Micro Test Chapter 3

Micro Test Chapter 3 Which of the following is NOT equal to 1 mm? A) 0.001 m B) 106 nm C) 0.1 cm D) 100 μm E) 10-3 m - ANS D) 100 um What structure does light pass through after leaving the condenser in a compound light microscope? A) ocular lens B) objective lens C) specimen D) illuminator - ANS C) specimen Which of the following pairs is mismatched? A) nigrosin - negative stain B) methylene blue - simple stain C) acidic dye - capsule stain D) basic dye - negative stain E) crystal violet - simple stain - ANS D) basic dye - negative stain Which of the following places the steps of the Gram stain in the correct order? 1-Alcohol-acetone 2-Crystal violet 3-Safranin 4-Iodine A) 1-2-3-4 B) 2-1-4-3 C) 2-4-1-3 D) 4-3-2-1 E) 1-3-2-4 - ANS C) 2-4-1-3 Which of the following pairs is mismatched? A) alcohol-acetone — decolorizer B) crystal violet — basic dye C) safranin — acid dye D) iodine — mordant E) carbolfuchsin — basic dye - ANS C) safranin - acid dye Which of the following is NOT true regarding the acid-fast stain? A) It is used to identify members of the genus Mycobacterium. B) Acid-fast cells retain the primary dye after treatment with acid-alcohol. C) If cells are acid-fast, they are gram-negative. D) Acid-fast cells appear red in a completed acid-fast stain. E) Non-acid-fast microbes appear blue in a completed acid-fast stain. - ANS C) If cells are acid-fast, they are gram negative The purpose of a mordant in the Gram stain is to A) remove the simple stain. B) make the bacterial cells larger. C) make the flagella visible. D) prevent the crystal violet from leaving the cells. E) make gram-negative cells visible. - ANS D) prevent the crystal violet from leaving the cells Which of the following places the steps in the correct sequence? 1-Staining 2-Making a smear 3-Fixing A) 1-2-3 B) 3-2-1 C) 2-3-1 D) 1-3-2 E) The order is unimportant. - ANS C) 2-3-1 The negative stain is used to A) visualize endospores. B) determine Gram reaction. C) determine flagella arrangement. D) visualize capsules. E) determine cell size. - ANS E) determine cell size Simple staining is often necessary to improve contrast in which microscope? A) compound light microscope B) phase-contrast microscope C) darkfield microscope D) fluorescence microscope E) electron microscope - ANS A) compound light microscope Which microscope is used to see internal structures of cells in a natural state? A) compound light microscope B) phase-contrast microscope C) darkfield microscope D) fluorescence microscope E) electron microscope - ANS B) phase-contrast microscope Which microscope uses visible light? A) confocal microscope B) differential interference contrast microscope C) fluorescence microscope D) scanning acoustic microscope E) scanning electron microscope - ANS B) differential interference contrast microscope Which microscope achieves the highest magnification and greatest resolution? A) compound light microscope B) phase-contrast microscope C) darkfield microscope D) fluorescence microscope E) electron microscope - ANS E) electron microscope In using this microscope, the observer does NOT look directly at an image through a lens. A) compound light microscope B) phase-contrast microscope C) darkfield microscope D) fluorescence microscope E) electron microscope - ANS E) electron microscope This microscope produces an image of a light cell against a dark background; internal structures are NOT visible. A) compound light microscope B) phase-contrast microscope C) darkfield microscope D) fluorescence microscope E) electron microscope - ANS C) darkfield microscope A virus measures 100 nm in length. What is its length in μm? A) 10 μm B) 1 μm C) 0.1 μm D) 0.01 μm E) 0.001 μm - ANS C) 0.1 um Which of the following is never useful for observing living cells? A) phase-contrast microscope B) darkfield microscope C) scanning acoustic microscope D) scanning electron microscope E) brightfield microscope - ANS D) scanning electron microscope A microorganism measures 5 μm in length. Its length in mm would be A) 500 mm. B) 50 mm. C) 0.5 mm. D) 0.05 mm. E) 0.005 mm. - ANS E) 0.005 mm Which of the following correctly traces the path of light through the compound microscope? A) light source; condenser; specimen; objective lens; ocular lens B) condenser; light source; specimen; ocular lens; objective lens C) light source; specimen; condenser; objective lens; ocular