Question 1

Which of the following best describes a facultative anaerobe?

Accepted Answer

A microbe that can utilize oxygen but can also grow in its absence.

Question 2

A bacterium isolated from a salt lake requires at least 9% NaCl for growth and grows optimally at 25% NaCl. Which term best describes this organism?

Accepted Answer

Obligate halophile

Question 3

Which of the following environmental factors does NOT directly affect the function of microbial metabolic enzymes?

Accepted Answer

Light intensity

Question 4

A patient is diagnosed with a viral infection. The virus is found to have a helical capsid and an envelope. Which of the following is most likely true about the release of this virus from the host cell?

Accepted Answer

It is released by budding (exocytosis), allowing the host cell to survive for some time.

Question 5

Which of the following best explains why HIV can only infect certain host cells?

Accepted Answer

HIV requires the presence of a CD4 marker and a co-receptor on the host cell surface.

Question 6

Which of the following is a correct sequence of events in the multiplication cycle of an enveloped animal virus?

Accepted Answer

Adsorption → Penetration → Uncoating → Synthesis → Assembly → Release

Question 7

A microbiologist is studying a virus that contains single-stranded RNA which can be immediately translated by host ribosomes. Which type of viral genome does this virus possess?

Accepted Answer

+ssRNA

Question 8

Which of the following is a real-world example of lysogenic conversion, where a bacteriophage imparts new pathogenic properties to a bacterium?

Accepted Answer

Corynebacterium diphtheriae producing diphtheria toxin

Question 9

Which of the following best describes the function of reverse transcriptase in HIV?

Accepted Answer

It synthesizes DNA from an RNA template.

Question 10

A laboratory is using turbidometry to estimate bacterial population size. Which principle is this method based on?

Accepted Answer

The degree of cloudiness (turbidity) of the culture medium reflects the relative population size.

Question 11

Which of the following statements about prions is TRUE?

Accepted Answer

Prions are infectious proteins that contain no nucleic acid.

Question 12

A bacterial culture is in the exponential (log) phase of growth. If the number of cells doubles every 30 minutes, and you start with $$1 	imes 10^3$ cells, how many cells will there be after 2 hours?

Accepted Answer

$$1.6 	imes 10^4$

Question 13

Which of the following best describes a mutualistic relationship in microbiology?

Accepted Answer

Both organisms benefit from the interaction.

Question 14

Which of the following is a correct description of a mesophile?

Accepted Answer

A microbe with an optimum growth temperature between 20°C and 40°C.

Question 15

Which of the following is a distinguishing feature of enveloped viruses compared to naked viruses?

Accepted Answer

Enveloped viruses acquire their envelope from the host cell membrane during release.

Question 16

A virus is found to have a polyhedral nucleocapsid, a helical tail, and attachment fibers. This virus most likely infects:

Accepted Answer

Bacterial cells

Question 17

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

The parent cell divides into two daughter cells after duplicating its chromosome and forming a transverse septum.

Question 18

Which of the following is a correct statement about viroids?

Accepted Answer

Viroids are short pieces of RNA with no protein coat, and they infect plants.

Question 19

A microbiologist is analyzing a culture and observes that the pH has dropped to 4.5. Which group of microorganisms is most likely to thrive in this environment?

Accepted Answer

Acidophiles

Question 20

Which of the following is a key difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle results in immediate lysis of the host cell, while the lysogenic cycle involves integration of viral DNA into the host genome without immediate lysis.

Environmental Factors Influencing Microbial Growth and Population Analysis

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