New
New
Year 10
AQA
Foundation

The effect of temperature on the rate of decomposition by an enzyme: practical

I can carry out an experiment to investigate how temperature affects the rate of decomposition of milk by an enzyme.

New
New
Year 10
AQA
Foundation

The effect of temperature on the rate of decomposition by an enzyme: practical

I can carry out an experiment to investigate how temperature affects the rate of decomposition of milk by an enzyme.

Lesson details

Key learning points

  1. Use an enzyme (e.g. lipase) to decompose milk.
  2. Measure the change in pH as the milk is decomposed.
  3. Estimate the rate of decomposition by measuring the change in pH.
  4. Compare the rate of decomposition at different temperatures.

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.

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.

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.
Teacher tip

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
An enzyme is an example of a catalyst. What do catalysts do?
Slow down how quickly reactions happen.
Correct answer: Speed up how quickly reactions happen.
Change the reactions that take place.
Q2.
Enzymes are made up of chains of amino acids. Amino acids combined together make what type of molecule?
Carbohydrate
Correct answer: Protein
Fat (lipid)
Vitamin
Q3.
The image is a simplified diagram of an enzyme. Which of the following would be the best label to use to replace 'A'?
An image in a quiz
substrate
enzyme
Correct answer: active site
substrate site
complex
Q4.
What do we mean by the rate of decomposition?
How quickly populations of decomposers reproduce.
How quickly populations of decomposers die.
Correct answer: How quickly organic matter is broken down.
How many decomposers there are in a population.
Q5.
Which of the following will help to increase the rate of decomposition?
Correct answer: Warmer temperatures
Colder temperatures
Correct answer: Wetter conditions
Dry conditions
Reducing the levels of oxygen that is available
Q6.
Why is decomposition in ecosystems important?
Correct answer: It recycles important elements so they can be used by other organisms
Decomposers produce food for other all organisms in the rest of the food chain
Decomposers provide a food source for plants
Elements are used up during decomposition, this stops them from building up

6 Questions

Q1.
What is meant by pH?
The colour that an indicator changes when added to a substance.
Correct answer: How acidic or alkaline a substance is.
The acidity of a substance.
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 ...
Correct Answer: end point, endpoint
Q3.
Cresol red is a solution which changes colour. What are solutions that change colour called?
Correct Answer: indicators, indicator, an indicator
Q4.
What pH does milk become when it decays?
alkaline
Correct answer: acidic
neutral
a gas
Q5.
When carrying out a practical activity, a precise, measurable and testable statement based on observations about how something works is called a ...
prediction
measurement
observation
Correct answer: hypothesis
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?
milk volume
Correct answer: milk temperature
enzyme temperature
pH of the milk

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