Chapter 41 HW

A human eats a deer. Which of these terms applies to the relationship between the human and the deer?

predation

(The human is the predator and the deer is the prey)

Humans and sharks both eat fish. Which of these terms applies to the relationship between the human and the shark?

competition

(The human and the shark are both competing for a resource (fish).)

Humans who have pets tend to be healthier than humans who do not have pets. Which of these terms applies to the relationship between a human and a pet?

mutualism

(In mutualism, both members of the species pair benefit; in this case the human is healthier and the pet is getting room and board.)

Which of these terms applies to the relationship between a dog and a blood-sucking tick?

parasitism

(The tick benefits at the expense of the dog; the dog is the host and the tick is the parasite.)

An egret eats insects stirred up by grazing animals. Which of these terms applies to the relationship between the egret and the grazing animal?

commensalism

(In commensalism, one member of the species pair benefits and the other is unaffected; in this case the egret is getting a meal and the grazing animals are unaffected.)

According to the principle of competitive exclusion, two species cannot continue to occupy the same _____.

ecological niche

(The competitive exclusion principle 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.)

Of the choices below, which best describes the effect predation has on the predator/prey organisms involved in the relationship?

benefit ... harmed

(The predator eats (a benefit), and the prey is eaten (a harm).)

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.)

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)

In an ecosystem, phytoplankton are _____.

producers

(Autotrophs, such as phytoplankton, are producers.)

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.)

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 cow eating grass is an example of a _____.

primary consumer

(By feeding on a producer, the cow is acting as a primary 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 ate the human that ate the cow that ate the grass is the tertiary consumer.)

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

its food source

(An organism's trophic level is determined by what it eats.)

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.)

Which of the following best illustrates ecological succession?

Grass grows on a sand dune, is replaced by shrubs, and then by trees

(This illustrates the replacement of species as a community matures.)

Which of the following statements is in accordance with F. E. Clements’ view that species in a community function as an integrated unit?

A community at a particular site has only one stable equilibrium

(According to Clements’ view, biotic interactions cause the species in a community to function as an integrated unit--in effect, a superorganism--with only one stable equilibrium.)

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 from the mainland correlate to how many individuals will colonize the island and the number of species it can support.)

Caribbean coral reef communities have been strongly influenced by an unknown pathogen that causes white-band disease. 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.)

What is directional selection?

type of natural selection where one extreme phenotype is favored over others, leading to a shift in the population's trait distribution towards that extreme

What is disruptive selection?

a type of natural selection where extreme traits are favored over intermediate traits, leading to increased phenotypic and genetic variation within a population

What is stabilizing selection?

a type of natural selection that favors intermediate phenotypes (or traits) and selects against extreme variations, leading to a narrowing of the range of phenotypes in a population