Question Detail

MIC 121 Mcb compilations Objective Question

Question

Why might an undefined medium be chosen over a defined medium?
Options
A Because it is necessary for autotrophic organisms
B Because it always has a higher pH
C Because it is always less expensive than defined media
D Due to its ability to support microorganisms that cannot grow on defined media
Correct Answer
Correct Answer

Option D is the correct answer.

Detailed Explanation

Undefined media (also known as complex media) contain ingredients like yeast extract or peptone, which have unknown exact chemical compositions. This makes them rich in various nutrients and growth factors, allowing them to support the growth of a wider range of microorganisms, especially fastidious ones, that might not grow on a chemically defined medium. While often less expensive (option C), the primary reason for selection is usually its broad growth support.

Hint

Consider the nature of an undefined medium – what does 'undefined' imply about its ingredients and its effect on microbial growth?

Question Info