Download balanced diet

Nutrition
Biology
Learning Outcome 1
• Explain in simple terms why food is
required by animals.
You are what you eat!!
• In this lesson you will
– Look at what is a balanced diet
– Carry out food tests on
• Starch
• Glucose
• Protein
• Fat
– Discuss what happens if you don’t eat
a balanced diet
Balanced Diet
What is a balanced diet?
• Your diet must include all groups of
food substances
– Carbohydrates, fats, proteins, minerals
and vitamins
• It must also include water and fibre.
• A balanced diet is a diet that
provides enough of these
substances in the correct
proportions to keep you healthy.
Carbohydrates
• Carbohydrates give us
energy.
• Chemical elements – C, H
and O.
• Starch is made from simple
sugars called glucose
Testing for glucose
1. Pour some glucose solution into a
test tube
2. Add a few drops of benedict's
solution
3. Heat in a water bath
Testing For Starch
• Put a few drops of
starch solution on a
spotting tile.
• Add a few drops of
iodine.
Proteins
• Proteins are needed for
growth and repair.
• Proteins are made from
amino acids
• Chemical elements – C, H, O,
N
Testing for Proteins
1. Put 2 ml of protein
solution in a test tube
2. Add 2ml of Biurets
reagent
Fats
• Fats are an energy store,
protecting vital organs and
providing insulation.
• Fats contain C, H and O
• Fats are made from a glycerol
molecule and three fatty acids.
Testing for fat (the emulsion
test)
• Add a few drops of cooking oil into
a test tube
• Add 2cm3 ethanol and shake
• Add 2cm3 water and shake again.
Nutrients
Learning Outcomes
• list the chemical elements that make up:
– carbohydrates
– fats
– Proteins
• Describe the synthesis of large molecules
from smaller basic units
• list the principal sources of, and describe
the importance of carbohydrates, fats,
proteins,.
Quick Revision
• A balanced diet must contain all the
essential nutrients in the correct amounts
and proportions.
• The nutrients needed are
–
–
–
–
–
–
–
Carbohydrate
Fat
Protein
Vitamins
Minerals
Fibre
Water.
Main Nutrients
Nutrient
Elements
present
Use in body
Good food
sources
Carbohydrate
Carbon,
hydrogen,
oxygen
Source of
energy
Rice, potato,
bread
Fats and oils
Carbon,
hydrogen,
oxygen
Source of
energy
Insulation
Butter, milk,
cheese, egg
yolk
Protein
Carbon,
hydrogen,
oxygen,
nitrogen
Growth and Meat, fish, eggs,
tissue repair soya, milk
What you really need to
remember!!
• Carbohydrates, fats and proteins
are all made up of the elements
carbon, hydrogen and oxygen
• Proteins always contain nitrogen
and sometimes sulphur
• One way to remember this is
– Carb O Hydrate
Carbohydrates
• Large carbohydrates molecules
such as starch and glycogen are
made up of long chains of smaller
units, e.g. monosaccharides
(glucose), which are held together
by chemical bonds
Fats
• Fats are made up of three fatty
acids and a glycerol
Proteins
• Proteins are made up of long chains
of amino acids
Food Tests
• What is the test for starch?
• What is the test for glucose?
• What is the test for protein?
• What is the test for fats?
• What does a positive result look like?
Learning Outcomes
• list the principal sources of, and describe
the importance of:
–
–
–
–
vitamins (C and D only)
mineral salts (calcium and iron only)
fibre (roughage)
water
• describe the deficiency symptoms for:
– vitamins (C and D only)
– mineral salts (calcium and iron only)
Vitamin C
• Function
– Maintain healthy skin and gums
• Good Food Source
– Citrus fruits, black currants, cabbage,
tomato, guava, mango
• Effect of deficiency
– Scurvy
• Bleeding under skin
• Bleeding gums
Vitamin D
• Function
– Needed to maintain hard bones
– Helps absorb calcium from small intestine
• Good Food Source
– Milk, cheese, egg yolk, fish liver oil
– Made in skin when exposed to sunlight
• Effect of deficiency
– rickets
Calcium
• Function
– Healthy teeth and bones
– Normal blood clotting
• Good Food Source
– Milk, cheese, fish
• Effect of deficiency
– Rickets
– Slow blood clotting
Iron
• Function
– Formation of haemoglobin in red blood cells
• Good Food Source
– Red meat, liver, kidney, eggs, green
vegetables (spinach), chocolate
• Effect of deficiency
– Anaemia
• Constant tiredness
• Lack of energy
Fibre
• Function
– This is cellulose which we can not digest
– It adds bulk to the undigested food in the
intestines, maintaining peristalsis
• Good Food Source
– Vegetables, fruit, wholemeal bread
• Effect of deficiency
– Constipation
– Long term deficiency may lead to bowel
cancer
Water
• Function
– Formation of blood, cytoplasm
– Solvent for transport of nutrients and
removal of waste
– Enzymes only work in solution
• Good Food Source
– Drinks, fruits, vegetables
• Effect of deficiency
– dehydration
Pupil activity
• Design a mind map to summarise
the information you have been
taught so far on Nutrients.
Main
Nutrients
fibre
vitamins
Nutrients
water
minerals
Learning Outcomes
• understand the concept of a
balanced diet
• describe:
– a balanced diet related to age, sex
and activity of an individual
– the effects of malnutrition in relation to
starvation, coronary heart disease,
constipation and obesity
What happens if you don’t
eat a balanced diet.
What is this cartoon
trying to demonstrate?
Can you think of any
examples of health
problems that arise
from not eating a
balanced diet?
Give three examples and
explain the effects on
health.
Dietary requirements
• Adequate diet
– Provides sufficient energy for the
performance of metabolic work
• Balance diet
– Provides all the dietary requirements in
the correct proportions
• 1/7 fat
• 1/7 protein
• 5/7 carbohydrate
Dietary requirements
• Energy is provided by fat and carbohydrate
intake
• Dietary requirements depend on
– Age
• Energy demand increases until we stop growing
– Sex
• Males use up more energy than females
– Activity
• Physical work will use up more energy than office work.
An Unbalanced diet
Malnutrition
• An unbalanced diet could lead to
– Obesity
• Risks include coronary heart disease and diabetes
– Too much animal fat can lead to high
cholesterol
• Risks include coronary heart disease and angina
– Lack of protein in diet can lead to kwashiorkor
– Lack of fibre can lead to constipation and
bowel cancer
– Vitamin and mineral deficiencies
teeth
• There are different types of teeth, each
specially shaped to perform a particular
job.
– Incisor
• A broad flat sharp tooth found at the front of the
mouth. Designed for biting and cutting food.
– Canine
• A sharp pointed tooth for piercing flesh and tearing.
– Pre-molar & molar
• A broad flat tooth with many cusps. Its rough
surface is used for crushing, grinding and chewing
food
Structure of a tooth
• Colour in your
diagram of the
tooth,
• Colour in the
positions of the
different types of
teeth in the
human jaw
Structure of a tooth
enamel
crown
root
dentine
gum
Pulp cavity
cement
Causes of dental decay
• Bacteria and food deposits form plaque
• Bacteria feed on sugars and produce
acid
• Acid dissolves the enamel forming a hole
• Dentine dissolves more rapidly
• If hole reaches pulp cavity can lead to
bacterial infection, toothache and
abscess
Proper care of teeth
• Avoid sugary foods
• Use dental floss or a tooth pick
• Use a fluoride toothpaste
• Visit dentist regularly
Fluoride
• Growing children absorb fluoride
from their diet
• It becomes part of enamel of
developing teeth
• Enamel becomes more resistant to
tooth decay