FORM 2 CHAPTER 3 NUTRISION

3.1 : analysing classes of food
3.2: evaluating the importance of a balance diet
3.3: understanding the digestive system
3.4: understanding the process of absorption of

digested food
3.5 understanding the reabsorption o water

and defecation
3.6 put into practice the habits of healthy eating

Seven Classes of food

carbohydrates protein fats

Fibre mineral vitamin water

a. Contain carbon,
hydrogen, and
oxygen.

b. Function: Supply
most of the
energy our body
needs.

c. Examples:

sugar, rice,
potato,sweet potato

a. Contain carbon,
hydrogen, oxygen,
and nitrogen.

b.Needed for growth
and repair of body
tissues.

c. Examples: fish,
meat, egg

DISEASE: KWASIORKOR
CAUSES: LACK OF PROTEIN

a.Contain
carbon,
hydrogen, and
oxygen.

b.Help to keep us
warm and
protect internal
organs.

c.Examples:
butter, coconut
oil, corn oil,
margarine,

a.Organic compounds
needed in small
amounts by our
body.

b.Needed for health
and growth.

VITAMIN

Water Fat-soluble
soluble

B, C A, D, E, K

Vitamin Source Function Deficiency
Disease
A Carrot, liver, ◼ For night vision
fish liver oil, ◼ Healthy skin ◼ Night blindness
and green ◼ Skin infections
vegetables
◼ Beriberi
B Eggs, milk, ◼Releases energy ◼ Anaemia

meat, yeast, from ◼Scurvy (bleeding
gums)
and cereals carbohydrates

◼ Healthy nervous
system

◼ Healthy skin

◼ Formation of red
blood cells

C Fresh fruits and ◼Healing of

vegetables wounds

◼ Resistance to
Diseases

Vitamin Source Function Deficiency
disease
D Made by our ◼Strong bones
body in and teeth ◼Rickets (soft
sunlight, also bones and dental
found in milk, ◼May be needed decay)
eggs, fish liver for reproduction
oil ◼ Helps to fight ◼ Sterility
against diseases
E Vegetable oil, ◼ Clotting of blood ◼Prolonged
whole grains, bleeding
nuts,
wheatgerm

K Made in the
human
intestines, also
found in egg
yolk, green
vegetables

DISEASE: BERIBERI
CAUSES: LACK OF VITAMIN B

DISEASE: RICKET
CAUSES: LACK OF VITAMIN D, CALCIUM
OR PHOSPORUS

DISEASE: SCURVY (BLEEDING GUMS)
CAUSES: LACK OF VITAMIN C

a.Inorganic
compounds
needed by our
body,

b.Needed for
healthy growth
and development.

Mineral Source Function Deficiency
disease
Calcium Cheese, ◼Strong bones and
milk, eggs, teeth ◼ Rickets
green ◼ Blood clotting ◼ Osteoporosis
vegetables ◼ Muscle and nerve ◼ Prolonged
activities bleeding
◼ Muscular cramps

Sodium Table salt, ◼Maintains body ◼ Muscular cramps
cheese, fluid
meat ◼ Anaemia
◼Proper
Iron Meat, eggs, functioning of ◼Goitre (swelling of
Iodine green nerves the thyroid gland in
vegetables the neck)
◼Needed to form
Seafood, haemoglobin in red
iodised salt blood cells

◼Needed to make
harmones of the
thyroid gland

Mineral Source Function Deficiency disease
Phosphorus ◼ Rickets
Eggs, meat, ◼Strong ◼ Weakness
milk, cheese, bones and
vegetables teeth

◼ Muscle
contraction

◼Stores
energy

Potassium Meat, nuts, ◼Maintains ◼ Weak muscles
bananas body fluid ◼ Paralysis

◼Proper
functioning of
nerves

◼Regulation
of heartbeat

DISEASE: GOITRE
CAUSES: LACK OF IODINE

DISEASE: RICKET
CAUSES: LACK OF VITAMIN D, CALCIUM
OR PROTEIN

a.Made up of cellulose

b.Prevent constipation

c.Sources of food:
green vegetables,
oat, and fruits.

a. Solvent for many
substances in the
body

b.Regulate body
temperature

Tittle : Food test
Aim
: To test for

1. Starch (Iodine test)

2. Glucose (Benedict’s test)
3. Protien (Millon’s test)
4. Fat (Emulsion test)

A. Iodine test for starch (kanji / 淀粉）

1. Add few drops of iodine solution (brown) onto any
food sample (eg: rice, banana, meat, noodle)

- If starch is present in the food sample, it will turn

blue black .

- Video :
https://www.youtube.com/watch?v=5YMDOX71TeI

Please click if you
want to see the
result.

Tittle : Food test
: To test for

2. Glucose

B. Benedict’s test for glucose (glukosa /葡萄糖）
1. 2cm3 of Benedict’s solution （blue） is added into
food sample in a test tube.
2. Heat the mixture in a water bath.

• If glucose is present in the food sample:
The blue mixture will turn to red-orange.

Video ：
https://www.youtube.com/watch?v=tO4h6NbofGk



WHY water bath is used???

1. To make sure the samples are at a constant
temperature.

2. So that the content in test tube will not spill
(melimpah/洒出来）.

Tittle : Food test
: To test for

3. Protein

C. Millon’s test for Protein

1. 2-3 drops of Millon’s reagent（clear） is added into
food sample in a test tube.

2. Heat the mixture in a water bath.

• If protein is present in the food sample:
1) White precipitate (mendakan/沉淀物）is formed
2) Then turn to red-orange precipitate when heated.

Video ：
https://www.youtube.com/watch?v=yE9HAXXNy7M

Please click if you
want to see the
result.

