Exam 27: Bacteria and Archaea

Figure 27.2 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 (i.e., a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following questions. Figure 27.2 -During which two times can the recipient accurately be described as "recombinant" due to the sequence of events portrayed in Figure 27.2?

The following questions refer to Figure 27.1 below, which is the same as Figure 27.10 in the textbook. In this 8-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. Figure 27.1 -If it occurs in the absence of any other type of adaptation listed here, which of these is least reasonable in terms of promoting bacterial survival over evolutionary time in a low-glucose environment?

Figure 27.2 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 (i.e., a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following questions. Figure 27.2 -Which question, arising from the results depicted in Figure 27.2, is most interesting from a genetic perspective, and has the greatest potential to increase our knowledge base?

Which of the following are responsible for many human diseases?

Which statement about gram-negative bacteria is correct?

Match the numbered terms to the descriptions that follow. For each item, choose all appropriate terms, but only appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph -an organism that relies on photons to excite electrons within its membranes

Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods would not generally inhibit bacterial growth?

If all prokaryotes on Earth suddenly vanished, which of the following would be the most likely and most direct result?

Which of the following obtain energy by oxidizing inorganic substances; energy that is used, in part, to fix CO₂?

The following questions refer to structures found in a gram-positive prokaryotic cell. -Which of the following is composed almost entirely of peptidoglycan?

The following questions refer to Figure 27.1 below, which is the same as Figure 27.10 in the textbook. In this 8-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. Figure 27.1 -If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophage are excluded from the bacterial cultures, then which of these is a means by which beneficial mutations might be transmitted horizontally to other E. coli cells?

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

Mycoplasmas are bacteria that lack cell walls. On the basis of this structural feature, which statement concerning mycoplasmas should be True?

Regarding prokaryotic reproduction, which statement is correct?

The data were collected from the heterocytes of a nitrogen-fixing cyanobacterium inhabiting equatorial ponds. Study the graph below and choose the most likely explanation for the shape of the curve.

Though plants, fungi, and prokaryotes all have cell walls, we place them in different taxa. Which of these observations comes closest to explaining the basis for placing these organisms in different taxa, well before relevant data from molecular systematics became available?

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

Which is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell?

Figure 27.2 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 (i.e., a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following questions. Figure 27.2 -What is occurring at Time C that is decreasing the DNA content?

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