Deck 3: Microscopy and Cell Structure

Question 1

Individual atoms on the surface of prepared samples can be observed by using the

A) scanning electron microscope.
B) dark-field microscope.
C) atomic force microscope.
D) phase contrast microscope.
E) light microscope.

Answer 1

C

Question 2

Which microscope would be the BEST selection for examination of a virus?

A) Confocal scanning laser microscope
B) Scanning electron microscope
C) Dark-field light microscope
D) Atomic force microscope
E) Compound light microscope

Answer 2

B

Question 3

In viewing a microscopic specimen, oil is used to

A) increase the refraction AND increase the reflection.
B) decrease the refraction AND increase the reflection.
C) decrease the refraction AND increase the resolution.
D) increase the reflection AND increase the resolution.
E) increase the resolution AND increase the refraction.

Answer 3

C

Question 4

Which may result in Gram-positive bacteria appearing to be Gram-negative?

A) Decolorizing too long AND using young cultures.
B) Decolorizing too short AND using young cultures.
C) Decolorizing too long AND using old cultures.
D) Decolorizing too short AND using old cultures.
E) Forgetting to decolorize AND using old cultures.

Question 5

The microscope that allows the specimen to appear three-dimensional is the

A) phase contrast microscope.
B) differential interference contrast microscope.
C) fluorescence microscope.
D) dark-field microscope.
E) compound microscope.

Question 6

The order of reagents in the Gram stain reaction is

A) safranin, alcohol, methylene blue, iodine.
B) crystal violet, iodine, alcohol, safranin.
C) methylene blue, alcohol, safranin, iodine.
D) crystal violet, alcohol, iodine, safranin.
E) alcohol, safranin, iodine, crystal violet

Question 7

An electron microscope must use electromagnet "lenses" shaped like donuts to direct the electrons onto the specimen. Why?

A) Electrons are particles but there are other particles in air as well. Without a vacuum, the electrons would strike and be scattered by the particles within the air.
B) Electrons are highly radioactive, and the chamber must be completely sealed to prevent them from escaping and contaminating the lab area.
C) This is the method for fixing the specimen to the slide grid for an electron microscope. Without fixing the specimen by vacuum, it would slide off and we wouldn't be able to visualize it.
D) All of the answer choices are True.
E) None of the answer choices is True.

Question 8

If everything else is equal, the best way to observe more details in a microscopic specimen is to

A) increase resolution.
B) increase magnification.
C) increase reflection.
D) increase scatter.
E) decrease resolution.

Question 9

The resolving power of a microscope is described as the ability of the microscope to

A) separate clearly two objects that are very close together.
B) magnify an object.
C) separate the colors of an organism's internal structure.
D) magnify structures at various depths in a tissue.
E) combine the images of two objects that are very close together.

Question 10

The two magnifying lenses found in a light microscope are the

A) basic and transverse.
B) small and large.
C) ocular and objective.
D) simple and phase.
E) ocular and phase.

Question 11

Which of the following stains are considered differential?

A) Capsule stain AND Gram stain.
B) Flagella stain AND acid-fast stain.
C) Acid-fast stain AND Gram stain.
D) Acid-fast stain AND capsule stain.
E) Gram stain AND flagella stain.

Question 12

The Gram stain and the endospore stain both use

A) crystal violet.
B) iodine.
C) safranin.
D) malachite green.
E) acidic dyes.

Question 13

Basic dyes

A) have a negative charge.
B) have a positive charge.
C) are electrically neutral.
D) contain both positively and negatively charged particles.
E) are always blue.

Question 14

An electron microscope must use electromagnet "lenses" shaped like donuts (with a hole in the middle) to direct the electrons onto the specimen. Why aren't they solid, like the lenses in a light microscope?

A) A magnetic field cannot be applied across a completely solid object-there must be an opening within the object for the field to be applied through.
B) Electrons are particles, and particles cannot travel through a solid item. The hole in the middle allows them to travel from the source of the electrons to the specimen.
C) The electrons would destroy the electromagnet material unless there was a physical hole for them to travel through on their way to the specimen.
D) The user has to be able to physically look through the magnets to focus the beam of electrons onto the specimen, since the metal of the magnets is opaque. Without a hole in the middle, the user wouldn't be able to see!
E) All of the answer choices are correct.

