BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 1

BIOLOGY FORM 4
CHAPTER 6
NUTRITION PART 1
(6.1 - 6.3)

NUTRITION
• Nutrition = entire process by which
organisms obtain energy & nutrients from
food
• Function: For growth, maintenance & repair
of damaged tissues.
• Nutrients = substances required for the
nourishment of an organism

Types Of Nutrition
AUTOTROPHS HETEROTROPHS
(autos : self ; trophos : feed)
Use simple inorganic substances
and either light energy
(photosynthesis) or chemical
energy (chemosynthesis) to
synthesise food.
Obtains energy through
intake & digestion of
organic substances
(animal / plant tisssue)

AUTOTROPHIC
Photosynthesis Chemosynthesis
• Photoautotrophs
• Uses energy from sunlight
to produce organic
molecules from CO2 and
H2O.
• Eg. All green
plants
• Chemoautotrophs
• Uses energy from oxidation of
inorganic substances to synthesise
organic compounds
• Eg. Sulphur bacteria oxidizes
sulphur to sulphate &
Nitrosomonas sp. oxidizes
ammonium to nitrate

HETEROTROPHIC
Holozoic Nutrition Saprophytism
The organism feed by
ingesting solid
organic matter which
is then digested and
absorbed into their
bodies.
Eg. human, animals
and insectivorous
plants
Saprophytes.
Feed on dead and
decaying matter.
Include bacteria
and fungi which
digest the food
externally before
the nutrients are
absorbed.
Parasitism
Obtains nutrients
from living
organisms
The parasite
obtains nutrients
by living on or in
the body of the
host.
Eg. fleas, lice and
tapeworms

Holozoic Nutrition
Herbivores Carnivores
• Animal that feeds on
plants
• Organism that eats other
animals.

Saprophytism
 Organism that feeds on the excrement or the dead bodies
or tissues of others (dead & decaying matter)
 Saprophytes cannot make food for themselves
 include :
 most fungi (the rest being parasites);
 many bacteria and protozoa;
 animals such as dung beetles
 a few unusual plants, including several orchids.

Parasitism
 Organism that feeds on the living bodies or
tissues of others
 Fungi
 Bacteria
 Virus
 Protozoa

Food is needed for:
1. Energy and warmth
2. Growth
3. Repairing and replacing tissues
4. Keeping the body healthy and fight disease

• All food is made up of 7 different nutrients.

ENERGY VALUE OF FOOD
Only 3 food classes release energy:
1. Carbohydrate – 17 KJ/g
2. Lipid/Fat – 38 KJ/g
3. Protein – 22 kJ/g
• Energy released from food is calculated in
KiloJoule(KJ) or Calorie (Cal)

How do you find how
much energy is present
in a peanut?
 Burn a peanut
 Record rise in
temperature of a
known volume of
water.

Why is it better to have a larger
volume of water?
To absorb more heat.

Q = mc
4.2 kJ kg-1 C-1
Heat energy =
mass x specific heat capacity x temperature rise
Energy in peanut =
mass of water x 4.2 x temperature rise in C
Mass of food sample

Question:
A group of biology students would like to
compare the energy stored in two types of
nuts: a peanut and an almond.
Describe an experiment to show how this is
carried out. In your report include:
i) The apparatus required; (You can present
this in the form of a diagram.) (2)

ii) The method; (3)
Known quantity of the nut (kept constant for
both nuts) ignited and held under test tube
with known amount of water (kept constant
for both nuts). The temperature of water
before lighting the nut and after burning will
be recorded.
iii) The measurements that need to be taken;
 Initial temperature and final temperature
 Mass of peanut/almond
 Volume of water (2)

iv) The factors that need to be kept constant
throughout the experiment; (2)
Same mass of nut and same quantity of
water.
v) ONE possible source of error. (1)
 Heat loss to surroundings
 Heat reaching water not evenly spread
out
 Burning of nut is not complete

Burning food in a
bomb calorimeter.
How is the energy content of food
found out?

Bomb Calorimeter
The apparatus which is used to find the energy
content of food.
Better than previous
setup:
1. No heat loss to air.
2. Even heat spread.

