Question 1

You are observing a bacterial specimen on the 100x objective but have forgotten to put the immersion oil on the slide.The specimen will appear

Accepted Answer

A)  smaller with better resolution. 
B)  larger with poor resolution. 
C)  somewhat fuzzy with poor resolution. 
D)  the same. 
A)  smaller with better resolution. 
B)  larger with poor resolution. 
C)  somewhat fuzzy with poor resolution. 
D)  the same. C

Question 2

What is the total magnification of a specimen viewed with a 10x ocular lens and a 35x objective lens?

Accepted Answer

A)  10x 
B)  3.5x 
C)  350x 
D)  3,500x 
A)  10x 
B)  3.5x 
C)  350x 
D)  3,500x C

Question 3

If a microbiologist forgot to heat-fix a bacterial smear before staining,what would probably happen?

Accepted Answer

A)  Bacteria might wash off the slide. 
B)  The stain would not stick to the bacteria. 
C)  The bacteria might decolorize too quickly. 
D)  The color of the stain would be too dark to see the bacteria. 
A)  Bacteria might wash off the slide. 
B)  The stain would not stick to the bacteria. 
C)  The bacteria might decolorize too quickly. 
D)  The color of the stain would be too dark to see the bacteria. A

Question 4

You are performing a Gram stain on Gram-positive bacteria and you stop after the addition of the mordant.What is the appearance of the bacteria at this point?

Accepted Answer

A)  purple 
B)  colorless 
C)  pink 
D)  blue 
A)  purple 
B)  colorless 
C)  pink 
D)  blue

Question 5

Resolution is

Accepted Answer

A)  the ability to detect individual cells. 
B)  using a microscope to be seen. 
C)  increasing the size of an image. 
D)  the smallest distance two objects can be separated and still be distinguished. 
A)  the ability to detect individual cells. 
B)  using a microscope to be seen. 
C)  increasing the size of an image. 
D)  the smallest distance two objects can be separated and still be distinguished.

Question 6

Which images display organelles?

Accepted Answer

A)  1 and 2 
B)  2 and 4 
C)  1 and 3 
D)  3 and 4 
A)  1 and 2 
B)  2 and 4 
C)  1 and 3 
D)  3 and 4

Question 7

CASE HISTORY
Jared,a 48-year-old,previously healthy man,was admitted to a hospital in Columbus,Ohio,after six days of increasing dyspnea (shortness of breath)and watery diarrhea.Jared also complained of a dry cough,myalgia (muscle pain),nausea,and vomiting.He appeared flushed and had dry mucous membranes.His temperature was 39°C (102.2°F),and his pulse rate was 103 beats per minute.Chest radiographs showed pneumonia with consolidation (formation of a firm mass)of the left lower lobe.His c-reactive protein (crP,a blood protein produced by the liver)was greater than 220 milligrams per liter (mg/l),a high level that indicates inflammation.
Before onset of symptoms,Jared recalled having cleaned the filter of an outdoor whirlpool spa.Culture from Jared's sputum and from the spa filter revealed Gram-negative bacilli consistent with Legionella pneumophila.The diagnosis was confirmed by fluorescence microscopy using direct fluorescent antibody (DFA)stain.The patient received intravenous amoxicillin and clarithromycin antibiotics for eight days before his condition returned to normal.
If the technician conducting the Gram stain in this case study had left ethanol on the prepared slide longer than necessary,what might be the effect on this slide and identification?

Accepted Answer

A)  The bacteria on the slide may have been decolorized Gram-positive bacilli. 
B)  None. The timing of ethanol does not affect the outcome of a Gram stain. 
C)  None, since the bacteria appear Gram negative, they could not have been over-decolorized. 
D)  The bacteria on the slide may have been cocci rather than bacilli. 
A)  The bacteria on the slide may have been decolorized Gram-positive bacilli. 
B)  None. The timing of ethanol does not affect the outcome of a Gram stain. 
C)  None, since the bacteria appear Gram negative, they could not have been over-decolorized. 
D)  The bacteria on the slide may have been cocci rather than bacilli.

Question 8

The size at which objects become visible depends on the resolution of the observer's eye.Typically eagles can resolve objects much smaller or farther away than humans can.Please explain why.

Accepted Answer

Resolution is achieved by focusing an im

Question 9

Which microscope technique is best used for visualizing the surface structures of cells and viruses?

Accepted Answer

A)  phase-contrast 
B)  bright-field 
C)  scanning electron 
D)  darkfield 
A)  phase-contrast 
B)  bright-field 
C)  scanning electron 
D)  darkfield

Question 10

What is an advantage of fluorescence microscopy?

