Unit 5.3 (Difficulty: Very Hard) Detecting Microorganisms in Food

Which type of media has an exact chemical composition that is known and is often used for metabolic experiments?

Selective media allow for the growth of all types of microorganisms, distinguishing them based on specific characteristics.

What is the assumption made when enumerating microorganisms on a plate regarding the origin of each colony?

In immunological methods, an ______ is a molecular marker on the microorganism unique to that microorganism.

Match the following media types with their respective characteristics:

Which method offers a more time-efficient measure of microbial activity by assessing a characteristic directly related to it?

The polymerase chain reaction (PCR) is only useful for qualitative detection of specific organisms and cannot be used for quantification.

What is the primary limitation of using a medium with >300 colonies for enumeration?

Results from cultures are usually reported in ______, representing colony forming units per milliliter in the original sample.

Match each term with its correct description within the context of microbial detection:

Which of the following statements accurately describes the advantage of molecular biology methods over traditional culturing methods?

Complex media are preferred over defined media when conducting metabolic experiments due to their known exact chemical compositions.

Briefly explain why MacConkey agar is considered a differential medium.

To enumerate microorganisms with a dilution of $10^{-5}$ and a colony count of 50, the CFU/mL in the original sample is ______.

Match the following dilution factors with the corresponding CFU/mL calculation, assuming a plate count of 45 colonies:

Which of the following is an example of an indirect method for detecting microorganisms?

When using serial dilutions to enumerate microorganisms, it is acceptable to count plates with more than 300 colonies for accurate enumeration.

Explain the significance of using both selective and differential media in identifying a specific pathogen in a mixed culture.

In PCR, the amplification of DNA or RNA allows for detection of specific ______ even when present in small quantities.

Match the following scenarios with the most appropriate type of microbial detection method:

Which of the following is a disadvantage of using complex media compared to defined media?

Immunological methods rely on amplifying the genetic material of microorganisms for detection.

Explain why culturing is often the first step in identifying microorganisms in food, even with faster methods available.

When performing serial dilutions, a countable range typically falls between ______ and ______ colonies to ensure accuracy.

Match the following descriptions with the appropriate type of culture medium:

What is the primary advantage of using lateral flow assays in food microbiology?

Defined media is easier to make compared to complex media due to its simple and known composition.

Why is it essential to dilute samples when enumerating microorganisms from a food sample? Explain the rationale.

The countable range in serial dilutions is typically considered inaccurate if it goes below ______ colonies, as the results can lack statical backing.

When might you prefer to use immunological methods over PCR for detecting a foodborne pathogen?

An antibody recognizes the bacterial antigen and amplifies the antigen itself facilitating higher sensitivity.

A $10^{-3}$ dilution yields 330 colonies. How would you record the plate and why?

While performing PCR, one strand of DNA can be used to create ______ of copies.

Match the method for detecting enumeration of microorganisms with the correct way it helps:

Regarding the relationship of Molecular Biology and Microbial methods, which statement is true?

Titratable acidity helps determine how well microbes grew in the atmosphere.

Is MacConkey agar selective or differential?

An antibody is considered a ______ marker.

Match the following reagents to the appropriate media usage: