Media Preparation and Sterilization: A Comprehensive Guide for Biotechnology Students

Question 1

What is the primary objective of sterilization in media preparation?

Accepted Answer

Eliminating all living organisms to prevent contamination

Answer

Adjusting the pH of the media to optimize growth

Answer

Enhancing cell growth by providing essential nutrients

Answer

Removing impurities that may interfere with cell metabolism

Question 2

Which sterilization method is most suitable for liquid culture media?

Accepted Answer

Autoclaving

Answer

Filtration

Answer

Lyophilization

Answer

Radiation

Question 3

What is the standard temperature used in autoclaving microbiological media to achieve sterilization?

Accepted Answer

121°C

Answer

100°C

Answer

115°C

Answer

134°C

Question 4

What is the role of a biological indicator in sterilization?

Accepted Answer

Confirming the effectiveness of the sterilization process

Answer

Eliminating bacterial spores

Answer

Detecting the presence of contaminants

Answer

Adjusting the pH of the media

Question 5

Which of the following is NOT a recommended aseptic media transfer technique?

Accepted Answer

Pipetting media using non-sterile tips

Answer

Using proper aseptic technique

Answer

Pouring media into sterile containers

Answer

Filtering media through a sterile membrane

Question 6

What is the prime consideration in media sterilization?

Accepted Answer

Ensuring and maintaining sterility

Answer

Preventing media contamination

Answer

Achieving consistent media composition

Answer

Optimizing pH for cell growth

Question 7

Which advantage is unique to defined media?

Accepted Answer

Precise control over nutrient composition

Answer

Support for a wider variety of organisms

Answer

Lower preparation cost

Answer

Simulation of natural growth conditions

Question 8

Which of the following is NOT a method for sterilizing culture media?

Accepted Answer

Incubation

Answer

Autoclaving

Answer

Tyndallization

Answer

Membrane filtration

Question 9

What is the primary purpose of sterilization in bioprocess engineering?

Accepted Answer

To prevent contamination and ensure the safety and efficacy of the product

Answer

To improve the efficiency and productivity of the process

Answer

To standardize the product and meet regulatory requirements

Answer

To reduce the cost of production and increase profitability

Question 10

Which of the following is the most common method of sterilization in bioprocessing?

Accepted Answer

Autoclaving

Answer

Filtration

Answer

Heat only

Answer

Ultraviolet light

Question 11

What is the purpose of aseptic operations in media preparation?

Accepted Answer

To prevent contamination during media preparation and ensure the sterility of the media

Answer

To reduce the risk of contamination and protect the product from spoilage

Answer

To increase the shelf life of the media and maintain its quality

Answer

To improve the efficiency of the process and reduce production time

Question 12

What is the difference between a defined medium and a complex medium?

Accepted Answer

Defined medium contains known chemical composition, while complex medium contains undefined or unknown components

Answer

Complex medium is more nutritious than defined medium

Answer

Defined medium is used for research, while complex medium is used for industrial applications

Answer

There is no major difference between defined and complex media

Question 13

Which of the following is NOT a commonly used method for sterilizing culture media?

Accepted Answer

Freezing

Answer

Heat

Answer

Filtration

Answer

Radiation

Question 14

When choosing the right culture medium for a microorganism, which factor is LEAST important from a scientific perspective?

Accepted Answer

How much it costs

Answer

What nutrients it needs

Answer

Its pH and oxygen needs

Answer

Its reaction to antibiotics

Question 15

When preparing media, what is a potential source of contamination and how can you address it?

Accepted Answer

Improper sterilization of glassware

Accepted Answer

Contaminated water used for preparation

Answer

Incorrect pH of the media

Answer

Incorrect storage temperature

Question 16

What are some potential drawbacks of common sterilization methods used in media preparation?

Accepted Answer

Heat sterilization can change the makeup of the culture media.

Accepted Answer

Filtration might not completely remove viruses because of their small size.

Answer

Radiation sterilization is generally considered safe and environmentally friendly.

Answer

Aseptic techniques ensure the complete removal of all microorganisms from the media.

Question 17

What is the primary purpose of employing autoclaves in media sterilization?

Accepted Answer

To generate high pressure and temperature, eliminating microorganisms

Answer

To filter out unwanted particles

Answer

To use chemicals to inhibit microbial growth

Answer

To irradiate the media with ultraviolet light

Question 18

Which sterilization method is most suitable for heat-sensitive media?

Accepted Answer

Filtration

Answer

Autoclaving

Answer

Dry heat sterilization

Answer

Ultraviolet irradiation

Question 19

What is the purpose of adding antibiotics or antifungals to culture media?

Accepted Answer

To prevent contamination

Answer

To enhance cell growth

Answer

To induce cell differentiation

Answer

To improve product yield

Question 20

Autoclaving is a sterilization method that utilizes:

Accepted Answer

High pressure and high temperature steam

Answer

Radiation

Answer

Chemical agents

Answer

Ultrafiltration

Question 21

The practice of maintaining sterility throughout media preparation and transfer is called:

Accepted Answer

Aseptic technique

Answer

Sanitation

Answer

Sterilization

Answer

Disinfection

Question 22

A crucial step in preparing chemically defined media is:

Accepted Answer

Adjusting the pH to the desired level

Answer

Sterilizing the glassware

Answer

Autoclaving the medium

Answer

Adding antimicrobials

Question 23

Chemically defined media are used in biotechnology primarily to:

Accepted Answer

Precisely control the nutritional composition of the medium

Answer

Simplify media sterilization

Answer

Increase the cell growth rate

Answer

Reduce the risk of contamination

Question 24

The optimal pH range for the growth of most bacteria is:

Accepted Answer

6.5 to 7.5

Answer

4.5 to 5.5

Answer

8.5 to 9.5

Answer

10.5 to 11.5

Question 25

Over-sterilization of culture media can lead to:

Accepted Answer

The degradation of essential nutrients

Answer

Faster cell growth

Answer

Improved product yield

Answer

Increased contamination risk

Question 26

Air filters are primarily used for sterilization to:

Accepted Answer

Prevent contamination from airborne microbes

Answer

Eliminate surface contamination

Answer

Inactivate viruses

Answer

Remove dissolved impurities