Subject: Biology Title:

NameDuty Cheung Wai Yee Author of p.1 – p.9 Fung Ying ChiAuthor of p.10 – p.18 Leung Shuk MingAuthor of p.19 – p.25 Duty List:

Introduction: 1.Target Audience: F.3 students with average ability. 2. How to use these slides? This is a teaching material for lecturing. These slides will be accompanied with food labels and some food samples.

Objectives: Balanced diets Deficiency diseases Functions of different food substances Function of foodTypes of food substances We should know……

What is Food? Food is something that living organisms take into their bodies to provide energy and to help them to develop and to live. The food for Human is made of SEVEN components. These components are called food substances.

Seven Food Substances Food Substances Carbohydrates Proteins WaterDietary FibreMineralsVitamins Fats

Functions of Food 1. Provide Energy 2. Growth and Repair 3. Keep Healthy

Carbohydrates Food source: Functions of carbohydrates:   Supply energy   Food reserve   Structural materials

Proteins Food source : Functions of proteins :   For growth and repair

Fats Food source: Functions of fat:   Supply energy   Food reserve   Heat insulator   Structural material of cell membrane

Vitamins Examples of vitamins: Vitamin A C D Functions of vitamins:   To keep us healthy

Minerals Examples of minerals: Calcium iron Functions of minerals:   To keep us healthy

Dietary fibres Food source: Functions of dietary fibres:   To prevent constipation

Water Functions of water:   Main component of cells   Transport of dissolved materials

Deficiency diseases - Lack of certain vitamin and mineral will cause deficiency disease Food substances Deficiency disease Vitamin ANight blindness Vitamin CScurvy Vitamin D and CalciumRickets ironAnaemia

Night blindness - Vitamin A is needed for the formation of pigment in retina which is necessary for night vision. Therefore lack of vitamin causes night blindness

Scurvy - Lack of vitamin C would result in poor healing of wounds and bleeding gum

  Calcium is need for the formation of bones and teeth.   Vitamin D helps the absorption of calcium.   Lack of vitamin D and calcium would result in Rickets i.e. bones becomes soft and weak Rickets

Anaemia - Iron is needed for the formation of haemoglobin in red blood cells. - Lack of iron causes anaemia.

Balanced Diet - A diet which contains all the seven food substances in right amount. - The amount of the food substances for each individual depended on:  S Sex   Occupation   Age   Physical activities

Reversion Quiz 1.How many food substances are contained in human food? A.Five B.Six C.Seven

2.Which of the following food substances promote growth? Reversion Quiz A.Proteins B.Carbohydrates C.Fats

Reversion Quiz 3.Lack of Iron will cause A.Rickets B.Anaemia C.Scurvy D.Overweight

Reversion Quiz 4.Meat contains no A.Fats B.Water C.Dietary Fibre D.Proteins