Microbes and Their Impact on Human History
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Questions and Answers

What is the main characteristic that distinguishes prokaryotes from eukaryotes?

  • Size and complexity
  • Presence of a nucleus (correct)
  • Type of genetic material
  • Mode of reproduction

    • Who is credited with the discovery of the largest bacterium?

  • Louis Pasteur
  • Alexander Fleming
  • Sergei Winogradsky (correct)
  • Robert Koch

    • Which type of microbe requires a microscope to be seen?

  • Bacteriophage
  • Prion
  • Protozoa (correct)
  • Yeast

    • What is the significance of metagenomes in understanding microbial populations?

    <p>They capture the genetic diversity of entire microbial communities</p> Signup and view all the answers

    What was Lynn Margulis's proposed mechanism for the evolution of eukaryotic organelles?

    <p>Endosymbiosis</p> Signup and view all the answers

    What did Carl Woese's analysis of DNA from prokaryotes living in hot springs reveal?

    <p>They were a distinct form of life</p> Signup and view all the answers

    What did microbiologists do to define microbial species despite the difficulty in defining them?

    <p>Devised working definitions of microbial species</p> Signup and view all the answers

    How did Woese's discovery impact the classification scheme of five kingdoms?

    <p>It replaced the five kingdoms with three equally distinct groups called domains</p> Signup and view all the answers

    What substance did Alexander Fleming discover that kills bacteria?

    <p>Penicillium mold</p> Signup and view all the answers

    What is the main purpose of immunization?

    <p>To stimulate an immune response by inoculation with an attenuated pathogen</p> Signup and view all the answers

    What did Sergei Winogradsky and others demonstrate about the importance of bacteria?

    <p>Bacteria play a crucial role in geochemical cycling</p> Signup and view all the answers

    What are endosymbionts?

    <p>Microbes that live inside a larger host organism</p> Signup and view all the answers

    What is resolution in the context of observing microbes?

    <p>The smallest distance by which two objects can be separated and still be distinguished</p> Signup and view all the answers

    What does detection refer to in the context of observing microbes?

    <p>The ability to determine the presence of an object</p> Signup and view all the answers

    What does magnification mean in the context of observing microbes?

    <p>An increase in the apparent size of an image to resolve smaller separations between objects</p> Signup and view all the answers

    Which type of microscopy is described as the simplest?

    <p>Light microscopy</p> Signup and view all the answers

    What is the main difference between a simple stain and a differential stain?

    <p>A simple stain adds dark color specifically to cells, but not to the external medium or surrounding tissue, while a differential stain stains types of cell differently to distinguish them</p> Signup and view all the answers

    Which type of bacteria retains the crystal violet stain in the Gram stain?

    <p>Gram-positive bacteria</p> Signup and view all the answers

    What is the main use of fluorescence microscopy in microbiology?

    <p>To label specific cells even in environmental samples</p> Signup and view all the answers

    What do molecules with fluorescence properties (fluorophores) do in fluorescence microscopy?

    <p>They absorb light of lower energy and then emit light of higher energy</p> Signup and view all the answers

    What is the size range of prokaryotes?

    <p>0.4–10 µm</p> Signup and view all the answers

    Which shapes of bacteria are common to many taxonomic groups?

    <p>Bacilli: rods, Cocci: spheres</p> Signup and view all the answers

    What must exist for electromagnetic radiation to resolve an object?

    <p>Contrast between object and its medium, Wavelength smaller than the object, Enough light intensity</p> Signup and view all the answers

    What is the wavelength range of visible light?

    <p>~400–750 nm</p> Signup and view all the answers

    What type of interaction occurs when the wavefront bounces off the surface of an object?

    <p>Reflection</p> Signup and view all the answers

    In bright-field microscopy, what is used to increase resolution?

    <p>Shorter-wavelength light</p> Signup and view all the answers

    What is the total magnification when the ocular lens has a magnification of 5X and the objective lens has a magnification of 20X?

    <p>100X</p> Signup and view all the answers

    How does fixation enhance the detection and resolution of cells under a microscope?

    <p>By making cells adhere to a slide in a fixed position</p> Signup and view all the answers

    What is the size range of prokaryotes?

