Microbiology Quiz - Bacteria and Microscopes
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Questions and Answers

Which type of bacteria is classified as bacilli?

  • Diplococcus
  • Streptobacilli (correct)
  • Cocci
  • Spirochete
  • What is the main purpose of a microscope in microbiology?

  • To increase brightness of specimens
  • To provide a bright field for observation
  • To magnify specimens to make them visible (correct)
  • To provide contrast between different specimens
  • What is a main characteristic of cocci bacteria?

  • They are rod-shaped
  • They are spiral in shape
  • They can form clusters (correct)
  • They are the largest type of bacteria
  • Which microscope type is most commonly used in microbiology?

    <p>Bright-field microscope (D)</p> Signup and view all the answers

    What does resolving power of a microscope refer to?

    <p>The minimum distance that separates two points (B)</p> Signup and view all the answers

    What is a characteristic feature of spirilla bacteria?

    <p>They are characteristically spiral (B)</p> Signup and view all the answers

    Which technique uses differences in contrast to render specimens visible?

    <p>Bright-field microscopy (D)</p> Signup and view all the answers

    What is the magnification achieved by a bright-field microscope with a 100-power objective lens and a 10-power ocular lens?

    <p>1000 times (B)</p> Signup and view all the answers

    What is the primary effect of moist heat on proteins?

    <p>Coagulation and denaturation of proteins (D)</p> Signup and view all the answers

    Which pasteurization method heats at 63°C for 30 minutes?

    <p>Holder method (C)</p> Signup and view all the answers

    Which pathogen is known to survive pasteurization?

    <p>Coxiella (B)</p> Signup and view all the answers

    What temperature and duration is needed for the Ultra-High Temperature (UHT) pasteurization method?

    <p>140°C for 15 seconds (D)</p> Signup and view all the answers

    What is a limitation of boiling water at 100°C in sterilization?

    <p>Certain bacterial toxins may survive (D)</p> Signup and view all the answers

    What process is used for intermittent sterilization?

    <p>Tyndallisation (D)</p> Signup and view all the answers

    What is the effect of free steam at 100°C used in sterilization?

    <p>It sterilizes articles when exposed for a period of 90 minutes (B)</p> Signup and view all the answers

    Which of the following is NOT a benefit of steam sterilization?

    <p>Guarantees complete sterility (B)</p> Signup and view all the answers

    What is one of the primary uses of formaldehyde gas?

    <p>Used to preserve biological specimens (C)</p> Signup and view all the answers

    Which chemical is described as being less irritating and more effective than formaldehyde?

    <p>Glutaraldehyde (B)</p> Signup and view all the answers

    How long does it typically take ethylene oxide to kill all microbes and endospores?

    <p>4 to 18 hours (B)</p> Signup and view all the answers

    What is the primary mechanism by which peroxygens disinfect microbes?

    <p>Oxidize cellular components (A)</p> Signup and view all the answers

    What is one of the primary uses of ozone in disinfection?

    <p>Disinfecting water (C)</p> Signup and view all the answers

    Why is hydrogen peroxide not recommended for treating open wounds?

    <p>It is quickly broken down by catalase. (D)</p> Signup and view all the answers

    What is a characteristic of peracetic acid as a disinfectant?

    <p>One of the most effective liquid sporicides available (C)</p> Signup and view all the answers

    What type of infections is glutaraldehyde particularly useful in disinfecting?

    <p>Infections requiring viricidal activity (D)</p> Signup and view all the answers

    What did Louis Pasteur demonstrate regarding fermentation?

    <p>It is caused by the growth of microorganisms. (C)</p> Signup and view all the answers

    Which disease did Robert Koch NOT work on?

    <p>Influenza (B)</p> Signup and view all the answers

    What distinguishes eubacteria from archaebacteria?

    <p>Biochemical differences. (A)</p> Signup and view all the answers

    What is true about thermoacidophiles?

    <p>They are commonly found in hot sulfur springs. (D)</p> Signup and view all the answers

    Which of the following is NOT a criterion of Koch's postulates?

