Bacterial Growth Curve and Reproduction
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Questions and Answers

What is the primary focus during the lag phase of bacterial growth?

  • Reproduction
  • Acclimation to new environment (correct)
  • Chromosome and plasmid reproduction
  • Death
  • Which phase of bacterial growth is characterized by reproduction being greater than death?

  • Death phase
  • Lag phase
  • Logarithmic or exponential phase (correct)
  • Stationary phase
  • What conditions can affect the length of the lag phase in bacterial growth?

  • Physiological history of the microorganism
  • Oxygen limitation
  • Inoculum size (correct)
  • Substrate limitation
  • During which phase of bacterial growth does reproduction equal death due to substrate limitation or adverse environments?

    <p>Stationary phase</p> Signup and view all the answers

    What happens during the death phase of bacterial growth?

    <p>Severe substrate limitation or waste accumulation</p> Signup and view all the answers

    In bacterial growth, what causes vigorous growth via binary fission?

    <p>Reproduction being greater than death</p> Signup and view all the answers

    Which type of microorganism prefers oxygen as a terminal electron acceptor but can grow without it?

    <p>Facultative anaerobe</p> Signup and view all the answers

    What is the electron acceptor used by strict or obligate anaerobes like Clostridium botulinum?

    <p>Nitrate (NO3)</p> Signup and view all the answers

    Which type of foods are described as low in carbohydrates but high in protein and fat?

    <p>Muscle-based foods</p> Signup and view all the answers

    What is the major function of the nutrient composition of food or substrate?

    <p>Source of energy</p> Signup and view all the answers

    Where do microaerophiles like Campylobacter jejuni grow best?

    <p>Low oxygen environments</p> Signup and view all the answers

    What type of spoilage is associated with fruits and vegetables due to their nutrient composition?

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

    What is the range of sodium chloride concentration for slightly halophilic bacteria to grow?

    <p>2 to 5%</p> Signup and view all the answers

    Which type of bacteria can grow with or without salt?

    <p>Salt tolerant bacteria</p> Signup and view all the answers

    What can contribute to spoilage in pasteurized milk, especially if they are psychrotrophs?

    <p>Survival of thermodurics</p> Signup and view all the answers

    What type of food are halophilic bacteria important in?

    <p>Salted food</p> Signup and view all the answers

    Which type of microbial association involves two or more microorganisms adversely affecting each other's growth?

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

    What do molds tend to accumulate as osmoregulators?

    <p>Polyols like glycerol</p> Signup and view all the answers

    Which mechanism do bacteria use to combat low water activity by accumulating 'compatible solutes'?

    <p>Accumulating intracellular compounds</p> Signup and view all the answers

    What is the main premise behind quorum-sensing in bacteria?

    <p>Cell-to-cell communication</p> Signup and view all the answers

    How does low relative humidity affect food stored under such conditions?

    <p>Leads to moisture loss</p> Signup and view all the answers

    What is a potentially hazardous food (PHF) characterized by?

    <p>Neutral pH, high protein, and high carbohydrate content</p> Signup and view all the answers

    What do synergistic microorganisms achieve when growing together?

    <p>Changes that neither could produce alone</p> Signup and view all the answers

    How can pasteurization contribute to a high SPC in milk?

    <p>Thermoduric survival</p> Signup and view all the answers

    What are the four common sources of cross-contamination mentioned in the text?

    <p>Food, people, equipment, work surfaces</p> Signup and view all the answers

    How does improper handling and storage affect microbial numbers on plants?

    <p>Increases microbial numbers</p> Signup and view all the answers

    Which type of water quality is essential for use in food industries according to the text?

    <p>Bacteriologically safe water</p> Signup and view all the answers

    What is a potential carrier of pathogens without showing symptoms mentioned in the text?

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

    How should water be treated for use in the food processing industry according to the text?

    <p>With chlorine treatment</p> Signup and view all the answers

    Which part of plants tend to contain less microorganisms according to the text?

    <p>Trimmed plants</p> Signup and view all the answers

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