BIOD 171 PORTAGE LEARNING EXAM 3 COMPLETE QUESTIONS WITH VERIFIED ANSWERS | RATED A+

BIOD 171 PORTAGE LEARNING EXAM 3 COMPLETE QUESTIONS WITH VERIFIED ANSWERS | RATED A+

List the four main steps used to prepare a DRY mount, and indicate which step is optional. -
Answer>>>Circle area on slide for specimen placement, Apple organism to slide (optional) and
air dry at room temperature
Why is it important to first clean your slide before applying your sample? - Answer>>>You must
remove any unwanted contaminants from the slide to get accurate results.
You wish to study the motility of a particular bacterium. What type of mounting technique would
you use? Explain your answer. - Answer>>>A wet mount is the best because the sample will
stay viable. Heat fixing kills the sample.
What are the two critical factors that influence your ability to see an object? - Answer>>>The
resolution and the contrast. Resolution is the distance between two objects where you can still
see them as separate. Contrast is the difference in light between two objects.
What dye do Gram-positive bacteria primarily retain? - Answer>>>Crystal Violet
You suspect a patient may have TB. Once a sample has been obtained, it is sent off to the lab for
an acid-fast stain. If the patient were infected with TB, describe what you would expect to see on
the stained side. - Answer>>>You would expect to see red cells (TB+) on a blue background(TB
negative)
Why are Gram-positive bacteria able to retain the crystal violet dye? - Answer>>>They contain a
thick peptidoglycan layer in their cell well that readily retains the dye.
What is the primary difference between TEM and SEM? - Answer>>>The electron passes
through the sample during TEM where as the electron is reflected off the sample during SEM.
Gram staining is based on what basic principle? - Answer>>>With the basic observation that
different types of bacteria react differently to various dyes.
What is a key determinant in bacteria being Gram-positive? - Answer>>>Gram-positive have a
thick peptidoglycan layer. Uses crystal violet and iodine. The resulting mixture is a purple
coloration of the cell.
What is the purpose of heat fixing a sample? - Answer>>>Heat fixing makes sure the samples
are tightly adhere to the glass slide.
What is the primary purpose of a wet mount? - Answer>>>Wet mounts are often perform to
visualize live cells and to see the motility and behavior of an organism.