NAME RATING:

Group No.
Schedule Date Submitted:

Experiment No. 19
PROPERTIES OF NUCLEIC ACIDS

The polymeric molecule, DNA, is the chemical basis of heredity and is

organized into genes, the fundamental units of genetic information. Knowledge
of the structure and function of nucleic acids is essential in understanding
genetics and provides the basis for future research.

OBJECTIVES:
1. To determine the properties of nucleic acids.

MATERIALS:
Mortar and pestle Yeast
Graduated cylinder (10 ml) Fine sand
Erlenmeyer flask Ether
Funnel Distilled water
2 beakers (100 and 250 ml) Toluene
Evaporating dish 10% hydrochloric acid
3 test tubes Bial’s reagent
Test tube brush 3% amyl alcohol
Test tube holder Diphenylamine reagent
Droppers Dilute ammonium hydroxide solution
Bunsen burner set Dilute nitric acid
Filter paper Ammonium molybdate solution
Match Concentrated nitric acid
Spatula 10% potassium hydroxide solution
Stirring rod

PROCEDURE:
1. Place 1 teaspoon of yeast in a mortar. Mix with a small pinch of sand. Add
15 drops of ether and 5 ml of distilled water. Mix well in a grinding motion.
Add a few drops of water in the process. Transfer the mixture into a flask
and add about 50 ml of distilled water. Add 10 drops of toluene with
54
 shaking motions in between the addition of toluene. Let stand for 20
minutes.
Carefully add 10% hydrochloric acid, stirring the solution thoroughly. Keep
on adding until precipitates form. Filter and save the filtrate and precipitate.

2. Place 5-10 drops of the filtrate in a test tube. Add 20 drops of Bial’s reagent.
Heat the mixture until it begins to boil. Cool then add 5 drops of 3% amyl
alcohol.

Result

3. Place 5 – 10 drops of the filtrate into a test tube. Add 5 drops of

diphenylamine reagent and heat in a boiling water bath for 5 minutes.

Result

4. Neutralize 1 ml of the filtrate with 10 drops of dilute ammonium hydroxide.

Add the same amount of dilute nitric acid. Add 10 drops of ammonium
molybdate solution. Warm the mixture over low flame for 5 minutes.

Result

5. Place 10 drops of the filtrate in an evaporating dish. Add 5 drops of

concentrated nitric acid. Heat and evaporate very carefully over a water
bath.

Result

6. Moisten the residue with 2-3 drops of 10% potassium hydroxide solution.

Result

7. Heat the mixture for 5 minutes. Note the change. Add 5 drops of water
then evaporate to dryness.

Result
55
QUESTIONS:
1. What are the components of nucleic acids?

2. List down foods that are rich in uric acid.

3. Draw the Watson and Crick model of a DNA and label its components.

56
NAME RATING:
Group No.
Schedule Date Submitted:

Experiment No. 20
ASCORBIC ACID CONTENT OF FRUITS

Ascorbic acid or vitamin C is a white, crystalline, water-soluble vitamin

found in many plant materials, especially citrus fruits.

OBJECTIVES:
1. To determine the ascorbic acid content of fruits.

MATERIALS:
6 test tubes 0.1N Sodium hydroxide solution
1 pipette Phenolphthalein
Test tube brush
Droppers
10% juice solution of different fruits

PROCEDURE:
1. Prepare your 10% juice solution as follows:
a. Place 1 ml of the pure juice extract in a clean test tube.
b. Add 9 ml of distilled water.
c. Shake vigorously for 1 minute.
2. Transfer 1 ml of the juice solution into a clean test tube.
3. Add 1 drop of phenolphthalein indicator.
4. Dip the pipette into the reagent bottle containing 0.1N sodium hydroxide
(NaOH) solution to get a certain amount of the base.
5. Add sodium hydroxide to the test tube containing the juice solution (one
drop at a time), shaking in between until a faint pink color appears.
6. Record the volume of sodium hydroxide used to neutralize the acid in the
juice.
7. Repeat procedures (2) through (7) using different extracts.
8. Dissolve a tablet of ascorbic acid in 9 ml of distilled water.
9. Repeat procedures (2) through (7) using the solution prepared in
procedure (8).
57
10. Calculate the ascorbic acid content of each solution using the formula

% Ascorbic acid = Normality of sample x MW of ascorbic acid x 100

1000

Normality of sample = Volume of NaOH used x Normality of NaOH x 10

Volume of sample

MW of ascorbic acid = 176.14 g/mole

S1 S2 S3 S4 S5 Tablet
Volume of sample
Volume of NaOH used
Normality of NaOH
Normality of sample
Per cent Ascorbic acid

11. Show the computations below.

58
QUESTIONS:
1. Aside from ascorbic acid, there are other organic acids found in fruits. Give
their chemical formula and identify a fruit that contain the following acids.
ACID CHEMICAL FORMULA OCCURRENCE
(fruit that contains the acid)

Citric acid

Malic acid

Tartaric acid

Succinic acid

Glyceric acid

Oxalic acid

Shikimic acid

Glycolic acid

Quinic acid

Aspartic acid

2. Aside from fruits name 10 vegetables that contain ascorbic acid.

59
NAME RATING:
Group No.
Schedule Date Submitted:

Experiment No. 21
MINERALS IN FOOD

Minerals are rock materials in the earth’s crust. Every living thing acquires
the minerals from the soil and water for the transport of those important minerals
to and within its living structure. Man gets his minerals from the food that he eats.
Chlorine, cobalt, copper, fluorine, magnesium, manganese, potassium, sodium,
sulfur and zinc are found in meat, liver, eggs, milk, cheese and vegetables. They
are essential to body functioning.

