Micro organisms and their applications

• What is the singular form of bacteria?

  Bacterium
• How often can bacteria replicate?

  Approximately every 20 minutes
• What is binary fission?

  Asexual reproduction of bacteria
• What does cell division refer to?

  Process by which cells duplicate
• What factors affect bacterial replication?

  Nutrients and suitable conditions
• What is a culture in microbiology?

  Grown deliberately by humans
• What is a colony in microbiology?

  A cluster of bacteria visible to the naked eye
• What is nutrient broth solution?

  A culture medium for bacteria growth
• What is an agar plate?

  A Petri dish containing agar gel
• How are agar plates created?

  By pouring hot molten agar into sterile dishes
• Why is sterilization important in microbiology?

  To prevent contamination by other bacteria
• What is a pathogen?

  A microorganism that causes disease
• What is the purpose of aseptic techniques?

  To avoid contamination during experiments
• How is an inoculating loop sterilized?

  By heating it to red hot in a flame
• What should be done after inoculating agar?

  Secure the lid with adhesive tape
• At what temperature are inoculated agar plates incubated?

  25°C
• Why are plates incubated for no more than 24–48 hours?

  To prevent growth of human pathogens
• What happens to bacteria when grown on agar?

  They form visible colonies
• How can the number of bacteria in a sample be estimated?

  By counting individual colonies on plates
• What is a serial dilution?

  A method to dilute a sample for accurate counting
• When can accurate calculations of bacteria be made?

  When the sample produces clear individual colonies
• What is required for handling micro-organisms safely?

  Specific techniques
• Why is studying micro-organisms important?

  It provides vital information about their growth
• What is the mean division time for bacteria population A?

  • 20 minutes
  • Bacteria divide every 20 minutes
• How many bacteria will be present after six hours if starting with one bacterium?

  262,144 bacteria
• How do you calculate the number of divisions in six hours for bacteria dividing every 20 minutes?

  Divide 360 minutes by 20 minutes
• What is the equation to calculate the number of bacteria at the end of the growth period?

  Initial bacteria × $2^{\text{number of divisions}}$
• How many divisions occur in six hours if the mean division time is 20 minutes?

  18 divisions
• What is the bacterial population after 18 divisions starting with one bacterium?

  262,144 bacteria
• What is the standard form of 262,144 bacteria?

  2.62 × 10$^5$ bacteria
• What happens to bacterial growth when food is refrigerated?

  Bacterial growth slows down
• What is the effect of freezing food on bacteria?

  Bacterial growth stops, but bacteria aren't killed
• What method kills bacteria in food?

  Cooking food at high temperatures
• What are the implications of bacterial growth in food storage?

  • Rapid growth can lead to spoilage
  • Slowing growth extends food shelf life
  • Cooking kills harmful bacteria
• What is the purpose of industrial fermenters?

  To grow bacteria and fungi in large amounts
• What is the main use of Penicillium mould in industrial fermenters?

  To produce penicillin, an antibiotic
• What materials are fermenters typically made from?

  • Usually made from stainless steel
  • Metal that will not corrode
• What is the function of the steam inlet in a fermenter?

  To sterilize the inside of the fermenter
• Why is the steam inlet important for fermenters?

  It prevents contamination by unwanted micro-organisms
• What does the nutrient inlet do in a fermenter?

  Allows sterile nutrients to enter the fermenter