A simple and easy to understand GCSE guide covering all the keywords and phrases you need to pass your exams. Made by Students for Students

1. Diet and Exercise
By Kashmala

2. Energy Resources
❖ Carbohydrates for Energy
❖ Proteins for Growth and Repair in Cells
❖ Fats for Energy and Making Cell Membrane
❖ Vitamins and Minerals for Keeping us Healthy
❖ Fibre to Keep the Digestive System working
❖ Water to Transport other Nutrients

3. Metabolism
Metabolism rate is the rate at which Chemical Reactions take place in
your body.
❖ Different Bodies have different rates
❖ Males usually have faster metabolic rate compared to Female
❖ Younger people have faster Metabolic rate than older people
❖ The greater the Proportion of Muscle:Fat in the body, the higher
the metabolic rate
❖ Can be Affected by your genes

5. Vitamin C
Vitamin C (ascorbic acid) is needed to help heal wounds and maintain
healthy connective tissue (which gives support to other tissues and
organs).
Good sources of vitamin C include:
● citrus fruits (such as oranges, lemons and limes)
● leafy green vegetables (such as sprouts and broccoli)
Vitamin C deficiency leads to scurvy. The symptoms of scurvy include
bleeding and swelling of the gums, loss of teeth, tiredness and muscle
and joint pain.

6. Vitamin D
The human body can make vitamin D when our skin is exposed to
sunlight.
Good dietary sources of vitamin D include:
● eggs
● margarine and breakfast cereals fortified with vitamin D
● oily fish
Vitamin D is needed to maintain healthy bones and teeth. Vitamin D
deficiency leads to rickets and bone pain.

7. Vitamin A
Vitamin A is needed to maintain good vision, healthy skin and strong
immunity against infection.
Good sources of vitamin A include:
● milk, and dairy products (such as cheese and yoghurt)
● mackerel and other oily fish
Vitamin A deficiency leads to night blindness, which is when a person
finds it difficult to see well in dim light.
The body can convert beta-carotene (found in carrots, spinach and
mangoes, for example) into vitamin A.

8. Calcium
Calcium is needed to maintain healthy bones and teeth, for normal
blood clotting and to control muscle contractions.
Good sources of calcium include:
● cheese
● eggs
● milk
● green leafy vegetables such as broccoli and cabbage
The symptoms of calcium deficiency include weak bones and teeth,
poor clotting of the blood and muscle spasms.

9. Irons
Iron is needed to produce haemoglobin, found in red blood cells.
Good sources of iron include:
● liver
● red meat
● beans and nuts
● dried fruits such as dried apricots
Iron deficiency causes anaemia. People with anaemia become tired
and weak because their blood does not transport enough oxygen.

10. Water
Water and dietary fibre (roughage) are also important components in
the diet.
About two-thirds of the human body is water. It is found in the
cytoplasm of our cells and in body fluids like blood.
Sources of water include:
● food
● drinks
● metabolic processes - such as aerobic respiration

11. Dietary Fibre
Dietary fibre consists of material in food that cannot be digested, in
particular cellulose from plant cell walls.
Sources of fibre include:
● fruit
● vegetables
● cereals
Dietary fibre is important because it provides bulk, which helps the
walls of the intestine move food and faeces along the gut. Lack of
dietary fibre can lead to constipation.

12. Balanced Diet
A balanced diet is a diet in which all the components needed to
maintain health are present in appropriate proportions.
The ‘eatwell plate’ shows the proportions of the different components
that should be eaten daily in a well-balanced diet.
A balanced diet should include appropriate proportions of
carbohydrate, protein, lipid, vitamins, minerals, water and dietary
fibre.

14. Energy Requirements:Age
The amount of energy we need tends to increase as we approach
adulthood.
The energy needs of adults go down as they age. For example,
people in their 50s need about 17% less energy in their diet than
people in their 30s.

15. ER:Activity Levels
People who are active tend to need more energy than sedentary
people. For example, an adult office worker might need 10,000 kJ
per day, but a manual worker might need 15,000 kJ per day.
ER:Pregnancy
In general, the greater a person’s mass, the more energy they
need. Men tend to need more energy than women, and a
woman’s energy needs increase when she is pregnant. This is
mainly because she is carrying extra mass.

16. Calorimetry
The energy content in a food sample can be measured using simple
calorimetry.
To carry out this experiment, you need to:
1. pour cold water into a boiling tube
2. record the starting temperature of the water
3. record the mass of the food sample
4. heat the food until it catches fire
5. heat the water using the flame from the burning food
6. record the final temperature of the water

18. Calculations
energy transferred (J) = mass of water (g) × 4.2 (J/g°C) × temperature
increase (°C)
Question:
When 0.5 g of food is burned, 10 cm3
of water warms up by 20°C.
What is the energy content of the food in J/g?
Answer:
1 cm3
of water has a mass of 1 g
energy transferred to water = 10 × 4.2 × 20 = 840 J
energy content of food = 840 ÷ 0.5 = 1680 J/g

19. Fair Testing
When comparing different foods, it is important to carry out a fair test.
Several variables should be kept constant:
● the starting temperature of the water
● the temperature increase
● the distance of the flame from the boiling tube
More reliable results can be obtained by repeating the experiment. The
biggest source of error in calorimetry is usually unwanted heat loss to
the surroundings.

20. Food Additives
Food may contain additives. These are substances intended to
improve the properties of the food.

21. E Numbers
Additives with an E number have been licensed by the European
Union. Some are natural and some are artificial. They have all been
safety tested and passed for use. The UK Food Standards Agency
sets strict limits on the amounts allowed in food.
Hazards of Food Additives
There are health hazards associated with certain food additives. For
instance, some additives:
● cause allergic reactions in some people
● may cause hyperactivity and behavioural problems in some
children
● have been associated with an increase in childhood asthma in
recent years

22. Glossary

23. KeyPoints
❖ Most people eat a varied diet which includes everything needed to
keep the body healthy
❖ Different people need different amounts of energy
❖ The Metabolic rate varies from person to person
❖ The more Exercise you do, the more food you need
❖ The temperature where you live also affects how much energy you
need to take in
❖ Malnourished is the condition when the body doesn’t get balanced
diet