Nutrition form 2 chapter 2 science

7/29/2019 Nutrition form 2 chapter 2 science

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CLASSES OF FOODS


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1. Food can be classified into seven main classes.

a. Carbohydrate

b. Protienc. Fat

d. Vitamin

e. Mineral salts

f. Fibre

g. Water


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a. Contain carbon,

hydrogen, and

oxygen.

b.Supply most of

the energy our

body needs.

c. Examples:sugar, starch,

cellulose,

glycogen.


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a.Contain carbon,hydrogen, oxygen,

and nitrogen.

b. Needed for growthand repair of body

tissues.

c. Examples: fish,

meat, egg


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a.Contain

carbon,hydrogen, and

oxygen.

b.Help to keepus warm and

protect internal

organs.

c.Examples:

animal fats,

vegetable oils


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a. Organic compounds

needed in small

amounts by our

body.

b. Needed for health

and growth.


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Vitamin Source Function Deficiency

disease

A Carrot, liver,fish liver oil,

and green

vegetables

For night vision Healthy skin

Night blindness Skin infections

B Eggs, milk,

meat, yeast,and cereals

Releases energy

fromcarbohydrates

Healthy nervous

system

Healthy skin

Formation of redblood cells

Beriberi

Anaemia

C Fresh fruits and

vegetables

Healing of

wounds

Resistance to

diseases

Scurvy (bleeding

gums)


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Vitamin Source Function Deficiency

disease

D Made by our

body in

sunlight, also

found in milk,

eggs, fish liver

oil

Strong bones

and teeth

Rickets (soft

bones and dental

decay)

E Vegetable oil,

whole grains,

nuts,

wheatgerm

May be needed

for reproduction

Helps to fight

against diseases

Sterility

K Made in thehuman

intestines, also

found in egg

yolk, green

vegetables

Clotting of blood Prolongedbleeding


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a.Inorganic

compounds

needed by ourbody,

b.Needed for

healthy growth

and development.


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Mineral Source Function Deficiency

disease

Calcium Cheese,

milk, eggs,

green

vegetables

Strong bones and

teeth

Blood clotting

Muscle and nerve

activities

Rickets

Osteoporosis Prolonged

bleeding

Muscular cramps

Sodium Table salt,cheese,

meat

Maintains bodyfluid

Proper

functioning of

nerves

Muscular cramps

Iron Meat, eggs,green

vegetables

Needed to formhaemoglobin in red

blood cells

Anaemia

Iodine Seafood,

iodised salt

Needed to make

harmones of the

thyroid gland

Goitre (swelling of

the thyroid gland in

the neck)


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Mineral Source Function Deficiency disease

Phosphorus Eggs, meat,

milk, cheese,

vegetables

Strong

bones and

teeth Muscle

contraction

Stores

energy

Rickets

Weakness

Potassium Meat, nuts,

bananas

Maintains

body fluid

Proper

functioning of

nerves

Regulation

of heartbeat

Weak muscles

Paralysis


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a.Made up of cellulose

b.Prevent constipation


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a. Solvent for many

substances in the

body

b.Regulate body

temperature


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Date :

Day :

Tittle : Food test

Aim : To test for starch, glucose, protien and fatMaterials :

Apparatus :

A. Iodine test for starch1. 2 cm3 of starch solution is poured into a test tube.

2. 2 drops of iodine solution are added . The colour

changes is observed.

B. Benedicts test for glucose

1. 2cm3 of glucose is poured into a test tube.

2. 2cm3 of Benedicts solution is added.

3. The mixture in a water bath as shown in figure 2.2 is

heated. Any changes in mixture is observed.


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C.Millons test for protien

1. 2 cm3 of albumen solution is poured into a test tube

2. 2 drops ofMillons reagent are added to the

albumen solution.

3. The mixture is heated in a water bath. Any changes

in the mixture is observed.

D. Emulsion test for fat

1. 5 drops of ethanol are added into a test tube.

2. 2 drops of cooking oil is added into the same test tube.

the mixture is shaked in the test tube.3. The distilled water is added into the same test tube

until it half full and shake.

4. The mixture is allowed to stand for about 2 minutes.


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Observation:

Test Observation Inference

Iodine test for

starch

The solution

becomes blue-

dark

Food contain

starch

Benedicts test

for glucose The red-orangeprecipitated is

formed

Food containglucose

Millons test for

protien

The redorange

precipitated is

formed

Food contain

protien

Emulsion test

for fat

The emulsion layer

occurs on the

solution

Food contain fat


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Discussion:

1. Water cannot mix with cooking oil

Conclusion :

1. Iodine solution turns the starch solution dark-blue2. Glucose solution forms a red-orange precipitate when heated

with Benedicts solution

3. Protien solution forms a red-orange when heated with

millons reagent

4. The mixture of fat, ethanol and water becomes cloudy becausean emulsion has been formed


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1. A balanced diet contains the right amount of the

seven classes of food to meet the dailyrequirements of the body.

2. A balanced diet is necessary for:a. supplying the required energy

b. balanced body growthc. maintaining the health of the body

d. preventing deficiency diseases such as scurvyand rickets


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FACTOR THE GROUP

REQUIRING MORE

ENERGY

REASON

A. Sex Men requiringmore energy of

the same age

and body size

Men are moreactive

B. Age Babies, children

and teenagers

require more

energy

This group is

more active and

the life process

are faster


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FACTOR THE GROUP

REQUIRING MORE

ENERGY

REASON

c. Body size Big sized

individualsrequire more

energy size

compared to

small sizedindividuals.

Big sized

individualsrequire more

energy for their

life process.

d. Physical

activity

An individual

who does heavy

work uses moreenergy

compared to

another who

does light work

Heavy work

require more

energy toperform.


