Multiple Choice Exam Questions. Structure and Function of Bacterial Cells.
Questions 11-44 refer to the following diagram of the murein subunit of the cell wall peptidoglycan of E. coli.
11. The peptide bond attaching N-acetyl-muramic acid to L-alanine is shown by pointer
A. I
B. II
C. III
D. IV
E. none of the above
12. The glycoside bond attaching N-acetyl-glucosamine to N-acetyl-muramic acid is shown by pointer
A. I
B. II
C. IV
D. V
E. none of the above
13. The pointer to the bond whose formation is inhibited by beta-lactam antibiotics is
A. II
B. III
C. V
D. VI
E. none of the above
14. The arrow pointing to the bond that is cleaved by lysozyme is
A. II
B. III
C. IV
D. V
E. none of the above
15. The function of peptidoglycan in the cell wall of the E. coli is to
A. serve as a permeability barrier to all solutes except H2O
B. prevent osmotic lysis of the cell protoplast
C. regulate the passage of solutes through the cell wall
D. regulate the passage of solutes into and out of the cell
E. none of the above
16. The interpeptide bridge of Gram-positive bacterial murein (e.g. the pentaglycine bridge in Staphylococcus aureus) connects
A. Diaminopimelic acid to D-alanine
B. L-lysine to D-alanine
C. L-lysine to D-glutamate
D. Diaminopimelic acid to D-lysine
E. D-lysine to L-lysine
17. Chemotaxis is
A. the use of an inorganic chemical as an energy source
B. bacterial growth in response to the addition of a specific growth factor in a culture medium
C. the form of energy that powers the bacterial flagellum
D. an increase in the internal osmolarity of a cell
E. movement by a bacterium in response to a chemical stimulus
18. The function of the sex (F) pilus of Escherichia coli involves
A. passage of solutes through the outer membrane
B. attachment of cells to inert surfaces
C. movement of cells in a type of twitching motion
D. transfer of DNA between bacteria during conjugation
E. segregation of the bacterial chromosome following replication
19. Which of the following is a function of bacterial polysaccharide capsules?
A. protect cells from phagotrophic engulfment and certain host defense mechanisms
B. generate energy
C. prevent osmotic lysis of the cell
D. active transport of solutes
E. none of the above
20. In medical situations, biofilms and slime layers may protect the organisms within the slime from
A. attack by phagocytes
B. interaction with antibodies and other immune components of the host
C. diffusion of antibiotics to the site of bacterial infection and growth
D. all of the above
E. none of the above
21. Both fimbriae (common pili) and capsules of bacterial cells may be involved in
A. trapping and storing nutrients on the cell surface
B. gliding motility
C. adherence to a surface or tissue
D. genetic exchange processes
E. all of the above
Questions 22 -26 refers to the drawing below of the ultra structure of the cell surface of Escherichia coli.
22. The structure shown by pointer III is
A. a porin
B. a phosphoplipid
C. the Braun lipoprotein
D. lipopolysaccharide
E. the flagellar P-ring
23. The function of this structure (pointer III above) is
A. active transport of solutes across the plasma membrane
B. support of the bacterial flagellum
C. maintain the lateral stability of the outer membrane
D. anchor the outer membrane to the underlying peptidoglycan sheet
E. allow passage of solutes through the outer membrane
24. Bracket B defines the limits of the
A. outer membrane
B. plasma membrane
C. cytoplasm
D. periplasm
E. glycocalyx
25. Which component is considered in medical situations as bacterial “endotoxin”?
A. I
B. II
C. V
D. D
E. E
26. Which component is cell wall murein?
A. I
B. II
C. IV
D. D
E. V
27. Polybetahydroxybutyric acid and glycogen are formed by bacterial cells as
A. reserves of carbon and energy
B. reserves of nitrogen
C. waste material
D. molecular ligands to attach bacterial cells to surface receptors
E. none of the above
28. A procaryote possessing carboxysomes and chlorosomes as inclusions in its cytoplasm probably has this type of metabolism.
A. photoautotrophic
B. photoheterotrophic
C. lithoautotrophic
D. heterotrophic
E. fermentative
29. The inclusion produced by Bacillus thuringiensis that is toxic to lepidopteran insects (moths and caterpillars) is
A. anthrax spores
B. parasporal crystals
C. dipicolinic acid
D. PHB
E. "BT"
30. Which inclusion listed below would you never expect to be found in an aquatic bacterium?
A. sulfur granules
B. gas vesicles
C. phycobilisomes
D. magnetosomes
E. none of the above
31. Compared to the vegetative cells that form them, bacterial endospores
A. have a surface structure consisting of additional unique layers
B. have a reduced number of ribosomes
C. lack any signs of detectable life
D. have increased resistance to boiling and desiccation
E. all of the above
32. The passage of a molecule across the bacterial cell membrane, which results in a chemical modification of the molecule is called
A. antiport (exchange diffusion)
B. facilitated diffusion
C. uniport
D. group translocation
E. active transport
33. Which type of bacterial transport system(s) requires ATP and establishes a concentration gradient resulting in a higher concentration of solute inside the cell?
A. binding-protein dependent transport
B. ion-driven transport
C. facilitated diffusion and group translocation
D. simple diffusion and facilitated diffusion
E. passive diffusion
34. Transport of glucose using a group translocation system rather than a binding protein dependent transport system is advantageous to a bacterium because
A. glucose, a disaccharide, is initially cleaved into its monosaccharide constituents during the transport process
B. glucose can be transported into the cell against an external concentration gradient
C. glucose is phosphorylated as it traverses the membrane which accomplishes the first step of glycolysis and conserves ATP
D. energy is not required for transport
E. it has the effect of decreasing the internal osmolarity within the cytoplasm of the cell
Questions 35-37 refer to the following diagram of the ultrastructure of the plasma membrane of Escherichia coli.
35. The lactose transport system (lactose permease) is an example of
A. a uniport process
B. an antiport process
C. a symport process
D. an ion-driven transport system
E. two of the above
36. Proton motive force is established on the membrane by means of
A. lactose transport
B. ATP synthesis
C. electron transport processes
D. proline transport
E. none of the above
37. Proton motive force on the membrane is apparently utilized during the process of
A. flagellar rotation
B. lactose transport
C. ATP synthesis
D. all of the above
E. none oif the above
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