Question 15

The major criteria used in placing bacteria into different groups is based on differences in

A) cell wall structure.
B) cell membrane permeability.
C) presence or absence of flagella.
D) detergent susceptibility.
E) presence or absence of cytoplasmic membrane.

Question 16

Electron microscopes differ from light microscopes in that

A) light replaces electrons.
B) glass lenses replace electromagnets.
C) resolution is lower.
D) magnification is lower.
E) magnification is higher.

Question 17

Which of the following microscope types would be least useful in viewing unstained living cells?

A) Phase contrast
B) Differential interference contrast
C) Bright-field
D) Dark-field
E) Fluorescence

Question 18

Specimens can be observed at the atomic level using a(n)

A) scanning electron microscope.
B) transmission electron microscope.
C) atomic force microscope.
D) fluorescence microscope.
E) light microscope.

Question 19

Eukaryotic cells are

A) less complex than prokaryotic cells.
B) members of the domains Bacteria and Archaea.
C) defined by the presence of a membrane bound nucleus.
D) able to reproduce more rapidly than prokaryotes.
E) defined by the presence of a cell wall.

Question 20

The use of oil with certain high-power objective lenses increases

A) magnification.
B) reflection.
C) resolution.
D) contrast.
E) color.

Question 21

The endospore stain

A) is applicable to many groups of bacteria.
B) usually shows the spores as pink structures among a background of blue cells.
C) uses crystal violet as the primary stain.
D) is an example of a negative stain.
E) is applicable to only a few groups of bacteria.

Question 22

Which amino acid is found only in the cell walls of bacteria?

A) Glycerol
B) L-form of glycine
C) Diaminopimelic acid
D) L-form of methionine
E) D-form of methionine

Question 23

Which terms refer to bacterial morphology?

A) Bacillus AND polyhedral
B) Coccus AND polyhedral
C) Coccus AND Bacillus
D) Polyhedral, coccus, AND Bacillus
E) Coccus AND squarish

Question 24

Which is True of simple diffusion of water?

A) Water usually enters a cell and produces a high osmotic pressure.
B) Water usually leaves the cell and produces negative osmotic pressure.
C) Water tends to enter and leave the cell equally, resulting in no pressure in the cell.
D) Water diffusion ultimately relies on the selectively permeable nature of the cell wall.
E) Water usually enters a cell and produces a very low osmotic pressure.

Question 25

Facilitated diffusion and active transport

A) both transport molecules into or out of a cell.
B) are both not very specific as to which molecules are transported.
C) both require a concentration gradient to function.
D) both require use of energy in order to transport the molecules.
E) both require a concentration gradient to function AND both require use of energy in order to transport the molecules.

Question 26

The proteins of bacteria that are involved in the movement of small molecules into the cell are called

A) transport proteins, carriers, AND peptidases.
B) transport proteins, permeases, AND carriers.
C) permeases, carriers, AND peptidases.
D) carriers, peptidases, AND porases.
E) peptidases, porases, AND permeases.

Question 27

Which is NOT True of the cytoplasmic membrane?

A) It defines the boundaries of the cell.
B) It is a selectively permeable barrier.
C) It consists mainly of a fixed, static, phospholipid bilayer.
D) It contains proteins used as selective gates and sensors.
E) All of the answer choices are True.

Question 28

The macromolecule found in the cell walls of all bacteria is

A) lipid A.
B) teichoic acid.
C) peptidoglycan.
D) glycocalyx.
E) chitin.

Question 29

The cell wall of Gram-positive bacteria

A) contains a thin layer of peptidoglycan.
B) contains a thick layer of peptidoglycan.
C) is an excellent barrier to most molecules.
D) contains an outer membrane containing LPS.
E) contains a thick layer of peptidoglycose.

Question 30

The cytoplasmic membrane of both eukaryotes and prokaryotes functions to

A) form rough and smooth endoplasmic reticulum.
B) produce energy in the form of ATP.
C) regulate movement of molecules that enter and leave the cell.
D) form lysosomes, peroxisomes, and Golgi apparatus.
E) produce peptidoglycan or chitin cell walls.

