6 Nutrition

6.1 TYPES OF NUTRITION

Nutrition

The entire process by which organisms obtain energy and

nutrient from food, for growth, maintenance and repair of damaged tissues

NutrientsThe energy are used:

The substances that are required for the nourishment of an organism.

For synthesis substances for growth, maintenance and repair of damaged tissues

For active transport For electrical

transmission of nerve impulses

To maintain a constant body temperature in birds and mammals

6.1 Types of nutrition

6.1 Types of nutrition

The two types of nutrition are:

a)Autotrophic nutrition b)Heterotrophic

nutrition

Autotrophic nutrition

Autotrophs (autos: self; trophos: feed) are organism which practise autotrophic nutrition.

Autotrophs synthesis complex organic compound from raw, simple inorganic substances, such as air and water, by using light or chemical energy.

Autotrophs manufacture their own food, either by photosynthesis or by chemosynthesis

Photosynthesis

Chemosynthesis

(photo:light) is the process in which photoautotrophs (green plants) produce organic molecules (glucose) from carbon dioxide and water (inorganic compounds) using sunlight as a source of energy.

(chemo: chemical) is the process in which chemoautotrophs synthesis organic compounds by oxidising inorganic substances such as hydrogen sulphide and ammonia.

Exp: sulphur bacteria

Autotrophic nutrition

Heterotrophic Nutrition

Heterotrophs (hetero: other) are organisms that cannot synthesise their own nutrients but instead must obtain the nutrients from other organisms.

Heterotrophic nutrition is a type of nutrition in which an organism obtains energy through the intake and digestion of organic substances usually plant and animal tissues.

Heterotrophs may practise holozoic nutrition, saprophytism or parasitism.

Holozoic Nutrition

The organisms feed by ingesting solid organic matter which is subsequently digested and absorbed into their bodies.

Holozoic Nutrition-Venus

flytraps

Humans,

herbivores,

omnivores,

carnivores,

carnivorous plants (pitcher plants and Venus flytraps)

Holozoic nutrition – pitcher plants

Humans,

herbivores,

omnivores,

carnivores,

carnivorous plants (pitcher plants and Venus flytraps)

Click icon to add picture

Saprophytism

The organisms (saprophytes) feed on dead and decaying matter.

 

Saprophytism

Exp: bacteria and fungi which digest their food externally before absorbing the nutrients into their bodies.

Parasitism- flea

Parasitism is a close association in which an organism (parasite) obtains nutrients by living on or in the body of another living organism (host). The parasite absorbs readily digested food from its host.

Parasitism- lice

fleas

lice

various bacteria

fungi

tapeworms

THE NECESSITY FOR A BALANCED DIET AND

DAILY ENERGY REQUIREMENT

6.2 Balanced Diet

The necessity for a balanced diet and daily energy requirement

The energy consumed by the body in a day while carrying out all the basic processes such as breathing, excretion and maintaining body temperature is known as the basal metabolic rate (BMR)

Balanced Diet

A balanced diet contains all the seven classes of nutrient which includes carbohydrates, proteins, lipids, vitamins, minerals, water and roughage in the correct proportion and quantity, to meet the daily requirements of the body.

A balanced diet is essential for a healthy growth and development of the body.

Balanced Diet

An adequate daily supply is required for every person. Carbohydrates and lipids provide energy

proteins promote growthMinerals, vitamins, water and roughage help to maintain health.

Balanced DietA balanced diet is able to fulfill the daily energy requirement of the human body.

Energy is needed to perform physical activities and to sustain vital functions such as heartbeat, breathing and for maintaining body temperature

Factors affecting daily energy requirement f the human body:

Age SexPregnancy and lactationOccupationSize or body weightClimate

Age

Growing children and teenagers need more energy compared to adults.

The metabolic rate in growing children and teenagers is higher than adults because they need more energy for growth.

Sex

A male adult needs more energy than a female adult of the same size and age.

The metabolic rate in males is much higher than that of females.

Pregnancy and lactation

Pregnant women require more energy to support growing foetuses.

Breast-feeding mothers need more energy to produce milk for their babies.

Occupation

A person who is very active and does heavy work need more energy each day than a person who is moderately active.

A moderately active person in turn requires more energy than a person who practises a sedentary lifestyle.

Size and body weight

Small sized people need more energy than big sized people.

The rate of heat loss in small sized people is higher than big size people because they have a large surface area per unit volume.

Climate

People living in cold countries require more energy to maintain body temperature compared to those living in tropics.

Energy content of food

Energy is obtained from oxidation of glucose during cell respiration. The unit for energy is Joule (J).

The energy value is the quantity of heat produced when one gram of food is completely oxidised. It measures the energy content of the food.

Energy content of food

The energy content of a particular food can be measured by burning known mass of the food completely in the presence of oxygen in a bomb calorimeter.

