Ch. 31

If a single, diploid G2 nucleus in an ascus contains 400 nanograms (ng) of DNA, then asingle ascospore nucleus of this species should contain how much DNA (ng), carried on how many chromosomes?

100, carried on 7 chromosomes

You observe the gametes of a fungal species under the microscope and realize that they resemble animal sperm. To which of the following group does the fungus belong?

Chytrids

Why are mycorrhizal fungi superior to plants at acquiring mineral nutrition from the soil?

Fungi secrete extracellular enzymes that can break down large molecules.

Based on the idea that fungi have pores between their cell walls, which allow cytoplasm to move from one end of the mycelium to the other, which of the following hypotheses is the most plausible?

If a single mycorrhizal fungus formed symbiotic associations with more than one tree, carbon could travel from one plant to another.

Asexual reproduction in yeasts occurs by budding. Due to unequal cytokinesis, the "bud" cell receives less cytoplasm than the parent cell. Which of the following should be true of the smaller cell until it reaches the size of the larger cell?

It should produce fewer fermentation products per unit time.

Which of the following best describes the physical relationship of the partners involved in lichens?

Photosynthetic cells are surrounded by fungal hyphae.

It has been hypothesized that fungi and plants have a mutualistic relationship because plants make sugars available for the fungi's use. What is the best evidence in support of this hypothesis?

Radioactively labeled sugars produced by plants eventually show up in the fungi with which they are associated.

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

The larger surface area allows for more material to be transported through the cell membrane.

Humans have immune systems in which lymph nodes are important, because many phagocytes and lymphocytes reside there. Given that a successful infection by S. schenkii damages lymph nodes themselves, which of the following is most probable?

Their conversion from yeast to hyphal morphology allows such fast growth that the body's defenses are at least temporarily overwhelmed.

Basidiomycetes are the only fungal group capable of synthesizing lignin peroxidase. What advantage does this group of fungi have over other fungi because of this capability?

This fungal group can break down the tough lignin, which cannot be harnessed for energy, to get to the more useful cellulose.

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

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

Which of the following has the LEAST affiliation with all of the others?

arbuscules

Deuteromycetes _____.

are the group of fungi that have, at present, no known sexual stage

Arrange the following in order from largest to smallest.

ascomycete, ascocarp, ascus, ascospore

The multicellular condition of animals and fungi seems to have arisen _____.

by convergent evolution

Orchid seeds are tiny, with virtually no endosperm and with miniscule cotyledons. If such seeds are deposited in a dark, moist environment, then which of the following represents the most likely means by which fungi might assist in seed germination, given what the seeds lack?

by providing the embryos with some of the organic nutrients they have absorbed

Fossil fungi date back to the origin and early evolution of plants. What combination of environmental and morphological change is similar in the evolution of both fungi and plants?

colonization of land and loss of flagellated cells

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?

cytoplasmic streaming in hyphae

Sexual reproduction has not been observed in Bd. If its morphology and genetics did not identify it as a chytridiomycete, then to which fungal group would Bd be assigned?

deuteromycetes

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

flagellated spores

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

fungal enzymes

When pathogenic fungi are found growing on the roots of grape vines, grape farmers sometimes respond by covering the ground around their vines with plastic sheeting and pumping a gaseous fungicide into the soil. The most important concern of grape farmers who engage in this practice should be that the _____.

fungicide might also kill mycorrhizae

The functional significance of porous septa in certain fungal hyphae is most similar to that represented by which pair of structures in animal cells and plant cells, respectively?

gap junctions — plasmodesmata

Plasmogamy can directly result in which of the following?

heterokaryotic cells, dikaryotic cells

What do fungi and arthropods have in common

hyphae

Mycorrhizae are to the roots of vascular plants as endophytes are to vascular plants' _____.

leaf mesophyll

If haustoria from the fungal partner were to appear within the photosynthetic partner of a lichen, and if the growth rate of the photosynthetic partner consequently slowed substantially, then this would support the claim that _____.

lichens are not purely mutualistic relationships

Some fungal species can kill herbivores while feeding off of sugars from its plant host. What type of relationship does this fungus have with its host?

mutualistic

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

plasmogamy

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?

prokaryotes

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

results in heterokaryotic or dikaryotic cells

After cytokinesis occurs in budding yeasts, the daughter cell has a _____.

similar nucleus and less cytoplasm than the mother cell

A billionaire buys a sterile volcanic island that recently emerged from the sea. To speed the arrival of conditions necessary for plant growth, the billionaire might be advised to aerially sow what over the island?

soredia

Given the eukaryotic structures they lack, it should be expected that microsporidians also lack _____.

the "9 + 2 pattern" of microtubules