Question 31

The acid-fast stain

A) is useful for distinguishing a small group of organisms, including Mycobacterium AND reflects differences in cytoplasmic membrane structure.
B) is useful for distinguishing a small group of organisms, including Mycobacterium AND uses carbolfuchsin and methylene blue.
C) is useful for distinguishing a small group of organisms, including Mycobacterium AND uses carbolfuchsin and safranin.
D) is useful for distinguishing a small group of organisms, including Mycobacterium AND uses crystal violet and safranin.
E) is useful for distinguishing a small group of organisms, including Bacillus AND uses crystal violet and safranin.

Question 32

Which molecule(s) is (are) NOT associated with the cell wall of Gram-positive bacteria?

A) Peptidoglycan
B) D-form amino acids
C) Teichoic acids
D) Peptidoglycan, D-form amino acids, AND teichoic acids
E) Lipopolysaccharide

Question 33

Most solutes pass through the cytoplasmic membrane via

A) osmosis.
B) diffusion.
C) transport proteins.
D) secretion.
E) aquaporins.

Question 34

The cell wall of Gram-negative organisms

A) has a thick peptidoglycan layer AND is characterized by an outer membrane containing LPS.
B) has a thick peptidoglycan layer.
C) has a thin peptidoglycan layer AND is characterized by an outer membrane containing LPS.
D) has a thin peptidoglycan layer.
E) is more permeable to various molecules than the Gram-positive cell wall.

Question 35

Which of the statements about immunofluorescence is NOT True?

A) Uses fluorescently tagged molecules.
B) Makes use of the specificity in binding of antibodies.
C) Uses the dye methylene blue.
D) Would require a special UV microscope.
E) These statements are all True.

Question 36

Which is (are) True concerning the cell wall of prokaryotes?

A) It determines the shape of the bacteria.
B) It prevents the bacteria from bursting.
C) It contains peptidoglycan.
D) It may be targeted by antimicrobials.
E) All of the answer choices are True.

Question 37

Penicillin would be most effective against

A) non-growing bacteria AND Gram-positive bacteria.
B) non-growing bacteria AND Gram-negative bacteria.
C) growing bacteria AND Gram-positive bacteria.
D) growing bacteria AND Gram-negative bacteria.
E) any actively growing bacteria.

Question 38

Endotoxin

A) consists of lipopolysaccharide.
B) determines bacterial shape.
C) may have different effects depending on the bacterial source.
D) is toxic due to the effects of the peptide side chains.
E) is found in Gram-positive cells.

Question 39

In a basic staining procedure, which is the correct order?

A) Fix, smear, stain
B) Smear, fix, stain
C) Fix, stain, decolorize
D) Smear, decolorize, stain
E) Smear, stain, fix

Question 40

Select the False statement regarding capsules.

A) Capsules may increase an organism's ability to cause disease.
B) Capsules are typically "negatively" stained.
C) Capsules may be stained as a wet mount.
D) Capsules are usually composed of polysaccharides.
E) Capsules take up stain well.

Question 41

Eukaryotic cells

A) are more obviously compartmentalized than prokaryotes.
B) usually have a single circular supercoiled piece of DNA.
C) contain peptidoglycan in the cell wall.
D) have the same size ribosomes as prokaryotes.
E) have a single circular supercoiled chromosome.

Question 42

LPS is found in the outer membrane of Gram-negative bacteria.

Question 43

Phagocytosis

A) is the ingestion of particles and may be performed by animal cells.
B) is the ingestion of particles and may be performed by bacteria.
C) is the secretion of proteins from a bacterium into the environment.
D) is the formation of a lysosome filled with peroxides.
E) is the uptake of particles across the animal cell wall.

Question 44

The capsule

A) may be used for protection AND may be involved in movement.
B) may be used to help the bacteria adhere to surfaces AND may be involved in movement.
C) may be used for protection AND may be used to help the bacteria adhere to surfaces.
D) may be involved in movement AND may be involved in energy production.
E) may be involved in energy production AND may be used for protection.

Question 45

Which of the following bacteria lack(s) a peptidoglycan cell wall?

A) Treponema pallidum
B) Mycobacterium tuberculosis
C) Mycoplasma pneumoniae
D) Staphylococcus aureus
E) These all contain a cell wall-they are bacteria.

