Question 1

The relationship between Merriam's kangaroo rats and large-seeded native bunchgrasses in southern Arizona demonstrates that

Accepted Answer

The relationship between Merriam's kangaroo rats and large-seeded native bunchgrasses in southern Arizona highlights that changes in environmental conditions may alter the nature of interspecific relationships. The kangaroo rats were initially thought to be seed predators of the bunchgrasses, but later research revealed that they were actually seed dispersers, which benefited the bunchgrasses. However, this relationship was dependent on certain environmental conditions, such as the presence of rodent burrows and low levels of grazing pressure. When these conditions were altered, the relationship between the kangaroo rats and bunchgrasses changed as well.

Question 2

Tree sloths feed on leaves and buds,which are digested by bacteria that inhabit the sloth's large stomach.While in a tree,the sloth is difficult for predators to find because it is tinted green from the cyanobacteria that live in its fur.A variety of nonbiting insects also live in the fur,but they appear to have no effect on the sloth.Based on this information,one can say that the sloth has mutualistic interactions with the _______ and the _______.

Accepted Answer

The sloth has a mutualistic relationship with the digestive bacteria, which help it digest its food, and the cyanobacteria, which provide camouflage.

Question 3

The relationship between a zebra and the lion that eats it is an example of what kind of interaction?

Accepted Answer

The relationship between a zebra and a lion that eats it is an example of consumer-resource interaction, where the lion (consumer) feeds on the zebra (resource) for energy and nutrients. It is not an example of competition, mutualism, amensalism, or commensalism.

Question 4

The fecal matter from giraffes helps fertilize a particular species of plant,thus increasing the plant's ability to grow in a particular area.The plant has no effect on giraffes.The relationship between the giraffes and the plants is best described as

Accepted Answer

The relationship between the giraffes and the plants is commensalism as the giraffes have no effect on the plant, but the plant benefits from the fecal matter of the giraffes.

Question 5

Although most herbivory involves an antagonistic interaction (i.e. ,one species benefits,the other is harmed),some herbivorous interactions do not.Which example is least likely to be an antagonistic interaction?

Accepted Answer

Bears eating blueberries and defecating the seeds throughout the forest is an example of mutualism, as the bear benefits from the food source and the blueberry plant benefits from the seed dispersal. The other options all involve some degree of harm or damage to the plant, making them antagonistic interactions.

Question 6

A moth and a beetle both lay eggs on the same species of plant and the larvae of both develop on the plant.Removal experiments show that the moth and the beetle each perform less well on the plant when the other species is removed.The relationship between the moth and the beetle is best described as

Accepted Answer

The relationship between the moth and the beetle is mutualism because both species benefit from the presence of the other. The removal experiments show that the presence of the other species increases the performance of each species on the plant, indicating a mutually beneficial relationship.

Question 7

A cow's rumen,or first stomach,provides the ideal environment for a variety of microbes.When a cow consumes grass,these microbes digest the grass,releasing nutrients both for their own and for the cow's use.While most of the microbes continue to live in the rumen,some of them are killed during the digestive process and provide additional nutrition for the cow.This complex relationship between the cow and her microbes has features of which two categories of interactions?

Accepted Answer

The relationship described between the cow and the microbes in its rumen exhibits qualities of mutualism (both the cow and microbes benefit from the relationship) and predation (some of the microbes are killed during digestion, providing additional nutrition for the cow).

Question 8

In what way does amensalism differ from commensalism?

Accepted Answer

In amensalism, one species is negatively affected while the other is unaffected. In commensalism, one species benefits while the other is unaffected.

Question 9

Which relationship does not involve negative effects for at least one of the species in the interaction?

Accepted Answer

Commensalism is a type of relationship where one species benefits without affecting the other species in any way, therefore there are no negative effects for any of the species involved.

Question 10

A bacterium that infects a fly causes it harm and is completely dependent on the fly for survival and reproduction.Over time,however,adaptations by both the fly and the bacterium decrease the negative effects of the bacterium on the fly.We can thus say that the relationship has evolved from parasitism toward

Accepted Answer

The relationship has evolved from parasitism to commensalism, where the bacterium benefits while the fly is neither harmed nor helped.

Question 11

Which example is a mutualistic interaction?

Accepted Answer

In a mutualistic interaction, both species benefit. In this case, the bacterial species provides usable nitrogen to the plant, which benefits the plant by allowing it to grow more effectively. In turn, the plant provides sugar nutrients to the bacteria, which benefits the bacteria.

Question 12

Two species of plants that are competitors in nature are grown together in the greenhouse.When they are fed additional nitrogen,species A thrives at the expense of species B.When they are fed additional phosphorus,species B thrives at the expense of species A.Increasing the concentration of carbon dioxide has no effect on either species.Both species show improved growth when they are given additional sunlight,but additional moisture has little effect on either one.Based on this information,which resource is most likely to be limiting for both species?

Accepted Answer

Both species show improved growth when given additional sunlight, indicating that sunlight is the limiting resource for both species.

Question 13

Amensalism does not show the same types of ecological and evolutionary dynamics as competition,consumer‒resource interactions,and mutualism.The reason is that amensalism

Accepted Answer

Amensalism involves only one species being harmed by the other, whereas other ecological interactions like competition, consumer-resource interactions, and mutualism involve at least two species interacting with each other. Therefore, amensalism does not show the same types of ecological and evolutionary dynamics as the other interactions.

Question 14

Leaf-cutter ants originated in

Accepted Answer

Leaf-cutter ants can only be found in Central and South America, making it most likely that they originated in South America.

Question 15

While pursuing prey,a bear smashes into and destroys a bush,and then continues pursuing its prey.The relationship between the bear and the bush would be described as

Accepted Answer

In amensalism, one species is negatively affected (in this case, the bush is destroyed) without having any effect on the other species (the bear). The bear is not benefiting or harming the bush, but the destruction of the bush is a result of the bear's pursuit of prey.

Question 16

Leaf-cutter ants that tend fungal gardens protect their crop from mold by means of

Accepted Answer

Leaf-cutter ants have a mutualistic relationship with a bacterium that produces antibiotics to protect their fungal gardens from mold.

Question 17

Which relationship is not a consumer-resource interaction?

Accepted Answer

Competition is an interaction between two or more organisms using the same resource, but it does not involve consumption of one organism by another.

Question 18

Which type of interaction is typically random and brief?

Accepted Answer

The answer of Which type of interaction is typically random...

Question 19

Which interspecific interaction has negative effects for both species involved?

Accepted Answer

In competition, both species are negatively affected as they are competing for limited resources.

Question 20

Two species of beetles are both herbivores on the same host plant,and the presence of either beetle species reduces the population growth of the other.The relationship between these beetles is best described as

Accepted Answer

The fact that the presence of either beetle species reduces the population growth of the other indicates that they are competing for the same resources (the host plant). This relationship is best described as competition.

Quiz 43: Ecological and Evolutionary Consequences of Interactions Within and Among Species