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AQA
GCSE Science A
Biology
Summary Notes

B 1 1.1 Keeping Healthy

Balanced Diet

A healthy diet contains the right balance of different foods.
A healthy diet contains the right amount of energy.
It will provide carbohydrates for energy.
It will provide fat for energy and insulation.
It will provide protein for growth and repair.
It will provide vitamins and minerals to help our bodies function well.
It will provide fibre to ensure food moves through our digestive systems efficiently.
It will provide water, which is essential for all body processes.
If a diet is unbalanced a person is malnourished.
This can lead to being too thin or fat and to deficiency diseases.

Balancing the energy

If you use more calories than you eat you will lose weight.
If you use less calories than eat you will gain weight.
Doing exercise uses up lots of calories.

The effect of exercise on health

Regular exercise keeps you healthy.
It maintains a good metabolic rate.
It requires energy so uses lots of calories.
If they are not used up they are stored possibly as fat.

Metabolic rate

The rate at which chemical reactions happen in the cells of your body.
One major metabolic reaction is respiration.
This releases energy from the food we eat.
Inherited factors affect metabolic rate:
Some people inherit genes that give them a higher or lower metabolic rate than others.
The higher the proportion of muscle to fat in your body, the higher you metabolic rate:
Muscle cells use more energy.
The more exercise you do the faster your metabolic rate:
More energy is needed.
The warmer it is, the lower your metabolic rate:
We use less energy to keep our body temperature at 37oC.
Therefore, the less exercise you take, and the warmer it is, the less food you need.

Obesity

Obesity is a disease where someone is carries too