Question 1

The association between bees and flowering plants is a well-known mutualism. What benefit do bees provide flowering plants?

Accepted Answer

Bees play a crucial role in pollination, transferring pollen from the male reproductive parts of one flower to the female reproductive parts of another flower, which allows plants to produce fruits and seeds. This increases genetic diversity and helps plants to reproduce more effectively, which is crucial for the survival of many plant species.

Question 2

Whitebark pine seeds are dispersed through a mutualism with Clark's nutcracker birds. If Clark's nutcracker went extinct, what is the most likely immediate outcome for pines?

Accepted Answer

Without Clark's nutcracker birds to disperse their seeds, whitebark pine seeds would likely fall and germinate close to the parent trees, leading to increased competition between seedlings and their parents for resources.

Question 3

Which of the following situations is/are likely to cause a mutualistic relationship to change to a parasitic or predatory relationship?
I. A damselfish has no parasites for a cleaner fish to eat.
II. Acacia plants provide nectar to ants living in their thorns.
III. A plant and its mycorrhizal fungi are living in nutrient-rich soil.

Accepted Answer

In mutualistic relationships, both organisms benefit from the interaction. However, if one organism no longer benefits or the relationship becomes one-sided, it can lead to a shift towards parasitism or predation. In the case of the damselfish and cleaner fish, if there are no parasites for the cleaner fish to eat, it may start feeding on the mucus or even the scales of the damselfish, leading to a parasitic relationship. The other scenarios, such as the acacia plant and ant interaction providing nectar to the ants or a plant and its mycorrhizal fungi living in nutrient-rich soil, are mutually beneficial and are unlikely to shift towards parasitism or predation.

Question 4

Which of the plots would be consistent with cleaner fish switching from a mutualistic to a parasitic relationship with damselfish when the cleaner fish does not obtain fitness benefits?

Accepted Answer

Panel c shows a mutualistic relationship between cleaner fish and damselfish where the cleaner fish obtains fitness benefits by removing ectoparasites from the damselfish. In panel d, the cleaner fish switches to a parasitic relationship where it no longer provides cleaning services and instead feeds on the mucus and tissue of the damselfish, resulting in negative fitness effects for the damselfish. Panels a and b do not show a shift in relationship from mutualistic to parasitic.

Question 5

In the interaction between yucca plants and yucca moths, yucca moths pollinate flowers and lay eggs in the flowers. If many eggs are laid in a flower, the yucca moth caterpillar will eat all the seeds. Explain why the relationship is considered a mutualism, even though the caterpillars eat the seeds. Be sure to discuss how both the yucca and yucca moth gain fitness benefits from this interaction.

Accepted Answer

The answer of In the interaction between yucca plants and...

Question 6

Oxpeckers are African birds that fly around large mammals and pick at both ticks and wounds on the animals. Scientists have debated whether oxpeckers are parasites or mutualists with large mammals. Draw bar graphs in the blank figures to show the relationships if oxpeckers are mutualists with large mammals. Plot a should show the abundance of ticks on large mammals in two conditions: if oxpeckers are present and if oxpeckers are absent. Plot b should show the number of offspring produced by oxpeckers if they are nesting near mammals with many ticks or nesting near mammals with few ticks. Explain why your drawings are consistent with mutualism.

Accepted Answer

The answer of Oxpeckers are African birds that fly around...

Question 7

Many animals disperse seeds away from parent plants. What benefits do animals gain from this mutualism? Give a specific example.

Accepted Answer

The answer of Many animals disperse seeds away from parent...

Question 8

What benefit do mammals and birds provide to a plant when they eat its fruit?

Accepted Answer

Mammals and birds provide a benefit to plants by consuming their fruits and dispersing the seeds to new areas. This enables the plants to colonize new areas and avoid competition with other members of the same species.

Question 9

The seeds of plants are moved to new areas by many animals, including birds, mammals, and insects. What benefit do animals gain from the plant in this mutualism?

Accepted Answer

Animals gain food from plants in this mutualism. As they transport the seeds of plants to new areas, they may eat parts of the plant or the fruit, providing them with nourishment. This benefits the plant as well, as it allows for wider dispersal and helps ensure their continued survival.

