Exam 2 Study Set

A biologist trying to determine the mechanism of adenosine triphosphate (ATP) production in a newly discovered bacterium provides several different substrates on which the bacteria can feed. Which of the following results would indicate that the species uses fermentation to produce ATP?

After exposure to amino acids, the bacteria produce a smell like rotting flesh.

What is the difference between an epidemic and a pandemic?

An epidemic is restricted to a local region; a pandemic is global

You are a forester charged with increasing productivity in a South American forest newly planted with pines from Oregon. You believe that the southern forest lacks the fungal diversity needed by the North American pines and that this lack of fungi is affecting the pines' productivity, but you have no evidence to support your ideas. Which of the following would be the best approach to assess the diversity of fungi likely contributing to tree productivity in the Oregon forest?

Do direct sequencing on representative soil samples from across the forest

What is the function of reverse transcriptase in retroviruses?

It uses viral RNA as a template for DNA synthesis

Which of the following traits do archaea and bacteria share?

Lack of a nuclear envelope and presence of a plasma membrane

You need to identify the major type of bacteria living on the shower curtain in your bathroom and find out what they use as a food source. What is the most efficient method for answering this question?

Enrichment culture

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

You acquire a soil sample and run an enrichment culture on it. You provide the organisms in the culture with all of the ingredients required for growth except for nitrogen. What result do you expect to have at the end of your experiment?

Nitrogen-fixing bacteria will significantly outnumber those incapable of fixing nitrogen

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.

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

Studies have shown that in some forest ecosystems carbon can move from one tree to another via mycorrhizal fungi. Which of the following features of fungal biology enables this?

The cells of fungal hyphae are connected by pores that allow passage of cytoplasm from cell to cell

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

They are not cellular.

A newly discovered organism is found to use sulfide (S2−) for aerobic respiration and carbon dioxide (CO2) from the air as a source of carbon, much like a plant. This organism must be a ________.

chemolithoautotroph

Some of the most useful phylogenetic trees are constructed from the alignment of 16S or 18S ribosomal RNA. What is the advantage of using rRNA over mRNA for the construction of phylogenetic trees?

mRNA transcripts vary greatly, as they are dependent upon the genome of the organism, whereas rRNA is found in all organisms

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

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 most direct ancestors of land plants were probably ________

green algae

A particular species of protist has obtained a chloroplast via secondary endosymbiosis. You know this because the chloroplasts ________.

have three or four membranes

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

have too few T cells to adequately fight infection

Which of the following is major characteristic of fungi that distinguishes them from other eukaryotes?

nutrient acquisition via external digestion

According to the phylogenetic tree in the accompanying figure, G. intestinalis constitutes a ________ group.

paraphyletic

Fungi that absorb nutrients from decaying plant matter are called ________.

saprobes

Some researchers have begun attempting to clean up oil spills by adding nonindigenous microbial hydrocarbon degraders to the spill, in the hope that these bacteria will neutralize the dangerous chemicals in the spill. This is an example of ________.

seeding

Using the data in the figure, how long does it take for virus A to go through one lytic cycle

45 minutes

Which of the following might be a result of adding a secondary consumer to the aquatic ecosystem in the accompanying illustration?

A decrease in the number of primary consumers

Which of the following statements best describes the term synapomorphy?

A trait that evolved in the most recent common ancestor of a monophyletic group

Over human history, which process has been most important in improving the features of plants long used by humans as staple foods?

Artificial selection

Which of the following statements does NOT explain the reason populations have been so adversely affected by pandemics such as the influenza pandemic of 1918 or the current AIDs pandemic?

Both viruses are very virulent and kill their hosts very rapidly.

In the figure, which graph of soil nitrogen loss over time most strongly supports the hypothesis that if the 20-cm-tall Dawsonia acts as a physical buffer, then it reduces water's ability to erode the soil and carry away its nitrogen?

D

Which of the following was a challenge to the survival of the first land plants?

