Human Food

BIOLOGY AND GEOLOGY DEPARTMENT NATURAL SCIENCE 3 ESO – BILINGUAL SECTION
I.E.S. Montecillos (Coín - Málaga)

2012-2013

Unit _: HUMAN FOOD
I. Food and nutrition. The nutrients

Whether you are an animal or another living thing, you need matter and energy to survive, matter for the structures of your body and energy for your vital functions. Nutrition includes different processes to getmatter and energy. Nutrition is an involuntary process in which different organs and different systems are involved. The chemicals that provide us with matter and energy are called nutrients and they are in food. Food is a voluntary process and it depends on our culture, economic factors, our climate, our religious beliefs, etc. Nutrients can be classified into two types: Inorganic nutrients. Theycome from animal or plant food, even from non-living matter. They do not give us calories. 1.- Water. It is the main component in living things. It performs very important functions in living things, for example it transports substances, controls the temperature in the body, etc. We need a constant supply to replace water lost through urinating, breathing, sweating. 2.- Minerals. We need them invery small proportions but they perform very important functions in the body. For example, iron is needed to make haemoglobin for blood; calcium and phosphate are needed for bones. Organic nutrients. They come from animal or plant food, only organic food. They are: 1.- Carbohydrates. They provide energy. The simplest one is glucose. The most complicated are cellulose and starch, made up of simplesugars, like glucose. 2.- Fats. They provide energy, act as an energy store and provide insulation. They are made up of fatty acids and glycerol. 3.- Proteins. They are needed for growth and the repair of tissue, defence against infections, the transportation of oxygen through the blood, etc. They are made up of amino acids. 4.- Vitamins. They can be fats or proteins. They are needed for a lot offunctions, like growth and to prevent diseases. 1

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HUMAN FOOD

BIOLOGY AND GEOLOGY DEPARTMENT NATURAL SCIENCE 3 ESO – BILINGUAL SECTION
I.E.S. Montecillos (Coín - Málaga)

2012-2013

ACTIVITIES 1.- What is the main difference between nutrition and food? 2.- What are the main functions of carbohydrates, fats and proteins? 3.- Why is it important have enough vitamins in our diet?

II.Foods and Energy

The calorie is a unit of food energy. A calorie is the amount of energy required to raise the temperature of one gram of water by one degree Celsius. The term kilocalorie (Kcal), referring to one thousand gram calories, is also used in nutrition. This unit is approximately equal to 4´18 KJ (Kilojoules). So, food energy is expressed in calories or joules, Kcal or KJ. 1Kcal =1000 gram calories 1Kcal = 4,18 KJ The kilojoule is the unit officially recommended by the WHO, but the calorie is still the most common unit in many countries. Vitamins, minerals, water and fibre do not give us energy. Our body uses them to build new cells and to control metabolic functions.

III.

Energy and nutrient needs vary in different people

The amount of each nutrient that yourequire will depend on your body´s individual needs. The balance of the different nutrients a person needs depends on things like: Age. Children and teenagers need more protein for growth. Older people need more calcium to protect against degenerative bone diseases (e.g. osteoporosis). Gender. Females need more iron to replace the iron lost in menstrual blood. Physical activity. Active people needmore protein for muscle development and more carbohydrates and oxygen for energy.

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The amount of energy you need from your food depends on your resting metabolic rate:

HUMAN FOOD

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BIOLOGY AND GEOLOGY DEPARTMENT NATURAL SCIENCE 3 ESO – BILINGUAL SECTION
I.E.S. Montecillos (Coín - Málaga)

2012-2013

1. You need energy to fuel the chemical reactions in the body that keep you...