Review questions for exam 1… Gen Micro
1. The endosymbiotic hypothesis is generally accepted as the origin of two eukaryotic organelles: mitochondria
and chloroplasts.
True False
2. RNA serves to convert the information stored in DNA to ________.
A. carbohydrates
B. protein
C. lipids
D. RNA
3. Archaea are cellular organisms that have unique cell membrane __________.
________________________________________
4. All cellular organisms can be placed into one of three __________, which include the Bacteria, Archaea, and
the Eukarya.
________________________________________
5. The __________ is the distance between the specimen and the objective lens when the specimen is in focus.
________________________________________
6. The useful magnification of a light microscope is limited by the ___________ of the light source being
utilized.
________________________________________
7. __________ is the process by which internal and external structures of cells and organisms are preserved and
maintained in position.
________________________________________
8. The Gram-staining procedure is an example of:
A. simple staining.
B. negative staining.
C. differential staining.
D. fluorescent staining.
9. An electron microscope uses __________ lenses to focus beams of electrons onto a specimen.
________________________________________
10. The _________________ microscope is capable of atomic resolution of specimens, even when they are
immersed in water.
________________________________________
11. When the cell wall is removed from a Gram-negative bacterium without removing the outer membrane, the
resulting form is called a(n) __________.
________________________________________
12. Molecules or regions of molecules that readily interact with water are said to be __________, whereas
molecules or regions of molecules that are insoluble in water or do not readily interact with water are said to be
hydrophobic.
________________________________________
13. A __________ is a polysaccharide layer that lies outside the cell wall and is not easily removed.
________________________________________
14. The most widely accepted current model for membrane structures is called the __________ model.
________________________________________
15. Small circular DNA molecules capable of replicating and containing genes that are useful but not necessary
to the bacterium are called __________.
________________________________________
16. Some species of aquatic bacteria use inclusion bodies known as ________ to orient themselves in Earth's
magnetic field.
________________________________________
17. _______ are the site of protein synthesis in the cell.
________________________________________
18.
A.
B.
C.
D.
All of the following statements about the periplasmic space are true except:
It is found only in gram-positive bacteria.
It is located between the plasma membrane and outer membrane of gram-negative bacteria.
It contains hydrolytic enzymes and binding proteins involved in nutrient acquisition.
All of the above are true.
19. Phosphorus can be obtained from organic sources only.
True False
20. Virus morphology does not include which of the following characteristics?
A. size
B. shape
C. presence or absence of an envelope
D. host range
21. __________ are glycoprotein spikes protruding from the outer surface of the viral envelope.
________________________________________
22. Icosahedral viruses are constructed from ring- or knob-shaped units called __________.
________________________________________
23. In an enveloped virus, the part of the virus including the nucleic acid genome and the surrounding protein
coat but not the envelope is called the
A. capsid.
B. nucleocapsid.
C. matrix.
D. virion.
24. Glycoprotein spikes protruding from the outer surface of viral envelopes function as
A. toxins.
B. factors that bind to host cells.
C. cell lysis factors.
D. factors needed for site specific recombination.
25. Viral envelopes are composed of
A. proteins.
B. lipids.
C. carbohydrates.
D. all of the choices
26. In which of the following stages of the viral infectious cycle do enveloped viruses usually acquire their
envelopes?
A. penetration
B. component biosynthesis
C. assembly
D. release
27. Nonenveloped viruses most often gain access to eukaryotic host cells by
A. fusion with the host cell plasma membrane followed by entrance of the nucleocapsid into the cytoplasm.
B. endocytosis.
C. pinocytosis.
D. nucleic acid injection through the plasma membrane.
28. Some viruses cause abnormal growth of cells rather than destruction. This is called __________.
________________________________________
29. Human cancer causing viruses most often have a ___________ genome.
A. ssDNA
B. dsDNA
C. ssRNA
D. dsRNA
30. Adult T-cell leukemia is thought to be caused by
A. herpesviruses.
B. retroviruses.
C. parvoviruses.
D. picornaviruses.
31. Microscopic or macroscopic degenerative changes or abnormalities in infected host cells and tissues are
called __________ __________.
________________________________________
32. 0.2 mls of a 10-4 dilution of a virus preparation yields 90 plaques. What is the number of PFU per ml in the
undiluted virus preparation?
A. 9.0  105
B. 4.5  106
C. 4.5  107
D. 9.0  108
33. Which of the following is not true of viroids?
A. Viroids are small circular ssRNA molecules.
B. Viroids have no protein capsids.
C. Viroid RNA does not serve as mRNA nor does it direct the synthesis of mRNA.
D. Extracellular viroids have a lipid bilayer envelope.
34. There are no known human diseases that have been linked to prions.
True False
35. Media containing some ingredients of unknown chemical composition are called __________ media.
A. undefined
B. complex
C. defined
D. synthetic
36. For surface cultivation of microorganisms, a sulfated polymer called agar can be extracted from
__________ and added to liquid media in order to cause it to solidify.
A. bacteria
B. animal fat
C. algae
D. fungi
37. Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the
halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave
the medium red. Onto MSA you inoculate a halophilic mannitol fermenter, a nonhalophilic mannitol fermenter,
and a halophilic mannitol nonfermenter. Thus, the medium is acting as a __________ medium.
