YIH YEE CHONG - Summative Assessment - Unit 2 Saliva Experiment

Starch and Amylase Report
Draft
Introduction
Starch is a carbohydrate normally found in potatoes, rice and pasta. Starch is made up
of many glucose units that are joined together. Enzymes that break down starch are called
amylases, which can be found in saliva. Iodine is a chemical element which can be used to
check if the starch is present. It is yellow in colour but when it is mixed with starch, it becomes
blue or black in colour. When Iodine is dropped into the starch-saliva mixture, it would turn blue
or black but after the starch is digested by the saliva, it would slowly turn yellow or red.
It is important to know the process of amylase breaking down starch because you would
know how long it takes for the amylase to break down starch properly.
Aim
To learn what happens to the starch when mixed with amylase after different amounts of time.
Hypothesis
The longer the time, the more starch will be broken down.
Materials
Corn starch - 1ml
Saliva - 3 ml
Water - 100ml
Measuring spoon
Measuring cup
2 cups
Spotting tile
Iodine solution bottle
Timer
Procedure
1.
100 ml of water was measured in the measuring cup and 1ml of corn starch was measured with
the measuring spoon.
2:
100ml of water and 1ml of corn starch were mixed into a starch solution in a cup.
3:
5ml of the starch solution was measured using the measuring spoon.
4:
1ml of saliva was measured using a measuring spoon and was mixed with the 5ml of starch
solution in another cup, which created the starch-saliva mixture.
5:
A drop of the starch-saliva mixture was placed in one of the cavities in the spotting tile and a
drop of Iodine solution was then also immediately placed in the cavity containing the
starch-saliva mixture.
6:
After 1 minute, step 5 was repeated.
7:
Step 5 was repeated again after 2, 4 and 8 minutes.
8:
Step 3 to Step 7 were repeated again to complete trials 2 and 3.
Results
Table 1: The color of Iodine, saliva and amylase mixture for Trial 1 after different amounts of
time.
Minutes 0 1 2 4 8
Colour for Black Black Black Black Extremely

Trial 1: dark brown
Colour for Dark brown Dark brown Dark brown Dark brown Light brown
Trial 2:
Colour for Black Extremely Dark brown Light brown Dark yellow
Trial 3: dark brown
Average Black Extremely Dark brown Dark brown Brown

dark Brown
Figure 1: Trial 1 results indicating the color of the mixture of Iodine, saliva and starch after
different periods of time.
Discussion
This experiment is not reliable because there is no consistency in the results for all the 3 trials.
The results for all the 3 trials were different. For the first trial, the color of the mixture of Iodine,
saliva and starch was black from 0 to 4 minutes and turned a little lighter to extremely dark
brown when it was 8 minutes. For the second trial, the color was always dark brown from 0 to 4
minutes, but after 8 minutes, it turned a little lighter. For the last trial, the color became lighter
each time, starting from 0 minutes to 8 minutes.
This experiment is not valid because although the same equipment and the same material were
used for each of the 3 trials, the amount of saliva used in Trial 1 was more than Trial 2 and 3
and the amount of Iodine solution used in Trial 2 was more than Trial 1 and 3 as the wrong
amount of the Iodine and the wrong measuring spoon was used.
The results of Trial 2 were mostly dark brown probably because there was more saliva in this
trial as the wrong measuring spoon was used. In Trial 3, the results were almost all black most
likely because there was more Iodine solution in each of the spotting tiles because there was
more than 1 drop of Iodine solution being squeezed out from the bottle It is hard to control the
amount of Iodine coming out from the bottle as it is hard. Also, when it was time to drop the
Iodine solution into the cavity of the spotting tile, it was not immediately dropped on the exact
time as time was needed to squeeze only a drop of it into the cavity.
This experiment validify the hypothesis as the starch is more broken down when there is longer
time.
Two ways to improve the validity of this trial are to check if the correct measuring spoon is used
for each trial and using a dropper instead of the bottle to drop the Iodine solution.
There were not any problems with completing Trial 1 as the same equipment, like the measuring
spoon, the same amount of liquid such as the Iodine solution and saliva, and the same material
were used.
This is Clara’s result. Her experiment’s aim is the same as this experiment’s aim, but the only
difference is that she heated the starch and amylase solution. The color of her result of her
mixture was orange, blue and black after 8 minutes for all the 3 trials. The color of the result of
this experiment’s mixture was extremely dark brown, light brown and dark yellow after 8 minutes
for all the 3 trials. Her first trial failed because she put too little starch for the starch solution, less
than 1g. For her second trial, it also failed because she put too much starch, more than 1g, for
her starch solution, but her third trial succeeded. As for this experiment, only the last trial
succeeded as when the Iodine solution was immediately placed in the cavity after creating the
starch and saliva mixture, it was black. After 8 minutes, it turned yellow.
Conclusion
According to the results, the color of the mixture of Iodine, saliva and starch was lighter after
long periods of time, which means that the starch was broken down.
Reference
Allott, A. (2019). MYP Life Sciences. Oxford University Press.

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YIH YEE CHONG - Summative Assessment - Unit 2 Saliva Experiment

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Starch and Amylase Report

Colour for Black Black Black Black Extremely

Average Black Extremely Dark brown Dark brown Brown

Allott, A. (2019). MYP Life Sciences. Oxford University Press.

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