Which of the following extremophiles might researchers most likely use as a model for the earliest organisms on Earth? A) an anaerobic archaean species B) an archaean capable of surviving in the polar ice caps C) a bacterium that thrives in a highly acidic environment D) a bacterium found on another planet or moon Mitochondria are thought to be the descendants of certain alpha proteobacteria. They are, however, no longer able to lead independent lives because most genes originally present on their chromosomes have moved to the nuclear genome. Which phenomenon accounts for the movement of these genes? A) plasmolysis B) conjugation C) horizontal gene transfer D) translation Bacteria perform each of the following ecological roles. Which role typically does NOT involve symbiosis? A) decomposer B) skin commensalist C) gut mutualist D) aggregates with methane-consuming archaea If all prokaryotes on Earth suddenly vanished, which of the following would be the most likely and most direct result? A) Human populations would thrive in the absence of disease. B) The recycling of nutrients would be greatly reduced, at least initially C) Bacteriophage numbers would dramatically increase. D) There would be no more pathogens on Earth. What is the goal of bioremediation? A) to improve human health with the help of living organisms such as bacteria B) to improve soil quality for plant growth by using bacteria C) to clean up areas pol uted with toxic compounds by using bacteria D) to improve bacteria for production of useful chemicals 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? A) Pickling: creates a pH at which most bacterial enzymes cannot function. B) Closing previously opened containers: prevents more bacteria from entering, and excludes oxygen C) Refrigeration: slows bacterial metabolism and growth D) Canning in heavy sugar syrup: creates osmotic conditions that remove water from most bacterial cells. Broad-spectrum antibiotics inhibit growth of most intestinal bacteria. Assuming that nothing is done to counter the reduction of intestinal bacteria, a hospital patient who is receiving broad-spectrum antibiotics is most likely to become A) deficlent in certain vitamins and nutrients B) antibiotic resistant C) unable to fix carbon dioxide D) unable to synthesise peptidoglycan The pathogenic prokaryotes that cause cholera are. A) archaea that release an exotoxin B) bacteria that release an endotoxin C) bacteria that release an exotoxin D) archaea that release an endotoxin In prokaryotes new mutations accumulate quickly in populations, while in eukaryotes new mutations accumulate much more slowly. The primary reasons for this are A) the DNA in prokaryotes is not as stable as eukaryotic DNA and is thus more likely to mutate B) prokaryote mutations are less effective than eukaryote mutations in providing variation for evolution C) prokaryotes have random mutations while eukaryotes can target genes for mutations; thus mutations may not accumulate as quickly in eukaryotes but they are more useful to the organism
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