Starter quiz
- True or false? Bacteria are eukaryotic.
- True
- False ✓
- How does penicillin directly impact bacteria?
- It stops the DNA from replicating.
- It stops the formation of the cell wall. ✓
- It stops the formation of the cell membrane.
- It stops the cytoplasm from dividing during replication.
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We grow microorganisms on agar gel because...- it contain nutrients. ✓
- it is translucent.
- it provides water. ✓
- it can be made in a container.
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- Which statements are correct?
- Antibiotics and antimicrobials are the same.
- Antimicrobials kill or slow the spread of microorganisms. ✓
- Antibiotics kill or slow the spread of bacteria. ✓
- Antibiotics only kill viruses.
- Antimicrobials kill viruses and antibiotics kill bacteria.
-
- When bacteria mutate and become less susceptible to the action of antibiotics they are said to have developed antibiotic ______.
- 'resistance' ✓
- Put the following steps in order to show how antibiotic resistance develops.
- 1⇔A random mutation occurs in the DNA of a bacterium.
- 2⇔The mutation gives the bacterium resistance to the antibiotic.
- 3⇔The bacterium reproduces passing on the mutation to the next generation.
- 4⇔Many bacteria are now resistant to the antibiotic.
- 5⇔The antibiotic no longer works.
Exit quiz
- You are investigating the effect of different antiseptic solutions on bacterial growth on an agar plate. Match the variables to their descriptors.
- independent variable⇔type of antiseptic ✓
- dependent variable⇔size of clear zone ✓
- control variables⇔incubation temperature and time ✓
Starting with sterilising the inoculating loop, put these steps in the correct order to explain how you culture bacteria using aseptic technique.- 1⇔Put the wire inoculating loop into the Bunsen burner flame until it glows.
- 2⇔Wait for the loop to cool before using it.
- 3⇔Open the bottle of bacteria and pass the neck of the bottle through the flame.
- 4⇔Dip the inoculating loop into the bottle of bacteria and then remove.
- 5⇔Flame the neck of the bottle again and replace the lid.
- 6⇔Lift the lid of the agar plate and use the loop to streak bacteria on the plate.
- 7⇔Flame the inoculating loop again to sterilise it.
- Match the aseptic technique to its purpose.
- flaming the inoculating loop⇔sterilises the wire to avoid contaminating the bacteria bottle ✓
- flaming the neck of the bottle⇔prevents bacteria escaping and contaminating the air ✓
- working next to a lit Bunsen burner⇔reduces risk of microorganisms settling on surfaces and equipment ✓
- using an autoclave⇔sterilises equipment by killing microorganisms using heat before use. ✓
- When using an agar plate with a live culture, what details should you write on the plate?
- your initials ✓
- the type of agar
- the date you prepared the plate ✓
- the type of bacteria used ✓
- the date you plan to collect your results.
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- In a school, what temperature should you incubate bacterial samples at?
- 25 °C ✓
- 30 °C
- 35 °C
- 37 °C
- 40 °C
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- The Oak pupils are discussing how to seal their agar plates before incubation. Who is correct?
Jun: We should not put any tape on the agar plate as this might prevent growth.
Jacob: We should put tape all the way around to make sure no bacteria escape.
Izzy: We should only use a few bits of tape to avoid anaerobic bacteria growing. ✓
Sam: We should only use two bits of tape so the plate can be opened and checked.
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Uncontaminated cultures of microorganisms are required to investigate the action of antimicrobials.
- Bacteria can be grown on an agar plate using aseptic techniques.
- Examples of aseptic techniques used in culturing bacteria.
- Discs soaked in antimicrobial substances can be used to investigate their effect on bacterial growth.
Common misconception
Pupils may think that all antimicrobial substances are equally effective against all microorganisms.
The effectiveness of different antimicrobial substances against bacteria can be tested.
Keywords
Aseptic technique - Practical methods that help to prevent contamination with unwanted microorganisms.
Agar plate - Petri dish containing growth medium solidified with agar jelly.
Culture - Growing cells or tissue in growth medium in a laboratory, usually in an incubator.
Antimicrobial - Substance that slows down or stops the growth of microorganisms such as bacteria.
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