超星 - 章节练习

单选题

Reverse transcriptase is an enzyme unique to the retroviruses.Which one of the following is a function of the reverse transcriptase?

A. DNase activity
B. RNA-dependent RNA polymerase activity
C. Integration activity
D. RNA-dependent DNA polymerase activity

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单选题

Viruses enter cells by adsorbing to specific sites on the outer membrane of cells. Each of the following statements regarding this event is correct EXCEPT

A. The interaction determines the specific target organs for infection
B. The interaction determines whether the purified genome of a virus is infectious
C. The interaction can be prevented by neutralizing antibody
D. If the sites are occupied, interference with viral infection occurs

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单选题

If deproteinized viral nucleic acid was added to cells, which would be able to make virus?

A. parainfluenza virus
B. rabies virus
C. poliovirus
D. measles virus

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单选题

The process by which bacteriophage P1 packages random phage-genome-sized pieces into phage heads and thereby allows transfer of pieces of the bacterial chromosomal DNA between bacteria is called

A. generalized transduction
B. non-general transposition
C. specialized transduction
D. high-frequency recombination
E. None of the above

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单选题

The viral DNA of the temperate phage, instead of taking over the functions of the cell’s genes, is incorporated into the host DNA and becomes a prophage in the bacterial chromosome, acting as a gene. This happens in

A. lysogeny
B. spontaneous induction
C. lytic phase
D. adsorption
E. none of these

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单选题

The time it takes one bacterium to become two bacteria is referred to as

A. the culture doubling time
B. the generation time
C. the mass doubling time
D. the incubation time
E. None of the above

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单选题

Most pathogenic bacteria are

A. obligate aerobes
B. facultative anaerobes
C. microaerophiles
D. obligate anaerobes
E. None of the above

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单选题

The growth rate of bacteria during the exponential phase of growth is

A. Zero
B. Increasing
Constant
Decreasing
E. Negative

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单选题

The ability to use compounds and ions other than oxygen as terminal oxidants in respiration is a widespread microbial trait. This capacity is called

A. Photosynthesis
B. Fermentation
C. Anaerobic respiration
D. Substrate phosphorylation
E. Nitrogen fixation

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单选题

Lack of the enzymes catalase and superoxide dismutase may explain why certain bacteria are

A. unable to produce oxygen radicals when exposed to O2
B. able to grow in the absence of O2
C. killed by exposure to O2
D. able to respire in the presence of O2
E. able to respire in the absence of O2

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