lens D) condenser; light source; specimen; objective lens; ocular lens E) light source; condenser; objective lens; specimen; ocular lens - ANS A) light source; condenser; specimen; objective lens; ocular lens line "c" points to the microscope's A) illuminator. B) condenser. C) ocular lens. D) objective lens. - ANS B) condenser Which microscope can be used to visualize DNA or botulinum toxin? A) compound light microscope B) phase-contrast microscope C) scanning tunneling microscope D) confocal microscope E) scanning electron microscope - ANS C) scanning tunneling microscope Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light? A) compound light microscope B) phase-contrast microscope C) darkfield microscope D) fluorescence microscope E) electron microscope - ANS D) fluorescence microscope Which microscope is most useful for visualizing a biofilm? A) compound light microscope B) phase-contrast microscope C) fluorescence microscope D) scanning acoustic microscope E) transmission electron microscope - ANS D) scanning acoustic microscope Which microscope takes advantage of differences in the refractive indexes of cell structures? A) compound light microscope B) phase-contrast microscope C) darkfield microscope D) fluorescence microscope E) electron microscope - ANS B) phase-contrast microscope You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the first dye. What is the appearance of the bacteria at this point? A) purple B) red C) colorless D) brown - ANS A) purple You are performing a Gram stain on gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point? A) purple B) red C) colorless D) brown - ANS B) red You are performing a Gram stain on gram-negative bacteria and you stop after the decolorizer step. What is the appearance of the bacteria at this point? A) purple B) red C) colorless D) brown - ANS C) colorless You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the counterstain. What is the appearance of the bacteria at this point? A) purple B) red C) colorless D) brown - ANS A) purple Which type of stain is most useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection? A) negative stain B) simple stain C) Gram stain D) endospore stain E) flagella stain - ANS C) Gram stain Which of the following pairs is mismatched? A) confocal microscope - produces a three-dimensional image B) darkfield microscope - uses visible light C) fluorescence microscope - uses a fluorescent light D) scanning electron microscope - produces a three-dimensional image E) scanning tunneling microscope - allows visualization of atoms - ANS C) fluorescence microscope - use a fluorescent light What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens? A) 4.5x B) 10x C) 45x D) 100x E) 450x - ANS E) 450x You are studying a cell structure that is approximately 100 nm in size. Which of the following provides the greatest magnification you can use to see this structure? A) brightfield microscope B) darkfield microscope C) transmission electron microscope D) phase-contrast microscope E) scanning electron microscope - ANS E) scanning electron microscope Which microscope uses two beams of light to produce a three-dimensional color image? A) fluorescence microscope B) phase-contrast microscope C) darkfield microscope D) DIC microscope E) electron microscope - ANS D) DIC microscope Which microscope is used to see intracellular detail in a living cell? A) fluorescence microscope B) two-photon microscope C) atomic force microscope D) transmission electron microscope E) brightfield microscope - ANS B) two-photon microscope Which microscope is used to observe viruses and the internal structure of thinly sectioned cells? A) transmission electron microscope B) darkfield microscope C) fluorescence microscope D) brightfield microscope E) scanning electron microscope - ANS A) transmission electron microscope Which microscope is used to see detail of a 300-nm virus? A) fluorescence microscope B) phase-contrast microscope C) darkfield microscope D) DIC microscope E) electron microscope - ANS E) electron microscope Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin. Through the microscope, the green structures are A) cell walls. B) capsules. C) endospores. D) flagella. E) The answer cannot be determined. - ANS C) endospores Which step in the Gram stain is the critical step in differentiating gram-positive cells from gram-negative cells? A) safranin