Lab 1 Test Bank

Lab safety and Microscope Use

LAB SAFETY

True/ False

FOpen-toed shoes and shorts above the knee are allowed to wear in lab.

TMost fires in Micro lab are started from improper use of Bunsen burners and hot instruments

TThe best way to deal with a fire in the lab is to just get away from it, cover it, and let it burn out. Remember, a lab coat can be taken off and used to put out a fire if someone’s hair catches fire, etc.

FThere is no food, drink, or water bottles allowed in a micro lab, but chewing gum is okay.

FThe biohazard bag is for any and all hazardous materials, including a toothpick you put in your mouth, gloves, disposable Petri dishes, and paper towels used to dry your hands.

TFor the glassware flasks and tubes, make sure all labels are removed, and all grease marks are erased when you are done.

FIf there is a spill, leave it for Andrea to clean up.

TFirst aid kit is in the cabinet near Andrea’s door.

Describe the correct way to pick up the microscope for use:

TThe arm should face you as you lift it up. Hold with one hand under base, gently set on desk

near edge, and then turn the arm away from you. Fold up dust cover and put it in the drawer.

FWhen you are done with the microscope, leave the condenser in the lowest position; this is

called racking up the condenser.

TFocusing: Two knobs, coarse and fine adjustment. Fine adjustment is smaller and concentric to the coarse adjustment knob. The coarse knob moves the stage a lot, and the fine knob moves it a little.

TChanging the distance between the stage and the objectives to focus is called the “working distance”.

TPARFOCAL: This term refers to the factory adjustment which means that once you are focused with the scanning objective, you are focused with all of the objectives (except for fine adjustment for minor corrections). If you lose focus, always go back to the scanning objective.

The condenser should be racked down when viewing a slide under low power.

False

The scanning objective lens can safely be cleaned with Kim wipes. FALSE

The clarity of viewing E. coli is best by using a total magnification of 400X FALSE.

The microscopic field of view is largest at a total magnification of 1000X. FALSE

Closed toe shoes are required in science laboratories to protect feet against spills and broken glass. TRUE

It is better to adjust the voltage knob the to control the volume of light on the slide microscope, rather than the iris diaphragm. FALSE

The resolving power of a microscope is affected by the magnifying power of the objective lenses.

TRUE

You have prepared a wet mount of pure culture of an unknown organism. All of the organisms

are vibrating back and forth in in the center of the field. This is true motility. FALSE

Multiple Choice: Select the single best answer to the following.

Before leaving lab,

A.Be sure to put equipment back in tote box on the rack in the front of the class.

B.Make sure your area has been disinfected before and after lab

C.Make sure your microscope has been put away properly.

D. All of the above

E. A and C only

What is the function of the substage adjustment knob (left side, under stage)? What happens

when you turn it?

A. It raises and lowers the condenser.

B. It is the course focus adjustment

C. It opens or closes the iris of the condenser

D. It turns the light source on and off

E. None of the above

F.All of the above

The ocular is

A. the eyepiece.

B. It magnifies ten times and focuses the image on the retina.

C. There are two oculars.

D. Do not touch your eyelashes to them or they will get oil on them.

E. To clean, squirt alcohol onto lens paper and wipe, then wipe with dry lens paper.

F. All of the above

G. B, C only

H. None of the above

The ocular that is adjustable:

A.has a diopter adjustment ring (knurled knob with ridges), with plusses, minuses,

and a zero on it.

B.What happens when you move it? It moves the left ocular up and down.

C.The purpose of this is to allow the left eye to be focused independently of the right eye

D.The coarse adjustment knob is for the right eye focus.

E. If you still see two images, you have a convergence problem and you’ll need to keep one eye closed.

F.Everyone has one dominant eye. You may need to close that eye when you want to use the pointer, if it is on the wrong side for you.

G.Between the oculars is a disc with numbers on it. This determines the interpupillary distance in mm (distance between your pupils).

H. All of the above

I.B, C, D only

J.None of the above

What is true about the four objective lenses:

A. The scanning (red ring) objective is the smallest, and magnifies 4x.

B. Since the ocular is 10x, the total magnification on the scanning objective is 400x.

C. The low power objective is 10x, total mag = 100x.

D. The high dry objective is 40x, total mag = 400x.

E. The oil immersion objective is l00x, total mag = 1000x.

F.All of the above

G.A, C, D, E only

H. None of the above

When first trying to identify an object on a slide for the first time:

A. Always start with the scanning objective

B.Make sure the condenser is racked up.

C.Rack up the coarse knob so the stage is all the way up.

D.Look at the slide, then lower the stage with the coarse knob until it comes into focus.

E.Only after that can you switch to the next power up (yellow low power).

F.To focus from now on, ONLY use the fine adjustment knob.

G. All of the above

H.A & B only

I. None of the above

Inside the condenser is a lever: the iris diaphragm lever. This opens and closes like the iris in your eye (pupil) to regulate the amount of light allowed in. The condenser takes light from the lamp and makes the rays into a point on the slide. The iris does the following four things:

A. Regulates light intensity

B.Contrast: (when iris is open, the contrast decreases)

C.Depth of field (when iris is open, only the foreground is in focus. When the iris is closed, the depth of field increases and everything is in focus.

