Q: Which of the following statements about agar is TRUE?

Agar solidifies at approximately $$40\text{–}45^\circ\text{C}$$

Question 1

Which of the following best describes a chemoautotroph?

Accepted Answer

Uses chemical compounds as an energy source and CO$$_2 as a $$carbon source

Question 2

A bacterial culture is grown in a medium containing yeast extract. Which type of culture media is this?

Accepted Answer

Complex media

Question 3

Which of the following statements about agar is TRUE?

Accepted Answer

Agar solidifies at approximately $$40	ext{–}45^\circ	ext{C}$$

Question 4

A patient develops an infection from a biofilm on a catheter. Which process allows bacteria in the biofilm to coordinate their activities?

Accepted Answer

Quorum sensing

Question 5

Which group of bacteria would be most likely to survive in a food preserved with high salt concentrations?

Accepted Answer

Obligate halophiles

Question 6

During which phase of bacterial growth does the number of cells remain constant because cell division equals cell death?

Accepted Answer

Stationary phase

Question 7

Which of the following is the LEAST resistant to microbial chemicals?

Accepted Answer

Enveloped viruses

Question 8

A microbiologist wants to sterilize surgical instruments. Which method should be used to destroy endospores?

Accepted Answer

Autoclave

Question 9

Which of the following is a mechanism of action for phenolics?

Accepted Answer

Damage membranes and proteins

Question 10

A bacterium is found growing at pH 2. Which term best describes this organism?

Accepted Answer

Acidophile

Question 11

Which of the following is TRUE about obligate anaerobes?

Accepted Answer

They grow without O$$_2$$ and lack catalase, SOD, and peroxidase

Question 12

A disk diffusion test is performed to evaluate the effectiveness of an antimicrobial agent. What does a large zone of inhibition indicate?

Accepted Answer

The antimicrobial is more effective

Question 13

Which of the following is a degerming agent that removes microbes by washing them away?

Accepted Answer

Soaps and detergents

Question 14

A bacterium is classified as a mesophile. At which temperature would it most likely grow best?

Accepted Answer

$$37^\circ	ext{C}$$

Question 15

Which nutrient is essential for the synthesis of ATP, DNA, RNA, and phospholipids in bacteria?

Accepted Answer

Phosphorus

Question 16

A bacterial cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell undergoes plasmolysis and cannot grow

Question 17

Which of the following best describes the mechanism of action for quaternary ammonium compounds (quats)?

Accepted Answer

Alter membrane permeability

Question 18

A microbiologist wants to distinguish between two bacterial species based on their ability to ferment lactose. Which type of media should be used?

Accepted Answer

Differential media

Question 19

Which of the following is the most common target of disinfectants?

Accepted Answer

Cell membrane

Question 20

A bacterium is able to grow both in the presence and absence of O$$_2$$, and possesses catalase and SOD enzymes. Which classification best fits this organism?

Accepted Answer

Facultative anaerobe

Microbial Growth & Cultures

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