Question 1

Which image shows Giardia lamblia visualized with a scanning electron microscope?

Accepted Answer

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

Question 2

In Gram-negative cells,which layer is disrupted by the decolorizer in the Gram-staining procedure?

Accepted Answer

A)  techoic acids 
B)  outer membrane 
C)  peptidoglycan 
D)  mycolic acid 
A)  techoic acids 
B)  outer membrane 
C)  peptidoglycan 
D)  mycolic acid

Question 3

CASE HISTORY
Purna,a six-year-old boy in India's state of Assam,fell ill with fever.At the time,prolonged rainfall had left vast pools of water,breeding mosquitoes.First the boy felt intense chills,and his temperature rose to 40° C (104° F).He experienced nausea and intense headaches and vomited repeatedly.The fever subsided,only to return three days later.After several weeks of cycling fevers,Purna was at last brought to a clinic for examination.He showed extreme anemia,with enlarged spleen and liver.A blood film slide revealed Plasmodium falciparum,a parasite that causes malaria.In the Assam outbreak of malaria,400,000 people were infected.Some travelers who returned to the United States experienced malarial symptoms months afterward.
Explain the role of fixation and staining in the use of microscopy to identify malaria infection.

Accepted Answer

Fixation kills the cells and stabilizes

Question 4

You are performing a Gram stain to differentiate between Gram-positive and Gram-negative bacteria.At the end of the procedure,a Gram-positive cell will appear

Accepted Answer

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

Question 5

Which of the following statements is INCORRECT?

Accepted Answer

A)  In fluorescence microscopy, fluorescent-labeled cellular structures are identified. 
B)  In light microscopy, the object appears light against a dark background. 
C)  In phase-contrast microscopy, organelles appear as light/dark patterns by variation in refractive indexes. 
D)  Electron microscopy uses electrons to visualize the specimen. 
A)  In fluorescence microscopy, fluorescent-labeled cellular structures are identified. 
B)  In light microscopy, the object appears light against a dark background. 
C)  In phase-contrast microscopy, organelles appear as light/dark patterns by variation in refractive indexes. 
D)  Electron microscopy uses electrons to visualize the specimen.

Question 6

Immersion oil is used with the ________ objective.

Accepted Answer

The answer of Immersion oil is used with the ________...

Question 7

What is the difference between a simple and a differential stain? Give one example of a simple stain and one example of a differential stain.

Accepted Answer

A simple stain uses one dye and does not

Question 8

CASE HISTORY
Marianna and Julio,two children in Oklahoma aged 8 and 11,fell ill with food poisoning after consuming commercially canned hot dog chili sauce.The children complained of double vision and an inability to move their facial muscles.
Examination showed normal vital signs,symmetrical weakness (equal on right and left sides),and fixed pupils due to cranial nerve palsy (paralysis).Upper body paralysis gradually spread downward,and breathing became labored.
Botulinum toxin was identified in their blood by fluorescent monoclonal antibodies (antibodies produced by a genetically uniform cell culture).
The children were placed on mechanical ventilation (a machine that assists breathing)and treated with botulinum antitoxin.After several days,the children were removed from mechanical ventilation.They underwent physical rehabilitation for a full recovery.
The chili sauce was traced to a canning facility where six swollen cans tested positive for botulinum toxin A.From the cans,inspectors cultured a bacterium that grew only without oxygen,as in a closed can.A microscope showed that the bacterium had a distinctive club-shaped appearance.The bacterium was Clostridium botulinum,which produces botulinum toxin,the cause of botulism.One end of the club-shaped cell contains an endospore,an inert form of the cell that can germinate and grow in a closed container of food.Growing cells produce botulinum toxin,leading to botulism,a life-threatening form of paralysis.Microscopy of the pathogen's unique form confirms the identification.
Why was fluorescence microscopy used to help identify the causative agent of the children's disease,rather than bright field?

Accepted Answer

Both antibodies and toxin are too small

Question 9

Which type of stain would be the most useful in helping clinicians decide which class of antibiotics to prescribe?

Accepted Answer

A)  negative stain 
B)  simple stain 
C)  endospore stain 
D)  Gram stain 
A)  negative stain 
B)  simple stain 
C)  endospore stain 
D)  Gram stain

Question 10

What is the purpose of fixation in a staining procedure?

Accepted Answer

A)  to preserve the organisms 
B)  to adhere bacterial cells to the slide 
C)  to impart color to the sample 
D)  to heat the sample 
A)  to preserve the organisms 
B)  to adhere bacterial cells to the slide 
C)  to impart color to the sample 
D)  to heat the sample

Question 11

Which of the following statements about the Gram stain is most correct?

