Microbiology- Exam 2

Which of the following is (are) used to classify viruses? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. - Capsid symmetry - Type of nucleic acid present - Viral genome size - Viral particle size

- Capsid symmetry - Type of nucleic acid present

You suspect that your patient has a urinary tract infection caused by Proteus vulgaris, a motile bacterium with peritrichous flagella. Which of the following physical states of media is best for observing motility of this pathogen once isolated? - Broth media - Semisolid deep - Solid plate - Solid slant

- Semisolid deep

In a DNA strand, the phosphate group of one nucleotide is connected to _______ in the adjacent nucleotide - The 3' Carbon - The 5' carbon - The phosphate group - The nitrogenous base

- The 3' Carbon

You observe that when you grow Serratia marcescens at human body temperature, the resulting bacterial colonies appear white. However, when you grow the same bacterium at room temperature, the colonies that grow are red. This difference in pigmentation is best described as a ____________. - phenotype difference - genotype difference - genome difference - gene difference

- phenotype difference

Which of the following RNA brings the correct amino acid to a ribosome to build proteins during translation? - mRNA - tRNA - rRNA - all of the above

- tRNA

The rabies virus primarily affects the nervous system. The specificity that the rabies virus has for neuronal host cells is primarily dictated by __________________________. - the type of nucleic acid used for its viral genome (single-stranded, antisense RNA) - the spikes that protrude from its viral envelope - the helical shape of its viral capsid - the segmented nature of its viral genome

- the spikes that protrude from its viral envelope

Viruses are considered to be non-living pathogens for which reason? - their extremely small size - their ability to synthesize only some of their own components - their lack of metabolic processes - their unique type of cells

- their lack of metabolic processes

Which property is not used to classify viruses? - type of nucleic acid present - capsid symmetry - presence or absence of an envelope - tissue types infected

- tissue types infected

Mycobacterium tuberculosis are grown for 80 hours. During that time, they go through four generations of growth. What is the generation time? - 10 hours - 20 hours - 40 hours - 20 minutes

- 20 hours

Staphylococcus aureus is grown in heart-infusion broth at 37°C. If you start exponential phase with 100 cells, and after 90 minutes you have 800 cells, what is the generation time for S. aureus? - 11.25 minutes - 0.03 minutes - 0.11 minutes - 30.00 minutes

- 30.00 minutes

In Eukaryotes, which of the following is the most condensed form of DNA? - A chromosome - DNA wrapped around a histone - A nucleosome - A nucleiod

- A chromosome

Which description of antigenic drift and antigenic shift in the influenza virus is incorrectly matched? - Antigenic drift: Spontaneous mutation leads to a minor change in HA or NA spikes. - Antigenic drift: A host vaccinated against an influenza strain before antigenic drift may lack effective immunity and be susceptible to infection. - Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans. - Antigenic shift: May result in a pandemic outbreak due to widespread lack of immunity

- Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans.

Which replicative step(s) do animal viruses and bacteriophages have in common? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. - Attachment - Assembly - Uncoating - Penetration

- Attachment - Assembly - Penetration

Which statement is not true about the virus capsid? - Both bacteriophage and animal viruses have capsids. - The capsid determines the shape of the virus. - The capsid is made of one or more types of protein subunits. - Because the capsid is not essential to the virus, it is not a useful target for antiviral drugs.

- Because the capsid is not essential to the virus, it is not a useful target for antiviral drugs.