OBJECTIVES:
1. To determine the amount of minerals present in different foods.

MATERIALS:
8 bottle caps Dried beans
Balance Powdered milk
Bunsen burner set Bread
Match Any vegetable
Crackers Cheese
Peanut butter Chocolate

PROCEDURE:
1. Weigh the bottle cap.

2. Weigh 5 grams of each food sample and place it in the bottle cap.

3. Heat gently until a gray ash remains.

4. Cool and weigh again.

5. Determine the amount of minerals in each of the foods.

Percent ash = mass of ash x 100
mass before heating
60
 SUBSTANCE MASS BEFORE MASS OF ASH MASS LOSS PER CENT ASH
HEATING (g) (g) (g) (Minerals)

Crackers

Peanut butter

Dried beans

Powdered milk

Bread

Vegetable

Cheese

Chocolate

QUESTIONS:
1. What are the different classifications of minerals?

61
NAME RATING:
Group No.
Schedule Date Submitted:

Experiment No. 22
ANALYSIS OF BLOOD

Blood is the fluid of life because it carries oxygen from the lungs to the body
tissues and carbon dioxide from the body tissues to the lungs. Blood is the fluid of
growth because it carries nutrients from digestion and hormones from glands.
Blood is the fluid of health because it carries disease-fighting substances to the
tissue and waste to the kidneys. Blood also act as defense because it fight
infections and scavenge debris tissue.
The blood consists of 55% plasma and 45% cells called formed elements.
These are the red blood corpuscles (erythrocytes), white blood corpuscles
(leukocytes) and blood platelets (thrombocytes).
Blood contains the substances like glucose, iron, albumin, sodium,
potassium and phosphorus.

OBJECTIVES:
1. To detect the presence of blood by Hemin Test.
2. To identify the various constituents of blood.
3. To test for the presence of substances in the blood.

MATERIALS:
4 Test tubes Blood (human)
Evaporating dish 1% NaCl (0.1g NaCl in 100ml Glacial HAc)
Test tube brush 10% Acetic acid
2 Beakers (100 ml and 250ml) Benedict’s reagent
Funnel 10% Nitric acid
Bunsen burner set 5% Ammonium molybdate solution
Droppers 5% Silver nitrate solution
Glass slide 10% Hydrochloric acid
Microscope 5% Potassium thiocyanate
Filter paper

62
PROCEDURE:
A. Hemin Test
1. Place 4 drops blood on a glass slide and add 4 drops of 1% NaCl
solution.
2. Evaporate the mixture over low flame.
3. Cool and examine the crystals under the microscope.
4. Draw the crystals.

B. Blood Constituents
1. Mix 5 ml of blood with 45 ml of distilled water in a beaker.
2. Heat the contents.
3. Acidify with 2-3 drops of acetic acid.
4. Continue heating the mixture until a coagulum is formed and the
supernatant liquid becomes clear.
5. Filter.
6. Reserve the coagulum for iron test.
7. Use the filtrate for the following tests:
a. Benedict’s Test
i. Place 2 ml of the filtrate in a test tube.
ii. Add 3 drops of Benedict’s reagent.
iii. Boil over the water bath and until a brick red precipitate is
formed.
b. Test for Phosphates
i. Place 2 ml of the filtrate in a test tube.
ii. Add 5 drops of 10% nitric acid.
iii. Add dropwise 2 ml of 5% ammonium molybdate solution.
iv. Boil the mixture until a yellow precipitate is obtained.
63
 c. Test for Chlorides
i. Place 1ml of the filtrate in a test tube.
ii. Acidify with 5 drops of 10% nitric acid.
iii. Add 2-3 drops of 5% silver nitrate solution.
iv. Note the formation of a white precipitate.
d. Test for Iron
i. Heat a small amount of the coagulum in an evaporating dish
until the organic matter has burned away.
ii. Cool.
iii. Place the ash in a test tube.
iv. Dissolve the ash using 1-2 ml of 10% hydrochloric acid.
v. Add 2-3 drops of 5% potassium thiocyanate solution.
vi. Note the color produced.

Test Chemicals Result Interpretation

added

Benedict’s
Test

Test for
Phosphates

Test for
Chlorides

Test for Iron

64
QUESTIONS:
1. Enumerate and define five common blood diseases.
DISEASE DEFINITION

2. Discuss briefly how blood circulates in the body.

65
NAME RATING:
Group No.
Schedule Date Submitted:

Experiment No. 23
CONSTITUENTS OF URINE

Urine is a pale yellow fluid secreted as waste from the blood by the kidneys,
stored in the bladder, and discharged in the urethra. It is made up of water,
nitrogenous organic compounds, non-nitrogenous organic substances and
inorganic salts.

