Mastering Ch. 54

An earthworm that feeds on the remains of plants and animals is acting as a ________.

detritivore (the earthworm is feeding on the remains of dead organisms)

According to the principal of competitive exclusion, two species cannot continue to occupy the same ________.

ecological niche (the competitive exclusions principal states that when the populations of two species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other species)

Which of the following best illustrates ecological succession?

grass grows on a sand dune, is replaced by shrubs, an then by trees (this illustrates the replacement of species as a community matures)

The term used to describe a harmless organism resembling a harmful one is ________.

Batesian mimicry (in Batesian mimicry, a palatable or harmless species mimics an unpalatable or harmful model)

Caribbean coral reef communities have been strongly influenced by an unknown pathogen that causes white-band diseases. How can the effect of white-band disease best be described?

a cascade event that shifts the entire makeup of the community (the removal of the corals shifts the food supply within the reef, resulting in a completely different species composition)

Which of these is a starting point for primary succession?

a surface exposed by a retreating glacier (such a surface lacks any life and is thus a starting point for primary succession)

An organism's "trophic level" refers to ________.

its food source (an organism's trophic level is determined by what it eats)

Cellulose-digesting microorganisms live in the guts of termites and ruminant mammals. The microorganisms have a home and food, and their hosts gain more nutrition from their meals. This relationship is an example of ________.

mutualism (the cellulose-digesting microorganisms have a home and place to live; the hosts get nutrients from the microorganism's breakdown of cellulose)

A cow eating grass is an example of a ________.

primary consumer (by feeding on the producer, the cow is acting as a primary consumer)

In an ecosystem, phytoplankton are ________.

producers (authotrophs, such as phytoplankton, are producers)

When a human eats a steak, the human is acting as a ________.

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 ________.

tertiary consumer (the shark that are the human that ate the cow that ate the grass is the tertiary consumer)

According to MacArthur and Wilson's hypothesis of island biogeography, species immigration and extinction rates on a particular island correlate to ________.

the island's size and distance from the mainland (both the island's size and its distance form the mainland correlate to how many individuals will colonize the island and the number of species it can support)

Keystone species are those species ________.

whose absence would cause major disruption in a community (a keystone species makes an unusually strong impact on community structure)