Group Particulars Kilo Calories
Man Sedentary work 2350
Moderate work 2700
Heavy work 3200
Woman Sedentary work 1800
Moderate work 2100
Heavy work 2450
Pregnancy + 300
Lactation 0 - 6 months + 550
6 - 12 months + 400
FACTORS THAT AFFECTING THE DAILY ENERGY
REQUIREMENT

Group Particulars Kilo Calories
Infants 0 - 6 months 118 / Kg
6 - 12 months 108 / kg
Children 1 - 3 years 1125
4 - 6 years 1600
7 - 9 years 1925
Boys 10 - 12 years 2150
13 - 15 years 2400
16 - 18 years 2600
Girls 10 - 12 years 1950
13 - 15 years 2050
16 - 18 years 2050

The amount of energy needed by a
person depends upon:-
1) age
2) sex
3) body size
4) temperature (climate)
5) job

FACTORS THAT EFFECTING THE DAILY
ENERGY
BODY SIZE/weight
An individual of bigger size
require more energy than
another of smaller size.
SEX
ADULT MALES REQUIRE
MORE ENERGY THAN
ADULT FEMALE.MEN
GENERALLY ARE
PHYSICALLY MORE ACTIVE
AND HAVE LESS BODY FAT.

A balanced diet is composed of the
right amounts of:-
1. Water
2. Carbohydrates
3. Lipids
4. Proteins
5. Mineral salts
6. Vitamins
7. Dietary fibre or
roughage

1. Water
2. Carbohydrates
3. Lipids
4. Proteins
5. Mineral salts
6. Vitamins
7. Dietary fibre or roughage
The food guide pyramid

SELECTION OF AN APPROPRIATE BALANCED
DIET
ATHELETES
CARBOHYDRATES:
provide extra energy
PROTEINS
:build up
muscles
REDUCE
INTAKE OF
FATS
VEGETARIANS
EAT A VARIETY
OF VEGETABLES,
FRUITS, CEREALS
AND BEANS
TAKE A
VITAMIN B12
SUPPLIMENT AS
IT ONLY FOUND
IN ANIMAL
SOURCES
PREGNANT
WOMEN
PROTEINS: the
building of the foetal
tissue
CALCIUM &
PHOSPHORUS:
build the bones
IRON: for the foetus
to make red blood
cells
CUT DOWN ON SUGAR
AND FATS

INFANTS
PROTEINS: build
soft tissue
CALCIUM &
PHOSPHORUS:
build bones and
teeth
CARBOHYDRATES:
provide energy for
growth
BREAST MILK IS THE
BEST FOOD
CHILDREN
NEED
ENERGY-RICH
FOOD
PROTEINS, IRON,
CALCIUM &
PHOSPHORUS : for
their rapid growth
TEENAGERS
GIRLS: IRON:
making red
blood cells to
replace those
lost during
their
menstrual
periods
CUT DOWN AN
OIL-RICH
A DIET OF
CEREALS, LEAN
MEAT, FISH,
VEGETABLES
AND FRUITS

Components of a balanced diet :-
1. Water
2. Carbohydrates
3. Lipids
4. Proteins
5. Mineral salts
6. Vitamins
7. Dietary fibre or roughage

WATER
Water is very essential to the survival of human as all
metabolic reactions take place in solution.
Water makes up about 70% off the total body weight.
Controlling
the body
temperature
Removing
excretory
products
Controlling the
concentration of
blood
Transporting
foods during
digestion
As a
lubricant
As a medium
for biochemical
reactions in the
body
FUNCTIONS
OF WATER
Failure to replace the lost water results in dehydration.
A serious loss of water can be fatal.

Animals get water from:-
1. Drinking
2. Eating
3. Chemical reactions e.g.
respiration
O2
food
ATP
H2O

Uses of carbohydrates:-
a) provide energy (17kJ/g)
Sugar in energy drink
equivalent to six pastries.

Question:
Give biological explanations for each
of the following statements:
The diet of athletes is usually high in
carbohydrates. (5)
Athletes need a lot of energy. Carbohydrates are
the body’s main energy source. Carbohydrates
like starch in bread are digested into glucose.
Glucose is used in respiration to release energy. If
athletes take in monosaccharides, i.e. sugars e.g.
glucose, they are provided with energy very
quickly.

Cell wall
c) to build cell walls in
plants
b) to store energy
e.g. starch in
potatoes or roots
Storage
organs

d) fibre is important to prevent constipation
Food sources of fibre:
whole wheat, bran, fresh or
dried fruit & vegetables.
Constipated!!