Question 46

The nucleus

A) is a single phospholipid membrane sac containing prokaryotic DNA.
B) is a smaller structure contained within the eukaryotic nucleolus.
C) is a double membrane sac containing DNA and is found in eukaryotes.
D) cannot transport molecules to the cytoplasm due to the double membrane barrier.
E) is a triple phospholipid membrane sac containing prokaryotic RNA.

Question 47

The cytoskeleton

A) is a dynamic structure composed of microtubules, microfilaments, and intermediate filaments.
B) is a static structure that gives a rigid, defined shape to the cell.
C) consists of flagella, filaments and cilia that have been internalized.
D) has no known function in an animal cell.
E) is a dynamic structure composed of nucleic acids, phospholipids, and proteins.

Question 48

Movement in bacteria

A) is directly to or away from a stimulus.
B) relies on the beating of cilia.
C) is often referred to as run and tumble.
D) may involve pili.
E) is often referred to as run and tumble AND may involve pili.

Question 49

Bacillus and Clostridium are medically relevant groups of bacteria that characteristically stain acid-fast.

Question 50

Lysosomes are bags of digestive enzymes found in prokaryotic cells.

Question 51

Smooth endoplasmic reticulum is involved in protein synthesis.

Question 52

The membranes of eukaryotes and mycoplasma

A) contain peptidoglycan.
B) contain sterols for strength.
C) contain ergosterol.
D) are fixed static structures.
E) are phospholipid unilayers.

Question 53

Peptidoglycan

A) may be digested by penicillin.
B) consists of a long string of NAG coupled to a long string of NAM.
C) may be digested by lysozyme.
D) is found in bacteria, archaea, and plants.
E) is only found in Gram-positive cells.

Question 54

An advantage of the smaller size of prokaryotes, compared to eukaryotes, is

A) high surface area relative to low cell volume AND slower growth rates.
B) high surface area relative to low cell volume AND more rapid growth rates.
C) more rapid growth rates AND compartmentalization of cellular processes.
D) compartmentalization of cellular processes AND low surface area relative to low cell volume.
E) more rapid growth rates AND low surface area relative to high cell volume.

Question 55

Endospores are

A) a dormant cell type.
B) a type of reproduction.
C) obligate intracellular parasites.
D) sensitive to damaging environmental conditions.
E) made by all bacterial genera.

Question 56

Penicillin affects the synthesis of phospholipids, thereby producing weak membranes and lysis of the bacteria.

Question 57

Endospores are involved in bacterial reproduction.

Question 58

The structures used for motility in both eukaryotes and prokaryotes are

A) cilia.
B) flagella.
C) pili.
D) fimbriae.
E) microvilli.

Question 59

Which is NOT True of mitochondria and chloroplasts?

A) They contain DNA and 70S ribosomes.
B) They are found in all organisms.
C) They are capable of performing protein synthesis.
D) They generate ATP.
E) They are membrane-bound organelles.

Question 60

Extrachromasomal DNA is found in ________.

A) mitochondria AND plasmids
B) mitochondria only
C) plasmids only
D) nucleoid AND nucleolus
E) mitochondria AND nucleus

Question 61

You explain to Petrus and his grandmother that the cause of her infection is likely E. coli, and that the organism produces ________ that allow it to attach to the epithelial cells of the urinary tract.

A) flagella
B) a slime layer
C) a glycocalyx
D) pili
E) cilia

Question 62

You inform the patient that the results of the Gram stain indicate to you that the bacteria in her throat are ________ in shape, and have a ________ cell wall.

A) round; thin
B) cylindrical; thick
C) round; thick
D) spiral; thick
E) cylindrical; thin

Question 63

A new medication is developed that targets and binds to the lipid A portion of LPS in Gram-negative bacterial cells. This drug shows a high degree of binding and activity against purified lipid A in an experiment carried out in test tubes. Based on this information,

A) we should fast-track this drug and get it out to physicians immediately to help prevent Gram-negative toxic/septic shock in humans.
B) we should do some animal testing with intact Gram-negative cells and the medication before we jump to any conclusions.
C) we should next proceed by repeating the experiment in test tubes using intact Gram-negative cells to see if the drug binds with the same strength.
D) we should abandon the drug entirely. Binding to lipid A won't kill the bacteria, so the drug is useless to develop further. 
E) we should assume that the medication will be effective against all bacteria, including Mycoplasmas, and that it is ready for use in humans.

