BIOS 280 Test 2 Questions and Answers 100% Solved
What is Koch's third postulate? Correct Ans-Cells from a pure culture of the suspected
organism should cause disease in a healthy animal
What is Koch's third postulate? Correct Ans-Cells from a pure culture of the suspected
organism should cause disease in a healthy animal
What is Koch's fourth postulate? Correct Ans-The organism should be reisolated and
shown to be the same as the original
Why is Koch's 4th postulate necessary? Correct Ans-Koch's (along with Pasteur's)
approaches were so successful that the causative agents for 20 other diseases were
discovered, it led to the development of culturing methods.
Which postulate led to the development of culturing methods? Correct Ans-Postulate 4
What are some problems inherent to studying microorganisms? Correct Ans-1. They are
invisible and widely distributed
2. Usually need to grow under controlled situations, in lab
3. Strains must be separated
, BIOS 280 Test 2 Questions and Answers 100% Solved
T or F: Most major discoveries in microbiology are not based on anything one can see.
Correct Ans-True
What was a big breakthrough for microbiological discoveries? Correct Ans-Pure cultures
pure culture technique Correct Ans-a laboratory technique used to ensure the growth of
only one type of microbe on a culture medium in a petri dish or in a broth medium
Pure cultures led to the development of: Correct Ans-broth, solid culture media and
sterilization techniques
What two techniques were needed for pure cultures? Correct Ans-culturing technique and
aseptic technique
Colonies usually come from hoe many cells initially? Correct Ans-1-2 cells
How do we get a pure culture? Correct Ans-Isolate colonies
, BIOS 280 Test 2 Questions and Answers 100% Solved
Explain the formation of isolated colonies Correct Ans-1. Mixture of cells in sample
2. Separation of cells by spreading or dilution on surface of agar
(incubation)
3. Growth increases the number of cells
4. Microbes become visible as isolated colonies containing millions of cells
What is an example of a method of isolating bacteria? Correct Ans-The streak plate
method
What is the goal of the streak plate method? Correct Ans-Isolated colonies for further
purification
What are the types of media? Correct Ans-Liquid
Semisolid
Solid
What type of media was a breakthrough making streak plates possible? Correct Ans-Streak
plates - solid agar
, BIOS 280 Test 2 Questions and Answers 100% Solved
Who had the original idea for agar and who took the credit? Correct Ans-Fanny Hesse had
the idea while Walther Hesse received credit
Who invented the petri plate? Correct Ans-Julius Richard Petri
What did Walther originally use and why didn't it work before his wife suggested agar?
Correct Ans-Gelatin which softened at room temp and was eaten by bacteria (nutrient
source)
What solid media can keep cultures for months? Correct Ans-Slants
Give an example of liquid media. Correct Ans-TSB
T or F: Sulfur can swim through tough agar. Correct Ans-True
What are the two basic types of chemical content media. Correct Ans-1. Define (synthetic)
media
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