Download vitamin C

RevisionExercise5/answers/ymt/aoghss
1.
Fill in blanks
(i)
Of the seven main food substances taken in by humans,
carbohydrates
_____________ , ______________ , _______________ can
produce energy.
_______________ are necessary for growth and repair of body
tissues
fats, proteins
(ii)
Dissacharides and polysaccharides can be broken down by enzymes
with the presence of water. This process is called ______________ . hydrolysis
(iii)
_____________ and ____________ are examples of
polysaccharides.
Starch, glycogen
(iv)
_____________ is a very important part of our daily diet as they
Dietary fibre/roughage
stimulate _______________ .
peristalsis
(v)
Proteins are built from small units known as ______________ .
amino acids
(vi)
Excess proteins cannot be stored. The surplus amino acids resulting
from the breakdown of the excess proteins are ____________ in the deaminated
____________ . The eliminated amino group is converted into
liver
_______________ .
urea
(vii) Fats are made up of smaller units called ___________ and
______________ .
glycerol
fatty acids
(viii) The unit for energy value of food is called ____________ . The
apparatus used to measure the energy value of food is called
kilojoules
________________ .
2.
Proteins
calorimeter
True or false
Study each of the following statements. Correct by rewriting it if it is false.
(i)
We can take vitamins when we are
hungry.
F Vitamins can be obtained from food. Extra
vitamin requirement must be taken as
prescribed by a medical doctor.
(ii)
Proteins are only for growth and
repair
F Proteins are also involved in enzyme
formation.
(iii)
We cannot make vitamins. All of
F Some vitamins can be manufactured by the
them must be obtained from food.
body under certain conditions. e.g. vitamin D
can be manufactured by the skin when
exposed to UV light.
(iv)
We become fat only when we take
in excess fat.
F Our body can convert proteins and
carbohydrates into fats when they are in
excess.
(v)
Water can be obtained from the
water we drink only.
F Water can also be obtained from food.
(vi)
All vitamins are destroyed by heat.
F Some vitamins are not destroyed by heat.
RevisionExercise5/answers/ymt/aoghss
(vii) Basal metabolic rate is the rate at
which the minimum amount of
energy is needed by an individual to
keep the heart beating.
(viii) The digestion of vitamins requires
enzymes
3.
4.
5.
F BMR is the rate at which the minimum
amount of energy is needed by an individual
to keep the person alive.
F Vitamins cannot be digested by the body
because we do not have enzymes to do this.
Complete the following table:
Food
Food test
Is heating required
Result
reducing sugars
Benedict’s test
yes
brick-red precipitate
starch
iodine test
no
blue black colour
proteins
biuret test
no
purple colour
fats
spot test
no
a translucent spot appears
vitamin C
using DCPIP
no
DCPIP is decolourized
State the deficiency disease of each of the following:
Vitamin / mineral
Deficiency disease
vitamin A
night blindness
vitamin C
scurvy
vitamin D
rickets
iron
anaemia
calcium
rickets
Answers only
(i)
W: fat
X: carbohydrates
Y: water
Z: protein
(ii)
Beans also contain mineral and vitamins which are not shown in
the table
(iii)
(1) butter
(2) cabbage
(iv)
6.
Beans are most suitable for vegetarians.
Beans contains the highest percentage of carbohydrate which
can supply energy.
Beans also have relatively high percentage of proteins for
growth.
Answers only
RevisionExercise5/answers/ymt/aoghss
(i)
The food contains too much carbohydrates/fats.
It does not contain vitamin C/dietary fibres
(ii)
We can eat less chips/less sugar for coffee.
We can eat fresh fruits/vegetables.
(iii)
The diseases are:

constipation: caused by a lack of dietary fibres

scurvy: lack of vitamin C