bio-form-4-chapter-6-nutrition

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CHAPTER 6: NUTRITION
6.1 TYPE OF NUTRITION
Nutrition = process by which organisms obtain nutrients and energy from food.
Type of nutrition Definition Examples 
Autotrophic
Nutrition
Living organisms that are capable of producing
its own food from simple inorganic compounds
 Plants 
 Bacteria
Photosynthesis
Organisms that synthesis food from inorganic
compounds such as water and carbon dioxide
using sunlight as source of energy
 Green plants
 Algae
Chemosynthesis
Organisms that synthesize food from simple
inorganic compounds using energy released
from oxidizing minerals like nitrates, carbon
dioxide and sulphides
 Sulphur bacteria
Heterotrophic
Nutrition
Living organisms that feed on other living things
Holozoic Nutrition
Saprophytism
Parasitism
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6.2 BALANCED DIET
1. A balanced diet contains the main nutrients which include carbohydrates, fats, proteins,
vitamins, minerals, water and roughage in the correct proportions to meet the body’s daily
requirements.
2. The importance of a balanced diet:
(a) to allow the organism to function efficiently by providing daily energy requirement
(b) for metabolism and maintain a healthy life
(c) for growth and repair damage tissues
(d) to supply essential nutrients 
 Daily energy requirement
1. Energy can be obtained from carbohydrates and fats. Proteins are only used if there is a
shortage of carbohydrates and fats.
2. Energy requirement vary according to:
(a) Age - Children and teenagers require more energy because they
have a higher metabolic rate
(b) Sex - A male adult need more energy because they usually have
relatively less fatty tissues as heat insulator and a higher rate
(c) Body size and weight - People with bigger body size and weight will require more
energy for their basal metabolism
(d) Occupation and
lifestyle
- A person who does heavy work will need more energy than a
person who only moderately active, and thus requires more
energy than a sedentary worker.
(e) Pregnancy and
lactation
- Pregnant women and breast-feeding mothers require more
energy.
(f) Climate - A person who lives in a cold country needs more energy to
maintain his body temperature than a person living in the
tropics. 
Determination of energy value in food samples
Energy value of food = Defined as the energy produced when 1 gram of food is completely 
 burned. The unit for energy value of food is joule per gram (J/g) or 
 kilojoules per gram (kj/g)
 Energy value if food can be measured through the use of either simple calorimeter or
bomb calorimeter.
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Simple calorimeter Bomb calorimeter
Balanced Diet
 Diet refers to the kind of food that we eat and drink regularly.
 A balanced diet contains carbohydrates, proteins, fats, vitamins, minerals, fibers and 
water in the right proportions.
Class of food Importance 
Carbohydrate
Protein
Fat
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. 
4. Water
 Water makes up 70% of total body mass.
 Each day about 2.5/3.0 litre of water is lost in the body through sweating, excretion, 
defecation and respiration.
 Functions of water includes:
a) Solvent for various biochemical reactions
b) To transport hormones, ingested food, heat and gases.
c) Coolant that carries away heat to be eliminated.
d) Providing structure and support
e) Essential component of the blood, digestive juices and lubricant in joints.
5. Vitamins and Minerals
Name of the
vitamin
Sources Functions Deficiency diseases
Vitamin ‘A’ Green leafy 
vegetables, carrot, 
milk, milk products, 
fish, fish liver oil.
Increases resistance 
power against 
diseases, protects 
the eyes from 
infections, helps in 
seeing in dim light, 
required for making 
rhodopsin.
Retarded growth, 
health of the skin is 
affected, night 
blindness leading to 
Xerophthalmia.
Vitamin ‘D’ Fish liver oil, milk, 
butter, eggs, 
manufactured by the 
body in sunlight. It is 
caused sunshine 
vitamin.
Helps the body 
absorb calcium from 
food.
Brittle bone, 
Osteomalacia in 
adults. Rickets in 
children. Smptoms - 
poor growth, 
deformation of bones
resulting in bow legs 
and defective ribs.
