Contains the full lesson along with a supporting toolkit, including teachers’ notes.
Living processes require energy and so the most basic function of food is to supply us with energy – typically 8 to 12 MJ (million joules) per day (equivalent to 2000 to 3000 kilocalories per day), depending on a person’s general activity level.
Our energy requirement is met mainly by carbohydrates. However, a human being would not survive on a diet of sugar alone. Our diet should also contain water, protein, fat, and small amounts of certain minerals and vitamins. It is also desirable to include a certain amount of roughage in the diet.
1 kcal = 4184 J = 4.184 kJ;
1 kilocalorie is often written as 1 Calorie (with a capital ‘C’)
Average human daily requirements
A balanced daily diet should provide about 10 MJ of energy, about 70 g of protein and about 20 g of fat, as well as essential micronutrients (i.e. minerals and vitamins). Bread, potatoes and rice contain 30% to 50% starch (a carbohydrate) and could supply most of the energy requirement. The nutritional components of some common foods are shown in the table.
Cattle breeds in Ireland
In Ireland there are about 5 million beef cattle and 1.4 million dairy cows. The annual beef output is approximately 500,000 tonnes, 90% of which is exported – mainly to the UK. The annual milk output is about 6 billion litres, 85% of which is exported as milk or dairy products.