quiz 2

A colony of antibiotic-resistant bacteria is mixed with a colony of antibiotic-sensitive bacteria. After a few days ALL of the bacteria are now resistant to the antibiotic. Which of these is most likely to result in this rapid spread of resistance in a bacterial population? (HINT: assume no antibiotic resistant bacteria died) A) Conjugation B) Binary fission C) Transformation D) Transduction

A

Binary fission in prokaryotes is a form of _____________________ because a single individual is the sole parent and passes copies of all its genes to its offspring. A) asexual reproduction B) sexual reproduction C) mitosis D) meiosis

A

One criticism of the conclusion of Lederburg and Tatum that their experiment provided evidence for genetic recombination between bacteria is that it could be that the cells of the two strains do not really exchange genes but instead leak substances that the other cells can absorb and use for growing. This possibility was ruled out by a follow-up experiment performed by Bernard Davis. He constructed a U-tube (seen in the image above) in which the two arms are separated by a fine filter. The pores of the filter are too small to allow bacteria to pass through but large enough to allow easy passage of the fluid medium and any dissolved substances. Strain A was put in one arm; strain B in the other. After the strains had been incubated for a while, Davis tested the content of each arm to see if cells had become able to grow on a minimal medium, and none were found. How did the Davis experiment support the conclusion of Lederburg and Tatum? A) It ruled out the possibility the medium contained substances that allowed the Strain A and B bacteria to grow on a minimal medium. B) It demonstrated that bacterial DNA is passed from one individual to another. C) It demonstrated that bacteria that are kept physically separate experience genetic recombination.

A

The bacterium Bacteroides thetaiotaomicron is common in the human gut and is very good at digesting polysaccharides that we find indigestible. By breaking down these polysaccharides, the bacteria produce smaller compounds that our bodies can use for nutrients and energy. When Bacteroides thetaiotaomicron escapes the gut, it can cause infections and abscesses in many parts of the body. Infection from Bacteroides thetaiotaomicron is an important side effect of abdominal surgeries and populations of the bacteria are almost universally resistant to penicillin. Bacteroides thetaiotaomicron has a thin layer of peptidoglycan and outer membrane with lipopolysaccharides. It cannot tolerate the presence of oxygen. Bacteroides thetaiotaomicron can be classified as a ________________________________________. A) gram(-) obligate anaerobe B) gram(-) obligate aerobe C) gram(+) obligate anaerobe D) gram(+) obligate aerobe

A

Which of the following statements about the systemic effect of bacterial cells on human health is true? A) Gram(-) bacteria are more likely to cause systemic effects because their outer membrane protects them from antibiotics, making treatment more difficult. B) Gram(+) bacteria are more likely to cause system effects because the peptidoglycan in their cell walls is tough and hard for medicine to penetrate. C) Gram (+) bacteria are more likely to cause systemic effects because the lipopolysaccharide (LPS) in their membranes can act as a toxin. D) Gram(-) bacteria are more likely to cause systemic effects because their lack of an outer membrane means they can more quickly infect host cells.

A

A colony of antibiotic-resistant bacteria is mixed with a colony of antibiotic-sensitive bacteria. After a few days grown in the presence of antibiotics, all of the bacteria are resistant to the antibiotic. Which of these is most likely to result in this rapid spread of resistance in a bacterial population? A) Conjugation B) Transformation C) Transduction D) All of the above are equally responsible for the spread of antibiotic resistance

A transformation: prokaryotes aquire genes from the surrounding environment conjugation: 2 living prokaryotes join together transduction: host cells transfer bacteria

Prokaryote populations have a great amount of genetic diversity - how does this large amount of genetic variation arise? Select all that apply. A) They have extremely short generation times and large populations. B) They can exchange DNA with many types of prokaryotes by way of horizontal gene transfer. C) Prokaryotes lack a nucleus. D) Prokaryotes have simpler metabolic abilities than eukaryotes.