OBJECTIVES:
1. To determine the components of urine.
2. To identify tests for the different components.

MATERIALS:
Graduated cylinder (10 ml) Barium chloride solution
6 test tubes Dilute nitric acid
Droppers Silver nitrate
Test tube brush Ammonium hydroxide solution
Stirring rod Magnesium sulfate solution
Glass slide and cover slip Concentrated hydrochloric acid
Microscope Saturated calcium chloride solution
Acetic acid Concentrated nitric acid

PROCEDURE:
1. For sulfates, acidify 5 ml of urine with 5 drops of acetic acid and add 5
drops of barium chloride solution.

Result

2. For chlorides, acidify 5 ml of urine with 2-3 drops of dilute nitric acid and
then add 5 drops of silver nitrate.

Result

66
3. For triple phosphates, place 5 ml of urine in a test tube. Add 10 drops of
ammonium hydroxide then 20 drops of magnesium sulfate solution. Allow
to stand in a cool dry place until the next laboratory period. Examine the
crystals under a microscope. Draw the crystals.

4. For uric acid, acidify 10 ml of urine with 2 ml of concentrated hydrochloric

acid and stir well. Allow to stand until the next laboratory period. Examine
and draw the crystals.

5. For oxalic acid, add 20 drops of saturated calcium chloride solution to 10

ml of urine. Acidify by adding 10 drops of acetic acid. Let it stand until the
next laboratory period. Examine and draw the crystals.

67
 6. For albumin, place carefully 20 drops of concentrated nitric acid in a test
tube. With the tube inclined, pour about 2 ml of urine on the side so as to
form a layer over the acid. Allow to stand.

Result

QUESTIONS:
1. What is meant by urolithiasis?

2. Give four important functions of the kidneys.

3. Explain why urine is normally acidic.

68
NAME RATING:
Group No.
Schedule Date Submitted:

Experiment No. 24
ANALYSIS OF SALIVA

Saliva is a mixture of the secretions of the three pairs of salivary glands, the
parotid, the submaxillary, sublingual and numerous small buccal glands. It is a
colorless, slightly viscid, opalescent fluid. The composition varies with the relative
proportion of the secretions of the different glands. The secretion of the parotid is
more watery and rich in ptyalin, while those of the submaxillary and sublingual are
more viscid, containing more mucin, a glycoprotein, and poorer in ptyalin.
The secretion of the saliva is influenced by several factors, namely:
1. Psychic factor: A reflex stimulation due to the thought, sight, or smell of
food.
2. Chemical factor: Due to the stimulation of the taste buds by such
substances as sugar, salt, condiments and other dissolved chemical
substances.
3. Mechanical factor: Due to the mastication of substances in the mouth.

OBJECTIVES:
1. To detect the presence of substances in saliva.
2. To identify the various constituents of blood.

MATERIALS:
8 Test tubes 10% Acetic acid
Watch glass Iodine solution
Test tube brush 3M Nitric acid
2 Beakers (100 ml and 250 ml) Benedict’s reagent
Funnel 10% Nitric acid
Bunsen burner set 5% Ammonium molybdate solution
Graduated cylinder (10 ml) 5% Silver nitrate solution
Dropper 10% Hydrochloric acid
Litmus paper (red and blue) Barium chloride solution
Filter paper NH3 solution
Saliva
69
PROCEDURE:
A. Acidity or Alkalinity
1. Place a strip of red and blue litmus paper on a watch glass.
2. Place a drop of saliva on both strips.

Result: Red litmus paper

Blue litmus paper

B. To 1ml of saliva add a drop of iodine solution.

Result:

C. To 1 ml of saliva add1 ml of 3M nitric acid, and heat on the water bath for
3 minutes. Add a few drops of NH3 solution.

Result:

D. Constituents of Saliva
1. Place 10 ml of saliva in a test tube.
2. Acidify with 5 drops of 3M nitric acid and heat to boiling.
3. Filter and use the filtrate for the following tests:
a. Benedict’s Test
i. Place 2 ml of the filtrate in a test tube.
ii. Add 3 drops of Benedict’s reagent.
iii. Boil over the water bath.

Result:

b. Test for Phosphates

i. Place 2 ml of the filtrate in a test tube.
ii. Add 5 drops of 10% nitric acid.
iii. Add dropwise 2 ml of 5% ammonium molybdate solution.
iv. Boil the mixture.

Result:

70
 c. Test for Chlorides
i. Place 1ml of the filtrate in a test tube.
ii. Acidify with 5 drops of 10% nitric acid.
iii. Add 2-3 drops of 5% silver nitrate solution.

Result:

d. Test for Sulfates

i. Place 5 ml of filtrate in a test tube.
ii. Acidify with 5 drops of acetic acid.
iii. Add 5 drops of barium chloride solution.

Result: QUESTIONS:
1. Give five (5) functions of saliva

2. Enumerate three (3) ways to prevent bad breath