Practical methods that help to prevent contamination with unwanted microorganisms.

Petri dish containing growth medium solidified with agar jelly.

Growing cells or tissue in growth medium in a laboratory, usually in an incubator.

Substance that slows down or stops the growth of microorganisms such as bacteria.

The effect of antimicrobial substances on bacterial growth: practical

Biology

Pupils learned about human and plant defences against pathogens, the role of white blood cells in the human immune system, and the use of vaccination to protect against communicable diseases.

This unit covers vaccines, medicines, and monoclonal antibodies for disease prevention and treatment. It explains aseptic techniques, medicine development, and antibody uses. The focus is on ethical considerations, risk evaluation, and societal impacts of scientific advances.

Medicines and new treatments for disease

Physical activity and equipment requiring safe use

You are investigating the effect of different antiseptic solutions on bacterial growth on an agar plate. Match the variables to their descriptors. 

Put the wire inoculating loop into the Bunsen burner flame until it glows.

Wait for the loop to cool before using it.

Open the bottle of bacteria and pass the neck of the bottle through the flame.

Dip the inoculating loop into the bottle of bacteria and then remove. 

Flame the neck of the bottle again and replace the lid.

Lift the lid of the agar plate and use the loop to streak bacteria on the plate.

Flame the inoculating loop again to sterilise it.

Starting with sterilising the inoculating loop, put these steps in the correct order to explain how you culture bacteria using aseptic technique.

sterilises the wire to avoid contaminating the bacteria bottle

prevents bacteria escaping and contaminating the air

reduces risk of microorganisms settling on surfaces and equipment

sterilises equipment by killing microorganisms using heat before use.

Match the aseptic technique to its purpose.

the date you plan to collect your results.

When using an agar plate with a live culture, what details should you write on the plate?

In a school, what temperature should you incubate bacterial samples at?

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.

The Oak pupils are discussing how to seal their agar plates before incubation. Who is correct?

It stops the formation of the cell membrane.

It stops the cytoplasm from dividing during replication.

How does penicillin directly impact bacteria?

We grow microorganisms on agar gel because...

Antibiotics and antimicrobials are the same.

Antimicrobials kill or slow the spread of microorganisms.

Antibiotics kill or slow the spread of bacteria.

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 {{}}.

A random mutation occurs in the DNA of a bacterium.

The mutation gives the bacterium resistance to the antibiotic.

The bacterium reproduces passing on the mutation to the next generation.

Many bacteria are now resistant to the antibiotic.

Put the following steps in order to show how antibiotic resistance develops.

Content guidance

Risk assessment required - equipment

Adult supervision required

This lesson will be removed by end of Summer Term 2025.

The effect of antimicrobial substances on bacterial growth: practical

Lesson outcome

Content guidance

This lesson will be removed by end of Summer Term 2025.