Biology - B1


Health and Fitness


Being healthy means being free of any infections or diseases.


Being fit is a measure of how well you can perform physical tasks. 'Fit' is not a precise term and can be measured in different ways, the four s's and cardiovascular efficiency.

The Four S's 

Strength, Speed, Suppleness and Stamina.

Cardiovascular Efficiency 

How quickly heart rate returns to normal after exercise, the ability of the heart to supply the muscles with oxygen. Stamina is a good indication of cardiovascular efficiency. It can be tested by measuring oxygen uptake during exercise, and blood pressure.

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Blood Pressure

Blood Pressure

When the heart contracts, the blood in the arteries is put under pressure. Blood pressure is measured in mmHg (millimetres of mercury) and is written like this -

Systolic (heart contracting) --> 120/70 <-- Diastolic (heart filling)

Increased Blood Pressure

Factors that will increase blood pressure include stress, alcohol, high salt levels in diet, smoking and being overweight. The effects of high blood pressure include burst blood vessels, a stroke in the brain and kidney failure.

Decreased Blood Pressure

Factors that will decrease blood pressure include regular exercise and a balanced diet. The effects of low blood pressure include poor circulation, dizziness and fainting.

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Thrombosis and Heart Disease

Cholesterol Build Up

Cholesterol can build up in the arteries. This forms a plaque which restricts and/or blocks blood flow.


Thrombosis is a blood clot and restricts blood flow.

Heart Disease

The coronary arteries deliver blood to the heart. If these become narrowed due to plaque, blood flow to the heart becomes restricted and receives less oxygen. If a thrombosis is present, and the heart receives no oxygen, this will cause a heart attack.

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Balanced Diet

Nutrients and their Functions

Carbohydrates - these provide energy, and are made up of simple sugars like glucose. Theya re stored in the liver as glycogen or converted into fats.

Fats - these provides energy, acts as an energy store and provides insulation.

Proteins - these are needed for growth and repair of tissue, and to provide energy in emergencies. They are made up of amino acids. They don't get stored.

Vitamins and Minerals - these have various functions, e.g. vitamin C prevents scurvy and iron (a mineral) is needed to make haemoglobin for healthy blood.

Water - this prevents dehydration.

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Healthy Eating Factors

Individual Needs

The amount of nutrients an individual needs depends on things such as age, gender and physical activity.

Age - children and teenagers need more protein for growth. Older people need more calcium to protect against degenerative bone diseases like osteoporosis.

Gender - Females need more iron to replace the iron lost in menstrual blood.

Physical Activity - Active people need more protein for muscle development, and more carbohydrates for energy.

Some people, however, choose not to eat certain foods for religious reasons, personal reasons or medical reasons.

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Diet Problems


This is caused by eating too little protein. A common symptom is a swollen stomach. It is very common in developing countries, where there are low protein diets. The reasons for this include overpopulation and lack of money.

Body Mass Index (BMI)

BMI = body mass (kg) / (height)2 (m)

EAR Protein

EAR (g) = 0.6 x body mass (kg)

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