Carbohydrates are made up of the elements carbon (C), hydrogen (H) and oxygen (O). These elements combine to form simple sugar molecules, e.g. glucose. When several sugar molecules join together they form long chains of starch. During digestion, the starch is broken into individual sugar molecules.
Further Investigation Find out more about photosynthesis by going to YouTube and watching the video ‘Photosynthesis | Photosynthesis in plants | Photosynthesis – Biology Basics for children | elearnin’ (4:52).
(1) A glucose unit
(2) Starch
(3)
Starch after digestion
Digestion of carbohydrates
Classification and sources of carbohydrates Carbohydrates are categorised into three groups.
Sugars Starch Dietary fibre
Sugar, honey, cakes, biscuits, jam, fruit, sweets and soft drinks
Cereals, pasta, flour, bread and potatoes
Whole cereals, oatmeal, wholemeal bread, outer skins of fruit and vegetables