Accepted Answer

A)  It allows for the preservation of the specimen. 
B)  It provides the greatest resolution. 
C)  It has the ability to stain live specimens. 
D)  It has the ability to detect specific microbes. 
A)  It allows for the preservation of the specimen. 
B)  It provides the greatest resolution. 
C)  It has the ability to stain live specimens. 
D)  It has the ability to detect specific microbes.

Question 11

Which of the following is the correct order of the Gram-stain regents?

Accepted Answer

A)  iodine, crystal violet, safranin, ethanol 
B)  ethanol, crystal violet, safranin, iodine 
C)  crystal violet, ethanol, iodine, safranin 
D)  crystal violet, iodine, ethanol, safranin 
A)  iodine, crystal violet, safranin, ethanol 
B)  ethanol, crystal violet, safranin, iodine 
C)  crystal violet, ethanol, iodine, safranin 
D)  crystal violet, iodine, ethanol, safranin

Question 12

What is the purpose of the mordant in the Gram-stain procedure?

Accepted Answer

The iodine solution used in the Gram sta

Question 13

Using the figure below,which of the following images depicts the absorption of light?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 14

Refraction occurs by the ________ of light and is the key property enabling a lens to magnify an image.

Accepted Answer

The answer of Refraction occurs by the ________ of light...

Question 15

Electron microscopy uses beams of ________ to generate high-resolution images.

Accepted Answer

The answer of Electron microscopy uses beams of ________ to...

Question 16

Compare and contrast darkfield,phase-contrast,and fluorescence microscopy.

Accepted Answer

Darkfield,phase-contrast,and fluorescenc

Question 17

Which microscope uses variations in refractive indexes to display specimens?

Accepted Answer

A)  bright-field 
B)  fluorescence 
C)  phase-contrast 
D)  transmission electron 
A)  bright-field 
B)  fluorescence 
C)  phase-contrast 
D)  transmission electron

Question 18

In the figure below,line "D" points to the microscope's

Accepted Answer

A)  ocular lens. 
B)  objective. 
C)  condenser. 
D)  light source. 
A)  ocular lens. 
B)  objective. 
C)  condenser. 
D)  light source.

Question 19

A ________ is the only way to observe live specimens.

Accepted Answer

The answer of A ________ is the only way to...

Question 20

The bending of light as it enters a substance that slows its speed is known as

Accepted Answer

A)  reflection. 
B)  refraction. 
C)  absorption. 
D)  scattering. 
A)  reflection. 
B)  refraction. 
C)  absorption. 
D)  scattering.

Exam 3: Observing Microbes

You are observing a bacterial specimen on the 100x objective but have forgotten to put the immersion oil on the slide.The specimen will appear

What is the total magnification of a specimen viewed with a 10x ocular lens and a 35x objective lens?

If a microbiologist forgot to heat-fix a bacterial smear before staining,what would probably happen?

You are performing a Gram stain on Gram-positive bacteria and you stop after the addition of the mordant.What is the appearance of the bacteria at this point?

Resolution is

Which images display organelles?

The size at which objects become visible depends on the resolution of the observer's eye.Typically eagles can resolve objects much smaller or farther away than humans can.Please explain why.

Which microscope technique is best used for visualizing the surface structures of cells and viruses?

What is an advantage of fluorescence microscopy?

Which of the following is the correct order of the Gram-stain regents?

What is the purpose of the mordant in the Gram-stain procedure?

Using the figure below,which of the following images depicts the absorption of light?

Refraction occurs by the ________ of light and is the key property enabling a lens to magnify an image.

Electron microscopy uses beams of ________ to generate high-resolution images.

Compare and contrast darkfield,phase-contrast,and fluorescence microscopy.

Which microscope uses variations in refractive indexes to display specimens?

In the figure below,line "D" points to the microscope's

A ________ is the only way to observe live specimens.

The bending of light as it enters a substance that slows its speed is known as

Microbes Shape Our History

Basic Concepts of Infectious Disease

Living Chemistry: From Atoms to Cells

Cell Biology of Bacteria and Eukaryotes

Bacterial Growth, Nutrition, and Differentiation

Bacterial Metabolism

Bacterial Genetics and Biotechnology

Bacterial Genomes and Evolution

Bacterial Diversity

Eukaryotic Microbes and Invertebrate Infectious Agents

Viruses

Sterilization, Disinfection, and Antibiotic Therapy

Normal Human Microbiota: a Delicate Balance of Power

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The Immune System: Adaptive Immunity

Immune Disorders, Tools, and Vaccines

Microbial Pathogenesis

Infections of the Skin and Eye

Infections of the Respiratory Tract

Systemic Infections

Infections of the Digestive System

Infections of the Urinary and Reproductive Tracts

Infections of the Central Nervous System

Diagnostic Clinical Microbiology

Epidemiology: Tracking Infectious Diseases

Environmental and Food Microbiology

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