Biology Unit 1 Chapter 1 Notes

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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
Can be found in meats, fish and eggs
Builds new tissue (cells)
which is important if you are growingand also if you need to
repair damage tissue
They are made up of amino acids
Can be found in rice, pasta, potatoes and bread aswell as sugars
Provides energy for the body
Rice, pasta potatoes are better for slow-release energy
Sugars are better for quicker release energy
Found in foods such as butter, sugars and oils
Fats provide stored energy
Allchemical reactions that happen in the body happen in a watery environment
keep the cells hydrated) and without it the chemical reactions would not happen
Found in water
Helps prevent constipation
Found in vegetables, fruit and wholemeal
Vitamins and minerals:
Are required for general health (healthy functioning of the body )
If you don't have enough of a certain type of vitamins you may suffer from deficiency
Needed in small amounts and found in foods such as fruit and vegetables

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If you don't have a balanced dietyou may suffer from malnutrition (they may be malnourished).…read more

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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
Type 2 diabetes
Evaluating claims made by a slimming programme:
Benefits Problems
Low-carbohydrate Such a drastic change in diet can have a negative effect on the
diets can help you to body
lose weight very Exercise is not encouraged by this…read more

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Diseases caused by bacteria include: food poisoning, cholera, typhoid, whooping cough
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 make hundreds of thousands of copies of itself
Eventually the copied viruses fill the whole host cell and cause it to burst open
The viruses are then passed out in the bloodstream, the airways, or…read more

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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
antibodies to kill a particular pathogen (while multiplying rapidly).…read more

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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 such as sore throats.
Antibiotics and vaccinations may no longer be effective against a new resistant strain of the
pathogen. The new resistant strain spreads rapidly as people aren't immune to it and there is no
effective treatment.
In some cases, dead or inactivated pathogens stimulate antibody production.…read more

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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 infectious and contagious and were
responsible for many deaths.…read more

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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 re-solidifies at around 50°C. The nutrients mentions above are added to the agar to
provide ideal growing conditions for cultures (population of bacteria).…read more

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


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