A & B

In 1946, Lederburg and Tatum conducted a classic experiment in microbiology. They studied two different strains of E. coli bacteria (strain A and strain B). E. coli is a rod-shaped bacterium with a thin layer of peptidoglycan and a complex outer membrane. Strain A grows on a minimal medium (a gel-based substance that contains nutrients for bacterial growth) only if the medium is supplemented with methionine and biotin; strain B grows on a minimal medium only if it is supplemented with threonine, leucine, and thiamine (see image above). The notation below the label "Strain A" means that these bacteria can synthesize threonine, leucine, and thiamine but not methionine or biotin. Strain B can synthesize methionine and biotin but not threonine, leucine, or thiamine. A minimal medium lacks threonine, leucine, thiamine, methionine and biotin. When Strain A E. coli are mixed with Strain B E. coli (the middle test tube in the image above) and allowed to incubate for several hours in a complete medium, the resulting bacteria can grow on a minimal medium. The Lederburg and Tatum experiment provided evidence for genetic recombination between bacteria but could not provide evidence of a mechanism for this recombination. Which of the following are possible methods of genetic recombination in bacteria? A) Conjugation B) Transformation C) Transduction D) Binary fission

A & B & C

Which of the following are true of model organisms used in biology research? A) They are non-human organisms. B) They are typically easy to breed and maintain in a laboratory. C) They tend to have short generation times. D) They typically do not share many characteristics with humans. E) They often share genetic traits with humans.

A & B & C & E

Identify the true statements about the nutritional modes in bacteria. Select all that apply. A) Phototrophs may be autotrophs or heterotrophs. B) All phototrophs are heterotrophs. C) Chemotrophs may be autotrophs or heterotrophs. D) Autotrophs may be chemotrophs or phototrophs. E) All heterotrophs are phototrophs. F) Heterotrophs may be chemotrophs or phototrophs. G) All autotrophs are chemotrophs. H) All chemotrophs are autotrophs.

A & C & D & F

Azotobacter is a genus of bacteria that live in soil and have the following characteristics: They are bacilli. They are gram-negative. They are obligate aerobes. They can fix nitrogen. (Unlike some other nitrogen-fixing bacteria, which associate with the roots of plants, Azotobacter species are free-living.) Select the statements that are true for bacteria in the genus Azotobacter. A) They are shaped like rods. B) They require amino acids or other organic molecules as a source of nitrogen. C) They appear purple after Gram staining. D) They have the appearance of coils or corkscrews. E) They are poisoned by O2. F) They can convert atmospheric nitrogen to ammonia. G) They use O2. H) They have a relatively thin layer of peptidoglycan in their cell wall.

A & F & G & H

(decreasing oxygen concentrationgraph) Based on the information in this graph, you would predict nitrogen-fixing bacteria would live in environments with a: A) high oxygen concentration. B) low oxygen concentration. C) high nitrogen concentration. D) low nitrogen concentration.

B

In 1946, Lederburg and Tatum conducted a classic experiment in microbiology. They studied two different strains of E. coli bacteria (strain A and strain B). E. coli is a rod-shaped bacterium with a thin layer of peptidoglycan and a complex outer membrane. Strain A grows on a minimal medium (a gel-based substance that contains nutrients for bacterial growth) only if the medium is supplemented with methionine and biotin; strain B grows on a minimal medium only if it is supplemented with threonine, leucine, and thiamine (see image above). The notation below the label "Strain A" means that these bacteria can synthesize threonine, leucine, and thiamine but not methionine or biotin. Strain B can synthesize methionine and biotin but not threonine, leucine, or thiamine. A minimal medium lacks threonine, leucine, thiamine, methionine and biotin. When Strain A E. coli are mixed with Strain B E. coli (the middle test tube in the image above) and allowed to incubate for several hours in a complete medium, the resulting bacteria can grow on a minimal medium. What type of bacterium is E. coli? A) Gram(+) bacillus B) Gram(-) bacillus C) Gram(+) coccus D) Gram(-) coccus

B

In 1946, Lederburg and Tatum conducted a classic experiment in microbiology. They studied two different strains of E. coli bacteria (strain A and strain B). E. coli is a rod-shaped bacterium with a thin layer of peptidoglycan and a complex outer membrane. Strain A grows on a minimal medium (a gel-based substance that contains nutrients for bacterial growth) only if the medium is supplemented with methionine and biotin; strain B grows on a minimal medium only if it is supplemented with threonine, leucine, and thiamine (see image above). The notation below the label "Strain A" means that these bacteria can synthesize threonine, leucine, and thiamine but not methionine or biotin. Strain B can synthesize methionine and biotin but not threonine, leucine, or thiamine. A minimal medium lacks threonine, leucine, thiamine, methionine and biotin. When Strain A E. coli are mixed with Strain B E. coli (the middle test tube in the image above) and allowed to incubate for several hours in a complete medium, the resulting bacteria can grow on a minimal medium. Which of the following is a reasonable conclusion from the Lederburg and Tatum experiment? A) Bacterial conjugation is responsible for the production of E. coli that can grow on a minimal medium. B) Some form of recombination of genes had taken place between the genomes of the two strains to produce individuals capable of growing on minimal medium. C) Bacterial transformation is responsible for the production of E. coli that can grow on a minimal medium. D) Bacterial transduction is responsible for the production of E. coli that can grow on a minimal medium.

