XLD agar serves which purpose when used in the bacterial fecal culture?
a. Evaluation of general flora and predomi-nant species
b. Selection of enteric pathogens such as Salmonella, Aeromonas, and others
c. Inhibition of normal flora and selection of enteric pathogens
d. Enrichment for enteric pathogens such as Salmonella and others
C
The specimen should be inoculated to a moderately selective agar such as Hektoen enteric (HE) or XLD media. These media inhibit growth of most Enterobacteriaceae, allowing Salmonella and Shigella spp. to be detected.
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A cell that neither gains nor loses water when it is immersed in a solution is what?
A. hypertonic to its environment. B. metabolically inactive. C. hypotonic to its environment. D. isotonic to its environment.
Which of the following statements is true regarding cell-cell adhesion?
A) Adhesion is coordinated with many cellular processes except cell survival. B) Adhesion molecules include plakoglobulin, which cements two cells together. C) Adherens junctions are exclusive to plant cells. D) Adhesive junctions are characterized by the attachment of long molecules of hyaluronate. E) Adhesive junctions are dynamic in response to cellular signals.
Your lab director requests that you add new growth medium to the mammalian cell cultures before heading home from the lab on a Friday night. Unfortunately, you need to make fresh medium because all the premixed bottles of medium have been used
One of the ingredients you know you need to add is a mix of the essential amino acids (those that cannot be made by the cells, but are needed in proteins). On the shelf of dry chemicals you find the amino acids you need, and you mix them into your medium, along with all the other necessary nutrients, and replace the old medium with your new medium. On Sunday, you come in to the lab just to check on your cells and find that the cells have not grown. You are sure you made the medium correctly, but on checking you see that somebody wrote a note on the dry mixture of amino acids you used: "Note: this mixture contains only ?-amino acids." A. What is the meaning of the note and how does it explain the lack of cell growth in your culture? B. Are there any organisms that could grow using this mixture? Justify your answer.
The presence-absence test is a modification of which test?
A. Membrane filter B. Virus plaque assay C. MPN D. None of these choices are correct.