Exam 26: Bacteria and Archaea

To establish a link between a specific bacterium and a skin disease, researchers have shown that the bacterium was present in sick persons but not in healthy individuals. They isolated the bacterium in a pure culture and demonstrated that experimental healthy animals injected with this culture became sick. What other experiment do researchers need to perform to be absolutely sure that the bacterium is responsible for the disease?

Bacteria able to perform the NH4+ + NO2− → N2 + 2H2O reaction have been discovered in laboratory bioreactors and wastewater treatment systems. Researchers predicted that these bacteria should exist in oceans. They measured the concentration of NH4+, NO2−, NO3−, and O2 in the Black Sea as a function of water depth (M. Kuypers et al. 2003 Anaerobic ammonium oxidation by anammox bacteria in the Black Sea. Nature 422:608-11) to determine where in the sea the bacteria might live. By analyzing data presented in the accompanying figure, at what depth would you expect to find the bacteria? (Note: In the figure, different scales are used to show concentrations of NH4+, NO2−, NO3−, and O2.)

Imagine that you are given some chemoorganotrophic bacteria to grow. What should you use as a source of energy for this type of bacteria?

You run an osteology lab, where students are able to study the bone structure of various species. To produce clean bones, you introduce insects and bacteria to remove all remaining flesh. Which bacteria would be the best purchase for your lab?

What kind of molecules serve as electron acceptors in cellular respiration?

A prokaryote that obtains energy and carbon as it decomposes dead organisms is a(n) ________.

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

What is the characteristic feature of the Chlamydiales phylum?

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

Which of the following groups is characterized by unusual flagella contained within a structure called the outer sheath?

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

Which of the following obtain energy by oxidizing inorganic substances to obtain energy that is used, in part, to fix carbon dioxide?

Which of the following extremophiles might researchers most likely use as a model for the earliest organisms on Earth?

Which of the following traits do archaeans and bacteria share?

Prokaryotes are classified as belonging to two different domains. What are the domains?

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?

What organisms are most numerous on Earth?

What is the goal of bioremediation?

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?

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 ________.