Question 1

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

Accepted Answer

In budding yeast, the daughter cell receives a similar nucleus but less cytoplasm compared to the mother cell, as the budding process results in an asymmetrical division.

Question 2

Canadian and Swiss researchers wanted to know if the diversity of arbuscular mycorrhizal fungi (AMF) was important to the productivity of grasslands (M.G.A. van der Heijden, J. N. Klironomos, M. Ursic, P. Moutoglis, R. Streitwolf-Engel, T. Boler, A. Wiemken, and I. R. Sanders. 1998. Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability, and productivity. Nature 396:69-72). Specifically, they wanted to know if it mattered which specific AMF species were present, or just that some type of AMF was present. They grew various plants in combination with one of four AMF species (A, B, C, and D), no AMF species (O), or all four AMF species together (A + B + C + D); and they measured plant growth under each set of conditions. All plant species were grown in each plot, so they always competed with each other with the only difference being which AMF species were present.
On the graphs, the x-axis labels indicate the number and identity of AMF species (bar 0 = no fungi; bars A - D = individual AMF species; bar A + B + C + D = all AMF species together). The y-axis indicates the amount (grams) of plant biomass for the species shown in italics above each graph. Graph e is the total biomass (grams) of all 11 plant species combined; graph f is the biomass of Bromus erectus plants only, separated from the total.

Based on graphs e and f, which is the most well-supported prediction for the effect on total plant biomass if AMF diversity were increased to eight species?

Accepted Answer

The answer of Canadian and Swiss researchers wanted to know...

Question 3

Deuteromycetes ________.

Accepted Answer

Deuteromycetes, also known as the "imperfect fungi," have no known sexual stage. They are often considered a form group rather than a phylogenetically related group.

Question 4

Early fungi probably formed mutualistic associations with early plants, providing nutrients to the plant and receiving energy-containing compounds. Evidence that plants' ability to form a mutualistic association with fungi is due to ancient genes includes which of the following occurrences?

Accepted Answer

The restoration of the ability to form mycorrhizae with fungi by a flowering plant after biologists transferred a gene from a liverwort to the flowering plant provides evidence that plants' ability to form a mutualistic association with fungi is due to ancient genes. This is because the gene transferred from a liverwort to a flowering plant is a homolog of a gene that likely existed in the common ancestor of liverworts and all other land plants.

Question 5

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

Accepted Answer

Plasmogamy is the stage where the fusion of cytoplasm and the formation of a dikaryotic mycelium occurs. If an enzyme that prevented the fusion of hyphae was introduced, plasmogamy would be prevented, and reproduction would be halted. Fertilization (fusion of nuclei) and karyogamy (fusion of haploid nuclei) occur later in the basidiomycete life cycle and would not be affected by the introduction of this enzyme. Germination refers to the initial growth of a spore or a seed and is not a stage in the basidiomycete life cycle.

Question 6

Some nematode worms suck plant juices from the roots of plants and are economically important agricultural pests. Some fungi are usually decomposers of plant material, but some trap and kill nematodes at times. Arthrobotrys traps and kills nematodes, especially when they lack nitrogen sources. These two facts suggest that farmers could find Arthrobotrys an important tool in combating nematode infestations. Which of the following research questions would make a good starting point for developing such a defense against plant-sucking nematodes?

Accepted Answer

This research question directly addresses the potential for using Arthrobotrys as a tool for controlling nematode pests in agriculture. By understanding the relationship between nitrogen fertilization and the ability of Arthrobotrys to trap and kill nematodes, farmers can optimize their use of this fungus as a biological control method. Option B is not directly related to Arthrobotrys or its potential use as a biocontrol agent. Option C is interesting, but does not provide practical information for developing a defense against nematodes. Option D is also interesting, but does not provide information relevant to the potential use of Arthrobotrys in agriculture.

Question 7

Some companies advertise and sell mycorrhizae to home gardeners and commercial farms, claiming that the presence of mycorrhizae improves plant growth and survival. If the company conducted experiments on plants with and without mycorrhizae, which of the following measurements would support their claim?

Accepted Answer

The increased production of corn ears in plants with mycorrhizae would support the claim that mycorrhizae improves plant growth and survival. The production of corn is a clear and measurable indicator of improved growth and yield, which supports the effectiveness of mycorrhizae in enhancing plant growth. The other options do not support the claim and may even suggest the opposite.

Question 8

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 statements should be an accurate characterization of the smaller cell until it reaches the size of the larger cell?

Accepted Answer

The smaller cell has less cytoplasm, which means it has a smaller amount of resources available to carry out metabolic activities such as fermentation. Therefore, it should produce fewer fermentation products per unit time. The other choices are not directly related to the process of unequal cytokinesis.

Question 9

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?