Question 10

You are studying a plant species that has a fungus growing in its roots. You remove the fungus and evaluate what happens to the plant. Which outcome indicates a mutualistic relationship?

Accepted Answer

A mutualistic relationship is one where both organisms benefit. If removing the fungus makes the plant less toxic to herbivores, it suggests that the fungus was helping the plant deter herbivores, benefiting the plant.

Question 11

A group of biologists are studying an interaction between coral and three species of crab (crab 1, crab 2, and crab 3). They discover that all three species of crab benefit from the coral by feeding on lipid-rich coral mucus. They conduct an experiment in which they remove each species of crab from the coral and then measure the extent to which the coral were overgrown by noxious algae. Based on the data in the figure, explain whether or not each of the three crab species is a mutualist with coral.

Accepted Answer

The answer of A group of biologists are studying an...

Question 12

The yucca moth

Accepted Answer

The yucca moth is known for its unique symbiotic relationship with the yucca plant. The moth helps to pollinate the yucca flowers by laying eggs in the flowers and transferring pollen at the same time. In return, the yucca plant provides a home for the moth's larvae to grow and develop.

Question 13

Yucca moths typically lay about six eggs in a yucca flower. If a biologist were to experimentally add 12 moth eggs to a yucca flower, what would be the most likely result?

Accepted Answer

Yucca moths have a mutualistic relationship with yucca plants, in which the moth pollinates the flower while laying its eggs in the flower's ovules. However, if too many eggs are laid in a flower, the plant can selectively abort that flower to prevent damage to its reproductive success. Therefore, the most likely result of adding 12 moth eggs to a yucca flower would be that the plant would selectively abort that flower.

Question 14

In the interaction between damselfish and cleaner fish, if a damselfish has few parasites, the cleaner fish will

Accepted Answer

Cleaner fish, when interacting with damselfish that have few parasites, may feed on the mucus or scales of the damselfish instead of removing parasites, as their primary food source (the parasites) is scarce. This behavior is a form of cheating in the mutualistic relationship where the cleaner fish typically eat parasites off the host fish.

Question 15

The association between bees and flowering plants is a well-known mutualism. What benefit do flowers provide bees?

Accepted Answer

Flowers provide bees with the nectar and pollen that they need for nutrition, making it the most important benefit that flowers offer to bees.

Question 16

(Figure 17.15) This figure indicates that yucca plants

Accepted Answer

The answer of  (Figure 17.15) This figure indicates that...

Question 17

Imagine that an acacia tree in the ant-plant mutualism is introduced to an island without ants. Over evolutionary time, natural selection from the lack of ants would probably lead to acacia trees that produce

Accepted Answer

The presence of ants in the ant-plant mutualism results in the ants protecting the acacia tree from herbivores, thereby decreasing the need for the tree to produce large amounts of nectar to attract ants. Therefore, in the absence of ants, natural selection would likely favor acacia trees that produce less nectar, as there is no longer a selective pressure to produce large quantities of nectar for ant protection.

Question 18

Which of the following statements about the mutualism between the yucca plant and the yucca moth is/are accurate?
I. This is an obligate mutualism.
II. Yucca moth caterpillars eat yucca seeds.
III. Yucca moths pollinate yucca flowers.

Accepted Answer

The mutualism between the yucca plant and the yucca moth is obligate, meaning both species depend on each other for survival. Yucca moth caterpillars do indeed eat yucca seeds, but this is part of the mutual agreement, as the moths also pollinate the yucca flowers, ensuring the plant's reproduction.

Question 19

Ants are often observed with aphids, small insects that feed on plants. The ants obtain nutritious nectar from the aphids. A biologist wants to test whether ants and aphids are mutualists. She removes ants from groups of aphids and compares them to controls. Which of the following outcomes is consistent with a mutualistic relationship between ants and aphids?

Accepted Answer

If more aphids are eaten by herbivores when ants are removed, it suggests that ants protect aphids from predators, indicating a mutualistic relationship where both species benefit.

Question 20

Ants have a mutualism with the forest herb trillium. A plant structure known as an elaiosome is part of this mutualism. What does the elaiosome do?

Accepted Answer

The elaiosome of trillium is a fleshy structure that provides proteins and lipids for ants to eat. In return, the ants disperse the trillium seeds and provide protection from herbivores.

Quiz 17: Mutualism