biology form 4 (6.1 n 6.2)
DESCRIPTION
chapter 6TRANSCRIPT
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)
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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