(1st Week )

Question 1

All of the following descriptions refer to the nuclear body in bac­teria EXCEPT

a. it represents about 10% of the cell volume
b. it lacks a nuclear membrane
c. it is composed of ribosomes
d. it is referred to as the nucleoid
e. it is free of ribosomes

Answer 1

it is composed of ribosomes

Question 2

Of the following bacterial components, which one exhibits the most antigenic variation?

Select one:

a. Ribosomes
b. Spores
c. Capsule
d. Lipid A of the endotoxin
e. Peptidoglycan

Answer 2

c.Capsule

Question 3

Bacteria that cause hospital acquired infections produce extracellular substances that allow them to stick firmly to medical devices, such as intravenous catheters, Which one of the following is the name of this extracellular substance?

Select one:

a. Flagella
b. Axial filament
c. Glycocalyx
d. Porin
e. Endotoxin

Answer 3

C-Glycocalyx

Question 4

DNA sequenceoriTis:

Select one:

a. Present in Vi plasmid
b. Important for plasmid replication
c. The sequence at which DNA transfer initiates during conjugation
d. Present in Fertility plasmid only

Answer 4

c.The sequence at which DNA transfer initiates during conjugation

Question 5

Mobile genetic elements include the following except:

Select one:

a. Chromosomal genes
b. Gene Cassette
c. Plasmids
d. Insertion sequence

Answer 5

a.Chromosomal genes

Question 6

Transformation

Select one:

a.No need for homology between the new and resident chromosome

b.The foreign DNA is incorporated into the host cell chromosome by site-specific
recombination

c. Can occur between cells of different species
d. Occurs for Competent cells only

Answer 6

d.Occurs for Competent cells only

Question 7

Which of the following events is most likely due to bacterial transformation:

Select one:

a.A formerly non-toxigenic strain of Corynbacterium diphtheria becomes
toxigenic

b.A strain of Neisseria gonorrhea starts producing plasmid mediated enzyme
similar to another Neisseria strain

c.A gene for ampicillin resistance from an Escherichia coli chromosome

d.A non-encapsulated strain of Streptococcus pneumoniae acquires a gene
for capsule formation from the extract of an encapsulated strain.

Answer 7

d.A non-encapsulated strain of Streptococcus pneumoniae acquires a gene
for capsule formation from the extract of an encapsulated strain.