Accepted Answer

A)  Crystal violet differentially stains Gram-positive cells. 
B)  Gram's iodine differentially stains Gram-positive cells. 
C)  Ethanol differentially destains Gram-negative cells. 
D)  Safranin differentially stains Gram-negative cells. 
A)  Crystal violet differentially stains Gram-positive cells. 
B)  Gram's iodine differentially stains Gram-positive cells. 
C)  Ethanol differentially destains Gram-negative cells. 
D)  Safranin differentially stains Gram-negative cells.

Question 12

Which of the following is FALSE about a properly completed Gram stain?

Accepted Answer

A)  It is a key tool used in the identification of bacterial species. 
B)  It is reliable only for fresh cultures. 
C)  It differentiates bacteria based on their cell wall components. 
D)  At the completion of the stain, Gram-negative cells stain purple. 
A)  It is a key tool used in the identification of bacterial species. 
B)  It is reliable only for fresh cultures. 
C)  It differentiates bacteria based on their cell wall components. 
D)  At the completion of the stain, Gram-negative cells stain purple.

Question 13

Magnification without increase in resolution is called ________.

Accepted Answer

The answer of Magnification without increase in resolution is called...

Question 14

Which of the following equals one millimeter?

Accepted Answer

A)  10-3 m 
B)  10-6 m 
C)  10-9 m 
D)  10-12 m 
A)  10-3 m 
B)  10-6 m 
C)  10-9 m 
D)  10-12 m

Question 15

In a compound microscope,which is the accurate pathway of light?

Accepted Answer

A)  light source, condenser, objective, specimen, eyepiece 
B)  condenser, light source, eyepiece, specimen, objective 
C)  eyepiece, objective, specimen, condenser, light source 
D)  light source, condenser, specimen, objective, eyepiece 
A)  light source, condenser, objective, specimen, eyepiece 
B)  condenser, light source, eyepiece, specimen, objective 
C)  eyepiece, objective, specimen, condenser, light source 
D)  light source, condenser, specimen, objective, eyepiece

Question 16

Why is the presence of a capsule clinically significant?

Accepted Answer

A)  It protects the bacterial cell from lack of nutrients. 
B)  It protects the bacterial cell from engulfment by white blood cells. 
C)  It protects the bacterial cell from heat. 
D)  It protects the bacterial cell from the staining regents. 
A)  It protects the bacterial cell from lack of nutrients. 
B)  It protects the bacterial cell from engulfment by white blood cells. 
C)  It protects the bacterial cell from heat. 
D)  It protects the bacterial cell from the staining regents.

Question 17

Which of the following depicts the steps of the Gram stain in the correct order?

Accepted Answer

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

Question 18

Using a compound microscope,the image is magnified at the ________ and the ________.

Accepted Answer

objective lens;ocula

Question 19

Oil immersion is used in which type of microscopy and on which objective?

Accepted Answer

A)  bright-field microscopy, 40X 
B)  bright-field microscopy, 100x 
C)  darkfield microscopy, 40x 
D)  darkfield microscopy, 100x 
A)  bright-field microscopy, 40X 
B)  bright-field microscopy, 100x 
C)  darkfield microscopy, 40x 
D)  darkfield microscopy, 100x

Question 20

The purpose of the condenser is to

Accepted Answer

A)  focus light rays onto the slide. 
B)  magnify the image from the objective lens. 
C)  decrease the refractive index. 
D)  improve resolution. 
A)  focus light rays onto the slide. 
B)  magnify the image from the objective lens. 
C)  decrease the refractive index. 
D)  improve resolution.

Exam 3: Observing Microbes

Which image shows Giardia lamblia visualized with a scanning electron microscope?

In Gram-negative cells,which layer is disrupted by the decolorizer in the Gram-staining procedure?

You are performing a Gram stain to differentiate between Gram-positive and Gram-negative bacteria.At the end of the procedure,a Gram-positive cell will appear

Which of the following statements is INCORRECT?

Immersion oil is used with the ________ objective.

What is the difference between a simple and a differential stain? Give one example of a simple stain and one example of a differential stain.

Which type of stain would be the most useful in helping clinicians decide which class of antibiotics to prescribe?

What is the purpose of fixation in a staining procedure?

Which of the following statements about the Gram stain is most correct?

Which of the following is FALSE about a properly completed Gram stain?

Magnification without increase in resolution is called ________.

Which of the following equals one millimeter?

In a compound microscope,which is the accurate pathway of light?

Why is the presence of a capsule clinically significant?

Which of the following depicts the steps of the Gram stain in the correct order?

Using a compound microscope,the image is magnified at the ________ and the ________.

Oil immersion is used in which type of microscopy and on which objective?

The purpose of the condenser is to

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

The Immune System: Inflammation and Innate Immunity

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

Filters

Using a compound microscope,the image is magnified at the and the .