B

In Tutorial #1, you learned about the Evolution Canyons in Israel. The south-facing slope (A) is hot and dry while the north facing slope (B) is cool and wet. Studies of bacterial populations living in the soils of Evolution Canyon have shown that these populations have different metabolic abilities depending upon whether they live on the north slope or the south slope. Which is a plausible hypothesis for why populations of the bacterium Bacillus subtilis living on south-facing slopes of Evolution Canyon have more efficient biosynthesis than those living on north-facing slopes? A) The bacteria are from different species and are expected to have different biosynthetic abilities. B) The south-facing slopes are a more extreme environment and efficient biosynthesis is an adaptation to this environment. C) The south-facing slope has more resources available for growth so the bacteria have more energy to biosynthesize at a greater rate. D) The south-facing slope is the more desirable habitat and the bacteria with greater biosynthetic ability outcompeted the others for this habitat.

B

Methanopyrus kandleri is an organism which lives in a hydrogen-carbon dioxide environment, and was first discovered in a hydrothermal vent where temperatures reached 230°F. What sort of organism is this most likely? A) Cyanobacteria B) Archaea C) Bacteria D) Protist

B

The bacterium Bacteroides thetaiotaomicron is common in the human gut and is very good at digesting polysaccharides that we find indigestible. By breaking down these polysaccharides, the bacteria produce smaller compounds that our bodies can use for nutrients and energy. When Bacteroides thetaiotaomicron escapes the gut, it can cause infections and abscesses in many parts of the body. Infection from Bacteroides thetaiotaomicron is an important side effect of abdominal surgeries and populations of the bacteria are almost universally resistant to penicillin. What is the best description of our symbiotic relationship with this bacterium when our guts are intact? A) Commensalism B) Mutualism C) Parasitism D) There is no symbiotic relationship between humans and our gut microbes

B

The nitrogen-fixing bacterium Rhizobium infects the roots of some plant species, forming a mutualism in which the bacterium provides fixed nitrogen and the plant provides carbohydrates. Scientists measured the 12-week growth of one such plant species (Acacia irrorata) when infected by six different Rhizobium strains. The resulting data are shown in the table and in the graph.Note: Without Rhizobium, after 12 weeks, acacia plants have a mass of about 0.1 g. Rhizobium strain 1 2 3 4. 5 6 Plant mass (g) 0.91 0.06 1.56 1.72 0.14 1.03 What conclusion can you draw from this data? A) None of the Rhizobium strains used in the study have a substantial positive effect in promoting plant growth. B) Some Rhizobium strains are much more effective at promoting plant growth than other strains; the most ineffective strains have little positive effect. C) All Rhizobium strains have a similar, highly positive effect on plant growth. D) Some Rhizobium strains are much more effective at promoting plant growth than other strains; however, even the most ineffective strains have a significant positive effect.

B

What are introns? A) The coding regions of a gene B) The non-coding regions of a gene C) Unique carbohydrates that are only found in the Archaea. D) Membrane-bound organelles that are only found in the Archaea.

B

Which of the following is a characteristic of the Archaea that results in the conclusion that they are more closely related to the Eukaryotes than they are to the Bacteria? A) Archaea have membrane-bound organelles. B) Archaea have introns. C) Archaea have peptidoglycan. D) Archaea are extremophiles.

B

While working for the Centers for Disease Control and Prevention (CDC), you are asked to describe the characteristics of two types of pathogenic bacteria: Neisseria meningitidis: causes bacterial meningitis Bacillus anthracis: causes anthrax poisoning You explain that N. meningitidis is a sphere-shaped bacterium that has a thick layer of endotoxic lipopolysaccharides in its cell wall and is not capable of forming an endospore, and that B. anthracis is a rod-shaped bacterium that has a thick layer of peptidoglycan in its cell wall and can form an endospore. If you perform a complete Gram stain on a sample of Bacillus anthracis, it will stain A) pink B) purple C) the bacterium is gram negative so it will not take up any stain and appear clear.