Which of the following is not a mechanism for horizontal gene transfer? - Conjugation - Transduction - Binary fission - Transformation

- Binary fission

Which of the following is a key distinguishing characteristic between budding and binary fission? - While binary fission results in the creation of genetically identical daughter cells, budding results in daughter cells that are genetically diverse. - Budding is a much more common mechanism of bacterial reproduction than binary fission is. - You will recall that budding is an example of sexual reproduction, whereas binary fission is an example of asexual reproduction. - Binary fission results in daughter cells of equal size, whereas budding is an uneven division

- Binary fission results in daughter cells of equal size, whereas budding is an uneven division

Chlamydia trachomatis is an obligate intracellular bacterium that causes the sexually transmitted disease chlamydia. When this bacterium was first discovered, it was classified as a virus. However, it was later re-classified as a bacterium. Which of the following is the most likely reason why C. trachomatis was reclassified as a living bacterial cell as opposed to a nonliving viral particle? - Chlamydia trachomatis is visible with a compound light microscope. - Chlamydia trachomatis is capable of performing metabolic processes. - Chlamydia trachomatis has a genome consisting of double-stranded DNA. - Chlamydia trachomatis lacks membrane-bound organelles, such as a nucleus.

- Chlamydia trachomatis is capable of performing metabolic processes.

Which of the following is an unsuitable culture method for an animal virus? - Direct inoculation of virus onto blood agar - Tissue culture method - Live animal inoculation - Injection of virus into embryonated eggs

- Direct inoculation of virus onto blood agar

Your elderly patient is affected by shingles. After careful observation, you note that the virus responsible for the infection has an icosahedral capsid, is enveloped, and has double-stranded linear DNA as its genetic material. Based on this information, in which of the following viral families would you group this viral pathogen? - Parvoviridae - Coronaviridae - Herpesviridae - Hepadnaviridae

- Herpesviridae

Choose the true statement about housekeeping genes in Escherichia coli. - Examples of housekeeping genes in E. coli include antibiotic resistance genes and lactose catabolism genes. - Housekeeping genes are constitutively expressed. - A housekeeping gene's expression should stop when the cell is placed in a different environment. - Most of E. coli's genome encodes housekeeping genes.

- Housekeeping genes are constitutively expressed

Which of the following is an example of phage conversion? - Infection of Streptococcus pyogenes with T12 phage enables the bacteria to produce erythrogenic toxins, allowing it to cause scarlet fever. - Despite a single infection, ultimately multiple host cells will carry the bacteriophage genome during the lysogenic replication cycle. - Lambda phages can use either the lytic cycle or lysogenic pathway for replication. - Following injection of viral nucleic acid into a host cell, the genetic material is incorporated into the host genome.

- Infection of Streptococcus pyogenes with T12 phage enables the bacteria to produce erythrogenic toxins, allowing it to cause scarlet fever.

Which of the following statements about transcription in prokaryotes is false? - It uses DNA as the template to make RNA. - It uses RNA polymerase as the main enzyme. - It is tightly regulated by the cell. - It occurs in the nucleus.

- It occurs in the nucleus.

Of the following enzymes, which are correctly matched with their function? To be marked correct, you'll need to select all correctly matched statements, as there may be more than one correct answer. - Ligase, covalently bonds adjacent Okazaki fragments - Primase, removes RNA primers - Helicase, relieves torsion stress as DNA unwinds - DNA polymerase III, builds most of the DNA on the leading and lagging strand

- Ligase, covalently bonds adjacent Okazaki fragments - DNA polymerase III, builds most of the DNA on the leading and lagging strands

Urinary tract infections are commonly caused by Staphylococcus saprophyticus and Escherichia coli, less commonly caused by Proteus mirabilis. You have a mixed culture of these pathogens, which you inoculate onto both MacConkey agar and nutrient agar, and then you incubate the plates at optimal growth conditions. On the MacConkey agar, E. coli appears pink, P. mirabilis appears colorless, and S. saprophyticus does not grow. All three microorganisms appear cream on the nutrient agar plate. What is the best explanation for this data? MacConkey agar is a selective medium whereas nutrient agar is a differential medium. - Nutrient agar is both a selective and differential medium. - MacConkey agar is a differential medium, whereas nutrient agar is a selective medium. - MacConkey is both a differential and a selective medium.

- MacConkey is both a differential and a selective medium.

