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MBIO 2305 Exam 1
| Question | Answer |
|---|---|
| Sari is a microbiology student attempting to identify a microbe that she can study for her senior thesis project. Which of the following headlines refers to a microbe that she might find interesting? | “Brain-eating amoeba strikes two teens in one week” |
| How did Louis Pasteur’s swan-neck flask improve upon previous experiments on spontaneous generation? | It allowed the boiled broth to remain exposed to air. |
| Manuel identified a microbe that is responsible for an unexplained respiratory illness in lab mice. He found the culprit in 14 ill mice, and he produced a pure culture of the microbe in the lab. He hasn’t yet received permission from the board of ethics t | Postulates #1 and #2 only |
| The first vaccination was performed by _______ , and the first antibiotic was discovered by _______. | Edward Jenner; Alexander Fleming |
| Lithotrophs are organisms that feed on _______ and were discovered by _______. | inorganic material; Sergei Winogradsky |
| Which of the following microbes is an example of an endosymbiont? | Both a) and b) are correct. |
| What does analysis of 16S rRNA sequences show? | Archaea are as distant from bacteria as they are from eukaryotes. |
| Your team recently discovered a new species of microbe living in the Bonneville Salt Flats of Utah. The single-celled organism lacks a nucleus, and its cell walls are not composed of peptidoglycan. In which of the following domains would you classify this | Archaea |
| Which of the following scientist–contribution pairs is matched correctly? | Ernst Ruska–built electron microscope Theodor Svedberg–built ultracentrifuge |
| Which of the following scientists did NOT contribute to discovering the identity of or the structure of genetic material? | Lynn Margulis |
| Which of the following statements about microbes is TRUE? | Choose this answer if all of the above are false. |
| Which of the following phenomena is vital for a lens to magnify an image? | Refraction |
| The total magnification of a light microscope is given by which formula? | Magnification of ocular × Magnification of objective |
| You performed a Gram stain on Staphylococcus aureus, which is a Gram-positive bacterium. It appeared pink under a microscope. What could explain this result? | You left the ethanol for too long. |
| Which of the following microscopes exposes specimens to a specific wavelength and forms an image with the light emitted at a longer wavelength? | Fluorescence microscope |
| Which of the following microscopes allows the best view of bacterial flagella during motility? | Dark-field microscope |
| The ________ microscope relies on the principle of interference to produce images of the specimen without staining or damaging it. | Phase-contrast |
| All of the following statements apply to scanning electron microscopy EXCEPT: | The embedded specimen is cut into thin sections with a microtome |
| Which of the following statements about the atomic force microscope is FALSE? | It cannot be used to view live bacteria. |
| You want to study the structure of a particular protein in bacteria. Which technique would you use? | X-ray crystallography |
| Which of the following is a key tool used in cell fractionation? | Ultracentrifuge |
| What is the structure in prokaryotes that performs the same function as mitochondria in eukaryotes? | Cell membrane |
| The hopanoids in bacteria are equivalent to the ______ in eukaryotes. | Sterols |
| Which of the following is found in the cell wall of a Gram-positive bacterium but NOT in that of a Gram-negative bacterium? | Teichoic acids |
| Most Gram-negative bacteria belong to what phylum? | Proteobacteria |
| The protein complex that mediates the formation of the septum in a growing bacterium is called the: | Divisome |
| Which of the following statements about the prokaryotic chromosome is true? | It has a single origin of replication, and the DNA is replicated bidirectionally. |
| It has been shown recently that many bacteria export bits of cytoplasm in membrane vesicles. What functions do these vesicles serve? | Attractors of partner heterotrophs Decoys for bacteriophages Vehicles for DNA transfer |
| What is an extension of the cytoplasm that attaches bacteria to a surface called? | Stalk |
| Bacterial flagella undergo ________ motion, and are driven by ________. | rotatory; proton motive force |
| Which of the following combinations include only macronutrients? | S, O, Mg, Ca, K |
| Which of the following uses preformed organic molecules for both carbon and energy? | Chemoheterotroph |
| Which of the following statements regarding the phosphotransferase system (PTS) is(are) TRUE? | The system has a modular design that accommodates different substrates. The substrate being transported is altered during passage into the cell. |
| _______ are iron-scavenging molecules secreted by bacteria. | Siderophores |
| A medium that exposes biochemical differences between two species that grow equally well is best described as a(n): | differential medium |
