Unit 8: Ch.24.MC

How were conditions on the early Earth of more than 3 billion years ago different from those on today's Earth?

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

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

The first genes on Earth were probably

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?

Approximately how far back in time does the fossil record extend?

Scientists hypothesize that prokaryotes evolved before eukaryotes because

Suppose it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.5-billion-year-old stromatolites. Which of the following structures would be surprising to observe? I. RNA II. vesicles III. A nucleus IV. ribozymes

In 2009, which of the following did scientists discover was possible on early Earth?

The first genetic material on early Earth was most likely

Which of the following is likely the greatest impact that organisms have ever had on Earth?

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

The predatory bacterium Bdellovibrio bacteriovorus 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. Bacteriovorus on its way to the prey's cytoplasm? 1. Membrane composed mostly of lipopolysaccharide 2. Membrane composed mostly of phospholipids 3. peptidoglycan 4. capsule

Jams, jellies, preserves, honey, and other foodstuffs with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment

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 structure(s)? 1. Nucleoid region 2. endospore 3. fimbriae 4. plasmids

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

The typical prokaryotic flagellum features

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

Which statement about the genomes of prokaryotes is correct?

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

Prokaryotes' essential genetic information is located in the

Chloramphenicol is an antibiotic that targets prokaryotic (70S) ribosomes, but not eukaryotic (80S) ribosomes. Which of these questions stems from this observation plus an understanding of eukaryotic origins?

Match the numbered terms to the description that follows. Choose all appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph a prokaryote that obtains both energy and carbon as it decomposes dead organisms

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

Match the numbered terms to the description that follows. Choose all appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph an organism that obtains energy from light

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

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

Although not present in all bacteria, this cell covering often enables cells that possess it to resist the defenses of host organisms, especially their phagocytic cells.

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

Why can prokaryotic populations be magnitudes larger than populations of multicellular eukaryotes? I. Prokaryotes are small. II. Prokaryotes reproduce by binary fission. III. Prokaryotes often have short generation times. IV. Prokaryotes have cells walls primarily made of cellulose.

Regarding prokaryotic genetics, which statement is correct?

Which of these statements about prokaryotes is correct?

Which of the following is least associated with the others?

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?

Suppose bacteria are grown on a petri dish that contains nutrient agar and the antibiotic ampicillin. After observing the bacteria growth on the plate for two days, you notice that only some of the bacteria have survived. What is a plausible explanation for your observations?

Scientists have identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains?

Which statement about the domain Archaea is true?

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

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

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

The thermoacidophile Sulfolobus acidocaldarius lacks peptidoglycan, but still possesses a cell wall. What is likely to be true of this species? 1. It is a bacterium. 2. It is an archaean. 3. The optimal pH of its enzymes lies above pH 7. 4. The optimal pH of its enzymes lies below pH 7. 5. It could inhabit certain hydrothermal springs. 6. It could inhabit alkaline hot springs.

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

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

What is a main difference between endotoxins and exotoxins?

Which of the following is an important source of endotoxin in gram-negative species?

The termite gut protist Mixotricha paradoxa has at least two kinds of bacteria attached to its outer surface. One kind is a spirochete that propels its host through the termite gut. A second type of bacteria synthesizes ATP, some of which is used by the spirochetes. The locomotion provided by the spirochetes introduces the ATP-producing bacteria to new food sources. Which of the following terms is (are) applicable to the relationship between the two kinds of bacteria? 1. mutualism 2. parasitism 3. symbiosis 4. Metabolic cooperation

In general, what is the primary ecological role of prokaryotes?

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

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. 1. Nutrient recycler 2. mutualist 3. commensal 4. pathogen 5. Primary producer

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