B4. NUTRITION
4.1 Nutrients
1. List the chemical elements that make up carbohydrates, fats and protein.
NUTRIENT
Carbohydrate
Fat
Protein
ELEMENTS PRESENT
Carbon, hydrogen, oxygen
Carbon, hydrogen, oxygen
Carbon, hydrogen, oxygen, nitrogen and sometimes sulphur
2. Define nutrition - taking in of nutrients which are organic substances & mineral ions (containing raw
materials or energy for growth & tissue repair), absorbing & assimilating them.
3. Describe the structure of large molecules made from smaller basic units.
Many large biological molecules are long chains of smaller units held together by chemical bonds
LARGE
MOLECULE
Large (complex)
CARBOHYDRATES
Starch,
Glycogen,
Cellulose
STRUCTURE
SMALLER BASIC
UNIT
Monosaccharides
(sugars) such as
glucose
LIPIDS
Fats & oils
3 fatty acids
chemically bonded
to 1 glycerol
PROTEINS
Amino acids
4. Describe the Food tests
Food tested
Starch
Name of test
Starch test
Reducing
sugars e. g.
glucose
Protein
Benedict’s test
Fats
Emulsion test
Biuret test
Method
Add a few drops of iodine solution (brown) to a
solution of the food.
Add an equal amount of Benedict’s solution
(light blue) to a solution of the food.
Boil carefully.
Add Biuret solution (light blue) to the solution
of food.
Dissolve the food in ethanol. Pour the solution
into a clean test tube of water.
Positive result
Blue/black
Blue green
orange brick red
Violet
White emulsion
5. List the principal sources of, and describe the importance of the following….
6. Describe the deficiency symptoms for Vitamin C and D and minerals calcium and iron.
Nutrient
Carbohydrates
Fats
Proteins
Vitamin C
Vitamin D
Principle sources
Rice, potato, yam,
bread, millet
Butter, milk,
cheese, egg yolk,
groundnuts.
Meat, fish, eggs,
soya, milk
Citrus fruits,
cabbage, tomato,
mango
Milk, cheese, egg
yolk, fish-liver oil
Calcium
Milk, cheese, fish
Iron
Red meat, liver,
kidney, green veg
Vegetables, whole
meal bread, fruit
Drinks, fruits, veg
Fibre
(cellulose)
Water
Use in the body
Source of energy
Source of energy; insulation against heat
loss; constituent of cell membranes and
some hormones
Growth; tissue repair; constituents of
enzymes, some hormones, antibodies,
hemoglobin, hair and nails
Needed to make healthy skin and gums
Needed to maintain hard bones; helps in
absorption of calcium from the small
intestine
Needed to form healthy teeth and bones;
and for normal blood clotting
Needed for formation of hemoglobin in
red blood cells
It adds bulk to food passing through the
intestines; helps to maintain peristalsis
Forms blood & cytoplasm; helps to
transport nutrients; removal of waste as
urine ; cooling of body by sweating;
enzymes only work in solution
Deficiency symptoms
Scurvy - bleeding under
skin & bleeding gums
Rickets - soft bones that
become deformed.
Rickets; slow blood
clotting
Anemia- tiredness and
lack of energy
Constipation; long term
can lead to bowel cancer
Dehydration
7. Describe the use of microorganisms in the manufacture of yogurt.
 The milk is heated to 700C and then cooled to kill organisms in the milk which might ferment it
making unpleasant tasting substances;
 Bacteria (Lactobacillus) is added to warm milk;
 Bacteria uses the sugar of milk (lactose) and converts it to lactic acid (fermentation) for energy;
 Lactic acid lowers the pH of the milk;
 This affects the proteins in the milk which coagulate forming clumps;
 The milk separates out into clumps called curds and the liquid called whey;
 The temperature is then reduced to 50C to prevent further bacterial action.