    <p>The organism must be capable of spontaneous generation. (B)</p> Signup and view all the answers

    What is the primary purpose of Gram staining in microbiology?

    <p>To differentiate between Gram +ve and Gram -ve bacteria (C)</p> Signup and view all the answers

    What color do Gram-positive bacteria appear after the Gram staining process?

    <p>Purple (D)</p> Signup and view all the answers

    Which component of the bacterial cell wall is responsible for its rigidity?

    <p>Peptidoglycan (D)</p> Signup and view all the answers

    Why do Gram-negative bacteria lose the crystal violet dye during the staining process?

    <p>They contain a lipid layer in their cell wall (C)</p> Signup and view all the answers

    What role does ethyl-alcohol serve in the Gram staining process?

    <p>It decolorizes Gram-positive bacteria (A)</p> Signup and view all the answers

    What is the function of safranin in the Gram staining procedure?

    <p>To counterstain and allow identification of Gram -ve bacteria (B)</p> Signup and view all the answers

    What is NOT a characteristic of Gram-positive bacteria?

    <p>They stain pink (D)</p> Signup and view all the answers

    Which of the following best describes a differential stain?

    <p>A stain that distinguishes between different types of bacteria (B)</p> Signup and view all the answers

    What serious complication can arise from a group A streptococcal infection?

    <p>Rheumatic fever (A)</p> Signup and view all the answers

    Which laboratory test is most commonly used for rapid detection of group A streptococcal antigen?

    <p>Throat swab antigen detection test (B)</p> Signup and view all the answers

    What type of infections is commonly preceded by the development of rheumatic fever?

    <p>Respiratory infections (B)</p> Signup and view all the answers

    What is the most widely used antibody test for group A streptococcal infection?

    <p>Antistreptolysin O (ASO) test (B)</p> Signup and view all the answers

    What type of hemolysis can be prevented with antimicrobial drugs in rheumatic fever patients?

    <p>Beta-hemolytic (B)</p> Signup and view all the answers

    What is a key initiating factor for acute glomerulonephritis after a Streptococcus pyogenes skin infection?

    <p>Immune-mediated response (A)</p> Signup and view all the answers

    Which of the following infections is specifically related to a strain of S. pyogenes that carries a prophage coding for pyrogenic toxin?

    <p>Scarlet fever (B)</p> Signup and view all the answers

    What type of streptococci are known as viridans group streptococci?

    <p>Alpha-hemolytic streptococci (C)</p> Signup and view all the answers

    Flashcards

    Bacterial Morphology

    The study of different shapes of bacteria

    Bacilli

    Rod-shaped bacteria

    Cocci

    Spherical bacteria

    Spiral bacteria

    Bacteria with a spiral or helical shape

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    Bright-field microscope

    A common microscope used to view bacteria by differences in contrast.

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    Resolving power

    The ability of a microscope to distinguish fine detail of the specimen.

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    Magnification (microscope)

    The ability to make an object appear much larger than its real size.

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    Microbial shape classification

    Grouping bacteria based on their shapes (rods, spheres, spirals)

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    Pasteurization

    A process that uses heat to kill harmful bacteria in food and dairy products while preserving quality.

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    Holder method

    A pasteurization technique that heats food at 63°C for 30 minutes.

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    Flash method

    A pasteurization technique heating food at 72°C for 15 seconds, followed by rapid cooling.

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    Boiling sterilization

    Using boiling water to kill most vegetative bacteria and viruses immediately, but not spores.

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    Tyndallization

    A sterilization method using free steam for several days with intermittent heating to kill bacterial spores.

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    Autoclave

    A device under pressure that uses steam for sterilization.

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    Moist heat sterilization

    Sterilization using heat and moisture to cause protein coagulation and denaturation.

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    Ultra-High Temperature (UHT)

    A pasteurization method using very high temperatures for a short time.

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    Pasteur's Fermentation Discovery

    Louis Pasteur found that fermentation is caused by the growth of microorganisms, disproving spontaneous generation.

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    Germ Theory of Disease

    The idea that specific microorganisms cause specific diseases.

