Memory Anchor:

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  Challenge:

Key Questions:

1. (Biology only) Required Practical 2 - Microbiology (Biology only) (AT Skills 1,3,4,8)
2. (Biology only) How do bacteria divide?
   • (Biology only) Bacteria divide by binary fission as often as once every 20 minutes.
3. (Biology only) When investigating the growth of bacteria, in what two ways can they be grown?
   • (Biology only) Bacteria are grown in a nutrient broth solution or as colonies on an agar gel plate.
4. (Biology only) What is special about the culture of organisms required when investigating the action of disinfectants and antibiotics?
   • (Biology only) Uncontaminated cultures of microorganisms are required for investigating the action of disinfectants and antibiotics.
5. (Biology only) How is an uncontaminated culture of microgransims prepared?
   • (Biology only) An uncontaminated culture is prepared using an aseptic technique.
6. (Biology only) Why are petri dishes and culture media sterilised before use?
   • (Biology only) Petri dishes and culture media are sterilised before use to avoid contamination; it removes any existing microbes.
7. (Biology only) Why are inoculating loops, used to transfer microorganisms to media, passed through a flame?
   • (Biology only) Inoculating loops, used to transfer microorganisms to the media, must be passed through a flame to sterilise them; it removes any existing microbes.
8. (Biology only) Why should the lid of the Petri dish should be secured with adhesive tape and stored upside down?
   • (Biology only) The lid of the Petri dish should be secured with adhesive tape and stored upside down to prevent microbes from the air contaminating the culture and prevent microbes from the culture escaping. They are placed upside down to prevent condensation forming on the lid which could drip onto the agar and contaminate the culture.
9. (Biology only) Why should cultures be incubated at 25oC in school laboratories?
   • (Biology only) Cultures are incubated at 25oC in school laboratories as it greatly reduces the chances of growing pathogens that are harmful to people at temperatures greater than 25oC.