Chapter 31 practice problems / quiz problems

Question 1

Fungi have an extremely high surface-to-volume ratio. What is the advantage of this characteristic to an organism that gets most of its nutrition through absorption?

Question 1 options:

This high ratio creates more room inside the cells for additional organelles involved in absorption.

This high ratio means that fungi have a thick, fleshy structure that allows the fungi to store more of the food it absorbs.

The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.

The lower volume prevents the cells from drying out too quickly, which can interfere with absorption.

Answer 1

The high ratio allows for more material to be acquired from the surroundings and transported through the cell membrane.

Question 2

If all fungi in an environment that perform decomposition were to suddenly die, then which group of organisms should benefit most, due to the fact that their fungal competitors have been removed?

Question 2 options:

grasses

protists

prokaryotes

flowering plants

Answer 2

prokaryotes

Question 3

When a mycelium infiltrates an unexploited source of dead organic matter, what are most likely to appear within the food source soon thereafter?

Question 3 options:

increased oxygen levels

larger bacterial populations

fungal haustoria

fungal enzymes

Answer 3

fungal enzymes

Question 4

A fungal spore germinates, giving rise to a mycelium that grows outward into the soil surrounding the site where the spore originally landed. Which of the following accounts for the fungal movement, as described here?

Question 4 options:

mycelial flagella

cytoplasmic streaming in hyphae

breezes distributing spores

karyogamy

Answer 4

cytoplasmic streaming in hyphae

Question 5

The adaptive advantage associated with the filamentous nature of fungal mycelia is primarily related to ________.

Question 5 options:

the ability to form haustoria and parasitize other organisms

an extensive surface area well suited for invasive growth and absorptive nutrition

the increased probability of contact between different mating types

the potential to inhabit almost all terrestrial habitats

Answer 5

an extensive surface area well suited for invasive growth and absorptive nutrition

Question 6

Some fungal species live in plants and can kill herbivores that feed on the plant. What type of relationship does this fungus have with its host?

Question 6 options:

predatory

mutualistic

commensal

parasitic

Answer 6

mutualistic

Question 7

At which stage of a basidiomycete’s life cycle would reproduction be halted if an enzyme that prevented the fusion of hyphae was introduced?

Question 7 options:

karyogamy

fertilization

plasmogamy

germination

Answer 7

plasmogamy

Question 8

Which feature seen in chytrids supports the hypothesis that they diverged earliest in fungal evolution?

Question 9 options:

the absence of chitin within the cell wall

coenocytic hyphae

flagellated spores

parasitic lifestyle

Answer 8

flagellated spores

Question 9

In most fungi, karyogamy does not immediately follow plasmogamy, which consequently ________.

Question 8 options:

means that sexual reproduction can occur in specialized structures

allows fungi to reproduce asexually most of the time

results in heterokaryotic or dikaryotic cells

results in multiple diploid nuclei per cell

Answer 9

results in heterokaryotic or dikaryotic cells

Question 10

Arrange the following in order from largest to smallest, assuming that they all come from the same fungus.

Question 10 options:

mycelium, gill, basidiocarp, basidium, basidiospore

gill, basidiocarp, basidiospore, basidium, mycelium

gill, basidiocarp, mycelium, basidium, basidiospore

mycelium, basidiocarp, gill, basidium, basidiospore

Answer 10

mycelium, basidiocarp, gill, basidium, basidiospore

Question 11

Compare and contrast the nutritional mode of a fungus with your own nutritional mode.

Answer 11

Humans and fungi are both heterotrophic! Unlike humans who eat large pieces of food and then break that down into smaller nutrients, fungi externally absorb food by secreting digestive enzymes that aid absorption, or pull small nutrients directly from an environment as well

Question 12

Suppose a certain fungus is a mutualist that lives within an insect host, yet its ancestors were parasites that grew in and own the insect’s body. What derived traits might you find in this mutualistic fungus?

Answer 12

The mutualist most likely inherited intense enzymes that allow digestion of the insect’s body to gain control. Since this would kill the insect, the fungi would not secrete these chemicals in order to continue a mutualistic relationship with the insect

Question 13

How does the morphology of multicellular fungi affect the efficiency of nutrient absorption?