B

While working for the Centers for Disease Control and Prevention (CDC), you are asked to describe the characteristics of two types of pathogenic bacteria: Neisseria meningitidis: causes bacterial meningitis Bacillus anthracis: causes anthrax poisoning You explain that N. meningitidis is a sphere-shaped bacterium that has a thick layer of endotoxic lipopolysaccharides in its cell wall and is not capable of forming an endospore, and that B. anthracis is a rod-shaped bacterium that has a thick layer of peptidoglycan in its cell wall and can form an endospore. Neisseria meningitidis is classified as a A) Gram(+) coccus B) Gram(-) coccus C) Gram(+) bacillus D) Gram(-) bacillus

B gram neg: a thin layer of peptidoglycan in its cell wall coccus: sphere shaped bacillus: rod shaped

While working for the Centers for Disease Control and Prevention (CDC), you are asked to describe the characteristics of two types of pathogenic bacteria: Neisseria meningitidis: causes bacterial meningitis Bacillus anthracis: causes anthrax poisoning You explain that N. meningitidis is a sphere-shaped bacterium that has a thick layer of endotoxic lipopolysaccharides in its cell wall and is not capable of forming an endospore, and that B. anthracis is a rod-shaped bacterium that has a thick layer of peptidoglycan in its cell wall and can form an endospore. If you perform a complete Gram stain on a sample of Neisseria meningitidis, it will stain A) purple B) pink C) the bacterium is gram negative so it will not take up any stain and appear clear.

B neg: pink pos: purple

Which of the following is(are) example(s) of lateral gene transfer in the prokaryotes? Select all that apply. A) Binary fission B) Conjugation C) Transduction D) Transformation E) Meiosis F) Sexual reproduction

B & C & D

Listeriosis is a serious bacterial infection in humans and is most often contracted by eating food contaminated with the bacterium Listeria. It can cause sepsis and meningitis, and is able to cross the placenta. Species within the genus Listeria have lots of peptidoglycan in their cell walls and are rod-shaped. Which of these terms apply to these bacteria? Select all that apply. A) Cocci B) Bacillus C) Spririlli D) Gram positive E) Gram negative F) Mutualism G) Commensalism H) Parasitism

B & D & H

In 1946, Lederburg and Tatum conducted a classic experiment in microbiology. They studied two different strains of E. coli bacteria (strain A and strain B). E. coli is a rod-shaped bacterium with a thin layer of peptidoglycan and a complex outer membrane. Strain A grows on a minimal medium (a gel-based substance that contains nutrients for bacterial growth) only if the medium is supplemented with methionine and biotin; strain B grows on a minimal medium only if it is supplemented with threonine, leucine, and thiamine (see image above). The notation below the label "Strain A" means that these bacteria can synthesize threonine, leucine, and thiamine but not methionine or biotin. Strain B can synthesize methionine and biotin but not threonine, leucine, or thiamine. A minimal medium lacks threonine, leucine, thiamine, methionine and biotin. When Strain A E. coli are mixed with Strain B E. coli (the middle test tube in the image above) and allowed to incubate for several hours in a complete medium, the resulting bacteria can grow on a minimal medium. Conjugation, transformation, and transduction are all examples of _________________. A) mitosis B) meiosis C) lateral gene transfer D) vertical gene transfer

C

One criticism of the conclusion of Lederburg and Tatum that their experiment provided evidence for genetic recombination between bacteria is that it could be that the cells of the two strains do not really exchange genes but instead leak substances that the other cells can absorb and use for growing. This possibility was ruled out by a follow-up experiment performed by Bernard Davis. He constructed a U-tube (seen in the image above) in which the two arms are separated by a fine filter. The pores of the filter are too small to allow bacteria to pass through but large enough to allow easy passage of the fluid medium and any dissolved substances. Strain A was put in one arm; strain B in the other. After the strains had been incubated for a while, Davis tested the content of each arm to see if cells had become able to grow on a minimal medium, and none were found. Which of the following is a valid conclusion of the Davis experiment? A) DNA is responsible for genetic recombination. B) Viruses are able to move bacterial DNA from one bacterium to another. C) The Strain A and Strain B bacteria must come in physical contact in order for genetic recombination to occur. D) Bacteria are capable of taking up naked DNA from the environment.

