BIOD 171 Portage Learning Exam 3
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Define the measurements micrometer and nanometer. - CORRECT ANSWER -A
micrometer is one-millionth of a meter and a nanometer is one-billionth of a meter.
What are the two critical factors that influence your ability to see an object? - CORRECT
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.
If you wish to increase the amount of light going into a microscope, what part would you adjust?
- CORRECT ANSWER - The iris diaphragm.
As light passes through a microscope, what is the last piece that light passes before reaching your
eyes? - CORRECT ANSWER - Once light passes through the sample and the objective
lens, it passes through the OCULAR LENS.
How is the total magnification of an object calculated? - CORRECT ANSWER - It is
calculated by multiplying the power of the objective and the power of the eyepiece.
What is one limitation of fixing your sample? - CORRECT ANSWER - Fixing your
sample requires you to irreversibly kill your sample.
This can make it impossible to determine the cell movement. You could distort the shape and
structure.
Phase-contrast microscopy provides what benefits to imaging? - CORRECT ANSWER -
Phase-contrast microscopy provides detailed images without staining.
, What is the distinguishing feature of dark field microscopy? - CORRECT ANSWER -
Dark field microscopy reflects light off of the specimen at an angle..
Unlike brightfieqld microscope, fluorescence microscopes illuminate samples through what
spectrum? - CORRECT ANSWER - The Ultraviolet Spectrum.
What is the primary difference between TEM and SEM? - CORRECT 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? - CORRECT 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? - CORRECT 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? - CORRECT ANSWER - Heat fixing makes
sure the samples are tightly adhere to the glass slide.
What is the primary purpose of a wet mount? - CORRECT ANSWER - Wet mounts are
often perform to visualize live cells and to see the motility and behavior of an organism.
The acid-fast stain is most often used to identify what specific microorganism? - CORRECT
ANSWER - Mycobacterium tuberculosis is the most common for an acid-fast stain.
What is the total magnification of a sample imaged with a 60x objective and a 10x eyepiece? -
CORRECT ANSWER - 60 x 100 = 600x magnification
True or False: A cell that is adherent, flat, and unstained is easily identified using bright field
microscopy. - CORRECT ANSWER - False
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Define the measurements micrometer and nanometer. - CORRECT ANSWER -A
micrometer is one-millionth of a meter and a nanometer is one-billionth of a meter.
What are the two critical factors that influence your ability to see an object? - CORRECT
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.
If you wish to increase the amount of light going into a microscope, what part would you adjust?
- CORRECT ANSWER - The iris diaphragm.
As light passes through a microscope, what is the last piece that light passes before reaching your
eyes? - CORRECT ANSWER - Once light passes through the sample and the objective
lens, it passes through the OCULAR LENS.
How is the total magnification of an object calculated? - CORRECT ANSWER - It is
calculated by multiplying the power of the objective and the power of the eyepiece.
What is one limitation of fixing your sample? - CORRECT ANSWER - Fixing your
sample requires you to irreversibly kill your sample.
This can make it impossible to determine the cell movement. You could distort the shape and
structure.
Phase-contrast microscopy provides what benefits to imaging? - CORRECT ANSWER -
Phase-contrast microscopy provides detailed images without staining.
, What is the distinguishing feature of dark field microscopy? - CORRECT ANSWER -
Dark field microscopy reflects light off of the specimen at an angle..
Unlike brightfieqld microscope, fluorescence microscopes illuminate samples through what
spectrum? - CORRECT ANSWER - The Ultraviolet Spectrum.
What is the primary difference between TEM and SEM? - CORRECT 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? - CORRECT 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? - CORRECT 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? - CORRECT ANSWER - Heat fixing makes
sure the samples are tightly adhere to the glass slide.
What is the primary purpose of a wet mount? - CORRECT ANSWER - Wet mounts are
often perform to visualize live cells and to see the motility and behavior of an organism.
The acid-fast stain is most often used to identify what specific microorganism? - CORRECT
ANSWER - Mycobacterium tuberculosis is the most common for an acid-fast stain.
What is the total magnification of a sample imaged with a 60x objective and a 10x eyepiece? -
CORRECT ANSWER - 60 x 100 = 600x magnification
True or False: A cell that is adherent, flat, and unstained is easily identified using bright field
microscopy. - CORRECT ANSWER - False