A. selective
B. differential
C. selective and differential
D. neither selective nor differential
38. Blood agar is both a differential and enriched medium.
True False
39. Colonies grow most rapidly at the __________ where oxygen and nutrients are readily available; however,
they grow less rapidly at the __________ where these materials have been depleted.
________________________________________
40. Most bacterial and archaeal cells divide by
A. mitosis
B. meiosis
C. binary fission
D. all of these
41.
A.
B.
C.
D.
The process of forming a cross wall between two daughter cells is known as
replication
septation
sporulation
mitosis
42. The site at which replication of DNA starts in bacterial cells is known as the __________ of
___________.
________________________________________
43. The purpose of the penicillin binding proteins is to link phospholipids together in the cellular membrane.
True False
44.
A.
B.
C.
D.
The actin-like protein that seems to be involved in determining cell shape is
MreB.
ActA.
SpnC.
FtsZ.
45. The limitation on microbial growth rate at high nutrient levels is
A. the rate of protein synthesis.
B. the rate of DNA replication.
C. the saturation of the transport proteins for nutrient uptake.
D. all of the choices.
46. A culture in a closed vessel to which no additional medium is added and from which no waste products are
removed is called a __________ culture.
A. continuous
B. batch
C. fed-batch
D. semicontinuous
47. Microorganisms are most nearly uniform in terms of chemical and physiological properties during
__________ phase.
A. lag
B. exponential
C. stationary
D. decline
48. When a young, vigorously growing culture of bacteria is transferred to fresh medium of the same
composition, the lag phase is usually short or absent.
True False
49. The __________ __________ is the length of time it takes for a population of microorganisms to double in
number.
________________________________________
50. If all cell components are synthesized at constant rates relative to one another, the culture is said to be in
__________ growth; however, if the rates of synthesis of some components change relative to the rates of
synthesis of other components, the culture is said to be in __________ growth.
________________________________________
51. At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At
9:00 p.m. the log phase culture has population of 65 million cells. The approximate number of generations that
has occurred is
A. 5.
B. 13.
C. 21.
D. 27.
52. At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At
9:00 p.m. the log phase culture has a population of 65 million cells. The mean generation time is approximately
A. 10 minutes.
B. 20 minutes.
C. 30 minutes.
D. 40 minutes.
53. Organisms that are not drastically affected by increased pressure are called
A. barotolerant.
B. osmotolerant.
C. barophilic.
D. osmophilic.
54. DNA of thermophiles is stabilized by binding of special nucleoid-associated proteins.
True False
55. Organisms that require high levels of sodium chloride in order to grow are called __________ organisms.
________________________________________
56.
A.
B.
C.
D.
Membranes of thermophilic bacteria are stabilized by phospholipids with
fatty acids that tend to be more saturated.
fatty acids that have lower molecular weights.
fatty acids that have more double bonds.
all of the choices
57. Organisms that grow best at pH levels above 10 are called __________ __________.
________________________________________
58. Quorum sensing in Gram-positive bacteria generally involves the use of ____________ as the external
signaling molecules.
________________________________________
59. An agent that kills bacteria is referred to as __________.
________________________________________
60. Which of the following lacks sufficient penetrating power for bulk sterilization?
A. Ultraviolet (UV) radiation at 260 nm.
B. X rays.
C. Gamma radiation.
D. Alpha and beta particles.
61. When comparing dry heat and moist heat sterilization, dry heat is
A. faster.
B. slower.
C. equally as fast.
D. sometimes faster but sometimes slower.
62. The type of filter used in a laminar flow biological safety cabinet is called a(n) __________ filter.
________________________________________
63. Joseph Lister
A. pioneered the use of gamma rays for sterilizing food.
B. demonstrated that microorganisms are carried on dust particles in the air.
C. revolutionized surgery by introducing phenol as a disinfectant.
D. designed and built the first autoclave.
64. The disinfecting properties of Lysol, a common household disinfectant, depend upon the presence of
__________.
________________________________________
65. The two most important alcohol germicides are __________ and __________.
A. ethanol; methanol
B. ethanol; isopropanol
C. methanol; butanol
D. methanol; isopropanol
66. The disinfectant screening method that is known as the ________ _________ test, which is used to
measure the potency of a disinfectant.
________________________________________
67. The higher the phenol coefficient value, the _______ effective the disinfectant under the test conditions.
________________________________________