Accepted Answer

Both fungi and plants evolved from aquatic ancestors and had to adapt to life on land. This involved the loss of flagellated cells and the development of structures that could support their bodies above ground.

Question 10

Use the following information to answer the question.
Canadian and Swiss researchers wanted to know if the diversity of arbuscular mycorrhizal fungi (AMF) was important to the productivity of grasslands (M.G.A. van der Heijden, J. N. Klironomos, M. Ursic, P. Moutoglis, R. Streitwolf-Engel, T. Boler, A. Wiemken, and I. R. Sanders. 1998. Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability, and productivity. Nature 396:69-72). Specifically, they wanted to know if it mattered which specific AMF species were present, or just that some type of AMF was present. They grew various plants in combination with one of four AMF species (A, B, C, and D), no AMF species (O), or all four AMF species together (A + B + C + D); and they measured plant growth under each set of conditions. All plant species were grown in each plot, so they always competed with each other with the only difference being which AMF species were present.
On the graphs, the x-axis labels indicate the number and identity of AMF species (bar 0 = no fungi; bars A - D = individual AMF species; bar A + B + C + D = all AMF species together). The y-axis indicates the amount (grams) of plant biomass for the species shown in italics above each graph. Graph e is the total biomass (grams) of all 11 plant species combined; graph f is the biomass of Bromus erectus plants only, separated from the total.

What is the most likely explanation for the observation that total biomass (graph e) does not vary with AMF diversity?

Accepted Answer

The answer of Use the following information to answer the...

Question 11

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

Accepted Answer

Chytrids are unique among fungi in having flagellated spores, allowing them to move in water and colonize new environments. This feature suggests that they diverged earliest in fungal evolution as it is a primitive characteristic not seen in other fungal groups. A, B, and D are not exclusive to chytrids and are also present in other fungal groups.

Question 12

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

Accepted Answer

Mycorrhizal fungi secrete extracellular enzymes that can break down large molecules, including those that contain essential minerals. This allows the fungi to access and acquire mineral nutrition from the soil more effectively than plant roots alone.

Question 13

Use the following information to answer the question.
For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection.
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?

Accepted Answer

Bd would be assigned to deuteromycetes, also known as "imperfect fungi," because they are characterized by the absence of observed sexual reproduction.

Question 14

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

Accepted Answer

In most fungi, karyogamy does not immediately follow plasmogamy, resulting in heterokaryotic or dikaryotic cells, which contain multiple haploid nuclei from different parents in a single cell. This allows for genetic diversity and the potential for sexual reproduction, as well as a means of surviving unfavorable conditions through asexual reproduction.

Question 15

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

Accepted Answer

Chytrids are the only fungal group that produce "motile" gametes, which resemble animal sperm, making them distinct from other fungal groups. The other options (zygomycetes, Basidiomycota, and Ascomycota) do not produce motile gametes.

Question 16

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?

Accepted Answer

Radioactively labeled sugars produced by plants have been shown to eventually show up in the fungi with which they are associated, indicating that the plants are providing sugars for the fungi's use. This is strong evidence for a mutualistic relationship between fungi and plants, where the fungi provide nutrients and minerals to the plants in exchange for sugars.

Question 17

The ascomycete Brachiola gambiae parasitizes the mosquito Anopheles gambiae. Adult female mosquitoes must take blood meals for their eggs to develop, and it is while they take blood that they transmit malarial parasites to humans. Male mosquitoes drink flower nectar. If humans are to safely and effectively use Brachiola gambiae as a biological control to reduce human deaths from malaria, then which of the following statements should be correct?

Accepted Answer

The most effective approach for reducing human deaths from malaria would be to use an ascomycete that kills the mosquitoes before they become capable of transmitting the malarial parasite. Therefore, Brachiola gambiae should kill the mosquitoes before the malarial parasite they carry reaches maturity. It would also be desirable for the ascomycete to not be harmful to other insects to prevent disruption of the ecosystem.

Question 18

Chitin is a long-chain polymer derived from glucose. It strengthens cell walls of fungi and the outer covering (exoskeleton) of arthropods (including crabs, shrimps, and insects). The presence of chitin in these groups is likely due to ________.

Accepted Answer

Chitin is present in fungi and arthropods, which are not closely related phylogenetically. This suggests it evolved independently in these groups through convergent evolution.

Question 19

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

Accepted Answer

The multicellular condition of animals and fungi is believed to have arisen by convergent evolution, where similar traits evolve independently in different lineages due to similar selective pressures, rather than from a common multicellular ancestor.

Question 20

Plasmogamy can directly result in which of the following?

Accepted Answer

Plasmogamy is the fusion of two haploid cells to form a heterokaryotic cell, which contains two separate haploid nuclei. Therefore, plasmogamy can directly result in heterokaryotic cells or dikaryotic cells.

Quiz 31: Fungi