________ RNA carries a genetic message in triplet code (codons) and is translated to build a protein. - Messenger - Ribosomal - Transfer - Alternative

- Messenger

CIDEX is an activated glutaraldehyde solution used to kill microbial cells on medical instruments. Which of the following terms best describes CIDEX? - Microbiostatic antiseptic - Microbiostatic disinfectant - Microbiocidal antiseptic - Microbiocidal disinfectant

- Microbiocidal disinfectant

Choose the true statement(s) about mutations. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. - Mutation leads to genetic and phenotypic variation within a species. - Evolution rates are faster in bacteria than in humans because most mutations in human cells are silent. - In humans, somatic cell mutations are not passed to offspring. - Mutations can provide an evolutionary benefit.

- Mutation leads to genetic and phenotypic variation within a species. - In humans, somatic cell mutations are not passed to offspring. - Mutations can provide an evolutionary benefit.

You wish to culture and quantify T4 bacteriophages. Which of the following techniques would be the most relevant? - Perform a latex agglutination test using T-even antibodies linked to latex beads. - Perform a tissue culture using HeLa cells. - Perform an allantoic cavity injection using an embryonated egg. - Perform a plaque assay using the bacterium Escherichia coli.

- Perform a plaque assay using the bacterium Escherichia coli.

Choose the true statement(s) about plasmids. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. - Plasmids usually consist of single stranded DNA. - Plasmids tend to exist outside of a cell's chromosome. - Plasmids often contain genes that confer a survival advantage to a cell. - Plasmid tend to be circular.

- Plasmids tend to exist outside of a cell's chromosome. - Plasmids often contain genes that confer a survival advantage to a cell. - Plasmid tend to be circular.

Which of the following microbial temperature classifications is improperly matched with its potential growth environment? - Thermophile - compost pile - Extreme thermophile - hydrothermal vent - Mesophile - human large intestine - Psychrotroph - arctic lake sediment

- Psychrotroph - arctic lake sediment

Key mechanisms of horizontal gene transfer include all of the following except: - Conjugation. - Transformation. - Transduction. - Reproduction.

- Reproduction.

Which of the following contributes to DNA replication accuracy? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. - The use of primase improves DNA replication accuracy. - The capacity to proofread improves DNA replication accuracy. - A slow rate of DNA replication contributes to accuracy. - DNA replication accuracy is improved thanks to complementary base pairing rules.

- The capacity to proofread improves DNA replication accuracy. - DNA replication accuracy is improved thanks to complementary base pairing rules.

Your patient has a suspected case of gas gangrene, which is caused by the obligate anaerobe Clostridium perfringens. Which of the following considerations should be made when culturing this organism? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. - The clinical specimen should be placed inside of a candle jar during incubation. - The clinical specimen should be placed inside a small anaerobic jar or chamber during incubation. - The clinical specimen should be quickly deposited and capped in a vial with a reducing agent. - The clinical specimen should be grown at a cooler temperature.

- The clinical specimen should be placed inside a small anaerobic jar or chamber during incubation. - The clinical specimen should be quickly deposited and capped in a vial with a reducing agent.

Which of the following is a key difference between lytic and lysogenic bacteriophage replication cycles? - Lysogenic bacteriophages release via host cell lysis, whereas lytic bacteriophages bud off from the host cell membrane. - Whereas lytic replication enables the infection of several hosts, lysogenic replication only allows for infection of a single host cell. - The lytic replication cycle ends with host cell lysis and release of newly formed bacteriophage particles, whereas lysogenic replication leads to prophage formation. - Lytic replication requires an uncoating step, whereas in lysogenic replication, the bacteriophage's nucleic acid is directly injected into the host cell.

- The lytic replication cycle ends with host cell lysis and release of newly formed bacteriophage particles, whereas lysogenic replication leads to prophage formation.

How do halophiles combat osmotic stress? - They enrich their plasma membrane with basic compounds to attract OH- ions to their cell surface. - They build special monolayer plasma membranes. - They use proton pumps to export excess protons from the cytoplasm. - They keep a high concentration of organic materials and ions in their cytoplasm.

- They keep a high concentration of organic materials and ions in their cytoplasm.

