Exam 27: Bacteria and Archaea

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. Faecal 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 statements is not true?

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. -Imagine that after generation 20,000, the experimental cells were grown in high-glucose conditions for 20,000 generations (using the same transfer process described). Refer to the y-axis on the graph and predict the fitness of the new lines when tested in low- and high-glucose conditions.

Which statement about the domain Archaea is accurate?

Which of the following involves metabolic cooperation among prokaryotic cells?

While examining a rock surface, you have discovered an interesting new organism. Which of the following criteria will allow you to classify the organism as belonging to Bacteria but not Archaea or Eukarya?

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. -If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophages are excluded from the bacterial cultures, then beneficial mutations might be transmitted horizontally to other E. coli cells via ________.

The following table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the question. Which species is most likely to be found in sewage treatment plants and in the guts of cattle?

In a hypothetical situation, the genes for sex pilus construction and for tetracycline resistance are located on the same plasmid within a particular bacterium. If this bacterium readily performs conjugation involving a copy of this plasmid, then the result should be the ________.

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

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. -If the vertical axis of the figure above refers to relative fitness, then which of the following is the most valid and accurate measure of fitness?

Nitrogenase, the enzyme that catalyses nitrogen fixation, is inhibited whenever free oxygen (O₂) reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O₂. Consider the colonial aquatic cyanobacterium, Anabaena, whose heterocysts are described as having "...a thickened cell wall that restricts entry of O₂ produced by neighbouring cells. Intercellular connections allow heterocysts to transport fixed nitrogen to neighbouring cells in exchange for carbohydrates". Think about this description of the colonial aquatic cyanobacterium, Anabaena. Which of the following questions below is important for understanding how nitrogen (N₂) enters heterocysts, and how oxygen (O₂) is kept out of heterocysts?

Which of the following describe all existing bacteria?

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?

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 ________.