Chapter 15

Which statement describes the critical distinction between arbuscular mycorrhizae and ectomycorrhizae?

Arbuscular mycorrhizae often grow farther into soil and involve more penetration into root cells

Acacia plants often have ants of the genus Pseudomymex associated with them. What benefit do the ants provide for the acacias?

Both A and B a) they limit herbivory by attacking potential herbivores b) they limit competition by removing other plants

The relationship between coral & algae is an example of a _____ association

Both A and B a)symbiotic b) mutualistic

Which of the following is an example of a facultative mutualism?

Desert ironwood serving as a nurse plant to many other species

For an ecological interaction to be a mutualism, the net benefits must

EXCEED the net costs for BOTH partners

Which statement about leaf-cutter ants is false?

Fungi-tending is a relatively recent innovation in ants (less than 3 million years old)

A seedling begins to grow very close a leaf-cutter ant colony. What are the costs and benefits of growing in that area?

The seedling might grow faster due to increased soil fertility around the colony

Which statement about symbiosis is true?

all mutualism & commensalism are cases of facilitation

A foundation of species in a commensalism

all of the above a) provides habitat for the other species b) enhances the survival of the other species c) is not impacted by other species

Which statement about the evolution of mutualisms and commensalism is true?

all of the above are true a) host-parasite relationship can evolve into commensalism b) host-parasite relationships can evolve into mutualisms c) parasites and hosts often coevolve

A bird species nests in a specific kind of tree. The tree is not harmed by the bird building its nest in the tree's branches, but the bird benefits from the shelter provided by the tree and is better able to successfully raise young. This is an example of

commensalism

According to the table, the relationship between the fungus and the fly in 1996 was a

commensalism

Suppose a salamander and a small tree are engaged in an ecological relationship in which only the salamander benefits, but the tree is not harmed. This relationship is a _____, and for the tree, it is______?

commensalism; facultative

A mycorrhizal-associated fungus grows between cells of the root of a plant, forming a mantle around the exterior of the root. This is an example of a(n)______ association.

ectomycorrhizal

When leaf-cutter ants encounter the parasitic fungus Escoyopsis, they

enlist help from other species

Grutter tested the effect of cleaner fish on species diversity in the Great Barrier Reef by

experimentally removing cleaner fish from certain reefs

Mutualism & commensalism are also called

facilitation

A fungus increases the ability of a plant to grow under high-salt conditions. For the plant, this association is a _______ mutualism

habitat

The international study conducted by Callaway and colleagues showed that the presence of neighboring plants often benefited the target plants at

high-elevation sites

According to the table, the relationship between the fungus and the fly in 1990 was a

host-parasite interactions

In the study by van der Heiiden and colleagues, the shoot biomass of the target plants was found to

increase at first and then LEVEL OFF as the number of mycorrhizal fungal species increased

From the act of pollinating flowers, a bee population gains the benefit of a 0.06 growth rate increase per month. However, the costs imposed by the flower (bees occasionally getting stuck, time spent pollinating the flower instead of pollination other species, etc) is a 0.02 reduction in growth rate per month. The flower gains benefits from the pollination that enhance its population growth rate by 0.05 per month, but it incus costs that reduce its growth rate by 0.05 per month. Which statement about the relationship between the bees and the flowers is true?

it is a commensalism

Janzen's studies of the ant-acacia system found that compared to plants with ant colonies, those without an associated ant colony weighed____ and were attacked by insect herbivores________.

less; more often

Pseudomyrmex ants that depend on acacias are _____ than species of the genus that are not associated with acacias.

more active and more aggressive

based on Grutter's studies, we can conclude that the presence of cleaner fish

reduces the parasite load of other fish

Because leaf-cutter ants and fungi help each other overcome plant defenses, the leaf-cutter ant-fungus mutualism can be described as a ______ mutualism.

service

Which criterion is most important in determining whether an ecological relationship is a symbiosis?

the degree of proximity between the two parties

Which statement about fig-fig wasp association is true?

these interactions show clear signs of coevolution

A bacterium provides essential amino acids to an aphid, which in turn provides sugars to the bacterium. Assuming that each partner is benefiting from the interaction, this would be an example of a ______ mutualism.

trophic

The studies by Pellmyr and Huth on yucca and yucca moths showed that

yucca plants impose penalties on moths that lay too many eggs

Al other factors being equal, which scenario is least likely to involve coevolution?

A FACULTATIVE INTERACTIOn in which the two parties are from different kingdoms

When did the relationship between the fungus and the fly first become a mutualism?

1999

Which statement about mutualism is true?

Mutualisms often impose costs on the partners

Which statement about mycorrhizae is true?

Mycorrhizae are symbiotic associations between plant roots & fungi

Which statement describes the most likely reason that a fish associated with a cleaner fish like Labroides dimidiates does not eat the cleaner fish, even when the cleaner fish is in its mouth?

The benefit the fish receives from the cleaner fish in parasite removal is greater than what it would gain by eating the cleaner fish