Chemistry
Project
Session : 2020-2021
A Project Report On
“digestion of starch by salivary amylase
and effect of temperature
and pH on it”
Submitted by Divey Singhal
Class – XIIth (Science)
Roll no. (cbse) –
Under the Guidance of
Mrs.CHANDNA
MA’AM (Chemistry)
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Table of Contents
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Certificate
Declaration
Acknowledgement
Aim of Project
Objective of the Project Report
Introduction
Apparatus Required
Procedure
Observation
Conclusion
Precaution
Bibliography
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Certificate
This is to certify that DIVEY SINGHAL student
of class XIIth (Sci.) has successfully prepared the report on the
Project entitled “To study the digestion of starch
by salivary amylase and effect of temperature and
pH on it” under the guidance of
Mrs. Chandna Ma’am (Chemistry).
The report is the result of his efforts & endeavours.
The report is found worthy of acceptance as final
Project report for the subject Chemistry
of class XIIth (sci.).
Signature of Chemistry Teacher
Signature of External Examiner
Signature of Principal
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Declaration
I hereby declare that the project work entitled
“ To study the digestion of starch by
salivary amylase and effect of temperature
and pH on it ” , submitted to Chandna Ma’am, is prepared by
me.
Divey Singhal
Class: XIIth (Science)
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Acknowledgement
I would like to express a deep sense of thanks and gratitude
to my project guide Mrs. Chandna Ma’am for guiding me
immensely
through the course of the project. He always envinced keen
intrest in my project. His constructive advice & constant
motivation have been responsible for the successful completion
of his project.
My sincere thank goes to our principal sir for his co-ordination
in extending every possible support for the completion
of this project.
I must thanks to my classmates for their timely help and
support for completion of this project.
Last but not the least, I would like to thank all those who had
helped directly or indirectly towards the
completion of this project.
Divey Singhal
Class- XIIth (Science)
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AIM
“ To study the digestion of
Starch by salivary amylase
and
effect of temperature
and pH on it. ”
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Objective of the Project Report
The main objective of this chemistry project report is
“To study the digestion of starch by salivary amylase
and effect of temperature and pH on it” .
1. To study the digestion of starch by saliva.
2. To study the effect of temperature on the digestion of
starch by saliva.
3. To study the effect of pH on the salivary digestion of
starch.
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Introduction
Every health book insists on the chewing of food. The act of
chewing stimulates the excretion of saliva. Saliva mixes up
with the food and helps its digestion. That is, the enzyme
ptyalin or amylase present in human saliva hydrolyzes the
big molecules of food into many molecules.
For example, starch into mono-saccnaricies maltose and
glucose; proteins into amino acids and fats into fatty acids
and glycerol.
Thus saliva not only helps in digestion of food but also
convert into energy generating substances. Further, enzyme
and their activity are very sensitive to temperature and pH.
Even a slight variation in these two factors, can disturb the
action of enzymes. In other words, digestion of food by
salivary amylase is also effected by temperature and pH and
can be verified experimentally.
For example, hydrolysis of starch can be verified by testing it
with iodine solution. Starch forms blue coloured complex
with iodine. If no starch is present in a system it will not give
blue colour with iodine.
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Apparatus Required
The requirements for experiment of chemistry project report
Are as follow:
1. Test tubes
2. Test tube stand
3. One dropper
4. Beaker
5. Stop watch
6. Starch
7. Iodine solution
8. Thermometer
9. Dilute HCl solution
10. Dilute NaOH solution
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Experiment 1
Aim:- To study the digestion of starch by saliva
Procedure for Chemistry Experiment 1 is:
1. Collection of Saliva:- Rinse mouth thoroughly with cold
water and ensure that it does not contain any food
particles. Now take about 250ml of lukewarm water in
the mouth and keep for about three minutes so that saliva
mixes up well with it. Spit this into a beaker. Filter, if
there is any suspended impurity clear filtrate is saliva
solution and contains enzyme ptylin.