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FACTOR THE GROUP

REQUIRING MORE

ENERGY

REASON

e. Weather Individuals living

in places with

cold weather

require moreenergy

compared to

individuals living

in places withwarm weather

More energy is

required to

maintain the

bodytemperature in a

cold place.


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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)


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Digestion

1. Digestion is the process of breaking down

complex food to simple molecules for absorption

the blood circulatory system.

2. Digestion take place in two stages:

a. physical digestion big pieces of food are

broken down into smaller pieces by teeth

b. chemical digestion enzymes break up

complex food molecules into smaller molecules


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3. Enzymes are proteins that speed up the process

of digestion. Enzymes break up complex food molecules

to smaller and simpler molecules.

4. Characteristic of enzymes

a. enzymes are small quantities only

b. enzymes are not destroyed at the end of digestion

c. specific enzymes act only in specific acidic or alkaline

conditions

d. specific enzymes act only on specific foods

e. enzymes function best at normal body temperature (370 C)

Enzymes are destroyed at high temperature.


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1. The digestive system consists of all the organ in

the body that help in the digestion of food.

2. The alimentary canal is made up of the mouth,

oesophagus, stomach, small intestine, big

intestine and anus (starts from the mouth and

ends at the anus).


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3. Summary of the digestive system

mouth oesophagus stomach small

intestine big intestine anus

4. Food is pushed along the alimentary canal by the

muscular walls that contract and expand alternately

through theprocess of peristalsis.


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Duodenum

Oesophagus

Mouth

Stomach

Lower part of

small intestine

Appendix


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1. Food is chewed and broken up into small pieces bythe teeth.

2. Small pieces of food have a wide surface area for

the saliva to act upon.3. The salivary gland secretes saliva that is alkalineand contains salivary amylase enzymes.

4. Salivary amylase digests starch into maltose(sugar)

amylase

starch maltose


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1. Food is pushed through the oesophagus into the

stomach by the alternating r contraction and

relaxation of the oesophagus.

2. This process of alternating muscular contraction

and relaxation is known asperistalsis.


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1. Food is mixed with gastric juice in the stomach.

2. Gastric juice is secreted from the cells of the stomachwall. Gastric juice contains:

a. hydrochloric acidb. enzymes (rennin and pepsin)

3. The function of hydrochloric acid include

a. providing an acidic medium for enzymic action.

b. killing bacteria found in foodc. neutralising the alkaline property of saliva


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Protien pepsin peptones/ polypeptides

4. Pepsin digest protien to peptones / polypeptides

5. Rennin coagulates milk in the stomach to help in the enzymic

enzymes.

rennin

Liquid milk protiens solid milk protiens


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1. The duodenum is the first part of the small intestine.

2. The duodenum received bile and pancreatic juice.

3. The function of bile are:

a. emulsification of fat

b. preparation of an alkaline medium for enzymic action

4. Pancreatic juice contains three types of enzymes:

a. maltaseb. protease

c. lipase


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5. The maltase digests maltose into glucose

maltase

maltose glucose

6. The protease digests peptones into amino acids

proteasepeptones amino acids

7. The lipase digests fat into fatty acid and glycerol

lipase

fat fatty acids + glycerol


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8. Digestion is completed in small intestine.

9. The digest food is then ready to be absorbed through

the thin walls of the small intestine into the bloodstream.

10. Food digestion is completed in the small intestine.

11. The end products of digestion are

a. Carbohydrate - glucose

b. Protien - amino acids

c. Fats - fatty acids and glycerol .


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E. BIG INTESTINE

1. Water is reabsorbed in the big intestine

2. Undigested food is expelled from the body

through the anus asfaeces.


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1. The inner surface of the small intestine has many

villi.

2. The villi increase the surface area for theabsorption of digested food.

3. Absorption is the movement of digested food intothe bloodstream


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Villus

Blood capillary


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Reabsorption of Water and Defecation

Residue from thesmall intestine

Solid waste called faeces

Stored in the last part of

the large intestine

Defecation through the anus

Reabsorption of water

+ minerals + vitamins


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Difficulty in defecation is called

constipation.

Prolonged and serious

constipation can lead to ..

Hemorrhoids (piles)

Cancer of the large intestine

Defecation is removal of faeces

from the body through the anus


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Why causes constipation?

Not eating enough roughage Not drinking enough water

Cause

Constipation


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1. Therefore, constipation can be cured

by taking laxatives

eating high fibre foods such as wholemeal cereals and

grains, fruits and vegetables taking more fluid

Remember, prevention is always better than curing


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Unhealthy eating habits is the main cause of many diseases

Too much sugar diabetes

Too much salt high blood pressure

Too much fat obesity, high blood cholesterol level, cancers

Too much food obesity

Too little food anorexia nervosa, bulimia

Too little roughage constipation, haemorroids

HEALTY EATING HABITS.


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So, cultivate healthy eating habits to stay healthy

Eat a variety food according to the recommended amount

shown in a food guide pyramid.

Eat least

Eat most


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Eat in moderation. Balance food intake with exercise

Choose nutritious food

Nutritious food

Fresh fruits

Fresh vegetables

Wholemeal

cereal, grains or

bread

Unpolished rice

Less nutritious food

Junk food

Highly processed

food

Fast foods

Fizzy drinks


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Read food labels

Do not be misled by food advertisements

Eat at regular time


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Nutrition

Healthy eating habits

Balanced diet

Absorption of

water and

dissolved minerals

Food

Classes,sources and

functions

Food tests Calorific value

Digestion

Absorption of

digested food Defecation

Summary Chart

Nutrition form 2 chapter 2 science

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Transcript of Nutrition form 2 chapter 2 science