Which of the following are ways that viruses differ from prokaryotes and eukaryotes? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. - Unlike prokaryotes and eukaryotes, viruses are classified as acellular particles. - Unlike prokaryotes and eukaryotes, viruses do not have genomes. - Unlike prokaryotes and eukaryotes, viruses are incapable of replicating independently from a host cell. - Unlike prokaryotes and eukaryotes, viruses are not considered alive.

- Unlike prokaryotes and eukaryotes, viruses are classified as acellular particles. - Unlike prokaryotes and eukaryotes, viruses are incapable of replicating independently from a host cell. - Unlike prokaryotes and eukaryotes, viruses are not considered alive.

Helicase: - Causes a bubble of single-stranded DNA to form. - Allows for DNA polymerase III to bind to the DNA. - Unwinds the DNA. - Relieves coiling tension that develops as the helix is unwound.

- Unwinds the DNA

Which of the following nitrogen bases is found only in RNA and NOT in DNA? - Uracile - Thymine - Cytosine - Guanine

- Uracile

Viral spikes - allow the virus to attach and enter host cells. - may be a target for the host immune system. - show specificity in binding to particular structures on the host cell. - all of the above

- all of the above

Which of the following terms refers to bacteria reproducing asexually by dividing the cell in half and resulting in two daughter cells? - budding - binary fission - sporulation - hypha

- binary fission

Viruses which infect many different tissues types are said to have a(n) - broad host range. - broad tropism. - narrow host range - narrow tropism

- broad tropism

Compared to eukaryotic genomes, only prokaryotic genomes: - have chromosomes contained in a nucleus. - contain DNA organized by histones. - contain usually one, circular chromosome. - contain plasmid DNA.

- contain usually one, circular chromosome.

Bacterial cells use DNA replication to: -copy their genetic material prior to binary fission. - manifest multiple phenotypes at once. - build functional proteins. - make back-up copies of their genome in case of a mutation.

- copy their genetic material prior to binary fission.

Nutrients that a cell needs to build new cells and make up a bulk of a cell's dry weight are called - micronutrients. - trace nutrients. - essential nutrients. - complex nutrients

- essential nutrients.

Which group of microbes prefers using oxygen but can survive without it? - obligate aerobe - obligate anaerobe - facultative anaerobe - aerotolerant anaerobe

- facultative anaerobe

The key event that occurs during lysogenic replication of bacteriophage that does not occur during lytic replication is - assembly of new phage by packing viral genomes into capsids. - attachment of the phage to specific proteins in the bacterial cell. - integration of the phage DNA into the host cell DNA. - penetration of the phage DNA into the host cell.

- integration of the phage DNA into the host cell DNA.

When a virus has an envelope, - it likely escapes its host cell by budding. - it likely escapes its host cell by lysis. - it may escape its host cell either by budding or by lysis. - it is always a bacteriophage.

- it likely escapes its host cell by budding

In which growth phase do bacteria adjust to their environment and grow little, if any? - lag - log - stationary - death

- lag

In which growth phase is characterized by bacteria growing exponentially? - lag - log - stationary - death

- log

Low-level disinfectants are sufficient to remove microbes from which of the following equipment tiers? - non-vital - semicritical - noncritical - vital

- noncritical

TRUE or FALSE: Bacterial endospore formation is a type of sexual reproduction. TRUE FALSE

FALSE

TRUE or FALSE: Both viruses and prokaryotes reproduce by binary fission TRUE FALSE

FALSE

TRUE or FALSE: Disinfectants are applied to living tissue such as skin. TRUE FALSE

FALSE

True or False: In both prokaryotes and eukaryotes, introns in mRNA have to be spliced and transported out of the nucleus before it can be translated TRUE FALSE

FALSE

TRUE or FALSE: A virus can contain any one of the following genetic material: double-stranded DNA,single-stranded DNA,double-stranded RNA or single-stranded RNA TRUE FALSE

TRUE

TRUE or FALSE: An organism's genotype influences its phenotype TRUE FALSE

TRUE