D.Resolution (sharpness of image). Resolution is best when iris is open all the way.

E. All of the above

F.D, E only

G. None of the above

Match the following objective lenses to their magnification

High dry _____ c

Scanning _____ a

Low power ______b

Oil immersion ______d

What does the iris diaphragm do?

a)Increases total magnification

b)Increases light when closed

c)Increases light when open

d)Adjusts the voltage intensity of the light

Place the below list of actions in the correct order:

  1. ______c
  2. ______b
  3. ______d
  4. ______e
  5. ______a

a)Use the fine focus knob

b)Place slide on mechanical stage and center the specimen

c)Rack the stage all the way down and place the scanning objective front and center

d)Rack the stage up while viewing from the side

e)Look through the ocular eyepieces while slowly lowering the stage

The letter “e” looks upside down and backward under a microscope, and when you move the stage to the right, it moves to the left when viewing through the ocular eyepieces. The term for this phenomenon is ______ inversion

When switching from one objective to the next, you do not completely lose sight of the specimen. The term for the phenomenon is ______parfocal

The resolving power of a microscope is a function of

a)The magnifying power of the lenses

b)The numerical aperature (NA) of the lenses

c)The wavelength of light

d)Both (a) and (b)

e)Both (b) and (c)

What is used to clean slides?

a)Kim wipes

b)Lens paper

What is used to clean microscope lenses?

a)Kim wipes

b)Lens paper

The microscope field of view is largest at what total magnification?

a)40x

b)100x

c)400x

d)1000x

What happens to the working distance when magnification is increased?

a)Increases

b)Decreases

c)Stays the same

Which lens has the shortest working distance?

a)Scanning

b)Low power

c)High power

d)Oil lens

What is the brightfield compound microscope used for?

  1. shows dark objects in a bright field
  2. shows bright objects in a dark field
  3. Used for seeing 3D images
  4. Used for viewing live cells

The knob used for focusing with the scanning objective is called?

  1. fine adjustment
  2. field of vision
  3. coarse adjustment
  4. magnification

STORING THE MICROSCOPE:

The arm should face your ____1_____, the dust cover in place, the AC (power) cord is wrapped loosely next to it, NOT wrapped around it. The condenser should be ______2______. The _____3______for power should be off. The ______4_____ should be turned to the ______5______. The _____7______should be racked down by using the ______6______. The scanning objective should be in place. Clean off the oil and other debris; wipe the ocular lens with lens paper only.

A 2.Racked Up

B 4.Voltage Regulator

C 6.Course Adjustment Knob

D 3. Toggle Switch

E 7.Stage

F 5.Lowest Setting

G 1.Body

What is the fine adjustment knob used for? (choose all that apply)

  1. focusing with oil immersion lenses
  2. focusing with high-dry lenses
  3. focusing with low power lenses
  4. focusing with scanning lenses

What is it called when a microscope has only one ocular lens?

  1. ocular
  2. eyepiece lens
  3. monocular
  4. binocular

What is the smallest organism that was viewed in lab?

  1. Algae
  2. Fungi
  3. Protozoa
  4. Bacteria

What is another name for an eyepiece lens on a microscope?

  1. ocular
  2. monocular
  3. binocular
  4. objective

What is the agar powder made of?

  1. seaweed
  2. nutrient rich broth
  3. bacteria
  4. gelatin

Answers to ABOVE diagram

  1. Ocular Lenses
  2. Revolving nose piece
  3. Objective Lenses
  4. Stage Clip
  5. Stage
  6. Iris Diaphragm
  7. Condenser
  8. Lamp
  9. Base
  10. Mechanical State Adjustment Knobs
  11. Course Focus Knob
  12. Fine Focus Knob
  13. Light Intensity Knob
  14. On/ Off Switch
  15. Arm

Identify the parts of the microscope identified with an arrow below. In the space below the figure, describe the function of each of the parts identified.


Why is immersion oil important in seeing bacteria through the microscope?

Immersion oil is important because it helps magnify the bacteria, which are the smallest organism. The oil helps bend the light differently to focus.

Why is it important to stain your specimen (such as cheek cells) before putting it under the microscope?

  1. There will not be much contrast if not stained, and it allows the iris to adjust better.
  2. To enlarge the cells
  3. This allows the cells to separate from each other which makes it easier to see under the microscope.
  4. You don’t need to stain

When preparing for a wet mount slide, how do you cover it to avoid bubbles?

  1. Use the cover slip and drop it parallel to the slide.
  2. Drop the cover slip down like a hinge (45 degree angle).
  3. Drop the cover slip from a 90 degree angle.

What are the proper steps of cleaning the slides?

  1. Throw the coverslip in the trash. Rinse the slide off with water and dry.
  2. Throw the coverslip in the trash. Rinse the slide off with water and scrub the slide with the cleanser. Dry.
  3. Throw the coverslip into the broken glass container. Rinse the slide off in water at the sink and scrub the slide down with the cleanser.
  4. Throw the coverslip into the broken glass container. Rinse the slide off in water at the sink and scrub the slide down with the cleanser. Rinse and dry and put the slides in the disinfectant tub at the sink.

