Unit 5.3 (Difficulty: Medium) Detecting Microorganisms in Food

Which method allows for both enumeration and biochemical testing of microorganisms?

Selective media allow all types of bacteria to grow, while differential media only allow certain bacteria to grow.

What is the purpose of using different types of media, growth temperatures, and atmospheres when culturing microorganisms?

A ______ medium has an exact chemical composition that is known.

Match the media type with its characteristic:

Why is MacConkey agar considered a differential medium?

In enumeration of microorganisms, it is assumed that each colony on a plate originates from multiple bacterial or yeast cells in the original liquid.

What is the typical unit used to report results in the enumeration of microorganisms?

In colony counting, a range of ______ colonies is considered countable.

What is a key advantage of using molecular biology methods, such as PCR, for detecting microorganisms in food compared to culturing methods?

PCR can detect only live microorganisms, not dead ones.

Name one advantage of using molecular biology methods over traditional culturing methods for detecting microorganisms.

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

What does an antibody recognize in immunological methods?

Lateral flow assays can only be used for quantitative testing in detecting microorganisms.

Name a method that can be used for both qualitative and quantitative testing using immunological methods.

Titratable acidity in milk is an example of a(n) ______ method for detecting microorganisms.

What is the primary advantage of indirect methods for detecting microorganisms?

Complex media have a precisely known chemical composition, allowing for detailed metabolic studies.

Name one ingredient commonly found in complex media.

A medium that allows only gram-negative bacteria to grow, such as MacConkey agar, is an example of a(n) ______ medium.

Which of the following best describes the purpose of differential media?

The primary purpose of enumerating microorganisms is to identify the specific species present in a sample.

What volume of media is typically plated when enumerating microorganisms?

The countable range for colonies on a plate is typically between ______ and ______ colonies.

Which of the following is a disadvantage of culturing microorganisms?

The exact chemical composition being unknown is the key characteristic of defined media.

Besides culturing, list another method used for detecting microorganisms in food.

The use of a suitable ______ in a petri dish is essential for culturing microorganisms.

What is the purpose of using different growth temperatures when culturing microorganisms?

Enumeration of microorganisms involves counting the viable and non-viable cells in a sample.

What does CFU stand for?

In molecular methods, ______ is a technique used to detect DNA or RNA of specific organisms.

Which type of method provides a more time-efficient way to measure microbial activity?

The molecular marker that an antibody recognizes is called an antigen.

Give an example of an immunological method used in detecting microorganisms.

While selective media facilitates the growth of chosen microorganisms, ______ media enable differentiation among them based on particular characteristics.

Which technique allows for the rapid detection of specific DNA or RNA sequences, making it ideal for quick identification of microorganisms?

Defined media cannot be employed for conducting metabolic experiments due to their known compositions.

A food sample is diluted to $10^{-5}$, and after plating, the count is determined to be 65. What is the bacterial load of the sample?

In a given media, if the number of colonies exceeds 300 per plate, the count is considered ______.