In what form are excess carbohydrates stored?
1) in plants:
2) in animals:
Name two places
in animals where
glycogen is stored.
starch
glycogen
Liver & muscles

Food rich in lipids:-
Nuts
Egg yolk

 uses of lipid
a) provide energy (39 kJ/g)
b) store energy

 uses of lipid
c) insulation in mammals
d) protection of delicate
organs from bumps
Fat around kidney.
Fat lines body wall of a rabbit.

Question:
Explain why one kilogram of starch crops
releases less energy when burnt, compared to
one kilogram of oil crops. (2)
Starch is a carbohydrate whilst oil is a lipid.
Carbohydrates have a lower energy content
than lipids.

 building blocks of a lipid molecule:
 Glycerol
 Fatty acids
A molecule of fat

 excess lipids are stored:-
1) in the ADIPOSE TISSUE under the skin
2) around organs
Fat around
heart.

What does this
pyramid show about
intake of lipids?
Few lipids must be
taken.

PROTEINS
 food rich in proteins:-
 Meat
 Fish
 Egg white
 Cheese

 Uses of proteins:-
1. for growth
2. for cell repair and replacement
3. to make enzymes
4. to make antibodies

Uses of proteins:-
a) provide energy (22 kJ/g)
during starvation when
carbohydrate & fat used up.

What are the building blocks
of proteins called?

MINERAL SALTS
 contain certain elements that help cells to
function properly

Mineral Sources Function
calcium Milk, cheese, green
vegetables, legumes.
Formation of
strong teeth &
bones.
Helps in blood
clotting
phosphorus Milk, cheese, meat,
grains.
Combines with
calcium to form
strong bones &
teeth.
Sodium
(common salt)
Salt To maintain
osmotic pressure
potassium Fruit Transmission of
nerve impulses.
Ferum( iron) Liver, kidney, raw egg Formation of
haemoglobin in red
blood cells.
Iodine Sea food Formation of the
hormone thyroxine.

CALCIUM
 is needed for:-
a) hard bones and teeth
b) muscles to contract
c) to clot blood
 is found in:
 milk
 cheese
 fish

Rickets:
deformed
bones
 deficiency of
calcium

IRON
 is needed to build the red pigment in blood
called haemoglobin

IRON
 is found in:
 red meat like liver &
kidneys
 green vegetables: spinach,
broccoli

Normal amount of
red blood cells
Anaemic amount of
red blood cells
A lack of iron results in:
ANAEMIA

Question:
Give biological explanations for each of the
following statements:
a) A dietician suggested to an anaemic person to
include liver in the diet. (5)
Person lacks iron. Red meat like liver is rich in
iron. Iron is needed to form haemoglobin in red
blood cells.

b) Nutritionists often
recommend a low
intake of fried foods. (5)
 Fats provide a lot of
energy. May lead to
obesity.
 Fried foods are rich in cholesterol that may
block arteries = higher risk for a heart attack.

VITAMINS
 needed in small quantities for the normal
chemical activities of the body
 cannot be used as:
 a source of energy
OR
 to build cell structures

A disease develops if a vitamin is missing. How
can the person be cured?
By taking the missing vitamin.

 vitamins can be :-
a) Water soluble – vitamins B and C
b) Fat soluble – vitamins A, D, E, K

Water-soluble vitamins are
lost from the vegetables
when they are boiled but
not when steamed.
Why is it better to
steam vegetables
rather than boil them?

VITAMIN SOURCES FUNCTIONS
A EGG, MILK,CARROT,
PAPAYA
• For growth and promote healthy
skin
• For good night vision
B EGG, YEAST, LIVER,
NUTS, TOMATO
• Promotes the effective functioning
of the nervous system
• Controls the supply of carbohydrates
to the muscle and nerve cells
C GREEN VEGETABLES,
TOMATO, LIME
• Increases immunity against diseases
• Promotes healthy skin
D EGG, MILK, COD LIVER
OIL
• Helps in the absorption of calcium
and phosphorus in the small
intestines
E VEGETABLE OIL, EGG,
LIVER, MILK,PALM OIL
• Maintains a healthy reproductive
system
K SUNFLOWER SEEDS,
MAIZE
• Necessary for the clotting of blood