C

The bacterium Bacteroides thetaiotaomicron is common in the human gut and is very good at digesting polysaccharides that we find indigestible. By breaking down these polysaccharides, the bacteria produce smaller compounds that our bodies can use for nutrients and energy. When Bacteroides thetaiotaomicron escapes the gut, it can cause infections and abscesses in many parts of the body. Infection from Bacteroides thetaiotaomicron is an important side effect of abdominal surgeries and populations of the bacteria are almost universally resistant to penicillin. What is the best description of our symbiotic relationship with this bacterium when our guts have been compromised and the bacteria are able to leave the abdomen? A) Commensalism B) Mutualism C) Parasitism

C

What type(s) of cells do you obtain after a F+ bacterium conjugates with a F- bacterium? A) Two bacteria with identical plasmid and chromosomal DNA, but one is F+, and the other F- B) One new F- bacterium which transferred the plasmid to the other cell, which is now F+ C) Two F+ bacteria with identical plasmid but not chromosomal DNA D) Two F+ bacteria with identical plasmid and chromosomal DNA

C

Which of the following can be concluded from this image? A) The Eubacteria and the Archaebacteria are more closely related to each other than either group is to the Eukaryotes. B) The Eukaryotes and the Bacteria are more closely related to each other than either group is to the Archaebacteria. C) The Archaebacteria and the Eukaryotes are more closely related to each other than either is to the Eubacteria.

C

Which of the following structures is found in ALL prokaryotes? A) Nucleus B) Mitochondria C) Ribosomes D) Flagella

C

While working for the Centers for Disease Control and Prevention (CDC), you are asked to describe the characteristics of two types of pathogenic bacteria: Neisseria meningitidis: causes bacterial meningitis Bacillus anthracis: causes anthrax poisoning You explain that N. meningitidis is a sphere-shaped bacterium that has a thick layer of endotoxic lipopolysaccharides in its cell wall and is not capable of forming an endospore, and that B. anthracis is a rod-shaped bacterium that has a thick layer of peptidoglycan in its cell wall and can form an endospore. Bacillus anthracis is classified as a A) Gram(+) coccus B) Gram(-) coccus C) Gram(+) bacillus D) Gram(-) bacillus

C

Porphyromonas gingivalis is a Gram(-) bacterium found in the human mouth. It is negatively affected by the presence of oxygen. What term best describes this bacterium? A) Facultative anaerobe B) Obligate aerobe C) Obligate anaerobe

C Obligate anaerobes cannot grow in the presence of oxygen Facultative anaerobes show better growth in the presence of oxygen but will also grow without it

A researcher discovers a new species of bacteria that obtains its energy from other organisms and its carbon from the atmosphere. This species can be categorized based upon its mode of nutrition as a: A) chemoheterotroph. B) photoautotroph. C) photoheterotroph. D) chemoautotroph.

D

In a hypothetical situation, the genes for sex pilus construction and for penicillin 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 A) the production of endospores among the bacterium's progeny. B) the subsequent loss of penicillin resistance from this bacterium. C) a bacterium that has undergone transduction. D) the rapid spread of penicillin resistance to other bacteria in that habitat.

D

One criticism of the conclusion of Lederburg and Tatum that their experiment provided evidence for genetic recombination between bacteria is that it could be that the cells of the two strains do not really exchange genes but instead leak substances that the other cells can absorb and use for growing. This possibility was ruled out by a follow-up experiment performed by Bernard Davis. He constructed a U-tube (seen in the image above) in which the two arms are separated by a fine filter. The pores of the filter are too small to allow bacteria to pass through but large enough to allow easy passage of the fluid medium and any dissolved substances. Strain A was put in one arm; strain B in the other. After the strains had been incubated for a while, Davis tested the content of each arm to see if cells had become able to grow on a minimal medium, and none were found. Based on your answer to the previous question, what is the mechanism of recombination that occurred in the Lederburg and Tatum experiment? A) Binary fission B) Transduction C) Transformation D) Conjugation

D

What is lateral gene transfer? A) Inheritance of a gene through mitosis B) Inheritance of a gene through meiosis C) Inheritance of a gene from a parent D) Physical transfer of a gene from a species in one lineage to a species in another lineage.

D

True or False. Based on this phylogenetic tree, the lack of a membrane-bound nucleus is a useful characteristic for distinguishing the Eubacteria from the Archaebacteria. True False

False

___________________ use light energy to drive the synthesis of organic compounds from carbon dioxide.

photoautotroph