| You want to count only the viable cells in a sample. What is the best technique to do this? | Streak plate method |
| The bacterium Sllub adirolfhtuos has a generation time of 20 minutes. Starting with one cell in log phase, how many minutes does it take to produce about a 1,000 cells? Assume all cells remain viable. | 200 |
| What is the correct order of phases in a bacterial growth curve? | lag → log → stationary→ death |
| What is the correct order of structures/processes used in biofilm formation? | Twitching motility → quorum sensing → microcolony → exopolysaccharide formation |
| In response to starvation conditions, ______ can form fruiting bodies comprised of about 100,000 cells. | Myxococcus |
| Viruses are | noncellular particles that take over the metabolism of a cell to generate more virus particles |
| The analysis of DNA sequences reveals | |
| Which of these groups are considered to be microbes, but NOT considered to be cells? | Viruses |
| The first cellular genomes to be sequenced were those of | Prions |
| Robert Koch won the Nobel Prize for his contribution to medical bacteriology regarding | Mycobacterium tuberculosis |
| The first person to visualize single-celled microbes was | Antonie Van Leeuwenhoek |
| Semmelweis and Lister noted that many of their patients’ deaths were due to | Pathogen transmission by doctors |
| Which commonly used microbial classification advancement led to the tree proposed by Carl Woese? | 16s rRNA sequencing |
| The X-ray diffraction studies by which of the following scientists concluded that DNA was a double helix? | Rosalind Franklin |
| Which of these answers correctly orders the series of microbes/cells from smallest to largest? | virus, bacterium, red blood cell, paramecium |
| Which of these answers arranges the steps of the Gram stain into the correct order? | crystal violet, iodine, decolorized, safranin |
| One advantage of a wet mount is | that the specimen is views in a natural state |
| What is the total magnification of a light microscope when using a 25X ocular and 40X objective lens? | 1,000x |
| What is the best explanation for a Gram-positive bacterium appearing pink after performing a Gram stain? | the decolorized was left on for too long |
| A common medium used for growing fastidious bacteria? | blood agar |
| Fluorescence microscopy using labeled antibodies is referred to as | Iummunofluorescene |
| Which of these techniques can be used to localize the proteins sequence at the origin of replication in the DNA of a bacterial cell? | fluorescence microscopy |
| Which type of microscopy provides a “false 3-D image”? | differential interference contrast |
| Which type of microscopy is used to view the internal structures of a specimen? | transmission electron |
| Which of the following would be MOST appropriate to visualize viral particles being assembled inside an infected bacterial cell? | transmission electron microscopy |
| The capsule polysaccharides form a slippery mucous layer that inhibits | phagocytosis |
| Specific membrane components, particularly ________, determine which substances are transported across the membrane. | hydrophobic |
| Which of the following types of molecules may passively diffuse across a membrane? | proteins |
| Which one of the following reinforces and stiffens membranes in bacteria? | a small uncharged molecule such as water |
| You study a bacterium that grows in very low-nutrient aqueous environments. Which type of transport mechanism is required to deliver nutrients from these environments where they are at a lower concentration than inside the cell? | active transport |
| The lipopolysaccharide of the outer membrane is of medical importance because it acts as a(n) | endotoxin |
| All of the following are components of peptidoglycan EXCEPT | lipopolysaccharide |
| Which is NOT a component of the wall of a Gram-negative bacterium? | teichoic acid |
| Directed movements toward or away from a chemical or physical signal are known as | chemotaxis |
| All the following are true about prokaryotic outer membranes EXCEPT that they | are lipid bilayers composed of identical phospholipids |
| Directed movements toward or away from a chemical or physical signal are known as | chemotaxis |
| Microbial endosymbionts | provide nutrition to host animals, including humans |
| Suppose Pasteur’s swan-necked flasks containing boiled broth became cloudy twenty-four hours after boiling. Which choice could best explain the turbidity or cloudiness in the broth without supporting spontaneous generation? | Endospores in the broth survived boiling and grew after the broth cooled |
| What was the basis for the original smallpox virus vaccine? | cowpox viruses |
| All of the following are true about penicillin EXCEPT that it | is produced by a bacterium |
| The gut microbiome of humans | allows us to digest cellulose |
| Carl Woese’s discovery replaced the classification scheme of five kingdoms with a scheme of three | Domains |
| Which one of the following reinforces and stiffens membranes in bacteria? | hopanoids |
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