Vitamin ‘E’ Milk, egg yolk, wheat
germ, green 
vegetables, 
vegetables oils,
Anti-oxidant, protects
vitamins A,C,D and K
and poly unsaturated
fatty acids.
Poorly understood in 
humans. Causes 
sterility in rats.
Vitamin ‘K’ Green vegetables 
legumes, milk 
products, meat, pig’s 
livers, egg yolk, 
produced by bacteria
in the gut.
Helps in clotting of 
blood
Spontaneous 
bleeding, blood takes
long time to clot.
Vitamin B1 Whole cereals, 
wheat germ, green 
vegetables, soya 
bean, yeast, milk, 
meat, seafood. 
Unpolished rice. 
Helps the body to 
oxidize food to 
release energy
Beri-beri affects 
nervous system, 
muscles become 
weak causing 
cramps, pain, 
numbness, may lead 
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to paralysis. 
Ratarded growth in 
children.
Vitamin B2 Peas, beans, oil 
seeds, green 
vegetables, yeast, 
milk, liver, meat, 
eggs, fish
Necessary for 
healthy skin, eyes 
and nerves 
Photophobia – eyes 
become sensitive to 
sunlight. Dry skin, 
sores on corners of 
mouth, tongue and 
lips.
Vitamin Niacin B3. 
Nicotinic acid
Cereals, yeast, meat,
liver
Necessary for 
enzyme activities
Pellagra – Skin 
legions, rashes, 
diarrhoea
Vitamin B*** Whole grains, green 
vegetables, fish, 
meat, groundnuts, 
potato, tomato
Necessary for amino 
acid and fatty acid 
metabolism
Dermatitis, 
Diarrhoea, Dementia 
(mental sickness) 
characterized by 3’D’
symptoms.
Vitamin Folic acid Green vegetables, 
sprouted seeds, 
cereals, egg and 
liver
Necessary for the 
production of RBC 
and nucleoprotein 
synthesis.
Haemoglobin content
of the blood will drop.
The number of RBC 
is reduced.
Vitamin B12 Milk, milk products, 
eggs, fish, meat and 
liver
Helps in formation of 
blood.
Acute anaemia
Vitamin C Citrus fruits like 
lemon and orange, 
gooseberry(amia), 
guava, green leafy 
vegetables, papaya, 
tomato, sprouted 
grams
Helps to bind the 
cells together and in 
the use of calcium by
bones and teeth. 
Necessary for 
production of strong 
skin and collagen 
fibre synthesis.
Scurvy – Symptoms 
– general weakness, 
bleeding gums and 
internal organs, 
anaemia and swollen
legs.
FUNCTIONS AND SOURCES OF MINERALS 
Mineral Source Functions Effects of deficiency
Calcium Milk, cheese, 
anchovies, 
cereals
 Form strong & healthy 
teeth & bones
 Assists in blood clotting
 Necessary for muscle 
contraction & 
transmission of nerve 
impulses
Rickets
Osteoporosis
Prolonged bleeding
Magnesium Cereals, green 
vegetables, 
milk, meat
 Necessary for muscle 
contraction
 Necessary for 
transmission of nerve 
impulses
 As a cofactors for 
various enzymes
Weak muscles
Convulsion
(Sawan)
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Phosphorus Milk, meat, 
cereals, eggs
 Forms strong bones 
and teeth
 Form ATP in cell 
respiration
Brittleness of bones
Tooth decay
Sodium Table salt, meat,
eggs, milk
 Maintains the balance 
of water in the body
 Maintains the osmotic 
pressure in the body
 Needed for 
transmission of nerve 
impulses
Muscular cramps
Potassium Milk, meat, 
banana, green 
vegetables
 For transmission of 
nerve impulses
 For muscle contraction
Disorder in the nervous 
system
Iodine Prawns, 
cockles, 
seafood, 
seaweed
 Produces thyroxine 
hormone
Goitre
Cretinism in children
Iron Liver, spinach, 
nuts, egg yolk
 Forms haemoglobin Anaemia
Fluorine Drinking water, 
tea, vegetables
 Harden enamel of teeth,
bones
Dental caries
6. Dietary Fibre (Roughage)
(a) stimulates peristalsis and assists the movement of food in the intestine
(b) helps to prevent constipation
(c) may protect colon cancer
(d) contains less fat and cholesterol which may decreases the risk of cardiovascular
diseases
Selection of an appropriate balanced diet:
Target group Appropriate balanced diet
Pregnant women  Adequate nutrients are needed for her own self &the foetus in
the womb
 More calcium and phosphorus are needed to form strong
bones and teeth for the baby.
