Chapter 7 - Proteins

Question 1

State the functions of protein.

Answer 1

1. Growth and repair of tissues
2. Source of energy when carbohydrates and fats are used up
3. Works with vitamins and minerals to help the body fight against diseases
4. Proteins are needed to make enzymes which speed up the numerous chemical reactions in our body

Question 2

Give the meaning of the term High Biological Value protein (HBV).

Answer 2

Proteins that provide the body with all the essential (or indispensable) amino acids in the right proportions.

Question 3

Name two sources of High Biological Value protein (HBV).

Answer 3

Eggs / Meat / Milk / Seafood / Tofu

Question 4

Give the meaning of the term Low Biological Value protein (LBV).

Answer 4

Proteins that lack one or more essential amino acids that the body needs.

Question 5

Name two sources of Low Biological Value protein (LBV).

Answer 5

Wheat / Rice / Peas / Nuts / Beans / Legumes

Question 6

Give the meaning of the term complementary protein.

Answer 6

Two or more plant foods with low biological value proteins which are combined together to provide all the essential amino acids which the body needs.

Question 7

Give an example of complementary protein.

Answer 7

Peanut butter with bread / Baked beans with rice / Dhal curry with bread or rice

Question 8

Name one deficiency disease which can result from a lack of protein.

Answer 8

Kwashiorkor / Marasmus

Question 9

Suggest ways to ensure that vegetarians consume enough High Biological Value (HBV) proteins in their diet.

Answer 9

One way is to combine food with different types of Low Biological Value (LBV) proteins in a meal so that amino acids lacking in one particular food can be complemented by those in another food.

For instance, they can consume baked beans on toasted bread. OR They can also consume lentil soup with pita bread.

Question 10

Name the four main chemical elements which make up protein.

Answer 10

● Carbon

● Hydrogen

● Oxygen

● Nitrogen

Question 11

Name the enzyme found in the stomach which converts protein to polypeptides.

Answer 11

Pepsin

Question 12

Name the enzyme which clots milk.

Answer 12

Rennin

Question 13

Name the enzyme produced by the pancreas which converts protein to peptides.

Answer 13

Trypsin

Question 14

Name the enzyme which converts peptides to amino acids.

Answer 14

Peptidases

Question 15

Explain what happens to excess protein in the body.

Answer 15

● Excessive proteins are broken down by the liver into
carbon-containing and nitrogen-containing amino
acids.

● Carbon-containing parts are converted to body fats.

● Nitrogen-containing parts are converted to urea and
excreted from our body as part of urine.

Question 16

Explain what happens to protein when heated.

Answer 16

● Chemical structure denatured changed which is
permanent irreversible.

● Coagulation setting occurs.

● Overheating causes protein food to become less
digestible.

● Description of changes with example from liquid to
semi-solid or solid, e.g. egg changes from translucent
to opaque, e.g. colour change from red to brown in
red meat.

Question 17

What are the symptoms of Kwashiorkor.

Answer 17

Kwashiorkor occurs in children between 18 months and 2 years.

Symptoms of kwashiorkor are : loss of hair colour, patchy scaly skin, bloated stomach and edema, muscle wasting.

Question 18

What are the symptoms of Marasmus.

Answer 18

Marasmus occurs in children between the ages of 6-18 months. They have a ‘skin and bones’ appearance.

Symptoms are loss of muscle mass / weakening of heart muscles / retarded brain growth and anaemia.