Exam 24: Early Life and the Diversification of Prokaryotes

In sexually reproducing lizards,recombination and meiosis result in offspring that have a variety of genetic material from both parents and high genetic diversity in the population.In contrast,what is one key way in which genetic diversity arises in non-sexually reproducing bacteria?

Which of the following steps has not yet been accomplished by scientists studying the origin of life?

In a hypothetical situation,assume that 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

In a hypothetical situation,a bacterium lives on the surface of a leaf,where it obtains nutrition from the leaf's nonliving,waxy covering while inhibiting the growth of other microbes that are plant pathogens.If this bacterium gains access to the inside of a leaf,however,it causes a fatal disease in the plant.Once the plant dies,the bacterium and its offspring decompose the plant.What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that apply.

Which of the following is a defining characteristic that all protocells or vesicles had in common?

The thermoacidophile Sulfolobus acidocaldarius lacks peptidoglycan but still possesses a cell wall.What is likely to be true of this species?

Suppose it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.5-billion-year-old rock formations.Which of the following structures would be surprising to observe?

Please use the following information to answer the question 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 neighboring cells.Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates." Which of the following questions arise from a careful reading of this quotation and are most important for understanding how N₂ enters heterocysts and how O₂ is kept out of heterocysts?

Figure 24.2 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 (in other words,a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA).Use Figure 24.2 to answer the following question(s). Figure 24.2 -Which two processes are responsible for the shape of the curve at time B? 1)transduction 2)entry of single-stranded Hfr DNA 3)rolling circle replication of single-stranded Hfr DNA 4)conjugation

Which of the following is an accurate characteristic of bacterial cell walls?

If archaeans are more closely related to eukaryotes than to bacteria,then which of the following is a reasonable prediction?

If new genetic variation in the experimental populations arose solely by spontaneous mutations,then the most effective process for subsequently increasing the number of individuals that possess all of these beneficial mutations is

What is one key difference between transduction and conjugation?

Plantlike photosynthesis that releases O₂ occurs in

Bacteria participate in many ecological interactions.Which of the following roles typically does not require or involve symbiosis?

Broad-spectrum antibiotics inhibit the growth of most intestinal bacteria.Consequently,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

Imagine a person ingests some food that causes them to become ill and have symptoms such as a diarrhea and fever.What kind of pathogenic bacterial poison could the person have been exposed to?

If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell but does contain the large circular chromosome,the regenerated bacterium will probably also

Which of the following describes an organism that obtains both carbon and energy by ingesting prey?

Which of the following is the correct sequence of events in the origin of life?