Exam 27: Bacteria and Archaea

Termites eat wood, but many do not produce enzymes themselves that will digest the cellulose in the wood. Instead, some termites house a complex community of protozoa, bacteria, and archaea that could help digest the cellulose. Imagine an experiment that fed termites either wood only or wood and antibiotics, and then measured the amount of energy extracted from the wood. If both groups gained equal amounts of energy, which of the conclusions is the most logical?

Which of the following traits do archaeans and eukaryotes share?

Chloramphenicol is an antibiotic that targets prokaryotic (70S)ribosomes, but not eukaryotic (80S)ribosomes. Which of these questions stems from this observation, plus an understanding of eukaryotic origins?

Which of the following involves metabolic cooperation among prokaryotic cells?

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. If infection primarily involves the outermost layers of adult amphibian skin, and if the chytrids use the skin as their sole source of nutrition, then which term best applies to the chytrids?

Use the information in the following paragraph to answer the question. A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. Which of the following statements about the cell wall is most probable?

Which of the following observations about flagella is accurate and is consistent with the scientific conclusion that the flagella from eukaryotes and bacteria evolved independently?

The following table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the question. Trait Plasmid Gram Staining Results Nutritional Mode Specialized Metabolic Pathways Other Features Species A R Variable Chemohetero- troph Aerobic methanotroph (obtains carbon and eneroy from methane) Fimbriae Species B None Variable Chemoauto- troph Anaerobic methanogen Internal membranes Species C R Negative Chemohetero- troph Anaerobic butanolic fermentation Flagellum Species D F Negative Chemohetero- \ roph Anaerobic lactic acid fermentation Pili SpeciesE None Negative Photoauto- troph Anaerobic nitrogen fixation and aerobic photosystems I and II Thylakoids Species D is pathogenic if it gains access to the human intestine. Which other species, if it coinhabited a human intestine along with species D, is most likely to become a recombinant species that is both pathogenic and resistant to some antibiotics?

Which statement about the domain Archaea is accurate?

Sexual reproduction in eukaryotes increases genetic variation. In prokaryotes, transformation, transduction, and conjugation are mechanisms that increase genetic variation. A fundamental difference between the generation of genetic variation in the two domains is ________.

Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods should be least effective at inhibiting bacterial growth?

Use the following information and graph to answer the question. The figure below depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at Time A. Assume that reciprocal crossing over occurs (in other words, a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). What process is occurring at Time C that is decreasing the DNA content?

Use the following information to answer the question. Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. When within their hosts, the algae are referred to as zoochlorellae. In aquaria with light coming from only one side, P. bursaria gather at the well-lit side, whereas other species of Paramecium gather at the opposite side. The zoochlorellae provide their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae with protection and motility. P. bursaria can lose its zoochlorellae in two ways: (1)if kept in darkness, the algae will die; and (2)if prey items (mostly bacteria)are absent from its habitat, P. bursaria will digest its zoochlorellae. A P) bursaria cell that has lost its zoochlorellae is aposymbiotic. If aposymbiotic cells have population growth rates the same as those of healthy, zoochlorella-containing P. bursaria in well-lit environments with plenty of prey items, then such an observation would be consistent with which type of relationship?

The following question refers to the figure. In this eight-year experiment, 12 populations of E. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor)E. coli population. The cells in the 12 cell lines grown in low-glucose conditions showed the effects of which of the following processes?

Recently, a microbe that is able to digest cellulose was discovered in a hot spring with an average temperature of 95°C. Predict the group to which this microbe most likely belongs.

Photoautotrophs use

Jams, jellies, preserves, honey, and other foods with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment ________.

Use the following information to answer the question. Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. When within their hosts, the algae are referred to as zoochlorellae. In aquaria with light coming from only one side, P. bursaria gather at the well-lit side, whereas other species of Paramecium gather at the opposite side. The zoochlorellae provide their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae with protection and motility. P. bursaria can lose its zoochlorellae in two ways: (1)if kept in darkness, the algae will die; and (2)if prey items (mostly bacteria)are absent from its habitat, P. bursaria will digest its zoochlorellae. Which of the following experimental results would suggest that the zoochlorellae and P. bursaria are mutualists?

If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell, the regenerated bacterium will probably also lack ________.

The following question refers to the figure. In this eight-year experiment, 12 populations of E. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor)E. coli population. Compare the bacteria in the figure above in generation 1 and generation 20,000. The bacteria in generation 1 have a greater ________.