Question 64

Prokaryotes may ingest particles via phagocytosis.

Question 65

A research laboratory is investigating environmental factors that would inhibit the growth of Archaea. One question they have is whether adding the antibiotic penicillin would be effective in controlling their growth. What do you think the outcome would be if they tried this?

A) The penicillin wouldn't affect the Archaea because it prevents cross-linking of peptidoglycan and Archaea don't have this compound in their cell walls.
B) The penicillin will inhibit peptidoglycan synthesis and thus cell wall formation in the Archaea, killing them.
C) The penicillin will slow down the growth of the Archaea by damaging the cell wall, but they will still be able to grow somewhat.
D) The penicillin will enhance the growth of the Archaea by providing a rich nutrient source.
E) The penicillin will inhibit cell division in the Archaea, forcing them to form endospores.

Question 66

Mitochondria and chloroplasts are thought to have once been free-living bacteria that invaded another cell.

Question 67

You want to examine the structure of the protein coat of a virus by microscopy. Which microscope is your best choice, and why?

A) The scanning electron microscope-it has excellent resolution and magnification (much higher than a light microscope), and can clearly visualize viruses.
B) An atomic force microscope-this has the highest resolution and magnification of the microscopes we discussed and we want to visualize a subcomponent of the virus particles.
C) A fluorescent microscope-this will let us tag the virus protein coat with colored dyes in order to visualize it using this light microscope at 1000x.
D) A bright-field light microscope-of course, we'll need to stain the viruses before we can visualize them against the bright white background at 1000x total magnification.
E) The phase-contrast microscope-it has excellent contrast and magnification, and can be used to visualize viruses very clearly.

Question 68

The lab report also details the results of a negative stain performed on the bacteria in the urine sample, in which the background of the sample is stained, rather than the cells themselves. The report indicates that the cells have a clear halo around them, indicating the presence of a(n) ________. You explain to Petrus that this structure helps bacteria avoid ________, part of the immune response.

A) endospore; phagocytosis
B) flagellum; antibodies
C) LPS; antibodies
D) capsule; pinocytosis
E) capsule; phagocytosis

Question 69

A research laboratory is trying to produce new antibiotics. They come up with a medication that detaches the hydrophilic heads from the phospholipids in cytoplasmic membranes. This drug

A) would be highly toxic and completely useless for human beings and could never be used-our cells also have cytoplasmic membranes with hydrophilic head groups!
B) would be highly toxic for human beings if taken orally, but might be useful as a topical antibiotic skin cream. The top layer of skin cells is dead anyway, so it wouldn't matter if this damaged those cells. 
C) would be highly toxic only to bacteria, making it an excellent drug to develop and test further. Humans have a different phospholipid structure in their cytoplasmic membranes from bacteria.
D) would generally not be toxic enough to damage Gram-negative bacteria, as their cytoplasmic membranes lie under a thick layer of peptidoglycan. However, it would be effective against Gram-positive cells.
E) would not work against any bacteria, because they do not have a cytoplasmic membrane; however, it might be effective against helminths and viruses.

Question 70

A newly developed antibiotic drug shows promise by inhibiting prokaryotic 70S ribosomes in initial studies. However, when animal studies are begun, it's noted that the drug also inhibits growth of animal cells. Select the statement that may be explain how this can be happening.

A) The function of ribosomes is identical, no matter their size, so a drug that can affect 70S ribosomes will also impair 80S ribosomes.
B) While the proteins made in the cytosol of eukaryotic cells are produced from the 80S eukaryotic ribosome, mitochondria and chloroplasts possess 70S ribosomes. This drug might be impairing the activity of chloroplasts in animal cells.
C) While the proteins made in the cytosol of eukaryotic cells are, indeed, produced from the 70S eukaryotic ribosome, mitochondria and chloroplasts possess 80S ribosomes. This drug might be impairing the activity of mitochondria in animal cells.
D) Perhaps the scientists accidentally combined their cultures of animal and bacterial cells-this might indicate that the drug is causing a reduction in growth in the culture, while really it's still just affecting the bacterial cells.
E) There really is no single explanation for this observation. Most likely, if the experiment was repeated, a completely different outcome would be observed.

Question 71

A new drug is developed that inhibits formation of flagella filament by impairing production of the protein flagellin. Is this going to be an effective medication?

