MCB 3020 MICRO LAB FINAL QUESTIONS AND
ANSWERS
(45x10)=450 - Answers - 7) What would the total magnification be on your microscope if
you used a 45X objective?
Bacteria that undergo photosynthesis; do not have chloroplasts - Answers - 8) How do
cyanobacteria differ from other forms of bacteria?
Pseudohyphae - Answers - 10) Yeast cells may form chains of buds called
________________.
1) 40X objective could be dirty/oily;
2) Diaphragm/condenser needs adjustment - Answers - 11) You are able to focus on a
specimen clearly using the 10X objective, however when you go to the 40X objective
and use the fine focus knob you are unable to focus on the specimen. Give 2 reasons
why this may occur (assume scope is parfocal):
tetrad - Answers - 12) Arrangement in which bacteria grow in groups of 4 is called
________________.
Sarcinia - Answers - 13) The arrangement in which bacteria grow in groups of 8 is
called?
Cell could dry up completely, crack; not be visible/clear enough to use - Answers - 14)
What could happen if you heat fixed a smear too long?
The characteristic of a microscope that allows you to adjust/change objectives with
minimal focus - Answers - 15) Define: Parfocal __________________.
Up, and even with stage - Answers - 16) For best resolution what position should the
condenser be in?
Is done to kill cell, and help to adhere to slide - Answers - 17) Why do you heat fix cells
before staining?
Ability to see between 2 points - Answers - 18) Resolution:
Diplococcus: In pairs
Staph--> in clusters - Answers - 19) How do diplococcus and staphylococcus differ in
their division patterns?
Purpose: to obtain a single colony
, Method: Obtain microbe from culture
spread onto plate 4 seperate times, each in different quadrant, each less than the
previous - Answers - 20) Briefly describe the streak plate method and state the purpose
of the streak plate:
Is done to lock-in "Complex" with the crystal violet in the cell - Answers - 21) What is the
purpose of the mordant in the gram stain?
Refraction - Answers - 22) Light bending ability of a medium:
Technique is done to prevent contamination of culture with unwanted microbes and
reduce contaminating yourself and environment - Answers - 23) When culturing
bacteria, why is it important to work asceptically?
Septae - Answers - 24) "_________________" hyphae have cross walls between cells.
Mycolic Acid - Answers - 25) Acid-Fast rods are surrounded by a waxy coat of
_____________ ______________.
So you can see the cells under the microscope, instead of one big "clump"; can't
distinguish individual cells from the others - Answers - 26) Why is it important to limit the
quantity of cells used to prepare a smear?
Liquid: Do not need addition DI water added to slide;
Solid Medium: DI water is needed (about a loop-full) before you can smear properly. -
Answers - 27) How does smear preparation of cells from a liquid culture differ from
preperation of cells from a solid medium?
6,000,000/mL - Answers - 28) You do a serial dilution experiment and count colonies on
plates from these dilutions. On the 1/1,000,000 plate you count 6 colonies. What was
the concentration in the starting culture?
Serum is typically used to fix this to stain; because heat-fixing can DISTORT - Answers
- 29) When doing a capsule stain why is it not advisable to use heat fixed smear?
exosporium - Answers - 30) An endospore has a thick protein coat called an
___________________.
Red/Pink - Answers - 31) If staining is done properly, an acid fast rod will be what color?
Negative - Answers - 32) IN KOH String test, gram "____________" will be sticky after
addition of 3% KOH.
Tuberculosis, Leprosy - Answers - 33) What 2 diseases are caused by acid fast rods in
the genus Mycobacterium?
ANSWERS
(45x10)=450 - Answers - 7) What would the total magnification be on your microscope if
you used a 45X objective?
Bacteria that undergo photosynthesis; do not have chloroplasts - Answers - 8) How do
cyanobacteria differ from other forms of bacteria?
Pseudohyphae - Answers - 10) Yeast cells may form chains of buds called
________________.
1) 40X objective could be dirty/oily;
2) Diaphragm/condenser needs adjustment - Answers - 11) You are able to focus on a
specimen clearly using the 10X objective, however when you go to the 40X objective
and use the fine focus knob you are unable to focus on the specimen. Give 2 reasons
why this may occur (assume scope is parfocal):
tetrad - Answers - 12) Arrangement in which bacteria grow in groups of 4 is called
________________.
Sarcinia - Answers - 13) The arrangement in which bacteria grow in groups of 8 is
called?
Cell could dry up completely, crack; not be visible/clear enough to use - Answers - 14)
What could happen if you heat fixed a smear too long?
The characteristic of a microscope that allows you to adjust/change objectives with
minimal focus - Answers - 15) Define: Parfocal __________________.
Up, and even with stage - Answers - 16) For best resolution what position should the
condenser be in?
Is done to kill cell, and help to adhere to slide - Answers - 17) Why do you heat fix cells
before staining?
Ability to see between 2 points - Answers - 18) Resolution:
Diplococcus: In pairs
Staph--> in clusters - Answers - 19) How do diplococcus and staphylococcus differ in
their division patterns?
Purpose: to obtain a single colony
, Method: Obtain microbe from culture
spread onto plate 4 seperate times, each in different quadrant, each less than the
previous - Answers - 20) Briefly describe the streak plate method and state the purpose
of the streak plate:
Is done to lock-in "Complex" with the crystal violet in the cell - Answers - 21) What is the
purpose of the mordant in the gram stain?
Refraction - Answers - 22) Light bending ability of a medium:
Technique is done to prevent contamination of culture with unwanted microbes and
reduce contaminating yourself and environment - Answers - 23) When culturing
bacteria, why is it important to work asceptically?
Septae - Answers - 24) "_________________" hyphae have cross walls between cells.
Mycolic Acid - Answers - 25) Acid-Fast rods are surrounded by a waxy coat of
_____________ ______________.
So you can see the cells under the microscope, instead of one big "clump"; can't
distinguish individual cells from the others - Answers - 26) Why is it important to limit the
quantity of cells used to prepare a smear?
Liquid: Do not need addition DI water added to slide;
Solid Medium: DI water is needed (about a loop-full) before you can smear properly. -
Answers - 27) How does smear preparation of cells from a liquid culture differ from
preperation of cells from a solid medium?
6,000,000/mL - Answers - 28) You do a serial dilution experiment and count colonies on
plates from these dilutions. On the 1/1,000,000 plate you count 6 colonies. What was
the concentration in the starting culture?
Serum is typically used to fix this to stain; because heat-fixing can DISTORT - Answers
- 29) When doing a capsule stain why is it not advisable to use heat fixed smear?
exosporium - Answers - 30) An endospore has a thick protein coat called an
___________________.
Red/Pink - Answers - 31) If staining is done properly, an acid fast rod will be what color?
Negative - Answers - 32) IN KOH String test, gram "____________" will be sticky after
addition of 3% KOH.
Tuberculosis, Leprosy - Answers - 33) What 2 diseases are caused by acid fast rods in
the genus Mycobacterium?
