Assignments for exam 1

If the limit of resolution of a light microscope is 200 nm, then the observer could very clearly see an individual cell of (A) ______ , but the observer could not clearly see an individual cell of (B)_______

A 250 nm B 150 nm

On a compound light microscope, the scanning objective lens magnifies at (A)_______ X, and the oil immersion objective lens magnifies at (B)_________ X. The scanning objective lens has a (C)______ lower numerical aperture (NA) than the oil immersion objective lens.

A. 4 B. 100 C. lower

What is growing on this plate? Choose one: A. Both bacteria and virus B. Virus only C. Neither bacteria nor virus D. Bacteria only

A. Both bacteria and virus

Which of the following are steps of the Gram stain? Choose one or more: A. Decolorizing with ethanol B. Fixing cells to the slide surface C. Staining with methylene blue D. Counterstaining with safranin

A. Decolorizing with ethanol B. Fixing cells to the slide surface D. Counterstaining with safranin

The antibiotic penicillin works by inhibiting the enzymes that are needed for the synthesis of peptidoglycan. Why is penicillin effective against Gram-positive cells but not against Gram-negative cells? Choose one: A. Gram-positive cells have nothing to hinder the drug's access to the enzymes it will inhibit, whereas a Gram-negative cell's outer membrane blocks access to the peptidoglycan of the cell wall. B. Both Gram-positive and Gram-negative cells have peptidoglycan, but it is essential only to the structure and support of Gram-positive cells. C. Gram-positive cells have peptidoglycan, but Gram-negative cells do not. D. The enzymes that create peptidoglycan in Gram-positive cells are different from the enzymes in Gram-negative cells, and the drug only works on the kind found in Gram-positive cells.

A. Gram-positive cells have nothing to hinder the drug's access to the enzymes it will inhibit, whereas a Gram-negative cell's outer membrane blocks access to the peptidoglycan of the cell wall.

Which of the following is part of ONLY the lysogenic cycle? Choose one: A. Phage DNA integrates into the host genome to form a prophage. B. Phage lyses the cell. C. Cell replicates phage DNA. D. Cell synthesizes phage capsid proteins.

A. Phage DNA integrates into the host genome to form a prophage.

Which of the following tasks would be a possible function of a bacterial pilus?Choose one or more: A. Pili are hollow so they can form a tube that connects the cytoplasm of two cells and allow for the transfer of genetic material between them. B. Pili are able to collect light used for photosynthesis. C.Pili rotate to allow the cell to propel itself forward in an aqueous environment. D. Pili can store energy that the cell can use at a later time. E. Pili allow cells to adhere to surfaces so that they do not get washed away from a favorable environment.

A. Pili are hollow so they can form a tube that connects the cytoplasm of two cells and allow for the transfer of genetic material between them. E. Pili allow cells to adhere to surfaces so that they do not get washed away from a favorable environment.

What is chemotaxis? Choose one: A. The ability to move toward or away from a chemical stimulus B. The ability to move nutrients across the cell membrane C. The ability to hide within another type of cell D. The ability to bind to a surface so as not to be moved away from a favorable environment

A. The ability to move toward or away from a chemical stimulus

This figure represents Choose one: A. a lysogenic cycle. B. stress-induced excision of phage DNA. C. a latent cycle. D. a lytic cycle.

A. a lysogenic cycle. A

Influenza strains demonstrate antigenic (A) _______when their envelope proteins continually mutate, thereby allowing the virus to evade the human immune system. However, when antigenic (B)______takes place, genes from two different influenza viruses combine.

A. drift B. shift

When bacterial samples are made to adhere to a slide, this process is called ________________. A. fixation B. staining C. resolution D. contrast

A. fixation

Which type of microscopy might use antibodies to label specific parts of the cell? Choose one: A. fluorescent B. electron C. phase-contrast D. light

A. fluorescent

HPV replicates when Choose one: A. keratinocyte growth and differentiation occurs. B. binding to the CD4 receptor on T cells. C. infecting basal cells. D. treated with antiviral drugs.

A. keratinocyte growth and differentiation occurs.

The viral-encoded enzyme required by HIV during infection is _______________.Choose one: A. reverse transcriptase B. RNA polymerase C. dehydrogenase D. DNA polymerase

A. reverse transcriptase

All successful viral replication cycles must, at minimum, achieve which of the following tasks? Choose one or more: A.Assembly of progeny virions B.Mutation within the genome C.Exit of virions and transmission D.Genome entry into host cellE.Host recognition and attachment

A.Assembly of progeny virions C.Exit of virions and transmission D.Genome entry into host cell E.Host recognition and attachment

Which of the following molecules is/are used to make lipopolysaccharide (LPS)? Choose one or more: A.Core polysaccharide B.N-acetylglucosamine C.Lipid A D.Teichoic acid E.O Antigen F.N-acetylmuramic acid

A.Core polysaccharide C.Lipid A E.O Antigen

Viruses use a relatively small number of virus-encoded proteins to take over the metabolism of their host cell. What implication(s) does this fact have on medical therapy? Choose one or more: A.Viral genomes have a fast mutation rate, even faster than that of bacteria. B.Antiviral agents have severe side effects. C.Antiviral agents are so successful that most viral disorders are now completely eradicated. D.Antiviral agents are difficult to discover.