B) alcohol-acetone C) iodine D) crystal violet - ANS B) alcohol-acetone You find colorless areas in cells in a Gram-stained smear. What should you apply next? A) an acid-fast stain B) a flagella stain C) a capsule stain D) an endospore stain E) a simple stain - ANS D) an endospore stain Which microscope is best used for observing the surfaces of intact cells and viruses? A) phase-contrast microscope B) darkfield microscope C) fluorescence microscope D) brightfield microscope E) scanning electron microscope - ANS E) scanning electron microscope Bacterial smears are fixed before staining to A) affix the cells to the slide. B) make their walls permeable. C) accept stain. D) make the cells visible. - ANS A) affix the cells to the slide The resolution of a microscope can be improved by changing the A) condenser. B) fine adjustment. C) wavelength of light. D) diaphragm. E) coarse adjustment. - ANS C) wavelength of light A student is looking at a bacterial specimen using the oil immersion lens, but has forgotten to put immersion oil on the slide. The specimen will appear A) smaller than it would if immersion oil was used. B) larger than it would if immersion oil was used. C) somewhat fuzzy and have poor resolution. D) the same as it would if the immersion oil was used. E) to have no color. - ANS C) somewhat fuzzy and have poor resolution The purpose of the ocular lens is to A) improve resolution. B) magnify the image from the objective lens. C) decrease the refractive index. D) increase the light. E) decrease the light. - ANS B) magnify the image from the objective lens In microscopy, the term resolution A) refers to the ability to distinguish fine structure and detail in a specimen. B) is the same as the total magnification of a specimen. C) is improved when longer wavelengths of light are employed. D) is only observed in stained specimens. E) refers to magnification when using the electron microscope. - ANS A) refers to the ability to distinguish fine structures and detail in specimen The counterstain used in the Gram stain is a basic dye. - ANS true In a completed Gram stain, gram-negative bacteria are colorless. - ANS false In a completed Gram stain, gram-positive bacteria are purple. - ANS true If acid-fast bacteria are stained with the Gram stain, they will stain gram-negative. - ANS false The limit of resolution of the compound microscope illuminated with visible light is approximately 0.2 μm. - ANS true Both phase-contrast microscopy and differential interference contrast microscopy are used to view the internal structures of cells without staining. - ANS true Cells viewed in darkfield microscopy appear similar to those stained with the negative stain. - ANS true The capsules and flagella of bacteria can be observed in gram-stained smears. - ANS false The greater resolution of the electron microscope compared to the compound microscope is due to the longer wavelengths of the electrons used to examine specimens. - ANS false Scanned probe microscopy is used to examine fine detail of molecular complexes, such as blood clots, or molecules, such as DNA. - ANS true In 1877, Robert Koch thought preparing permanently stained slides would be valuable. Why was his assessment correct? - ANS A method was needed to separate these different bacteria. he used permanently staining methods to begin the process of distinguishing microbes and identifying pathogens. These same techniques are essential in studying all microorganism, documenting infection, as well as useful for teaching and research In 1884, Hans Christian Gram described a method of staining bacterial cells while not staining surrounding animal tissues. However, he thought that the staining method he developed was faulty because not all bacteria stained. In a letter to the editor of the journal in which Gram published his findings, write your response to Gram's concern. - ANS Some of the bacteria (such as pneumucoccus) retained the stain (Gram +) while others did not (Gram -). This discovery is of great use in identification and classification of bacteria. It is also useful in deciding the treatment of bacterial disease, since penicillin is active only against Gram + bacteria; the cell walls of gram - bacteria will not take up either pencil in or gram stain. You are working in a clinical laboratory and you need to examine an unstained urine sample for the presence of bacteria. What