Biology Year 12 - Module 7 - Lesson 5

Microbial Testing

Use this worksheet after reading the lesson to practise the key ideas and prove you can meet the success criteria.

Name

Date

Class

1. Key Ideas

In remote Australian communities, tap water that looks clear can carry E. coli. Regular microbial testing of water and food is the only reliable way to detect contamination before people get sick — and the method used in a school lab is the same one used by public health authorities.

The purpose of microbial testing of water and food
Why serial dilution is necessary before plating

2. Success Criteria

By the end, you should be able to:

The purpose of microbial testing of water and food
The standard method: serial dilution, plating, colony counting
Key variables: independent, dependent, controlled

3. Key Terms

water and foodthe only reliable way to detect contamination before people get sick — and the method used in a school lab is the same o

Why serial dilutionnecessary before plating

Why colony countsestimates, not exact counts

Contaminated water and foodamong the leading causes of infectious disease globally

microbial contaminationinvisible — water containing dangerous levels of E

way to detect itthrough microbial testing

4. Activity: Build the Lesson Map

Use the lesson to complete the table. Keep answers brief but specific.

Prompt	Your answer
Main concept
Important example
Common mistake to avoid
How this links to the next lesson

5. Short Answer Questions

1. Explain this lesson goal in your own words: "The purpose of microbial testing of water and food". Use one specific example from the lesson.

Band 32 marks

2. Apply this idea to a new example: "The standard method: serial dilution, plating, colony counting". Show your reasoning clearly.

Band 43 marks

3. Analyse why this idea matters for understanding Microbial Testing: "Key variables: independent, dependent, controlled".

Band 54 marks

6. Extend: Apply the Idea

Band 5/65 marks

A student gives a memorised answer about Microbial Testing but does not use evidence or reasoning.

Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.

7. Multiple Choice

1. What is the best first step when answering a question about Microbial Testing?

A. Identify the key concept being tested

B. Write every fact from memory

C. Ignore the command word

D. Skip examples and evidence

2. Which answer would show stronger understanding of Microbial Testing?

A. An answer with accurate terms and reasoning

B. A copied definition only

C. A single-word response

D. An answer with no example

3. What should you do if a question asks you to explain?

A. Link the idea to a reason or cause

B. List unrelated facts

C. Only draw a diagram

D. Write the shortest possible answer

8. Success Criteria Proof

Finish with evidence that you can do each success criterion.

Success criterion 1

Prove that you can: The purpose of microbial testing of water and food