PORTAGE LEARNING BIOD 171 EXAM
ANSWERS|LATEST !!!!2026|GRADED A+| (EXAM
Define the measurements micrometer and nanometer. - 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? -
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? - ANSWER The iris diaphragm.
As light passes through a microscope, what is the last piece that light passes before reaching
your eyes? - 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? - 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? - 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.
1
, Phase-contrast microscopy provides what benefits to imaging? - ANSWER Phase-
contrast microscopy provides detailed images without staining.
What is the distinguishing feature of dark field microscopy? - ANSWER Dark field
microscopy reflects light off of the specimen at an angle..
Unlike brightfieqld microscope, fluorescence microscopes illuminate samples through what
spectrum? - ANSWER The Ultraviolet Spectrum.
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.
The acid-fast stain is most often used to identify what specific microorganism? -
ANSWER Mycobacterium tuberculosis is the most common for an acid-fast stain.
2
ANSWERS|LATEST !!!!2026|GRADED A+| (EXAM
Define the measurements micrometer and nanometer. - 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? -
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? - ANSWER The iris diaphragm.
As light passes through a microscope, what is the last piece that light passes before reaching
your eyes? - 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? - 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? - 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.
1
, Phase-contrast microscopy provides what benefits to imaging? - ANSWER Phase-
contrast microscopy provides detailed images without staining.
What is the distinguishing feature of dark field microscopy? - ANSWER Dark field
microscopy reflects light off of the specimen at an angle..
Unlike brightfieqld microscope, fluorescence microscopes illuminate samples through what
spectrum? - ANSWER The Ultraviolet Spectrum.
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.
The acid-fast stain is most often used to identify what specific microorganism? -
ANSWER Mycobacterium tuberculosis is the most common for an acid-fast stain.
2