 More iron-to build red blood cells to prevent anemia
 Avoid nicotine, caffeine and alcohol
Infants  Rapid growth – need more protein
 More calcium and phosphorus
 Mother’s milk contains all the nutrients and antibodies.
Children  Have slower growth rate compared to babies
 Need more protein for growth, should be more than their body
mass
 Need more carbohydrates and fats to supply energy because
they are very active.
 Need extra vitamin D
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 Minerals such as iodine is needed to produce thyroxine – for
physical and mental development
 More calcium and phosphorus.
Teenagers  Between the ages 12-19
 Grow very fast
 For girls, puberty begins at 12 years; rapid growth
 For boys, puberty begins at 14 years; rapid growth
 Need a lot of protein to build new protoplasm as well as
calcium and phosphorus.
 Very active, hence need more energy through carbohydrates.
 Female teenagers need more iron as they lose blood during
menstruation.
Athletes  Include more carbohydrates to supply energy to carry out the
vigorous activities in sports.
 More protein to build and replace damaged tissue.
 Calcium, sodium and potassium are needed to strengthen
bones and to prevent muscular cramps.
The aged  55 years and above – undergo the process of aging and slow
growth.
 Lose their appetite and are less active
 Diet should be rich in proteins, vitamins and minerals to
maintain good health and repair tissues. 
 Have weaker and more brittles bones, need more calcium
and phosphorus.
 Less active; need less carbohydrates and fats.
 Avoid food that contains high amount of fats, sugar and salt.
 Vegetables and fruits to replenish water in their body.
Vegetarians  Has to rely on alternative source of proteins since diet lacks
animal source of protein.
 Should consume more nuts and grains. 
People with 
specific diseases
 Depends on the disease
 Ex: osteoporosis: need more phosphorus, calcium and
vitamin D.
Food Test
Test For Food test Observation
Starch Iodine test
Reducing
sugar
Benedict’s test
Protein Millon’s test
Biuret’s test
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Lipid Ethanol-emulsion test
Grease spot test
Sudan III test
Vitamin C DCPIP test Percentage of Vitamin C in fruit juice
=
Concentration of Vitamin C in fruit juice
=
6.3 MALNUTRITION 
1. Malnutrition is failing health that results from not eating a balanced diet over a long
period of time.
2. Malnutrition refers to:
(a) undernutrition: resulting from inadequate consumption or excessive loss of nutrients
(b) overnutrition: resulting form overeating or excessive intake of specific nutrients
3. Effects on malnutrition
(a) Kwashiorkor
 caused by protein deficiency
 symptoms:
(i) swelling legs
(ii) underweight
(iii) ‘moon face’
(iv) swollen abdomen
(v) thin muscles but fat present
(vi) dry, sparse, thin hair
(vii) apathetic, little interest in his surrounding
(viii)stunted growth
(b) Marasmus
 caused by deficiency of energy and protein foods in children
 symptoms:
(i) underweight
(ii) ‘old man face’
(iii) thin muscles, thin fat
(iv) stunted growth
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Effects of Excessive Intake and Deficiency in Nutrients on Health
Nutrient Effects of excessive intake Effects of deficiency
Carbohydrate
Lipid 
Protein 
Vitamins
Minerals 
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	CHAPTER 6: NUTRITION