Tittle : Food test
: To test for

4. Fat

D(i). Emulsion test for Fat (oils)

1. Food sample + ethanol + distilled water in test tube.
2. Cover the test tube mouth with thumb and shake.

• If fat(oil) is present in the food sample:
1) A white emulsion (emulsi/乳状液）is formed

Video ：
https://www.youtube.com/watch?v=Xq6GJvPjUPA

Please click if you
want to see the
result.

Tittle : Food test

: To test for

4. Fat

D(ii) Spot test for Fat (oils)

1. Food sample (liquid/ small solid) is put on to a piece of
filter paper.

2. Wait for 2 minutes.

• If fat(oil) is present in the food sample:
1) A translucent (lutsinar/半透明）mark will remain on the

filter paper.

Conclusion :

1. Iodine solution turns the STARCH solution blue black.

1. GLUCOSE solution forms a red-orange precipitate when
heated with Benedict’s solution

2. PROTEIN solution forms a white precipitate, turns to red-
orange when heated with millon’s reagent (clear).

4. (i) The mixture of FAT, ethanol and water forms a white
emulsion.

(ii) FAT/OIL will leave a translucent mark on filter paper.

FOOOD TEST

Test Observation Inference

Iodine test for The solution Starch is
starch
becomes blue- present
Benedict’s test
for glucose black

Millon’s test for The brick-red Glucose is
protien
precipitate is present
Emulsion test
for fat formed

The red protein is

precipitate is present

formed

The emulsion layer Fat is present

is formed

Spot test for fat The translucent Fat is present.
mark is formed.

Questions [Students discussion]

1. Why is the heating in the Benedict's is test and
Millon's test carried out in a water bath?

2. You are given a food sample in powder form. How do
you determine the food class of the food sample?

Answer [Discussion by teacher]

1. To make sure the samples are at a constant
temperature.

1. First, mix the food sample in powder form with
distilled water. Then, carry out the Iodine, Benedict,
Millon and alcohol emulsion tests.

Questions [Students discussion]

3. What are the inferences you can make from each of
the activity above?

Inference:(Observeation + reason)

1. Activity A: The sample will change colour to dark blue
because of the presence of starch.

2. Activity B: A brick red precipitate will form because of the
presence of reducing sugar.

3. Activity C: A brick red precipitate will form because of the
presence of protein.

4. Activity D: A white colour suspension will form because of
the presence of fat.

Home Work (note book) 16th March

Home Work Answer (Discussion)

3.2

1. A balanced diet contains the right amount of the
seven classes of food.

2. A balanced diet is necessary for:
a. supplying the required energy
b. balanced body growth
c. maintaining the health of the body
d. preventing deficiency diseases such as
scurvy and rickets

We can refer to the FOOD PYRAMID as a guide to prepare a healthy
meal.

FACTOR THE GROUP REASON
REQUIRING MORE
A.Gender Men are more
ENERGY active
B. Age
Men requiring
more energy of
the same age
and body size

Babies, children This group is
and teenagers more active and
require more the life process
energy are faster

FACTOR THE GROUP REASON
REQUIRING MORE
c. Body size
ENERGY
d. Physical
activity Big sized Big sized
individuals individuals
require more require more
energy size energy for their
compared to life process.
small sized
individuals.

An individual Heavy work
who does heavy require more
work uses more energy to
energy perform.
compared to
another who
does light work

FACTOR THE GROUP REASON
REQUIRING MORE

ENERGY

e. Weather Individuals living in More energy is

places with cold required to

weather require maintain the body

more energy temperature in a

compared to cold place.

individuals living in

places with warm

weather

f. State of health Sick people are weak. They need food

suitable to their health condition.

Eg: 1)Porridge is easier to digest.

2) Diabetic patient can’t take much

carbohydrates as this will increase the

sugar level.

1. The calorific value of food is the total energy
produced when one gram of food is completely
burnt.

2. The quantity of energy in a food is measured in
calorie (cal) or joule (j)

3. 1 calorie (cal) = 4.2 joule (j)

1 kilocalorie (kcal) = 4.2 kilojoules (kJ)

Food Package Nutrition fact label.

content Amount per 275 g
Carbohydrate 30.3 g
Protein 9.6 g
Fat 3.7 g

Energy value of fat, protein and carbohydrate

Classes of food Energy value

(kJ/g) (kcal/g)

*Carbohydrates 17 4
(main energy source) 17 4

Proteins

Fats 37 9

If the calorific value of rice is 16 kJ/g, what is the calorific
value in 100 g of rice??

Solution: 100 g x 16 kJ/g = 1 600 kJ

Example 1: The table below shows the calorific value
of certain type of food.

Food Calorific value (kJ/100g)

Rice 1500 kJ

Fried egg 950kJ

Apple 160kJ

A boy eats 200 g of rice, 100 g of fried egg, and 50 g of apple.
The calorific value of the boy’s breakfast is:
(1500 x 2) + (950 ) + (160 ÷ 2) = 4030 kJ.

The Importance of Maintaining Health

According to survey (kajian/调查) in year 2016:

Health Problems of Percentage:
Malaysian
Diabetes 17.5%
High blood pressure 30%
High cholesterol 47%
Obesity 17%
Overweight 40%

Causes : unbalanced diet, lack of exercise,
Genetic, Unhealthy lifestyle

How to overcome these health issues?

1. Practise a healthy lifestyle : eat on time,
have enough sleep, rest well, don’t overstress
oneself, do not smoke, drink at least 8 glasses
of water everyday.

2. Eating balanced diet , eat food with less
sugar, less salt, less oil and fat.

3. Exercise regularly.

BMI (Body Mass Index)

BMI = Body mass (kg)

Height(m) x Height(m)