Q: Which of the following equations correctly represents the pressure and temperature conditions for autoclaving?

$$P = 15\ \text{lb/in}^2$$,\ T = 121^\circ\text{C}$

Question 1

Which of the following best describes a defined (synthetic) culture medium?

Accepted Answer

A medium in which all chemical components and their concentrations are known.

Question 2

Why is iron (Fe) considered a limiting nutrient for algal growth in the ocean?

Accepted Answer

Iron is present in very low concentrations in seawater, restricting algal biosynthesis and growth.

Question 3

Which macromolecule makes up the largest percentage of a bacterial cell's dry weight?

Accepted Answer

Protein

Question 4

A microbiologist wants to isolate a pure culture from a mixed sample. Which technique should they use?

Accepted Answer

Streak plate method

Question 5

Which of the following best describes a selective medium?

Accepted Answer

A medium that allows only certain types of microorganisms to grow while inhibiting others.

Question 6

Blood agar is an example of which type of medium?

Accepted Answer

Differential medium

Question 7

What is the main purpose of autoclaving culture media before use?

Accepted Answer

To sterilize the media by killing all organisms and spores.

Question 8

Which of the following is a component commonly found in complex (undefined) media but not in defined media?

Accepted Answer

Yeast extract

Question 9

A researcher is studying a fastidious microorganism. Which type of medium should they use to ensure optimal growth?

Accepted Answer

Enriched medium

Question 10

Which of the following equations correctly represents the pressure and temperature conditions for autoclaving?

Accepted Answer

$$P = 15\ 	ext{lb/in}^2$$,\ T = 121^\circ	ext{C}$

Question 11

Which of the following best explains why uptake of nutrients is preferred over de novo synthesis in microbes?

Accepted Answer

Uptake is less energy-consuming than synthesizing nutrients from scratch.

Question 12

A scientist wants to enrich for petroleum-degrading bacteria from a soil sample. Which approach should they use?

Accepted Answer

Grow the sample in a medium containing crude oil as the sole carbon source.

Question 13

Which of the following statements about minimal and rich media is correct?

Accepted Answer

Minimal media contain only the essential nutrients required for growth, while rich media contain additional nutrients to support faster or more robust growth.

Question 14

Which of the following is a correct statement about the use of agar in microbial culture media?

Accepted Answer

Agar is used as a solidifying agent and is typically added at 1.5% (w/v).

Question 15

A laboratory technician is using a streak plate method to isolate colonies. What is the main goal of this technique?

Accepted Answer

To obtain isolated colonies derived from a single cell.

Question 16

Which of the following best describes the function of a differential medium?

Accepted Answer

It distinguishes between different types of microorganisms based on their biochemical properties.

Question 17

Which of the following is a plausible reason why E. coli grows faster in 2xYT medium compared to LB medium?

Accepted Answer

2xYT contains higher concentrations of nutrients, supporting a higher growth rate.

Question 18

Which of the following is a correct statement about aseptic technique?

Accepted Answer

Aseptic technique prevents contamination of cultures by airborne microbes.

Question 19

Which of the following is a correct description of an enrichment culture?

Accepted Answer

A culture method that uses specific nutrients or conditions to favor the growth of particular microorganisms from a mixed community.

Question 20

Which of the following best explains why blood agar is considered a differential medium?

Accepted Answer

It allows visualization of hemolytic activity, distinguishing between bacteria that can lyse red blood cells and those that cannot.

Microbial Growth: Nutrition, Cultivation, and Enrichment

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