Desiccation

Angiosperms are the most successful terrestrial plants. Which of the following features is unique to them and helps account for their success?

Fruits enclosing seeds

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.

Which of the following is an important role for fungi in the carbon cycle?

Fungi release fixed carbon back to the environment for other plants and photosynthetic organisms to utilize.

Carl Woese and collaborators identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains?

Genetic characteristics such as ribosomal RNA sequences

In the accompanying figure, at the arrow marked II, what enzyme(s) is (are) being utilized?

Host cell DNA polymerase

Which of the three types of viruses shown in the accompanying figure has a capsid?

I, II, and III

Which adaptations of land plants are likely to provide Harold with future patients?

II and III

Refer to the study by Poulsen et al. and the accompanying figure. Latrunculin A is a reversible toxin that disrupts the formation of actin fibers. A culture of a particular species of diatom was treated with this toxin diluted in a buffer, while another culture was treated only with the buffer (no toxin; control). The motility of cells in each culture was assessed by counting the number of cells that were moving during a defined period of time. Which of the following conclusions is reasonable based on the figure?

In this species of diatom, fully formed actin fibers are necessary for movement.

You are a physician, and you suspect your patient has a viral infection that has never been seen in humans. The infection is localized in the cells along the lining of the small intestine. The cells in this area are regularly sloughed off and replaced with new cells; that is, these cells are constantly dividing. When you isolate this new virus and incubate it in culture, you discover that it does not replicate well in cultures that have slowly dividing cells, but it does much more damage in cultures that have actively dividing cells. What do these findings suggest about this new virus?

It is a double-stranded DNA virus.

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

Photosynthetic cells are surrounded by fungal hyphae

ccording to the endosymbiotic theory, why was it adaptive for the larger (host) cell to keep the engulfed cell alive, rather than digesting it as food?

The engulfed cell provided the host cell with adenosine triphosphate (ATP)

HIV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What are the practical consequences of these findings?

The flu virus can be transmitted more easily from person to person than HIV.

Why are seedless vascular plants considered paraphyletic rather than monophyletic?

The group includes their common ancestor but also the seeded descendants of that same ancestor.

In electron micrographs of HSV infection, the intact virus initially reacts with cell-surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations?

The viral envelope mediates entry into the cell, the capsid mediates entry into the nuclear membrane, and the genome is all that enters the nucleus.

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.

. Based on this information, which of the following statements is TRUE of the excavate lineage?

Their ancestors had mitochondria, but the mitochondria were lost over time in some lineages.

Which of the following statements is consistent with the assertion that protists are paraphyletic?

There is no common set of synapomorphies that define a protist.

What is the goal of bioremediation?

To clean up areas polluted with toxic compounds by using bacteria

Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6300 nucleotides. Its capsid is 25—30 nm in diameter and contains 180 identical capsomeres. If the yellow mottle virus begins its infection of a cell by using its genome as mRNA, which of the following would you expect to be able to measure

Translation rate

Chemicals, secreted by soil fungi, which inhibit the growth of bacteria are known as ________.

antibiotics

Lichens are symbiotic associations of fungi and ________.

cyanobacteria or algae

The major function of medicinal compounds in plants is to _______

defend the plant against herbivores

All fungi are ________.

heterotrophic

It has been hypothesized that fungi and plants have a mutualistic relationship because fungi provide critical nitrogen for the plants' use. How do we know this happens? In experiments using radioactively labeled ________

nitrogen, plants acquired more radioactive nitrogen when they were associated with fungi

Protists and bacteria are grouped into different domains because ________.

protists have a membrane-bounded nucleus, which bacterial cells lack

In the process of alternation of generations, the ________

sporophyte is diploid and produces spores

Biologists sometimes divide living organisms into two groups: autotrophs and heterotrophs. These two groups differ in ________.

their mode of nutrition

Viruses ________.

use the host cell to copy themselves and make viral proteins