type of light microscope should you use to observe this specimen? Explain your answer. - ANS To obtain maximum information from the urine sample, it is important to examine the urine using phase contrast microscopy. With unstained sample, phase contrast microscopy will allow light to pass through thick or dense part of the sample which gives important information regarding the urine sample. Which of the following is not equal to 1 m? A) 106 μm B) 109 nm C) 10 dm D) 100 mm E) None of the above - ANS D) 100 mm What structure does light pass through after leaving the condenser in a compound light microscope? A) Ocular lens B) Objective lens C) Specimen D) Illuminator - ANS C) specimen Which of the following pairs is mismatched? A) Gram-negative bacteria negative stain B) Iodine mordant C) Alcohol acetone-decolorizer D) Acid-alcohol decolorizer E) None of the above - ANS A) Gram negative bacteria - negative stain Place the steps of the Gram stain in the correct order: 1-Alcohol-acetone; 2-Crystal violet; 3-Safranin; 4-Iodine. A) 1-2-3-4 B) 2-1-4-3 C) 2-4-1-3 D) 4-3-2-1 E) 1-3-2-4 - ANS C) 2-4-1-3 Which of the following pairs is mismatched? A) Alcohol-acetone decolorizer B) Crystal violet basic dye C) Safranin acid dye D) Iodine mordant E) None of the above - ANS C) Safranin - acid dye The counterstain in the acid-fast stain is A) A basic dye. B) An acid dye. C) A negative stain. D) A mordant. E) Necessary to determine acid-fast cells. - ANS A) A basic dye The purpose of a mordant in the Gram stain is A) To remove the simple stain. B) To make the bacterial cells larger. C) To make the flagella visible. D) To prevent the crystal violet from leaving the cells. E) None of the above. - ANS D) To prevent the crystal violet from leaving the cell Place the following steps in the correct sequence: 1-Staining; 2-Making a smear; 3-Fixing. A) 1-2-3 B) 3-2-1 C) 2-3-1 D) 1-3-2 E) The order doesnʹt matter - ANS C) 2-3-1 The best use of a negative stain is A) To determine cell size. B) To determine cell shape. C) To determine Gram reaction. D) To see endospores. E) A and B - ANS E) A and B to determine cell size to determine cell shape Simple staining is often necessary to improve contrast in this microscope. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS A) Compound light microscope This microscope is used to see internal structures of cells in a natural state. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS B) Phase - contrast microscope Which of the following microscopes uses visible light? A) Confocal microscope B) DIC C) Fluorescence microscope D) Scanning acoustic microscope E) Scanning electron microscope - ANS B) DIC This microscope achieves the highest magnification and greatest resolution. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS E) Electron microscope In this microscope, the observer does not look at an image through a lens. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS E) electron microscope This microscope produces an image of a light cell against a dark background; internal structures are not visible. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS C) darkfield microscope Which of the following is not correct? A) 1 μm = 10-6 m B) 1 nm = 10-9 m C) 1 μm = 103 nm D) 1 μm = 10-3 mm E) 1 nm = 10-6 μm - ANS E) 1 nm = 10-6 um The counterstain in the Gram stain is A) A negative stain. B) A mordant. C) A basic dye. D) An acid dye. E) Necessary to determine the Gram reaction. - ANS C) A basic dye In Figure 3.1 line A points to the microscopeʹs A) illuminator. B) condenser. C) ocular lens. D) objective lens. - ANS C) ocular lens In Figure 3.1 line B points to the microscopeʹs A) illuminator. B) condenser. C) ocular lens. D) objective lens. - ANS D) objective lens In Figure 3.1 line C points to the microscopeʹs A) illuminator. B) condenser. C) ocular lens. D) objective lens. - ANS B) condenser The light that hits the specimen is scattered and does not come directly from the light source in this microscope. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS C) darkfield microscope This microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS D) Fluorescence microscope This microscope does not use a light. