Question 1

Which of the following best describes the difference between sterilization and disinfection in microbial control?

Accepted Answer

Sterilization destroys all forms of microbial life, including spores and viruses, while disinfection eliminates most pathogenic microorganisms except spores on inanimate objects.

Question 2

A bacterial culture is exposed to a disinfectant. If the decimal reduction time ($$D) is 2 $$minutes, how long will it take to reduce a population from $$10^6$$ cells to $$10^3$$ cells?

Accepted Answer

$$6$$ minutes

Question 3

Which enzyme is responsible for converting superoxide ($$O_2$$^-$$) into hydrogen peroxide (H_2O_2$) and oxygen (O_2$) in bacteria?

Accepted Answer

Superoxide dismutase (SOD)

Question 4

A patient develops a chronic infection on a catheter. Which microbial structure is most likely responsible for increased resistance to antibiotics and immune defenses?

Accepted Answer

Biofilm matrix

Question 5

Which of the following statements about the three-domain system is correct?

Accepted Answer

Eukarya includes organisms with a nucleus and membrane-bound organelles.

Question 6

Which method is most appropriate for direct detection of unculturable bacteria in environmental samples?

Accepted Answer

PCR (Polymerase Chain Reaction)

Question 7

A bacterium is classified as a thermophile. Which temperature range would you expect it to grow best in?

Accepted Answer

$$45-80\ ^\circ\mathrm{C}$$

Question 8

Which of the following is a key difference between Gram-positive and Gram-negative bacteria regarding resistance to disinfectants?

Accepted Answer

Gram-negative bacteria have an outer membrane that increases resistance.

Question 9

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

Accepted Answer

One cell divides into two genetically identical daughter cells after DNA replication and septum formation.

Question 10

Which of the following media would you use to distinguish between bacteria based on their ability to hemolyze red blood cells?

Accepted Answer

Differential media

Question 11

A researcher wants to isolate Salmonella from a mixed fecal sample. Which type of culture media should be used to increase the numbers of Salmonella to detectable levels?

Accepted Answer

Enrichment media

Question 12

Which of the following is NOT a method used for species identification in clinical microbiology?

Accepted Answer

Gram staining

Question 13

Which of the following statements about DNA replication is correct?

Accepted Answer

DNA replication is semiconservative, each new molecule contains one original and one new strand.

Question 14

Which of the following is a major function of cyanobacteria in the environment?

Accepted Answer

Oxygenic photosynthesis and nitrogen fixation

Question 15

Which of the following is a correct application of binomial nomenclature?

Accepted Answer

Escherichia coli: 'Escherichia' is the genus and 'coli' is the specific epithet.

Question 16

Which of the following is a key adaptation that allows Archaea to survive in extreme environments?

Accepted Answer

Ether-linked membrane lipids

Question 17

A hospital outbreak is traced using DNA fingerprinting. Which process is involved in this method?

Accepted Answer

Restriction enzyme digestion and gel electrophoresis

Question 18

Which of the following statements about microbial taxonomy is correct?

Accepted Answer

Taxonomy is concerned with evolutionary relationships, while identification focuses on diagnosing infections.

Question 19

Which of the following is a major ecological role of methanogens in the domain Archaea?

Accepted Answer

Methane production in anaerobic environments

Question 20

Which of the following is a correct description of a pure culture?

Accepted Answer

A population of microorganisms that all originate from a single cell or colony, containing only one species.

Microbial Growth, Control, Genetics, and Classification: Structured Study Notes

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