AQA GCSEScience A Revision notes- Biology

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B1.1 Keeping healthy

A combination of a balanced diet and regular exercise is needed to help keep the body healthy. Our bodies provide an excellent environment for many microbes which can make us ill once they are inside us. Our bodies need to stop most microbes getting in and deal with any microbes which do get in. Vaccination can be used to prevent infection.

Candidates should use their skills, knowledge and understanding to:

■ evaluate information about the effect of food on health

■ evaluate information about the effect of lifestyle on development of disease

■ analyse and evaluate claims made by slimming programmes, and slimming products.

Additional guidance:

Candidates will be given data to work from. 

B1.1.1 Diet and exercise

a) A healthy diet contains the right balance of the different foods you need and the right amount of energy. Carbohydrates, fats and proteins are used by the body to release energy and to build cells. Mineral ions and vitamins are needed in small amounts for healthy functioning of the body. A person is malnourished if their diet is not balanced. This may lead to a person being overweight or underweight. An unbalanced diet may also lead to deficiency diseases or conditions such as Type 2 diabetes.

Additional guidance:

Knowledge and understanding of the specific functions of nutrients and the effects of any deficiency in the diet are not required

b) A person loses mass when the energy content of the food taken in is less than the amount of energy expended by the body. Exercise increases the amount of energy expended by the body.

c) The rate at which all the chemical reactions in the cells of the body are carried out (the metabolic rate) varies with the amount of activity you do and the proportion of muscle to fat in your body. Metabolic rate may be affected by inherited factors.

d) Inherited factors also affect our health; for example cholesterol level.

e) People who exercise regularly are usually healthier than people who take little exercise.

Additional guidance:

The effect of exercise on breathing and heart rate is not required.

B1.1.2 How our bodies defend themselves against infectious diseases

Candidates should use their skills, knowledge and understanding to: 

■ relate the contribution of Semmelweis in controlling infection to solving modern problems with the spread of infection in hospitals

Additional guidance:

Candidates will be given data to work from. 

■ explain how the treatment of disease has changed as a result of increased understanding of the action of antibiotics and immunity

■ evaluate the consequences of mutations of bacteria and viruses in relation to epidemics and pandemics 

■ evaluate the advantages and disadvantages of being vaccinated against a particular disease.

a) Micro-organisms that cause infectious disease are called pathogens.

b) Bacteria and viruses may reproduce rapidly inside the body and may produce poisons (toxins) that make us feel ill. Viruses damage the cells in which they reproduce.

Additional guidance:

Knowledge of the structure of bacteria and viruses is not


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