The Effect Of Temperature on Enzymes

Purpose: To see how changes in temperature affect the enzymes rate of reaction


-7 Glucose test strips

-6 test tubes

-10 ml Milk per test tube

-Lactase Enzyme (5 drops per test tube)

-Hot Plate

-Oven Mittens



-Tap water

-6 Beakers

-A thermometer

Hypothesis: By increasing and decreasing the temperature, we will reduce the enzyme lactases ability to break down the lactose sugar found in milk (due to denaturing of the enzyme)


  1. Fill 6 test tubes with 10 ml of milk.
  2. Dip one of the glucose test strips into regular milk to have a control group. Record the temperature of the milk.
  3. Fill a beaker with ice, put one of the test tubes inside the ice for 10 minutes. After 10 minutes, dip a glucose test strip and record the temperature of the milk.
  4. Run the tap water at the coldest for less than a minute, fill a beaker with cold tap water, put one of the test tubes inside the water for 10 minutes. After ten minutes, dip a glucose test strip. Record the temperature of the milk.
  5. Boil the milk in a beaker on a hot plate. Once boiled, dip the glucose test strip. Record the temperature of the milk.
  6. Boil water in a kettle and pour into a beaker. Put one of the test tubes in the boiling water for 10 minutes. Once finished, dip one of the glucose test strips and record the temperature of the milk.
  7. Create a beaker with water of room temperature (about 23 degrees Celsius) by pouring hot and/or cold water, leave one of the test tubes of milk inside for 10 minutes. After, dip the glucose test strip in and record the temperature of the milk.
  8. Put one of the test tubes in a beaker of 39 degree Celsius water (body temperature), leave in for 10 minutes or until reached body temperature. Insert a glucose test strip, record the temperature of the milk.


Observations and Analysis: 

  • The hottest and room temperature had the same dark brown colour, therefore more glucose concentration. After that, body temperature and in ice had the closest colour.
  • The enzyme can function similar to inside the body at a high temperature of 93 degrees Celcius and of a similar temperature to body temperature of 25 degrees Celcius.


1. What are the observable effects that the changes in temperature had for each test tube?

There were no obvious observable effects. Using the glucose test strip, we could see that the glucose concentration had clearly changed depending on temperature. In certain test tubes, the glucose concentration was higher. This could be because the temperature caused the enzymes to no longer break down the sugar lactose. The temperature that had the least break down would have been room and boiling temp. The rest had a higher break down of sugar.

2. How did this lab help in understanding enzymes?

This lab helped us understand that enzymes are very sensitive and have very specific temperatures that they can fulfill their duties. When body temperature dropped only about ten degrees Celcius, the break down of enzymes changed mmol/L. That being said, our bodies need to hold extremely specific temperatures in order for functions to process.

3. What was the difference between boiled milk and hot milk?

The boiled milk had a much higher concentration of glucose than that of the hot milk. This means the boiling milk must’ve had its enzymes denatured by the temperature, causing a higher concentration of sugars that haven’t been broken down by the enzyme lactase.

4. How does this lab show how enzymes work in the body?

If the body temperature test tube was accurate, having seen that it produced a glucose test strip of about 56 mmol/L, it would have a glucose concentration in between all the different variations of temperature. This means that the enzymes of the test tube were not denatured and could not not break any sugars down nor were they sped up and started breaking more sugars than usual. The enzymes in the body have a specific temperature that helps them keep a specific sugar level that was clearly different than all the other temperatures when you look at the graph.

5. How could this lab have been improved? 

This lab could have been improved with specific temperatures rather than conditions. Also, more variation of temperature closer to body temperature to see more how an initial higher and lower temperature can affect enzymes.

Also, the reactions didn’t model definitions. By definition, the colder temperature should render the speed of the rate of enzymes breaking down sugars and high heat should do the opposite. As we see in the picture of the glucose test strips, ice, room temp, and boiling temp are of different temperatures but have very similar effects on the enzymes. So, this experiment might have factors that affected its accuracy.

Conclusion: This lab was an okay representation of the break down of sugars in different temperatures. An interesting thing that we didn’t predict is that, seen in the graph and the glucose test strips, the highest temperature and room temperature had the same effect on the enzymes.

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