic eruption

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Which best describes how an ecosystem changes naturally?
Ecosystems change gradually over many years from rocks to grass and shrubs, eventually reaching a stable state, such as a forest. This occurs via a process of primary succession.

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What is the Sun's most important role in ecosystems?
The Sun provides all the energy for making food in ecosystems.

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What are trophic levels?

Select all that apply.
They show the location of organisms in an ecosystem within an ecological pyramid hierarchy. The trophic level at the pyramid's base consists of producers, followed by successive levels of consumers.

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They are hierarchical layers of organisms in an ecosystem. Each level groups organisms with similar roles in the system beginning with producers, then primary, secondary, and tertiary consumers.

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Which describes how energy transfers through trophic levels?
Energy moves through trophic levels from producers to consumers. The amount of energy decreases by about 90% from one level to the next.

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In an ecological pyramid, what organisms could be at the bottom and top of the pyramid, respectively?

Select all that apply.
An ecological pyramid could have plants at the bottom and foxes at the top.

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An ecological pyramid could have phytoplankton at the bottom and sharks at the top.

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An ecological pyramid could have grass at the bottom and humans at the top.

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In an ecosystem, which level of consumer feeds on producers?
primary

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Which phrase best describes diverse ecosystems?
ecosystems that have a high variation of many species in many different ecological roles

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How does the role of fungi compare in a terrestrial ecosystem versus a marine ecosystem?
Fungi function as decomposers in both terrestrial and marine ecosystems, breaking down decaying matter, causing the nutrients to be released for use by other organisms.

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Which are conditions necessary for competition within an ecosystem?

Select all that apply.
a limited supply of a mutually needed resource

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an interaction between species or within a species

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What are examples of a mutualistic relationship?
butterflies pollinating flowers

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How do the symbiotic relationships of commensalism, mutualism and parasitism compare based on the benefit or harm to the organisms involved?

Match the description to its name.
mutualism : both organisms benefit, while neither are harmed

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parasitism : one organism benefits, while the other is harmed

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commensalism : one organism benefits, while neither are harmed

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Which describes how feedback systems control an ecosystem?
Feedback systems affect changes to a disturbance in the system.

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What is positive feedback?
a change in a system that amplifies a previous change

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In a grassland ecosystem, an ample supply of grass causes an increase in the rabbit population. The rabbit population is, in turn, controlled by its predator, the fox.

What feedback mechanism is this an example of, and why?
negative feedback; each change that caused an increase led to another change that reversed the increase

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What type of system is an ecosystem and why?
Open system, because energy and matter can move in or out of the ecosystem.

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Which statement best describes how matter and energy move through an ecosystem?
Matter is recycled through the system, but only a small proportion of energy flows through.

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What describes a food web?
interconnected pathways that show how various organisms feed

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Consider a food chain given by the following symbols:

Which symbol would represent the herbivore in this chain?
https://assets.learnosity.com/organisations/625/asset/media/1238070

^ correct

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Consider the food web shown:

What is the likely effect of removing the kite on the population of both snakes and mice?
The population of snakes would increase and the population of mice would decrease.

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In the example shown of a food chain in an ecosystem, what percent of the Sun's energy is available to the caterpillar and the bird for food?
The caterpillar has approximately 10% of the Sun's energy available to it, and the bird has approximately 1% available to it.

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