Question 1

Which of the following best describes the difference between defined and complex media used in laboratory culture of microorganisms?

Accepted Answer

Defined media have a precise chemical composition known, while complex media are composed of digests of chemically undefined substances.

Question 2

A microbiologist is culturing a nutritionally demanding organism. Which type of media would be most appropriate for this purpose?

Accepted Answer

Enriched media

Question 3

Which macronutrient is required by all cells and is a major element in all classes of macromolecules, making up about 50% of a typical bacterial cell's dry weight?

Accepted Answer

Carbon (C)

Question 4

Which of the following statements about micronutrients is correct?

Accepted Answer

Micronutrients are trace elements, often serving as components of cytochromes and FeS proteins involved in electron transport.

Question 5

A marine microbe requires sodium for growth. Which category does sodium fall under for this organism?

Accepted Answer

Special function element

Question 6

Which of the following is a correct example of a growth factor required by certain organisms?

Accepted Answer

Vitamin B12

Question 7

Which of the following best explains why agar is preferred over gelatin as a solidifying agent in microbial culture media?

Accepted Answer

Agar is not metabolized by most microbes and remains solid at higher temperatures.

Question 8

Which of the following statements about pure culture is correct?

Accepted Answer

A pure culture contains only a single kind of microbe.

Question 9

Which element is a key component of proteins, nucleic acids, and many cell constituents, and makes up about 13% of a typical bacterial cell's dry weight?

Accepted Answer

Nitrogen (N)

Question 10

Which of the following is a function of magnesium (Mg) in microbial cells?

Accepted Answer

Stabilizes ribosomes, membranes, and nucleic acids

Question 11

A student is preparing a medium to selectively inhibit the growth of Gram-negative bacteria while allowing Gram-positive bacteria to grow. Which type of media should be used?

Accepted Answer

Selective media

Question 12

Which of the following best describes the role of vitamins in microbial metabolism?

Accepted Answer

Vitamins function primarily as coenzymes in metabolic reactions.

Question 13

Which of the following elements is required for the synthesis of nucleic acids and phospholipids in microbial cells?

Accepted Answer

Phosphorus (P)

Question 14

Which of the following statements about contaminants in microbial culture is correct?

Accepted Answer

Contaminants are unwanted organisms in a culture.

Question 15

Which macromolecule makes up the largest percentage of dry weight in a typical bacterial cell?

Accepted Answer

Protein

Question 16

Which of the following is NOT a function of calcium (Ca) in microbial cells?

Accepted Answer

Required for synthesis of nucleic acids

Question 17

Which of the following best describes the use of differential media in microbiology?

Accepted Answer

Differential media contain an indicator, usually a dye, that detects particular chemical reactions occurring during growth.

Question 18

Which of the following elements is a key component of cytochromes and FeS proteins involved in electron transport?

Accepted Answer

Iron (Fe)

Question 19

Which of the following statements about the elemental composition of an E. coli cell is correct?

Accepted Answer

E. coli cells are composed of approximately 50% carbon by dry weight.

Microbial Metabolism: Chemistry, Nutrition, and Laboratory Culture

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