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Multiple Choice Quiz
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The significance of the plasma membrane is that
A)it selectively allows some molecules to pass into the organism
B)it prevents movement of molecules out of the organism
C)it is the site of protein synthesis
D)all of the above
The most commonly encountered bacteria are roughly spherical. The microbiological term describing this shape is
Another common bacterial shape is that of a rod, often called
In bacterial cells, ribosomes are packed into the cytoplasmic matrix and also loosely attached to the plasma membrane. What is the function of ribosomes?
A)Site of energy production
B)Site of protein synthesis
C)Site of genetic reproduction
What is a plasmid?
A)Self-replicating segment of double stranded DNA
B)Self-replicating segment of single stranded RNA
C)A bacterial chromosome
Plasmids are important to the genetics of many bacteria. This is because
A)they are inherited from one generation to the next.
B)they may carry genes that give their host a selective advantage.
C)they can render bacteria drug-resistant.
D)All of the above.
Bacteria do not always swim aimlessly but are attracted by such nutrients such as sugar and amino acids, and are repelled by harmful substances and bacterial waste products. Movement toward chemical attractants and away from repellents is called
A)gliding motility.
Some bacteria are considered pleomorphic. This means
A)they are shaped like bent rods.
B)they have a corkscrew shape.
C)they do not have just one shape.
D)they are not either bacilli or cocci.
Poly-beta-hydroxybutyrate inclusion bodies
A)protect bacteria from excessive drying.
B)store carbon for energy and biosynthesis.
C)turn reddish brown when stained with iodine.
D)are composed of polymers of glucose.
Gas vesicles in bacteria
A)help move cells to optimal nutrient levels.
B)store oxygen for growth anaerobically.
C)are bounded by a lipid bilayer membrane.
D)are bounded by a membrane impervious to gas.
Magnetostomes in bacteria
A)help cells attach to metal objects.
B)help cells to magnetically attach to each other.
C)help cells to float on the surface of fresh water ponds.
D)help cells to orient in the earth's magnetic field.
The 70S procaryotic ribosomes consist of
A)two 40S subunits.
B)a 50S and a 30S subunit.
C)a 40S and a 30S subunit.
D)a 50S and a 20S subunit.
Gram positive cells
A)have a second, outer membrane that helps retain the crystal violet stain.
B)have multiple layers of peptidoglycan that help retain the crystal violet stain.
C)have a thick capsule that traps the crystal violet stain.
D)have a periplasmic space that traps the crystal violet.
The presence of D-amino acids in the crosslinks of the peptidoglycan layer is most likely because
A)most peptidases can only cleave L-amino acids.
B)D-amino acids fit the structural constrains of the cell wall better than L-amino acids.
C)most L-amino acids have already been used for protein synthesis.
D)D-amino acids are easier to crosslink in the absence of ribosomes.
The third amino acid in the peptidoglycan crosslinking chain is either diaminopimilic acid or lysine because this amino acid must
A)be positively charged for a salt bridge to form.
B)be hydrophillic.
C)have a free amino group for peptide bond formation.
D)have a large R-side chain to fill space in the cell wall.
Gram positive cells
A)have thick, homogeneous cell walls.
B)have large amounts of teichoic acids.
C)do not have an outer membrane.
D)all of the above are true.
The outer membrane of Gram negative cells is more permeable than the plasma membrane because
A)LPS is larger than most membrane phospholipids.
B)lipoproteins stretch the outer membrane.
C)porin proteins establish holes in the outer membrane.
D)the core polysaccharide spans the lipid bilayer.
The most important role of the prokaryotic cell wall is to
A)maintain the shape of the cell.
B)protect the cell from osmotic pressures.
C)prevent ions from diffusing away from the cell.
D)block the effects of antibiotics like penicillin.
Which of the following is not true about capsules and slime layers?
A)They consist of secreted material lying outside of the bacterial cell wall.
B)They can prevent desiccation of bacteria cells.
C)They are required for bacteria to grow normally in culture.
D)They help bacteria resist phagocytosis by macrophages.
A)attach bacteria to various surfaces.
B)cause bacteria move through fluids.
C)sense changes in nutrient concentration.
D)are pathways for the secretion of exoenzymes.
A bacillus bacterium with a single flagellum at each end is described as
Which of the following is not true about bacterial flagella?
A)Most of their length consists of a hollow, rigid protein tube.
B)They are constructed largely of a single protein called flagellin.
C)They spin like wheels, either clockwise or counterclockwise.
D)They use cytoplasmic ATP as their primary energy source.
The flagellar filament grows by
A)enzymatic addition of subunits to the tip of the flagellum.
B)enzymatic addition of subunits to the base of the flagellum.
C)self-assembly of subunits traveling through the hollow flagellum to the tip.
D)self-insertion of subunits along the length of the filament.
How does a bacterium control the direction of swimming?
A)The length of the flagellum acts as a rudder to steer the bacterium.
B)The speed of rotation is faster when the bacterium is headed the correct way.
C)The bacterium can stop and spin until it is pointed the correct way.
D)The bacterium does not control the direction of its swimming.
The methyl-accepting chemotaxis proteins of bacteria
A)are directly connected to the flagellar motor to guide the bacterium.
B)can only sense conditions that are favorable for bacterial growth.
C)integrate multiple signals through a two component phospho-relay system.
D)tell the bacterium which way to go.
Bacteria accomplish chemotaxis by
A)Steering toward better growth conditions.
B)Making long, uninterrupted runs when conditions are good.
C)Frequently stopping and tumbling to better sense good conditions.
D)Stopping movement when conditions are good.
What is the purpose of bacterial endospores?
A)Allow the bacterium to make hundreds of "seeds" to spread on the wind.
B)Help the bacterium to differentiate into faster growing stages of bacteria.
C)Allow the bacterium to survive the absence of oxygen.
D)Allow the bacterium to survive extended periods of heat or dryness.

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