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

The simple microscopes used by the earliest practitioners of microscopy contained which of the following?

Which of the following is not an inoculating tool?

Newly inoculated cultures must be _____ at a specific temperature and time to encourage growth.

A reducing medium is used to culture ______ organisms.

Mannitol salt agar is selective for organisms in which bacterial genus?

If a microbiologist is studying a specimen at a total magnification of 950X, what is the magnifying power of the objective lens if the ocular lens is 10X?

Robert Koch and his colleagues first used agar in bacteriological media.Why was this ingredient an improvement on previous materials used to culture bacteria?

Humans can see objects as small as 0.1 mm.Leeuwenhoek's best microscope could magnify objects to 300X.Which of the following would be invisible using Leeuwenhoek's microscope?

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

Which type of microscopy transforms the subtle variations in cell density into differences in light intensity, allowing for increased internal detail without staining?

A microbiologist must culture a patient's feces for intestinal pathogens.Which of the following components would likely be present in a selective medium for this purpose?

The Gram staining procedure is best described as a ______ staining technique.

Mixed cultures are also referred to as contaminated cultures.

The wavelength of light used and the numerical aperture governs ______.

Which of the following is produced by adding 1% to 5% agar to nutrient broth that is then boiled and cooled?

The purpose of staining cells on a microscope slide is to ______.

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.To generate a pure culture of this pathogenic bacterium, the best choice is a(n) ______.

A microbiologist inoculates Staphylococcus aureus into a culture medium.Following incubation, both Staphylococcus aureus and Staphylococcus epidermidis are determined to be growing in this culture.What is the most likely explanation?

Basic dyes are

Eosin-methylene blue agar, or EMB, is a commonly used bacteriological medium for growing gram-negative bacteria from complex environments.It contains two dyes, 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 inhibits the growth of most gram-positive bacteria.If an organism consumes lactose, acid will be produced, causing the bacterial colonies to change color. Based upon this description, this medium is ______.