Question 1

Mixed cultures are also referred to as contaminated cultures.

Accepted Answer

Mixed cultures refer to the presence of two or more different types of cells or organisms in a single culture, while contaminated cultures refer to the presence of unwanted or harmful microorganisms in a culture. The two terms are not interchangeable.

Question 2

At the end of the Gram stain,gram-positive bacteria will be seen as pink cells.

Accepted Answer

Gram-positive bacteria will be seen as purple cells, not pink. Gram-negative bacteria will appear pink after the stain.

Question 3

The bacterium Neisseria gonorrhoeae causes the sexually-transmitted infection gonorrhea.Although it can be isolated from the vagina,there are numerous normal biota in that location as well.In order to culture this pathogenic bacterium,one should use:

Accepted Answer

Selective media should be used to culture Neisseria gonorrhoeae, as it allows for the selective growth of the pathogenic bacterium while inhibiting the growth of other normal vaginal biota. In particular, Thayer-Martin agar is commonly used as a selective medium for N. gonorrhoeae. Enrichment media and liquid media are not necessarily selective, and refrigeration temperature is suboptimal for the growth of N. gonorrhoeae.

Question 4

One colony typically develops from the growth of several parent bacterial cells.

Accepted Answer

A colony typically develops from the growth of a single parent bacterial cell, which divides repeatedly to form a visible mass of cells.

Question 5

Robert Koch and his lab workers first used agar in bacteriological media.Why did they find this media so much better than previous materials used to grow bacteria?

Accepted Answer

Agar, unlike previous materials used to grow bacteria, did not degrade or break down when bacteria grew on it. This allowed for accurate observations and isolation of individual colonies, which was critical for the development of pure cultures and identification of specific bacteria.

Question 6

A differential interference contrast microscope uses dyes to give colored,three-dimensional images.

Accepted Answer

A differential interference contrast microscope uses optical manipulation of light to create contrast between different features in a sample, without the use of dyes. It produces a 3D-like image by creating shading and contrast through the interference of polarized light.

Question 7

The bending of light rays as they pass from one medium to another is called refraction.

Accepted Answer

This is a basic concept in optics and is known as the law of refraction.

Question 8

Eosin-methylene blue agar,or EMB,is a commonly used bacteriological medium in a lab,used to grow gram-negative bacteria.There are two dyes in it,eosin and methylene blue,as well as the sugar lactose.Eosin is a pH indicator that changes color when the medium is acidic,while methylene blue reduces the growth of most gram-positive bacteria.If an organism uses lactose,acid will be produced changing the pH of the medium and subsequently causing the bacterial colonies to change color.
Based upon this description,this medium is:

Accepted Answer

EMB agar is both selective and differential. It is selective because it inhibits the growth of gram-positive bacteria, and it is differential because it distinguishes lactose fermenters, which change color due to acid production.

Question 9

A selective medium contains one or more substances that inhibit growth of certain microbes in order to facilitate the growth of other microbes.

Accepted Answer

A selective medium is designed to inhibit certain microbes by adding specific substances that prevent their growth, while allowing the growth of other desirable microbes. This helps in isolating and identifying specific microbial species in a mixture.

Question 10

Normal incubation temperatures range from 30^$\circ$to 60^$\circ$ C.

Accepted Answer

Normal incubation temperatures range from 86°F (30°C) to 140°F (60°C), not from 30°F to 60°F as stated in the statement.

Question 11

When comparing the uses and benefits of the transmission electron microscope to the scanning electron microscope,you could say that:

Accepted Answer

The transmission electron microscope is used for internal inspection of cells and subcellular structures, while the scanning electron microscope is typically used for external architecture of cells. The transmission EM does not necessarily require dyes and can be used to visualize various types of particles, including viruses and bacteria.

Question 12

Fixed smears of specimens are required in order to perform the Gram stain and endospore stain on the specimens.

Accepted Answer

Fixed smears are necessary for both Gram staining and endospore staining to prevent distortion or loss of morphology during staining and observation.