A) Potentially yes-it could be used against some bacteria, but wouldn't be effective for those that don't use a flagellum to move around.
B) Potentially yes, but only if it could be shown that the drug also didn't impair the production of the eukaryotic flagellum.
C) Not at all-our eukaryotic cells depend on flagella to move around in our body, and this drug would impair that function.
D) Not at all-bacterial flagella are produced using microtubules, not the protein flagellin. This drug would be useless in eliminating bacteria.
E) Not at all-this medication would affect cells like the ciliated respiratory epithelial cells, and would cause potentially fatal side-effects.

Question 72

Cilia and flagella project from the cell and are not covered by cytoplasmic membrane.

Question 73

You perform a rapid strep test on the patient, which comes up positive. You tell her that she most likely has strep throat, caused by Streptococcus pyogenes. You prescribe penicillin for her, and tell her that this antibiotic is effective because it interferes with the synthesis of ________ by the pathogen.

A) peptidoglycan
B) capsule material
C) ribosomes
D) proteins
E) ATP

Question 74

As she is preparing to leave your office, the patient mentions that her brother had pneumonia a couple of years ago and that penicillin had not helped him. You ask her if she remembers the name of the organism causing her brother's illness and she tells you it was Mycoplasma something or other, that she can't quite remember. You tell her that the reason penicillin did not help her brother is that 

A) you know her brother did not take the full course of antibiotics, so some of the Mycoplasma cells survived.
B) Mycoplasma species are Gram-negative, and penicillin cannot penetrate the LPS layer of these cells, so the cells survive.
C) Mycoplasma species are acid-fast bacteria, so they have mycolic acids in the cell wall that penicillin does not destroy.
D) Mycoplasma species do not have a peptidoglycan cell wall and are thus not impacted by penicillin.
E) Mycoplasmas are viruses and antibiotics do not work for viral infections.

Question 75

Your instructor wants you to bring in an example of a biofilm to your lab. Which choice is the best selection for bringing in an intact biofilm for further study?

A) Disconnecting and bringing in the old, mildewed showerhead from your bathroom.
B) Scraping the mold off the shower curtain in your bathroom into a paper cup using a butter knife.
C) Using a toothpick to scrape plaque off of your teeth and smearing it onto a slide to bring in to lab.
D) Wiping a sponge across a slimy boulder in a stream in a nearby park and bringing it in to lab.
E) Wiping a sponge across your dog's teeth, smearing it onto a glass slide and bringing it in to lab.

Question 76

When Petrus' grandmother's test results are sent to you, you discover that while her blood work is normal, her urine has Gram-negative bacilli in it. Based on this, you know that the cells are

A) stained blue and are cylindrical in shape.
B) stained purple and are cylindrical in shape.
C) stained pink and are spherical in shape.
D) stained pink and are cylindrical in shape.
E) stained green and are oval in shape.

Question 77

Please select the MISMATCHED pair.

A) Light microscope - 1,000-fold magnification
B) Acid fast stain - differential
C) Mycoplasma pneumoniae - flexible cells
D) Capsules and slime layers - phospholipids
E) Membrane-bound organelles - fungi

Question 78

Petrus asks you what the Gram-negative result means and you explain that the bacteria causing his grandmother's UTI

A) have a thin cell wall and an outer membrane which makes the cells less sensitive to the antibiotic penicillin.
B) have a thick cell wall and an outer membrane which makes the cells less sensitive to the antibiotic penicillin.
C) have no cell wall but they have a thick outer membrane which makes the cells less sensitive to the antibiotic penicillin.
D) have a thin cell wall and an inner cell membrane which makes the cells less sensitive to penicillin.
E) have no cell wall which makes the cells more sensitive to the antibiotic penicillin.

Question 79

Your patient asks you whether there were also viruses on the slide. You tell her

A) yes, but they are of no concern because they are part of her normal microbiota.
B) maybe, but there were too few to observe among the bacteria.
C) maybe, but viruses cannot be observed without an electron microscope.
D) unlikely, because viruses seldom cause sore throats in people.
E) no, because viruses would be destroyed by the decolorizing step of the Gram stain.

Question 80

Based on the Gram staining, you suspect that the patient has a ________ infection. 

A) fungal
B) bacterial
C) protozoan
D) algal
E) prion