Biology Homework 4 Exam Study Guide

________ form ectomycorrhizal relationships with temperate forest trees while ________ form arbuscular (endomycorrhizal) relationships with plants in grasslands and tropical forests.

Basidiomycetes; glomeromycetes

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?

Chytrids

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

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis.

What is the main structural difference between enveloped and nonenveloped viruses?

Enveloped viruses have a phospholipid membrane outside their capsid, whereas nonenveloped viruses do not have a phospholipid membrane.

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

T4 protein and T4 DNA.

Which of these fungal features supports the phylogenetic conclusion that fungi are more closely related to animals than to plants

The cell walls of fungi are made of chitin

Which of the following supports the argument that viruses are nonliving?

They are not cellular

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.

Viral envelopes can best be analyzed with which of the following techniques?

antibodies against specific proteins not found in the host membranes

Which of the following characteristics is unique to chytrids compared to other groups of fungi?

flagellated spores

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

Which of the following characteristics, structures, or processes is common to bacteria and viruses?

genetic material composed of nucleic acids

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome

Effective antiviral drugs are usually associated with which of the following properties?

interference with viral replication

The HIV protease has been the target of several anti-HIV medications called protease inhibitors. This antiviral strategy is possible because protease inhibitors ________.

prevent the formation of active viral proteins

Fungi that absorb nutrients from decaying plant matter are called

saphrophytes

Which of the following is characteristic of the lytic cycle?

A large number of phages are released at a time.

Predict what you would see if you were looking at a new species of Zygomycetes.

A zygote enclosed in a tough outer coat

Why is it more difficult to treat fungal infections than bacterial infections in humans?

Fungal and animal cells and proteins are similar. Thus, drugs that disrupt fungal cell or protein function may also disrupt human cell or protein function.

The vegetative (nutritionally active) bodies of most fungi are ________. I. composed of hyphae II. referred to as a mycelium III. usually underground

I,II, and III

You just discovered a new virus. This virus infects heart muscle, where it causes inflammation, and has a very high mutation rate. Which of the following is the best strategy for finding a treatment for this virus?

Identify the receptor this virus uses and develop an enzyme that blocks the receptor.

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.

In septate fungi, what structures allow cytoplasmic streaming to distribute needed nutrients, synthesized compounds, and organelles throughout the hyphae?

Pores in the septa

Poliovirus is an RNA virus of the picornavirus group, which uses its RNA as mRNA. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein-coding region (~7000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids results in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. What conclusion is most consistent with the results of the radioactive labeling experiment?

The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones.

Viruses use the host's machinery to make copies of themselves. However, some human viruses require a type of replication that humans do not normally have. For example, humans normally do not have the ability to convert RNA into DNA. How can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires?

The viral genome has genes coding for enzymes needed for its own reproduction.

Why is it important that ectomycorrhizal fungi (EMF) have peptidase enzymes?

These enzymes are needed to release nitrogen from dead plant material in colder environments.

When people die from HIV infections, it is usually because they ________.

They have too few T cells to adequately fight off infections.

What group of fungi has the ability to penetrate its host's cell wall, thus increasing the efficiency with which materials are passed from fungus to host?

arbuscular mycorrhizal fungi

You are given an organism to identify. It has a fruiting body that contains many structures with eight haploid spores lined up in a row. What kind of a fungus is this?

ascomycete

The sporangia of the bread mold Rhizopus are _____.

asexual structures that produce haploid spores

The first class of drugs developed to treat AIDS, such as AZT, were known as reverse transcriptase inhibitors. They worked because they ________.

bonded to the viral reverse transcriptase enzyme, thus preventing the virus from making a DNA copy of its RNA genome

Lichens are symbiotic associations of fungi and

cyanobacteria and green algae

Mimivirus contains some of the genes required for protein synthesis. This is cited as support for which hypothesis about the origins of viruses?

degeneration

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. We expect that the plants would

develop the typical symptoms of TMV infection

Long, branching fungal filaments are called

hyphae

In most fungi, karyogamy does NOT immediately follow plasmogamy, which consequently

results in heterokaryotic or potentially even dikaryotic cells

A virus consisting of a single strand of RNA, which is transcribed into complementary DNA, is a ________.

retrovirus

Which of the following could use reverse transcriptase to transcribe its genome?

ssRNA

A population of viruses with similar characteristics is called a ________.

strain