Exam 27: Bacteria and Archaea

In a bacterium that possesses antibiotic resistance and the potential to persist through very adverse conditions, such as freezing, drying, or high temperatures, DNA should be located within, or be part of, which structures? 1. nucleoid region 2. endospore 3. fimbriae 4. plasmids

Match the numbered terms to the description that follows. Choose all appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph Description: an organism that relies on photons to excite electrons within its membranes

Which of the following factors does not contribute to genetic diversity in prokaryotes?

Which statement about the genomes of prokaryotes is correct?

If new genetic variation in the experimental populations arose solely by spontaneous mutations, then the most effective process for subsequently increasing the prevalence of the beneficial mutations in the population over the course of generations is

Match the numbered terms to the description that follows. Choose all appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph Description: an organism that obtains both carbon and energy by ingesting prey

The following table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following questions. -Which species should be able to respond most readily to taxes (plural of taxis)?

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 chromosome have moved to the nuclear genome. Which phenomenon accounts for the movement of these genes?

Which statement about the domain Archaea is true?

Regarding prokaryotic genetics, which statement is correct?

Assuming that each of these possesses a cell wall, which prokaryotes should be expected to be most strongly resistant to plasmolysis in hypertonic environments?

Use the information in the following paragraph to answer the next few questions. 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. -This bacterium's ability to survive in a human who is taking penicillin pills may be due to the presence of 1. penicillin-resistance genes. 2. a secretory system that removes penicillin from the cell. 3. a gram-positive cell wall. 4. a gram-negative cell wall. 5. an endospore.

Use the following information to answer the questions below. Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O₂ reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O₂. Consider the colonial aquatic cyanobacterium, Anabaena, whose heterocytes are described as having "…a thickened cell wall that restricts entry of O₂ produced by neighbouring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighbouring cells in exchange for carbohydrates." -Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two "strategies" that nitrogen-fixing prokaryotes might use to protect these enzymes from oxygen? 1. couple them with photosystem II (the photosystem that splits water molecules) 2. package them in membranes that are impermeable to all gases 3. be obligate anaerobes 4. be strict aerobes 5. package these enzymes in specialized cells or compartments that inhibit oxygen entry

Which two structures play direct roles in permitting bacteria to adhere to each other, or to other surfaces? 1. capsules 2. endospores 3. fimbriae 4. plasmids 5. flagella

Prokaryotic ribosomes differ from those present in eukaryotic cytosol. Because of this, which of the following is correct?

Use the information in the following paragraph to answer the next few questions. 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. -What should be true of the cell wall of this bacterium?

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). Use this figure to answer the following questions. -What is occurring at Time C that is decreasing the DNA content?

The typical prokaryotic flagellum features

In a hypothetical situation, the genes for sex pilus construction and for tetracycline resistance are located together 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 predatory bacterium, Bdellovibrio bacteriophorus, drills into a prey bacterium and, once inside, digests it. In an attack upon a gram-negative bacterium that has a slimy cell covering, what is the correct sequence of structures penetrated by B. bacteriophorus on its way to the prey's cytoplasm? 1. membrane composed mostly of lipopolysaccharide 2. membrane composed mostly of phospholipids 3. peptidoglycan 4. capsule