1. What are the body's sources of energy? How much energy does each supply?

• Glucose: provides 4.1kcalg−1

• Fat: 9.3kcalg−1

• Protein: 4.1kcalg−1

2. What is meant by the respiratory quotient?

This is defined as the ratio of the volume of CO2 produced to the volume of oxygen consumed from the oxidation of a given amount of nutrient. Values for the different energy sources are:

• Carbohydrayte: 1.0

• Fat: 0.7

• Protein: 0.8

3 What is the recommended daily intake for protein and nitrogen?

• Protein: 0.80 gkg−1

• Nitrogen: 0.15 gkg−1

4. What is an essential amino acid? How many are there, and give some examples?

These are amino acids that cannot be synthesised by the body and need to be ingested. There are 9 of them; leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, histidine and valine.

5. What are the main carbohydrates in the diet?

Direct carbohydrate is composed mainly of the polysaccharide starch, some disaccharides such as sucrose and fructose and a small amount of lactose. Other important polysaccharides include cellulose, pectins and gums. These are not digested, and make up the roughage in the diet.

6. In what form is fat stored in the body?

As triglycerides.

7. What are these composed of?

These consist largely of long chain saturated and unsaturated fatty acids (predominantly palmitic, stearic and oleic acids) that have been esterified to glycerol.

8. What is an essential fatty acid? Which ones are there, and why are they particularly important?

These are fatty acids that cannot be synthesised in the body.