First of all we will set up the equipment. We will half fill the glass beaker with water, then we will put 5ml of milk into one test tube, and 5 drops of Rennin into the other. We will then place them into the glass beaker along with the thermometer. After that, we will place the glass beaker on the tripod and light the Bunsen burner. We must then heat the water to the right temperature (Experiment 1: 20°C, Experiment 2: 80°C, Experiment 3: 40°C) and after about 5 minutes at the right temperature we will pour the milk into the Rennin. Following that we will check the mixture every minute until the milk has set as a gel. This means that our results won’t be very accurate, as we will only be able to give the time to the nearest minute.
Fair Testing:
In this experiment there is only one variable, and that is the temperature of the water in the glass beaker. Everything else will remain as a constant: the amount of milk, the amount of Rennin, the amount of water in the beaker and how often we check to see if the milk has turned into a gel. The amount of milk will always be 5ml and the amount of Rennin will always be 5 drops. We will always half fill the beaker with water and we will use a timer so we can look at the milk exactly every minute. There is one thing that I do not believe will make it a fair test. This is that we will only look at the milk every 1 minute, we can’t change it because we have been given instructions to do so but if one tube turns to gel at 2 minutes 05 and another at 2 minute 55 there is a significant difference in time but they would both be recorded as 3 minutes. But this does not matter if what I predict is true.
Prediction:
I predict that the only test tube in which the milk will solidify is the one where the temperature is set at 40°C. I predict this because at 80°C the enzymes would have been denatured long ago and at 20°C the enzymes would be at too lower temperature to work properly. 40°C is closest of them all to body temperature (37°C) which is the temperature at which enzymes work best so I think the milk will only solidify in that one. I know this from work done in class on enzyme activity and I have found information from a secondary source, the Internet:
Temperature is important in all reactions. As the temperature increases, so does the rate of reaction. This is because heat energy causes more collisions between the enzyme and substrate. However, very high temperatures damage enzymes by denaturing them. This graph shows the effect of temperature on an enzyme-controlled reaction.
Taken from web-site: http://www.bbc.co.uk/education/gcsebitesize/science_biology/humans/enzymes_rev.shtml#enzyme4/
Results:
Conclusion:
After looking at my results I can see that my prediction was correct. The only tube in which milk set was the one at 40°C. The maximum time we left the other two in for was 15 minutes because we did not have much time in the lesson. Something else we should have done if there was more time is we should have repeated the experiment, but I believe it would leave us with exactly the same results. In relation to the task set, an enzyme works best at body temperature (around 37°C) but when it becomes to hot it is denatured and will no longer work, not even if you cool it back down again, whereas if the enzyme gets cooled down too low it will stop working but will start working again when you heat it back up. So if we heated the tube at 20°C up it would solidify eventually but if we cooled the 80°C tube down it would not solidify. So my prediction was correct, temperature does have an affect on enzyme activity.