A.Viral genomes have a fast mutation rate, even faster than that of bacteria. B.Antiviral agents have severe side effects. D.Antiviral agents are difficult to discover.

What is the total magnification when using a 100× objective and an ocular lens of 10×? Choose one: A. 100× B. 1,000× C. 10× D. 1×

B. 1,000×

Which part of the influenza virion facilitates interaction between the virus and the to-be-infected eukaryotic host cell? Choose one: A. Neuraminidase B. Hemagglutinin C. Matrix protein D. An ion channel

B. Hemagglutinin

Which of the following molecules are the sugars needed for the synthesis of bacterial cell walls? Choose one or more: A. Glucose B. N-Acetylmuramic acid C. D-Glutamic acidD.Ribose E. N-Acetylglucosamine F. D-Alanine

B. N-Acetylmuramic acid E. N-Acetylglucosamine

What is the purpose of applying immersion oil when the highest-power objective is in place? Choose one: A. To prevent the lens from becoming scratched B. To minimize the loss of light by refraction once light has left the slide C. To physically adhere the specimen to the slide surface D. To minimize the quantity of light allowed into the objective

B. To minimize the loss of light by refraction once light has left the slide

If the hemagglutinin spike were removed from the influenza viral envelope, then the virus would be unable to Choose one: A. translate its RNA into proteins. B. bind to its surface receptor. C. bud off of host cells. D. uncoat and remove its capsid.

B. bind to its surface receptor.

Consider the following image of acid-fast stained bacteria. What bacterial genus and species could the fuchsia-colored cells theoretically represent? Assume this is NOT a pure culture of only one bacteria; rather, this is a mixed culture. Choose one or more: A.Bacillus subtilis B.Mycobacterium smegmatis C.Mycobacterium tuberculosis D.Bacillus anthracis E.Mycobacterium leprae F.Bacillus cereus

B.Mycobacterium smegmatis C.Mycobacterium tuberculosis E.Mycobacterium leprae

Which of the following molecules would NOT be found as part of a bacterial cell's complex cell envelope? Choose one: A. Lipopolysaccharides B. A phospholipid bilayer C. DNA D. Peptidoglycan

C. DNA

A bacteriologist has Gram stained a mixed sample of unknown bacteria and has decolorized for one minute instead of 20 seconds. Which of the following best predicts the incorrect determination, if any, that will be made following the decolorization? Choose one: A. No incorrect determination will be made; the stain will still work. B. Gram-negative cells will be incorrectly identified as Gram positive. C. Gram-positive cells will be incorrectly identified as Gram negative.

C. Gram-positive cells will be incorrectly identified as Gram negative.

The lipids that make up the HIV envelope are derived from which of the following? Choose one: A. The cell wall of an infected T cell B. The cell membrane of an infected B cell C. The cell membrane of an infected T cell D. The cell wall of an infected B cell

C. The cell membrane of an infected T cell

Which of the following is NOT a type of viral evolution? Choose one: A. Viruses evolve within a host community to infect different species. B. Within an individual organism, viruses evolve variants that resist therapeutic agents. C. Within an organism, viruses evolve to become noninfectious to host cells. D. Within a viral population, different viral strains that vary in infectivity arise

C. Within an organism, viruses evolve to become noninfectious to host cells.

The time segment from approximately 9 weeks to 7.5 years represents A. a period marked by opportunistic infections. B. a period during which HIV is eliminated from the body. C. a period of infection during which there are no symptoms. D. a period when death is most likely to occur.

C. a period of infection during which there are no symptoms.

Most bacteria have Choose one: A. a single circular chromosome in the nucleus. B. multiple linear chromosomes in the nucleus. C. a single circular chromosome in the cytoplasm. D. multiple linear chromosomes in the cytoplasm.

C. a single circular chromosome in the cytoplasm.

The ability of the influenza genome to undergo __________ makes it capable of evolving novel strains that cause global pandemics. Choose one: A. reverse transcription B. budding C. gene reassortment (antigenic shift) D. gene mutation (antigenic drift)

C. gene reassortment (antigenic shift)

The main reason we stain organisms while viewing them is to Choose one: A. increase the resolution of the specimen. B. increase the magnification of the organism. C. increase the contrast between organisms and the surrounding medium. D. kill the organism to be handled.