Epithelium is thick and they are not easy to break apart from each other. They do not grow back quickly.

  1. True
  2. False

One of your oculars has a ______. When you are using it, switch that ocular to the ______eye.

  1. light, weak
  2. light, dominant
  3. pointer, dominant
  4. pointer, weak

Bacteria are small, so they always need ______to be seen.

  1. 10x
  2. 100x
  3. 1,000x
  4. 10,000x

Fill in the blanks:

The oil immersion lens has the _____1 (B)______depth of field. Start at ___2_ (E)____ and the bacteria will look like little dots. As you progress to _____3_(AD)_____, the dots are bigger, you can focus again. At 400x, you will start to see shapes. The details are not seen until you get to the oil immersion lens.

A. biggestD. 20xAC. 75x

B. narrowest E. 40xAD. 100x

C. 10xAB. 50xAE. 200x

Why is the oil immersion lens named as such?

  1. You must look through this lens only while the microscope is completely immersed in a vat of baby oil.
  2. The oil lobbyists in Washington want it that way.
  3. A drop of synthetic immersion oil is placed on the slide prior to observation.
  4. Tradition

How many basic shapes of bacteria are there?

  1. 3
  2. 2
  3. 1
  4. 64

Where do you place the coverslips when you are finished viewing a slide?

  1. In your pocket
  2. In your neighbors pocket
  3. In the garbage disposal
  4. In the broken glass container.

What virus may cause cervical cancer?

  1. Clowns
  2. Human Papillo Virus
  3. The cold virus
  4. The ebola virus

Which ocular should contain the pointer?

  1. The ocular of your dominant eye.
  2. The ocular of your nondominant eye.
  3. There is no pointer
  4. All of the above.

Which objective containers a sealer so that oil will not seep in?

  1. The oil immersion lens
  2. The 40x objective lens
  3. The 100x objective lens
  4. The 400x objective lens

What should be used to clean the slide?

  1. Your sleeve
  2. Alcohol
  3. Saliva
  4. Soda

How much does a damaged microscope objective lens cost to replace?

  1. $20
  2. $0
  3. $60
  4. $150

How do you clean the oil off the oil immersion lens?

  1. You don’t.
  2. Scrubbing vigorously.
  3. With steel wool.
  4. Dab at it with a clean paper towel until no more oil comes off.

The resolving power of a microscope is a function of

a)The magnifying power of the lenses

b)The numerical aperature (NA) of the lenses

c)The wavelength of light

d)Both (a) and (b)

e)Both (b) and (c)

When viewing an organism under the 10X objective, if you are having trouble focusing on the specimen to observe a particular cell, you should:

a. carefully adjust the “course” adjustment knob.

b. adjust one of the ocular lenses to adjust the magnification.

c. go to a higher power lens.

d. go back to 4X.

e. two of these are correct.

When a culture is spilled, how long do you leave disinfectant on it?

a)10 minutes

b)15 minutes

c)20 minutes

d)30 minutes

What would be the total magnification of an object viewed with a 15x ocular and the low power objective?

a)100x

b)150x

c) 300x

d)1000x

e)1500x

With your microscope, when changing from low to high power, it is necessary to:

a)lower the condenser

b) move the stage away from the objective lens

c)open the iris diaphragm

d)close the iris diaphragm

e)b and c are correct

What happens to the working distance when magnification is increased?

d)Increases

e)Decreases

f)Stays the same

What would be the total magnification of an object viewed with a 15x ocular and the oil immersion objective?

a. 100Xb. 150Xc. 300Xd. 1000Xe. 1500X

When focusing your microscope, which statement is FALSE?

a. Clean all lenses with lens paper before beginning.

b. Make sure the condenser is in its highest position.

c. Always begin with a scanning objective.

d. Use the coarse adjustment knob and then the fine adjustment knob with each objective lens.

e. Use the iris diaphragm to adjust the amount of light.

Which of the statements about immersion oil is FALSE?

a. It prevents the loss of light.

b. It is placed directly on the slide.

c. It has the same refractive index as glass.

d. It is used with the 40x objective.

e. It enhances the resolving power of the microscope.

Types of Media

True or False:

T: All purpose media is a nutrient agar that supports the growth of a wide variety of organisms, but does

not support fastidious organisms.

T: The purpose of Enriched Media is used to grow FASTIDIOUS organisms, such as pathogens.

T: Jams, jellies and preserves do not develop bacteria growth because sugar acts as a bacterial preservative.

What is an enriched media?

A. A type of media with added nutrients such as vitamins and amino acids.

B. It is used to grow bacteria which are hard to grow, known as FASTIDIOUS organisms.

C. Both A & B

Sabouraud’s Dextrose Agar (SDA)

A: is a media with high sugar content and an acidic pH.

B: SDA is considered an isolation media.

C: It favors the growth of molds and yeasts, but not bacteria.

D. A & B Only

E. All of the above

What is the difference between Broths and Slants?

A: Broths have no agar.

B: They do not have to be boiled, just stirred.

C: Slants have an agar and they are boiled.