    <p>0.4–10 µm</p> Signup and view all the answers

    What are the common shapes of bacteria found in many taxonomic groups?

    <p>Rods and spheres</p> Signup and view all the answers

    What is the wavelength range of visible light?

    <p>~400–750 nm</p> Signup and view all the answers

    What conditions must exist for electromagnetic radiation to resolve an object?

    <p>Contrast between object and its medium, wavelength smaller than the object, and others</p> Signup and view all the answers

    What is part of the spectrum of electromagnetic radiation?

    <p>Light</p> Signup and view all the answers

    What is a subcellular structure that is too small to resolve by light microscopy?

    <p>Subcellular structures are too small to resolve by light microscopy</p> Signup and view all the answers

    What is the main characteristic that distinguishes prokaryotes from eukaryotes?

    <p>Lack of a true nucleus and other membrane-bound organelles</p> Signup and view all the answers

    What is the main purpose of a simple stain?

    <p>To add dark color specifically to cells</p> Signup and view all the answers

    What distinguishes a differential stain from a simple stain?

    <p>A differential stain stains types of cell differently to distinguish them</p> Signup and view all the answers

    Which type of bacteria retains the crystal violet stain in the Gram stain?

    <p>Gram-positive bacteria</p> Signup and view all the answers

    What does fluorescence microscopy allow scientists to do?

    <p>Label specific cells even in environmental samples</p> Signup and view all the answers

    What happens when a specimen absorbs light of a defined wavelength and then emits light of lower energy?

    <p>It fluoresces</p> Signup and view all the answers

    What is the most famous differential stain mentioned in the text?

    <p>Gram stain</p> Signup and view all the answers

    What is the main characteristic of a differential stain?

    <p>It stains types of cell differently to distinguish them</p> Signup and view all the answers

    Which type of bacteria do not retain the crystal violet stain in the Gram stain?

    <p>Gram-negative bacteria</p> Signup and view all the answers

    What can fluorescence microscopy be used for in live organisms?

    <p>To observe fluorescence.</p> Signup and view all the answers

    What is the definition of resolution in the context of observing microbes?

    <p>The smallest distance by which two objects can be separated and still be distinguished</p> Signup and view all the answers

    What is the main difference between light microscopy and other types of microscopy?

    <p>Light microscopy is the simplest, while other types are more complex</p> Signup and view all the answers

    What does detection refer to in the context of observing microbes?

    <p>The ability to determine the presence of an object</p> Signup and view all the answers

    Which organisms fall within the size range that structures can be seen under a light microscope?

    <p>Protozoa, algae, fungi</p> Signup and view all the answers

    What is the definition of magnification in the context of observing microbes?

    <p>The increase in the apparent size of an image to resolve smaller separations between objects</p> Signup and view all the answers

    What is the significance of powerful microscopes in observing microbes?

    <p>They enable detection of microbes in familiar and unexpected habitats</p> Signup and view all the answers

    What is meant by the term 'microbes differ in size, over a range of a few orders of magnitude'?

    <p>Microbes have a wide range of sizes spanning several orders of magnitude</p> Signup and view all the answers

    What is the definition of absorption in the context of light interacting with an object?

    <p>The acquisition of the photon’s energy by the absorbing object</p> Signup and view all the answers

    In bright-field microscopy, what technique is used to increase resolution?

    <p>Use shorter-wavelength light</p> Signup and view all the answers

    What is the main purpose of fixation in microscopy?

    <p>To enhance detection and resolution of cells</p> Signup and view all the answers

    What does refraction refer to in the context of magnification by a lens?

    <p>The bending of light as it enters a substance that slows its speed</p> Signup and view all the answers

    How does total magnification in a compound microscope relate to the ocular and objective lenses?

    <p>Total magnification is the product of the magnification of the ocular and objective lenses</p> Signup and view all the answers

    What occurs when the wavefront interacts with an object smaller than the wavelength of light?

    <p>Scattering</p> Signup and view all the answers

    What is the main function of glass with curvature (lens) in magnification?

    <p>To bend light rays to intersect at a focal point</p> Signup and view all the answers

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