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Biology Revision ­ Unit 1 Chapter 1:

B1.1 ­ Keeping Healthy:

Healthy diets:

A healthy diet contains the right balance of the different foods you need and the right amount of
energy.

Proteins:

Can be found in meats, fish and eggs
Builds new tissue (cells)
which is important if you…

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If you don't have a balanced dietyou may suffer from malnutrition (they may be malnourished).
This may cause them to be:

overweight or underweight
suffer from d
eficiency diseasesand conditions such as Type 2 diabetes

Unbalanced diet: a diet than contain inadequate amounts of all the necessary nutrients required
for…

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For a healthy lifestyle we should:

Eat less animal products
Eat more fruit and vegetables and wholemeal foods
Eat less salt
Exercise regularly

This will reduce the risk of developing diseases later in life such as:

Heart disease and high blood pressure
Strokes
Type 2 diabetes
Osteoarthritis

Evaluating claims made…

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Diseases caused by bacteria include: food poisoning, cholera, typhoid, whooping cough



Viruses:

Are many times smaller than bacteria
Consist of fragments of genetic material inside a protective protein coat
Only reproduce inside host cells and damage the cell when they do this
Once inside the cell, they take over and…

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Note that:

That pathogens are not the disease ­ they cause the disease
White blood cells do not eat the pathogens ­ they ingest them
Antibodies and antitoxins are not living things ­ they are specialised proteins

Antibodies are produced by certain white blood cells, called lymphocytes, can produce specific…

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selection because those bacteria which are more able to survive against the antibiotics,
survive

2. Resistant individual pathogens survive and reproduce
3. The population of the resistant pathogens increases

Nowadays, in order to slow down the rate of development of resistant strains, antibiotics are not
used to treat non-serious infections…

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Semmelweiss recognised the importance of hand-washing in the prevention of spreading some
infectious diseases. By insisting that doctors washed their hands before examining patients, he
greatly reduced the number of deaths from infectious diseases in his hospital (from 12% to 1%).

He recognised that something on the patients hands were…

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Microorganisms can be grown in a culture medium (agar jelly) containing various nutrients that
the particular microorganism may need. These may include: carbohydrates (an energy source),
mineral ions ,vitamins and proteins

Agar is most commonly used as the growth medium. This is a soft, jelly-like substance that melts
easily and…

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In schools and colleges, cultures should only be incubatedat a maximum of 25°C to prevent the
growth of pathogens that grow at body temperature (37°C) and are potentially harmful to
humans.

In industry, higher temperatures can be used to produce more rapid growth.

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