The effect of temperature on the rate of decomposition by an enzyme: practical
Lesson details
Learning outcome
I can carry out an experiment to investigate how temperature affects the rate of decomposition of milk by an enzyme.
Key learning points
- Use an enzyme (e.g. lipase) to decompose milk.
- Measure the change in pH as the milk is decomposed.
- Estimate the rate of decomposition by measuring the change in pH.
- Compare the rate of decomposition at different temperatures.
Keywords
Enzyme - A protein which acts as a biological catalyst. This speeds up a reaction without being used up.
Active site - The part of an enzyme where the substrate binds.
PH - A measure of how acidic or alkaline a solution is.
End point - The point at which a reaction is complete, often indicated by a change in colour of an indicator.
Hypothesis - A precise, measurable and testable statement based on observations about how something works.
Common misconception
Several liquids are measured in this practical. The equipment used to measure the lipase should not be used to measure the liquids or the lipase may begin to digest fats before the practical starts.
To prevent contamination, ensure that the method is explained carefully and modelled through a demonstration or by watching the practical video.
Teacher tip
It is helpful as a class to think about the range of temperatures to be investigated so that pupils are able to share results to calculate a mean. Demonstrate the method or show the video so there is no uncertainty in how to proceed and students can carry the practical out with confidence.
Content guidance
Risk assessment required - equipment
Supervision
Adult supervision required
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.An enzyme is an example of a catalyst. What do catalysts do?
Q2.Enzymes are made up of chains of amino acids. Amino acids combined together make what type of molecule?
Q3.The image is a simplified diagram of an enzyme. Which of the following would be the best label to use to replace 'A'?

Q4.What do we mean by the rate of decomposition?
Q5.Which of the following will help to increase the rate of decomposition?
Q6.Why is decomposition in ecosystems important?
Assessment exit quiz
6 Questions
Q1.What is meant by pH?
Q2.In the practical looking at the decomposition of milk by an enzyme, the point at which a colour change indicates the change in pH is known as the ...
Q3.Cresol red is a solution which changes colour. What are solutions that change colour called?
Q4.What pH does milk become when it decays?
Q5.When carrying out a practical activity, a precise, measurable and testable statement based on observations about how something works is called a ...
Q6.In the practical where you looked at the effect of temperature on the decomposition of milk using an enzyme, which variable is the independent variable?
To help you plan your 10 biology lesson on: The effect of temperature on the rate of decomposition by an enzyme: practical, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 biology lesson on: The effect of temperature on the rate of decomposition by an enzyme: practical, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 biology lessons from the Living organisms and their environments unit, dive into the full secondary biology curriculum, or learn more about lesson planning.