Exam 24: Early Life and the Diversification of Prokaryotes

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 -What is occurring at time C that is decreasing the DNA content?

A fish that has been salt-cured subsequently develops a reddish color. You suspect that the fish has been contaminated by the extreme halophile Halobacterium. Which of these features of cells removed from the surface of the fish, if confirmed, would support your suspicion? 1) the presence of the same photosynthetic pigments found in cyanobacteria 2) cell walls that lack peptidoglycan 3) cells that are isotonic to conditions on the surface of the fish 4) cells unable to survive salt concentrations lower than 9% 5) the presence of very large numbers of ion pumps in the plasma membrane

The typical prokaryotic flagellum features

Please use the following information to answer the question(s) below. 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 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. -In which feature(s) should one be able to locate a complete chromosome of this bacterium? 1) nucleolus 2) pili 3) endospore 4) nucleoid

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

Photoautotrophs use

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1 -How many of these species probably have a cell wall that partly consists of an outer membrane of lipopolysaccharide?

Which of the following traits do archaeans and bacteria share? 1) composition of the cell wall 2) presence of plasma membrane 3) lack of a nuclear envelope 4) identical rRNA sequences

Please use the following information to answer the question(s) below. 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 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?

Please use the following information to answer the question(s) below. In Figure 24.1, data are presented from an eight-year experiment in which 12 populations of Escherichia 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 24.1 -If the vertical axis of Figure 24.1 refers to "Darwinian fitness," then which of the following is the most valid and accurate measure of fitness?

Genetic variation in bacterial populations cannot result from

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1 -Which species is most self-sustaining in terms of obtaining nutrition in environments containing little fixed nitrogen or carbon?

Regarding prokaryotic genetics, which statement is correct?

Thermoacidophiles are archaeans that are able to successfully live and reproduce in environments that are acidic, have high sulfur content and temperatures, and have little organic material. Consider the thermoacidophile Sulfolobus acidocaldarius. Which of the following graphs most accurately depicts the expected temperature and pH profiles of its enzymes? (Note: The horizontal axes of these graphs are double, with pH above and temperature below.)

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

Which of the following is a defining characteristic that all protobionts had in common?

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

Thiobacillus ferrooxidans is a type of bacteria that oxidizes iron compounds for energy and then uses that energy to build carbohydrates. We might best recognize this bacterium as the rust-colored ring that builds up inside toilet bowls. Thiobacillus ferrooxidans is an example of a

Fossilized stromatolites

Which of the following is the correct sequence of events in the origin of life? I. formation of protobionts II. synthesis of organic monomers III. synthesis of organic polymers IV. formation of DNA-based genetic systems