Vitamin Food source Deficiency
disease
A Milk, liver Night blindness
C Citrus fruit,
potatoes
Scurvy
C Citrus fruit,
potatoes
Scurvy
D Milk, liver Rickets
E Milk, liver Sterility
K Maize Hinders blood
clotting

Carrots are a rich source of
vitamin A
Vitamin A prevents night
blindness.
Function:
 Normal growth
 Healthy eyes and
skin

QUESTION:
Explain why the student used this picture when
mentioning night blindness. (2)
Night blindness is caused by a lack of Vitamin A
in the diet. 1 mark
Carrots are a good source of Vitamin A that can
help to prevent night blindness. 1 mark

aaaaaaa
Deficiency
disease:
• Beri-beri

Vitamin B comes from Peas, meat,
cereals,seafood

Characteristics/
Function:
 Healthy growth
 Healthy skin
Deficiency disease:
• Inflammation of lips
• Mouth sores
Vitamin B2 comes from
yeast, egg and meat.

Vitamin D is made by the
action of sunlight on the
skin.
Deficiency of
Vitamin D:
Normal Rickets

NOTE:
 Lack of calcium
 Lack of vitamin D
Reason:
Vitamin D helps the body to
absorb calcium from the
foods we eat.
The more calcium the body
can absorb, the stronger the
bones will become

Question:
What special provisions should be made in the
diet of young children and pregnant mothers?
Explain why each provision you mention is
important. (6, 4)
Young children:
1. High protein content food – e.g. meat for
growth
2. Drink a lot of milk – supplies proteins,
calcium, Vitamin A & D.
3. Include carbohydrate-rich foods – for energy

Pregnant women:
1. Folic acid (a vitamin B) – in
citrus fruit, legumes: to form
the nervous system of the
embryo
2. Food rich in iron – e.g. liver, green
vegetables: to have enough blood in
placenta to nourish embryo
3. Calcium-rich food – e.g. dairy products to
supply embryo with calcium to form its
skeleton

Question:
Give a biological explanation for each of the
following statements.
a) Daily inclusion of too much Vitamin C in the
diet is a waste. (2)
Vitamin C cannot be stored in the body as it
is water-soluble. Lost in urine.

Give a biological explanation for each of the
following statements.
a) Small doses of Vitamin D (5-10mg per day)
are recommended for housebound people
spending a lot of time indoors. (2)
Vitamin D cannot be made by the action of
sunlight on the skin. To have enough
Vitamin D, supplements are
needed.

Question:
Give biological explanations for each
of the following statements:
a) School canteens are encouraged
to sell unsweetened cereals rather
than sweets. (5)
Sweets are carbohydrates that
provide energy.
Too much sweets may lead to obesity.
Obesity leads to higher risk of diseases.
Sweets increase chance for tooth decay.

b) Young children are
encouraged to eat dairy
products regularly. (5)
Milk is rich in:
 calcium – needed to form
strong bones and teeth.
 proteins – needed for
growth.
 Vitamins – for healthy growth; e.g. vitamin A to
prevent night blindness and vitamin D to help in
the absorption of calcium and to prevent rickets.

DIETARY FIBRE or ROUGHAGE
 sources of fibre:-
 vegetables
 fresh fruit
 bran cereals
 wholemeal bread

Cellulose: is the main source of dietary fibre
Explain why although humans cannot digest
dietary fibre, it is still important.

Functions of roughage:-
1. adds bulk to the contents of the intestine
and keeps food moving along the gut
Gut

Functions of roughage:-
2. prevents constipation as fibre retains water
so that the faeces are soft
3. prevents cancer of the colon (part of the
intestine)
faeces

Food Test
Colour
change
Starch + iodine solution Yellow to blue
black
Iodine
solution
Starch

Look at this picture.
Is starch present in potato? Yes.