Energy content of food

Energy value of food (kJg-1) =

4.2 (Jg-1°C-1)x mass of water (g) x increase in temperature (°C)

mass of food sample (g) x 1000

Calculate the energy value of the peanut by referring to the data below.Mass of peanut o.5 g

Mass of water 20 gInitial temperature of water

25 ◦C

Final temperature of water

42◦C

What is the heat produced by 1 g cashew nut?

Mass of cashew nut o.5 g

Volume of water 20 cm³

Initial temperature of water

26 ◦C

Final temperature of water

68◦C

Nutrient content in food

Test for Reagent

Starch

Reducing sugarNon-reducing sugar

Dilute hydrochloric acid & Benedict’s solution

Nutrient content in food

Test for ReagentProtein Biuret’s test

(20% NaOH & 1% CuSO4)

Lipid -Vitamin C DCPIP

solution

Vitamins

a group of complex organic compounds

needed in small quantities

essential for the maintenance of good health and efficient metabolism.

Fat-soluble vitamins

Water-soluble vitamins

Fat-soluble vitamins are vitamins A, D, E and K and can be stored in body fat

Water-soluble vitamins include vitamins B and C.

They cannot be stored in the body, and have to be constantly supplied in the daily diet.

Vitamins

Sources, functions and effects of

vitamin deficiency:

ADairy products, egg yolk, buttter, fish liver oil, green vegetables

Functions

Formation of light-sensitive pigment in the retina.

Acts as an antioxidant.Maintenance of epithelial tissues.

Delay the ageing process

Symptoms of deficiency

night blindnessxeropthalmia (cornea becomes dry and opaque)

scaly skin

Ddairy products, egg yolk, cod liver oil, milk, (also synthesised in the human skin in the presence of sunlight)

Functions

Aids in the absorption of calcium and phosphorus ions in the small intestine for the formation of bones and teeth.

Symptoms of deficiency

Ricket – (poor teeth and bone formation in children)

Osteomalacia– softening of bones in adults

Ricket

EWheatgerm, nuts, green vegetables, grains, olive oil, milk

Functions

Produce red blood cells.Acts as an antioxidantprevents damage to phospholipids in plasma membranes

Symptoms of deficiency

Anaemiamuscular dystrophyliver damageinfertility

Kegg yolk, cabbage, spinach

Functions

important in blood clotting

Symptoms of deficiency

AnaemiaDefective blood clotting which leads to excessive bleeding

B1yeast extract, wheatgerm, whole grain, nuts, milk, liver, legumes

Wheatgerm

Yeast extract

Functions

precursor for coenzyme which functions in carbohydrates metabolism.

Symptoms of deficiency

Beri-beri (muscle weakness, nerve disorder, heart disorder, swollen feet and loss of skin sensitivity)

Beri-beri

B2yeast extract, wheatgerm, milk, liver, eggs, dairy products

Functions

component of coenzymes in energy metabolism.

for healthy nervous system.

Symptoms of deficiency

sore eyes and swollen tonguesskin lesions at the corner of mouth, nose and ears.

B3yeast extract, legumes, liver, lean meat, unpolished rice, fish

Functions

component of coenzymes in energy metabolism.

for healthy nervous system, skin and intestine

Symptoms of deficiency

pellagra (skin and gastrointestinal lesions, nervous, mental disorders and loss of appetite)

B5egg yolk, green vegetables, liver, fish , meat

Functions

component of coenzyme A, with a role in energy metabolism

Symptoms of deficiency

muscle cramps, fatigue, impaired motor coordination

B6liver, fish, meat, potatoes, whole grains, nuts, yeast extract, milk

Functions

coenzymes in amino acid metabolism

Symptoms of deficiency

muscular twitchingretarded growthkidney stones

B12milk, meat, eggs, cheese

Functions

a coenzymes in nucleic acid metabolism

formation of red blood cells.

Symptoms of deficiency

pernicious anaemianeurological disorderweight loss

Folic acidB9

green vegetables, oranges, nuts, legumes, whole grains

Functions

Acts as an coenzyme in nucleic acid and amino acid metabolism

Symptoms of deficiency

Anaemiagastrointestinal disturbancediarrhoeabirth defects

BiotinB7

legumes, vegetables, meat

Functions

A coenzyme in the synthesis of fat, glycogen and amino acids

Symptoms of deficiency

fatiguedepressionnauseamuscular pains

Ccitrus fruits, tomatoes, green peppers

Functions

required in the synthesis of collagen

maintenance of cartilage, bone, dentin and healthy blood vessels

a strong antioxidantAids in detoxificationimprove iron absorption

Symptoms of deficiency

poor collagen formationscaly skinscurvy (swollen, bleeding gums and

tooth loss)degeneration of blood vessels, muscles

and cartilageepithelial haemorrhagesdelayed wound healingimpaired immunity