2. Preparation of starch solution:- Take about 0.5g of starch
in 100ml beaker and add enough water to make a paste.
Dilute the paste by adding 50ml water and boil for about
5 minutes.
3. Digestion of starch:a. Take 5ml of the starch solution in a test tube. Add
2ml of saliva solution into it. Mix the solution well
by shaking the tube carefully and start a step watch.
b. After one minute, take out two drops of the mixture
solution from the test tube with the help of dropper
and transfer it into another test tube containing
about 1ml of 1% iodine solution. Note the colour
produced, if any.
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c.
d. Repeat this test after every one minute taking two
drops of the mixture solution and fresh 1% iodine
solution continue until the test shows no blue colour.
e. Record the time and blue colour intensity.
Observation
Time Passed after
Mixing
Colour Intensity
1
2
3
4
minute
minute
minute
minute
Deep
Blue
Light
No Blue
Blue
Blue
Absence of blue colour on addition to iodine solution means
absence of starch in the mixture solution. That is whole of
the starch has got digested or hydrolysed.
Conclusion
Starch gets hydrolysed by salivary amylase
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Experiment 2
Aim:- To study the effect of temperature on the digestion of
starch by saliva.
Procedure for Chemistry Experiment 2 is:
1. Take three test tubes and label these 1,2, and 3.
2. Take 5ml of the starch solution, 2ml of the saliva solution
and 5ml of water in each test tube. And shake the test
tubes carefully.
3. Place test tube number 1 in water at room temperature,
test tube number 2 in a beaker containing water at 50°C
and test tube number 3 in boiling water.
4. After 5 minutes, observe the colour change on mixing
two drops of the mixture of every tube with one ml of 1%
iodine solution. Note the intensity of blue coloured form.
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Observation
Time passed after
mixing saliva
s olution with starch
solution (in min)
Intensity of blue colour
Test tube 1 at
room
Test tube 2 at 50°𝑪 Test tube 3 in
5
temperature
Light blue
Blue
boiling water
Deep blue
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No blue colour
Light blue
Blue
7
-
Faint blue
Blue
8
-
No blue colour
Blue
9
-
-
Blue
10
-
-
Blue
Conclusion
Temperature affects the digestion of starch by
saliva.
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Experiment 3
Aim:- To study the effect of pH on the salivary digestion of
starch.
Procedure for Chemistry Experiment 1 is:
1. Take three test tubes and label these 1,2, and 3.
2. Add 5ml of the starch solution, 2ml of the saliva solution
in each test tube.
3. Now as 2ml of water in test tube number 1 2ml of Dilute
HCl in test tube number 2 and 2ml of Dilute NaOH
solution in test tube number 3 and shake carefully.
4. Keep the three test tubes in water at room temperature
for about 10 minutes.
5. Add 2 drops of the solution of each test tube with 1%
iodine solution and observe the colour change.
Observation
Colour produced (in test
Test tube
Solution taken
tube) with 1% iodine
solution
1
Starch + saliva + water
No blue colour
2
Starch + saliva +dil. HCl
Blue colour
3
Starch + saliva + dil. NaOH
Blue colour
Conclusion
Hydrolysis of starch by the enzyme does not take place in
the acidic or alkaline medium.
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Precaution
1. All apparatus should be clean and washed properly.
2. Add equal drops of iodine in all the samples while
testing for starch.
3. Temperature variation affects enzyme activity, so take
the readings at a constant temperature for all the
samples.
4. Delay in sampling or the reaction time may affect the
result. So, iodine drops must be added at fixed intervals
in all samples.
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Bibliography
1. Wikipedia-the free encyclopedia
2. http://www.google.com/
3. http://en.wikipedia.org
4. www.icbse.com
5. Comprehensive Chemistry
6. Chemistry NCERT Class XIIth
7. Dinesh chemistry
Thank you!!
-Divey Singhal
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