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

What happens during the death phase of bacterial growth?

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

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

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

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

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

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

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

Where do microaerophiles like Campylobacter jejuni grow best?

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

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

<p>Souring (C)</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% (A)</p> Signup and view all the answers

Which type of bacteria can grow with or without salt?

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

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

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

What type of food are halophilic bacteria important in?

<p>Salted food (D)</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 (C)</p> Signup and view all the answers

What do molds tend to accumulate as osmoregulators?

<p>Polyols like glycerol (A)</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 (B)</p> Signup and view all the answers

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

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

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

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

What do synergistic microorganisms achieve when growing together?

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

How can pasteurization contribute to a high SPC in milk?

<p>Thermoduric survival (A)</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 (C)</p> Signup and view all the answers

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

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

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

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

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

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

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