C. increase the contrast between organisms and the surrounding medium.

When culturing bacteriophage, at what point do the phage particles begin appearing in the growth medium?Choose one: A. lysogenic period B. latent period C. rise period D. eclipse period

C. rise period

Which of the following are parameters of classification by the Baltimore model of viral content? Choose one or more: A.Gene content: fewer than 5 genes versus more than 5 genes B.Having an envelope versus lacking an envelope C.Single-stranded nucleic acid versus double-stranded nucleic acid D.DNA versus RNA genome

C.Single-stranded nucleic acid versus double-stranded nucleic acid D.DNA versus RNA genome

Gram-Positive

Contains many layers of peptidoglycan Contains teichoic acid

Which of the following best describes this viral capsid? Choose one: A. Amorphous B. Tailed C. Filamentous D. Icosahedral

D. Icosahedral

Which of the following is NOT a stage in the lytic cycle? Choose one: A. Cell replicates phage DNA. B. Cell synthesizes phage capsid proteins. C. Phage lyses the cell. D. Phage DNA integrates into host genome to form prophage.

D. Phage DNA integrates into host genome to form prophage.

Which of the following is NOT a function of the cell membrane? A. structural support B. transport C. energy storage D. RNA production

D. RNA production

Cells that elongate their cell walls prior to septation and septate in parallel planes will form Choose one: A. chains of spheres (cocci). B. tetrads of rods (bacilli). C. tetrads of spheres (cocci). D. chains of rods (bacilli).

D. chains of rods (bacilli).

All of the following are examples of light microscopy EXCEPT Choose one: A. dark-field. B. phase-contrast. C. fluorescent. D. electron.

D. electron.

After binding to the host cell surface receptor, bacteriophages then Choose one: A. inject the capsid proteins into the host cell. B. release phage DNA into the extracellular environment. C. degrade and transport phage DNA into the host cell. D. inject phage DNA into the host cell.

D. inject phage DNA into the host cell.

During the period from 0 minutes to approximately 12 minutes A. cell lysis is occurring. B. lysogeny is occurring. C. phages are being released from cells. D. progeny phages are being assembled.

D. progeny phages are being assembled.

Which structure aids bacterial adherence to a substrate? Choose one: A. flagellum B. thylakoid C. septum D. stalk

D. stalk

Consider the following image. What bacterial genus and species could this theoretically represent? Assume this is a pure culture of only one bacteria. A. EscherichiE. Clostridium tetania coli B. Staphylococcus aureus C. Streptococcus pyogenes D. Mycobacterium leprae E. Clostridium tetani

E. Clostridium tetani

Gram-Negative

Has a single layer of peptidoglycan Contains lipopolysaccharide Has an outer membrane

(A) _______are infectious particles that consist of no nucleic acid at all. Rather, the biomolecule that makes up this infectious particle is (B) ______Once intracellular, this particle induces molecular chaos.

Prions protein

envelope

a membrane like layer that covers the capsids of some viruses

a differential stain used to identify bacteria that are not decolorized by acid-alcohol

acid fast stain

Viruses that infect bacteria are called .

bacteriophages

focuses light through specimen

condenser lens

Protein synthesis and cellular metabolism

cytoplasm

a form of microscopy in which the specimen is brightly illuminated on a dark background

dark field microscope

controls the amount of light passing through the specimen

diaphragm

The seasonal nature of influenza is due to antigenic

drift

rise period

during replication cycle, viruses are maturing and being released

A differential stain used to detect the presence and location of spores in bacterial cells.

endospore stain

Transport of nutrients into the cell

envelope

Contains the ocular lens

eye piece

uses a fluorescent dye that emits fluorescence when illuminated with ultraviolet radiation

fluorescent microscopy

adjusts the focus by raising and lowering the body tube

focusing knob

any kind of microscope that uses visible light to observe specimens

light microscope

projects light upwards through the diaphragm to allow you to see the specimen

light source

flagellum (flagella)

long, tail-like projection with whiplike or propeller motion that helps a cell move

When the (B) ______cycle takes place, phage DNA integrates into the bacterial chromosome and simply replicates along with chromosomal replication.

lysogenic

When the (A)________cycle takes place, bacteriophage genetics enter a cell, and then the cell makes many more bacteriophages and soon lyses.

lytic

cellular motility

movement of whole cell

colors the background, which makes capsules more visible

negative stain

the part of a compound light microscope that is located directly above the specimen and that magnifies the image of the specimen

objective lens

accentuates diffraction of the light that passes through a specimen

phase contrast microscope

In _______microscopy, small differences in refractive index between the cytoplasm and the surrounding medium allow visualization of the sample.

phase-contrast

Bacteriophage must be cultured in live, growing bacteria. When bacteria are exposed to phage, are then plated, and a lawn grows, eventually little small clear spots in the lawn develop. These dead spots are called ________.

plaques

After phage genetics have integrated into the bacterial chromosome, the phage is called a(n) _________

prophage

The viral capsid is _______that surrounds the viral genetics.

protein

DNA synthesis

replication

An electron microscope used to study the fine details of cell surfaces

scanning electron microscopy

Cytoplasm

the portion of the cell outside the nucleus

eclipse period

the time during viral multiplication when complete, infective virions are not present

very thin slices of a specimen are used, revealing the internal structure of microbial and other cells

transmission electron microscope

nucleic region

where DNA is found