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    Koch's Postulates

    A set of criteria used to determine if a specific organism causes a disease.

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    Prokaryotes

    Organisms without a nucleus, including bacteria and archaea.

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    Archaea

    A group of prokaryotes often found in extreme environments, like hot springs or salty places.

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    Formaldehyde gas

    A potent disinfectant that inactivates proteins by forming crosslinks, commonly used as formalin to preserve specimens and in vaccines.

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    Glutaraldehyde

    A sterilizing disinfectant, more effective than formaldehyde, used to disinfect hospital instruments, and even in embalming.

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    Ethylene Oxide

    A gaseous sterilizer that kills all microbes and endospores, but takes longer exposure time (4-18 hours).

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    Ozone

    A highly reactive oxygen form used to disinfect water, neutralizing tastes and odors, more effective than chlorine, but less stable.

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    Hydrogen Peroxide

    An antiseptic used for inanimate object disinfection, but not for open wounds due to catalase breakdown.

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    Peroxygens (oxidizing agents)

    Oxidize cellular parts of microbes, used to disrupt membranes and proteins.

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    Sporicidal

    Capable of killing bacterial spores.

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    Peracetic Acid

    A powerful liquid sporicide effective against bacteria, fungi, endospores, and viruses within minutes or 30 minutes, used in food and medical instrument disinfection.

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    What is Gram staining?

    A technique used to classify bacteria into two groups based on their cell wall properties: Gram-positive and Gram-negative.

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    Gram-positive bacteria

    Bacteria that retain the crystal violet dye during the Gram staining procedure, appearing purple under the microscope.

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    Gram-negative bacteria

    Bacteria that lose the crystal violet dye during the Gram staining procedure, appearing pink due to the counterstain.

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    What is the purpose of safranin in Gram staining?

    Safranin acts as a counterstain, staining all cells pink, making it easier to identify the Gram-negative bacteria.

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    Why do Gram-positive and Gram-negative bacteria stain differently?

    The difference lies in the structure of their cell walls. Gram-positive bacteria have a thicker peptidoglycan layer, making them retain the crystal violet dye.

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    What is peptidoglycan?

    A complex sugar polymer found in bacterial cell walls, providing strength and rigidity.

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    What role does ethyl alcohol play in Gram staining?

    Ethyl alcohol acts as a decolorizer, dissolving the lipid layer in Gram-negative cell walls, allowing the crystal violet to leach out.

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    How does the thick cell wall of Gram-positive bacteria contribute to dye retention?

    The thick peptidoglycan layer in Gram-positive bacteria shrinks during dehydration with ethyl alcohol, closing the pores and preventing the crystal violet dye from escaping.

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    Scarlet Fever Cause

    Caused by a strain of Streptococcus pyogenes carrying a prophage that codes for pyrogenic toxin.

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    Scarlet Fever Complication

    Scarlet fever can lead to long-term complications known as sequelae.

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    Septicemia

    A serious blood infection caused by bacteria.

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    Streptococcal Toxic Shock Syndrome

    A life-threatening condition caused by toxins released by Streptococcus pyogenes.

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    Rheumatic Fever Cause

    Caused by certain strains of Streptococcus pyogenes containing cell membrane antigens that cross-react with human heart tissue antigens.

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    Rheumatic Fever Timing

    Rheumatic fever usually appears 1-4 weeks after a Streptococcus pyogenes infection.

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    Acute Glomerulonephritis Cause

    Can develop 3 weeks after a Streptococcus pyogenes skin infection, potentially triggered by antigen-antibody complexes on the glomerular basement membrane.

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    Antimicrobial Therapy for Rheumatic Fever

    Antimicrobial drugs are important for preventing reinfection with group A streptococci in rheumatic fever patients.

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    Microbiology Lecture Notes PDF

    Description

    Test your knowledge on key concepts in microbiology, including the classification of bacteria and the functions of microscopes. This quiz covers essential characteristics of bacilli, cocci, and spirilla, along with microscopy techniques and magnification principles.

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