Pure Culture Flashcards
What is the primary purpose of isolating pure cultures in microbiology?
A. To study the collective characteristics of mixed bacterial populations
B. To enhance the growth of all organisms present in a culture
C. To study the cultural, morphological, and physiological characteristics of an individual organism
D. To facilitate the growth of unwanted organisms alongside desired bacteria
ANSWER: C
Who is recognized as the father of medical microbiology and contributed techniques for obtaining pure cultures?
A. Louis Pasteur
B. Alexander Fleming
C. Robert Koch
D. Antonie van Leeuwenhoek
ANSWER: C
Which of the following best defines a pure culture?
A. A culture that contains only unwanted organisms
B. A culture that contains more than one kind of organism
C. A culture that contains a desired organism and also unwanted organisms
D. A culture that contains only a single kind of organism
ANSWER: D
What is the main difference between a mixed culture and a contaminated culture?
A. A mixed culture contains organisms from different species, whereas a contaminated culture contains only pathogens.
B. There is no difference; both terms are interchangeable in microbiology.
C. A mixed culture contains more than one kind of organism, while a contaminated culture also has unwanted organisms.
D. A contaminated culture is used for antibiotic testing, whereas a mixed culture is not.
ANSWER: C
Which method is most commonly used by microbiologists to obtain pure cultures?
A. Pour plate method
B. Streak plate method
C. Liquid broth dilution
D. Gram staining technique
ANSWER: B
Why is it important to achieve good spacing between colonies on a streak plate?
A. To ensure all the organisms grow at the same rate
B. To avoid the use of selective growth media
C. To allow for the isolation of a single pure colony
D. To ensure the plate looks aesthetically pleasing
ANSWER: C
What is the assumed relationship between a single pure colony and its original cell on a streak plate?
A. The colony is a mixed population derived from multiple cells
B. The colony is unrelated to the original cell
C. The colony consists of genetically different offspring from the original cell
D. The colony is assumed to be the identical progeny of the original cell
ANSWER: D
Which of the following characteristics are considered when differentiating bacteria in a mixed culture?
A. Color, shape, and size
B. DNA and RNA sequences only
C. Antibiotic resistance patterns
D. Presence of endospores and flagella
ANSWER: A
After isolating a pure colony, what is the next step in studying a bacterium?
A. Discard the colony
B. Subculture and prepare stains to check for purity
C. Immediately start antibiotic sensitivity testing
D. Mix it with other species to observe competition
ANSWER: B
What is the ultimate goal of obtaining pure cultures according to Robert Koch’s postulates?
A. To create vaccines
B. To prove that a particular bacterium causes a specific disease
C. To find the best growth medium
D. To increase the resistance of bacteria against antibiotics
ANSWER: B
What is a pure culture?
A. A culture that contains only a single kind of organism
B. A culture that contains more than one kind of organism
C. A culture containing a desired organism along with unwanted organisms
D. A culture prepared using the streak-plate method only
ANSWER: A
Who was one of the first to recognize the importance of isolating bacteria to study pathogenic bacteria?
A. Louis Pasteur
B. Alexander Fleming
C. Robert Koch
D. Joseph Lister
ANSWER: C
What is the main difference between a pure culture and a mixed culture?
A. The use of different media
B. The number of different kinds of organisms present
C. The temperature at which they are incubated
D. The method by which they are obtained
ANSWER: B
Which method is most often used by microbiologists to obtain pure cultures?
A. Pour plate method
B. Gram staining
C. Streak plate method
D. Liquid culture dilution
ANSWER: C
What is assumed about a colony that arises from a single bacterial cell?
A. It is contaminated
B. It consists of multiple species
C. It is genetically identical to the original cell
D. It demonstrates the bacteria’s resistance to antibiotics
ANSWER: C