Question 13

The real image is the reverse of the actual specimen.

Accepted Answer

The answer of The real image is the reverse of...

Question 14

Let us say that the 100X magnification lens of your microscope has a resolving power of 0.15 microns (micrometers).The specimen that you will be looking at has bacterial cocci the size of 0.1 microns in diameter.Which statement is correct?

Accepted Answer

The resolving power of the lens is not high enough to clearly separate the individual bacterial cocci, therefore they will appear fuzzy and blend together. It is important to note that although the bacteria are not clearly visible, they may still be able to be identified based on their shape and arrangement.

Question 15

Bacterial cultures are easily identified from their microscopic appearance.

Accepted Answer

Bacterial cultures cannot be definitively identified by their microscopic appearance alone. Additional tests such as biochemical assays or genetic sequencing are necessary for accurate identification.

Quiz 3: Tools of the Laboratory: Methods for the Culturing of Microscopic Analysis of Microorganisms

Mixed cultures are also referred to as contaminated cultures.

At the end of the Gram stain,gram-positive bacteria will be seen as pink cells.

The bacterium Neisseria gonorrhoeae causes the sexually-transmitted infection gonorrhea.Although it can be isolated from the vagina,there are numerous normal biota in that location as well.In order to culture this pathogenic bacterium,one should use:

One colony typically develops from the growth of several parent bacterial cells.

Robert Koch and his lab workers first used agar in bacteriological media.Why did they find this media so much better than previous materials used to grow bacteria?

A differential interference contrast microscope uses dyes to give colored,three-dimensional images.

The bending of light rays as they pass from one medium to another is called refraction.

A selective medium contains one or more substances that inhibit growth of certain microbes in order to facilitate the growth of other microbes.

Normal incubation temperatures range from 30^$\circ$to 60^$\circ$ C.

When comparing the uses and benefits of the transmission electron microscope to the scanning electron microscope,you could say that:

Fixed smears of specimens are required in order to perform the Gram stain and endospore stain on the specimens.

The real image is the reverse of the actual specimen.

Let us say that the 100X magnification lens of your microscope has a resolving power of 0.15 microns (micrometers) .The specimen that you will be looking at has bacterial cocci the size of 0.1 microns in diameter.Which statement is correct?

Bacterial cultures are easily identified from their microscopic appearance.

Quiz 3: Tools of the Laboratory: Methods for the Culturing of Microscopic Analysis of Microorganisms

Mixed cultures are also referred to as contaminated cultures.

At the end of the Gram stain,gram-positive bacteria will be seen as pink cells.

The bacterium Neisseria gonorrhoeae causes the sexually-transmitted infection gonorrhea.Although it can be isolated from the vagina,there are numerous normal biota in that location as well.In order to culture this pathogenic bacterium,one should use:

One colony typically develops from the growth of several parent bacterial cells.

Robert Koch and his lab workers first used agar in bacteriological media.Why did they find this media so much better than previous materials used to grow bacteria?

A differential interference contrast microscope uses dyes to give colored,three-dimensional images.

The bending of light rays as they pass from one medium to another is called refraction.

A selective medium contains one or more substances that inhibit growth of certain microbes in order to facilitate the growth of other microbes.

Normal incubation temperatures range from 30 ∘\circ∘ to 60 ∘\circ∘ C.

When comparing the uses and benefits of the transmission electron microscope to the scanning electron microscope,you could say that:

Fixed smears of specimens are required in order to perform the Gram stain and endospore stain on the specimens.

The real image is the reverse of the actual specimen.

Let us say that the 100X magnification lens of your microscope has a resolving power of 0.15 microns (micrometers) .The specimen that you will be looking at has bacterial cocci the size of 0.1 microns in diameter.Which statement is correct?

Bacterial cultures are easily identified from their microscopic appearance.

Normal incubation temperatures range from 30^$\circ$to 60^$\circ$ C.