A Balanced Diet

Question 1

A balanced diet is best described as one that:

Accepted Answer

Contains all nutrients in the correct amounts and proportions — A balanced diet supplies every nutrient the body needs in the right quantities to stay healthy.

Question 2

Which nutrient is the body's main source of energy?

Accepted Answer

Carbohydrate — Carbohydrates such as starch and glucose are broken down in respiration to release energy, and are the body's main energy source.

Question 3

Proteins are needed mainly for:

Accepted Answer

Growth and repair of tissues — Proteins provide amino acids used to build new cells and repair damaged tissues.

Question 4

A shortage of vitamin C in the diet causes:

Accepted Answer

Scurvy — Vitamin C keeps tissues such as gums healthy; a lack causes scurvy, with symptoms including bleeding gums.

Question 5

Which mineral is needed to make haemoglobin in red blood cells?

Accepted Answer

Iron — Iron is a component of haemoglobin; a shortage reduces haemoglobin and causes anaemia.

Question 6

Why is dietary fibre (roughage) important even though it is not digested?

Accepted Answer

It helps the muscles move food along the gut and prevents constipation — Fibre adds bulk that the gut muscles can grip during peristalsis, keeping food moving and preventing constipation.

Question 7

A child with soft, bent bones is most likely lacking:

Accepted Answer

Vitamin D — Vitamin D is needed to absorb calcium for strong bones; a lack causes rickets, with soft and deformed bones.

Question 8

Calcium is required in the diet mainly for:

Accepted Answer

Strong bones and teeth — Calcium is deposited in bones and teeth, making them hard and strong.

Question 9

Fats and oils are important in the diet because they:

Accepted Answer

Provide a concentrated energy store and insulation — Fats store more energy per gram than carbohydrates and, under the skin, help insulate the body against heat loss.

Question 10

Which of these does NOT affect a person's daily energy requirement?

Accepted Answer

Eye colour — Energy needs depend on age, sex and activity (and pregnancy in women); eye colour has no effect on energy requirement.

Vitamin C	Keeps tissues healthy. Lack causes scurvy (bleeding gums).
Vitamin D	Helps the body absorb calcium. Lack causes rickets (soft, bent bones).
Calcium	Needed for strong bones and teeth.
Iron	Needed to make haemoglobin. Lack causes anaemia.

What is a balanced diet?

The main nutrients

Vitamins and minerals