Food Test
Colour
change
Protein
(Biuret test)
+ sodium hydroxide solution +
1-2 drops of copper sulfate
solution
Blue to purple
Egg white
[protein]
1. Sodium
hydroxide
solution2. Copper
sulfate
solution

A positive test for
protein was obtained
for………………albumin

Food Test
Colour
change
Oil
+ ethanol + shake + water +
shake
A white emulsion
forms

Food Test
Colour
change
Oil rub food onto a dry piece of
filter paper
A greasy spot
forms

Food Test
Colour
change
Glucose + Benedict’s solution or
Fehling’s solution + heat
Blue to brick red
or orange

Food Test
Colour
change
Starch + iodine solution Yellow to blue
black
Protein
(Biuret test)
+ sodium hydroxide solution +
1-2 drops of copper sulfate
solution
Blue to purple
Oil
1) + ethanol + shake + water +
shake
1) rub food onto a dry piece of
filter paper
A white emulsion
forms
A greasy spot
forms
Glucose + Benedict’s solution or
Fehling’s solution + heat
Blue to brick red
or orange

When the food to be tested is a solid:
1. Crush the food with some water using a
pestle and a mortar.
2. Filter.
3. Add the reagents to the filtrate.
pestle
mortar

MALNUTRITION
 Results from taking an unbalanced diet in
which certain nutrients are lacking , in
excess, or in the wrong proportions.
 Malnutrition leads to health problems and
diseases.

THE EFFECT OF MALNUTRITION
.
DEFICIENCY
IN
PROTEINS
Marasmus :
Lacks energy .
The child become
very thin and looks
old for his age
•Kwashiorkor : Stunted growth , muscles
that waste away, diarrhoea ,oedema
which causes the belly to swell, loss of
appetite and apathy.

• Rickets : CALCIUM & PHOSPHORUS. The child’s
bones are soft and can bend out of shape.
• Osteoporosis : CALCIUM,VITAMIN D &
PHOSPHORUS. The elderly ’s bones become
porous and break easily.
DEFICIENCY
IN
MINERALS
MALNUTRITIONTHE EFFECT OF MALNUTRITION

• Goiter : IODINE. Thyroid gland enlarges.
• Cretinisme : Lack of IODINE during
childhood. Mental & physical growth
retarded.
DEFICIENCY
IN
MINERALS
MALNUTRITIONTHE EFFECT OF MALNUTRITION

• Night blindness : VITAMIN A
• XerophthalmiaDEFICIENCY IN
VITAMINS

• Beri-beri : Vitamin B1
DEFICIENCY IN
VITAMINS

• Pellagra : Vitamin B2
DEFICIENCY IN
VITAMINS

• Scurvy : VITAMIN C
Symptoms: bleeding and
swollen gums.
DEFICIENCY IN
VITAMINS

• Rickets : VITAMIN D.DEFICIENCY IN
VITAMINS

•Sterility : VITAMIN E.
DEFICIENCY IN
VITAMINS

• Blood does not clot : Vitamin K
DEFICIENCY IN
VITAMINS

• Obesity
• Diabetes mellitus : A
higher risk of stroke, heart
diseases and kidney
failure.
EXCESSIVE
INTAKE OF
CARBOHYDRATES

• Gout : Raise the level
of uric acid in the
blood.
EXCESSIVE
INTAKE OF
PROTEINS

• Obesity : An obese person
is at higher risk of
developing high blood
pressure and heart
problems.
• Atherosclerosis : A person
leads to high blood
pressure, puts a strain on
the heart and increase the
risk of stroke
• Cardiovascular
disease
• Hypertension.
EXCESSIVE
INTAKE OF
LIPIDS

• High blood pressure :
COMMON SALT
• Damage the liver and
kidneys : IRON
• Bone formation in soft
tissues & promotes
formation of kidney
stones : CALCIUM
EXCESSIVE
INTAKE OF
MINERALS

• The liver and kidney will be
damaged : VITAMIN A,D,E & K
• an upset stomach : VITAMIN C
• Calcification of soft tissues:
VITAMIN D
• Hair loss, vomiting, bone
ache, joint pain, liver & bone
damage : VITAMIN A
• Numb feet, poor coordination:
VITAMIN B6
EXCESSIVE
INTAKE OF
VITAMINS

WAYS TO REDUCE THE CHANCE OF CONTRACTING
CERTAIN HEALTH PROBLEMS DUE TO ONE’S DIET
i. Cutting down on the intake of saturated fats,red
meat and organs.
ii. Cutting down on the intake of salt.
iii. Taking enough dietary fibre, which can help
lower blood cholesterol level.
iv. Having enough sleep daily.
v. Managing stress well.
vi. Exercising regularly.
vii. Abstaining from smoking and alcohol, which
cause high blood pressure.

BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 1

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BIOLOGY FORM 4 CHAPTER 6 - NUTRITION PART 1