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS E) Electron microscope This microscope takes advantage of differences in the refractive indexes of cell structures. A) Compound light microscope B) Phase-contrast microscope C) Darkfield microscope D) Fluorescence microscope E) Electron microscope - ANS B) Phase-contrast microscope The appearance of gram-positive bacteria after addition of the first dye in the Gram stain. A) Purple B) Red C) Colorless D) Brown E) None of the above - ANS A) Purple The appearance of gram-negative bacteria after addition of the mordant in the Gram stain. A) Purple B) Red C) Colorless D) Brown E) None of the above - ANS A) Purple The appearance of gram-negative bacteria after addition of the decolorizing agent in the Gram stain. A) Purple B) Red C) Colorless D) Brown E) None of the above - ANS C) colorless The appearance of gram-positive bacteria after adding the counterstain in the Gram stain. A) Purple B) Red C) Colorless D) Brown E) None of the above - ANS A) purple The appearance of gram-negative bacteria after completing the Gram stain. A) Purple B) Red C) Colorless D) Brown E) none of the above - ANS B) red Which of the following pairs is mismatched? A) Confocal microscope produces a three-dimensional image B) Darkfield microscope uses visible light C) Fluorescence microscope uses a fluorescent light D) Scanning electron microscope produces a three-dimensional image E) Scanning tunneling microscope allows visualization of atoms - ANS C) Fluorescence microscope - uses a fluorescent light What is the total magnification of a chloroplast viewed with a 10 × ocular lens and a 45× objective lens? A) 10× B) 45× C) 100× D) 450× E) None of the above - ANS D) 450x You suspect a 100 nm structure is present in a cell. Which of the following provides the lowest magnification that you can use to see this structure? A) Brightfield microscope B) Darkfield microscope C) Transmission electron microscope D) Phase-contrast microscope E) Scanning electron microscope - ANS E) scanning electron microscope This microscope uses two beams of light to produce a three-dimensional, color image. A) Fluorescence microscope B) Phase-contrast microscope C) Darkfield microscope D) DIC microscope E) None of the above - ANS D) DIC microscope This microscope is used to see intracellular detail. A) Fluorescence microscope B) Phase-contrast microscope C) Darkfield microscope D) DIC microscope E) None of the above - ANS B) Phase-contrast microscope Image looks like a negative stain in this microscope: A) Fluorescence microscope B) Phase-contrast microscope C) Darkfield microscope D) DIC microscope E) None of the above - ANS A) Fluorescence microscope This microscope is used to see detail of a 300 nm virus. A) Fluorescence microscope B) Phase-contrast microscope C) Darkfield microscope D) DIC microscope E) None of the above - ANS E) none of the above Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin. Through the microscope, the green structures are A) Cell walls. B) Capsules. C) Endospores. D) Flagella. E) Canʹt tell. - ANS C) Endospores Cells are differentiated after which step in the Gram stain? A) Safranin B) Alcohol-acetone C) Iodine D) Crystal violet - ANS B) Alcohol-acetone You find colorless areas in cells in a Gram-stained smear. What should you do next? A) An acid-fast stain B) A flagella stain C) A capsule stain D) An endospore stain E) A simple stain - ANS D) An endospore stain What Gram reaction do you expect from acid-fast bacteria? A) Gram-positive B) Gram-negative C) Both gram-positive and gram-negative D) Canʹt tell - ANS A) Gram-positive Bacterial smears are fixed before staining to A) Kill the bacteria. B) Affix the cells to the slide. C) Make their walls permeable. D) A and B. E) All of the above. - ANS D) A and B Kill the bacteria Affix the cells to the slide The resolution of a microscope can be improved by changing the A) Condenser. B) Fine adjustment. C) Wavelength of light. D) Diaphragm. E) Coarse adjustment. - ANS C) Wavelength of light Van Leeuwenhoekʹs microscope was a(n) A) Electron microscope. B) Phase-contrast microscope. C) Simple microscope. D) Confocal microscope. E) None of the above. - ANS C) Simple microscope The purpose of the ocular lens is to A) Improve resolution. B) Magnify the image from the objective lens. C) Decrease the refractive index. D) Increase the light. E) None of the above. - ANS B) Magnify the image from the objective lens The signal molecule produced in quorum sensing is A) Counterstain. B) Inducer. C) Light. D) Simple stain. E) None of the above. - ANS B) Inducer