Answer 13

Fungi have small,thin filaments of hyphae, when combined form an interwoven mass called a mycelium that penetrates wherever they are growing. This mass of thin filaments creates a large surface area which allows for efficient nutrient absorption.

Question 14

How are fungi important as decomposers, mutualists, and pathogens?

Answer 14

Decomposers: break down organic material like dead organisms and waste, which helps aid in recycling nutrients

Mutualists: Form mycorrhizal associations with plants, allowing plants to receive influxes of nutrients that aid in their life cycle

Pathogens: Fungi harm species and drive them into endangerment, and sometimes even extinction.

Question 15

If a plant has mycorrhizae, where might carbon that enters the plant’s stomata as CO2 eventually be deposited: in the plant, in the fungus, or both? Explain.

Answer 15

C02 that is captured by a plant’s stomata is then converted into sugar via photosynthesis. Some of this sugar is then used by the plant, while some is given to the fungi that is the plant’s mutualist.

Question 16

In terms of haploidy versus diploidy, how do the life cycles of fungi and humans differ?

Answer 16

The majority of the life cycle of fungi is in the haploid stage, while humans spend the majority of their time in the diploid stage

Question 17

Suppose that you sample the DNA of two mushrooms on opposite sides of your yard and find that they are identical. Propose two hypotheses that could reasonably account for this result.

Answer 17

The visible fungal structures may be reproductive structures of the same mycelium network, and these two mushroom heads are actually connected via interwoven networks of hyphae underground. They also could be a result of asexual reproduction through spores - hence why the are genetically the same.

Question 18

Why are fungi classified as opishtokonts despite the fact that most fungi lack flagella?

Answer 18

Genetic evidence confirms that fungi should be classified as opisthokonts, despite the fact that most lack flagella. Additionally, chytrids and other basal lineages of fungi have flagella, which suggest that most fungi lost their flagella due to a divergence from flagellated ancestors

Question 19

What features of chytrids supports the hypothesis that they include members of basal fungal lineages?

Answer 19

Flagellated spores , and molecular evidence also suggests that chytrids diverged early

Question 20

Give examples of how form fits function in zygomycetes, glomeromycetes, ascomycetes, and basidiomycetes.

Answer 20

In zygomycetes, the sturdy, thick-walled zygosporangium can withstand harsh conditions and then undergo karyogamy and meiosis when the environment is favorable for reproduction. In glomeromycetes, the hyphae have a specialized morphology that enables the fungi to form arbuscular mycorrhizae with plant roots. In ascomycetes, the asexual spores (conidia) are often produced in chains or clusters at the tips of conidiophores, where they are easily dispersed by wind. The often cup-shaped ascocarps house the sexual spore-forming asci. In basidiomycetes, the basidiocarp supports and protects a large surface area of basidia, from which spores are dispersed.

Question 21

Suppose that the mutation of an ascomycete changes its life cycle so that plasmogamy, karyogamy, and meiosis occurs in quick succession. How might this affect the ascospores and ascocarps?

Answer 21

Genetic diversity would go down, as dikaryotic forms would depreciate in time, and thus less genetic recombination will be undergone.

Mating events = one ascus, and not two. This is why genetic recombination will not occur, as two asci are needed for successful recombination

Question 22

What are some of the benefits that lichen algae can derive from their relationship with fungi?

Answer 22

Suitable growth environment, retention of water and minerals, protection from sunlight, and protection from predation

Question 23

What characteristics of pathogenic fungi results in their being efficiently transmitted?

Answer 23

A hardy spore stage enables dispersal to host organisms through a variety of mechanisms; their ability to grow rapidly in a favorable new environment enables them to capitalize on the host’s resources.

Question 24

How might life on Earth differ from what we know today if no mutualistic relationships between fungi and other organisms evolved?

Answer 24

Many different outcomes might have occurred. Organisms that currently form mutualisms with fungi might have gained the ability to perform the tasks currently done by their fungal partners, or they might
have formed similar mutualisms with other organisms (such as bacteria). Alternatively, organisms that currently form mutualisms with fungi might be less effective at living in their present environments. For
example, the colonization of land by plants might have been more difficult. And if plants did eventually colonize land without fungal mutualists, natural selection might have favored plants that formed more highly divided and extensive root systems (in part replacing mycorrhizae).