Biology B1 Revision

The revision notes i made for B1,

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B1 1.1
Friday, May 04, 2012
4:05 PM
Diet and exercise
A healthy diet has the right balance of food types. Carbohydrate, fat
and protein are used by the body to release energy and build cells.
Mineral ions and vitamins are needed to keep the body healthy. If the
diet is unbalanced a person can become malnourished.
If you exercise, more energy is used by the body. Exercise increases
the metabolic rate, which means that the chemical reactions in cells
work faster.
The proportion of muscle to fat in your body and you inherited
factors can also affect your metabolic rat.
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B1 1.2
20 May 2012
Weight problems
It is important for good health to get the energy balance correct.
If the energy you take in equals the energy you use then your mass
will stay the same. Eating too much food can lead to becoming
overweight and obese.
Long term obesity can lead to severe health problems including Type 2
diabetes (high blood sugar).
These problems can be reduced by eating less carbohydrate and
increasing the amount of exercise.…read more

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B1 1.3
20 May 2012
Inheritance, exercise and health
Your metabolic rate can be affected by the genes you inherit from your
There are 2 types of cholesterol. You need 'good' cholesterol for your
cell membranes to make vital substances.
Small numbers of the population inherit high levels of 'bad'
cholesterol, which can lead to heart disease.
Foods rich in saturated fat can also increase blood cholesterol
By exercising regularly a person can increase their metabolic rate and
lower high cholesterol levels.…read more

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B1 1.4
20 May 2012
Pathogens cause infectious diseases.
Pathogens are tiny microorganisms - usually bacteria or viruses.
When bacteria or viruses enter the body they reproduce rapidly. They
can make you feel ill by producing toxins (poisons).
Viruses are much smaller than bacteria and reproduce inside cells. The
damage cells also makes you ill.
Before bacteria and viruses had been discovered, a doctor called
Semmelweiss realised that infection could be transferred from person
to person.…read more

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B1 1.5
20 May 2012
Defence mechanisms
The skin prevents pathogens getting into the body.
Pathogens are also trapped by mucus and killed in stomach acid.
White blood cells are part of the immune system. They do three things
to defend the body:
They ingest pathogens. This means they digest and destroy them.
They produce antibodies to help destroy particular pathogens.
They produce antitoxins to counteract the toxins that pathogens
produce.…read more

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B1 1.6
20 May 2012
Using drugs to treat diseases
Antibiotics kill infective bacteria in the body.
Penicillin is an antibiotic, but there are many others. It was
discovered by Alexander Fleming in 1928.
Viruses are difficult to kill because they reproduce inside the body
cells, so any treatment could also damage the body cells.
Painkillers and other drugs relieve the symptoms of a disease but do
not kill the pathogen.
Your immune system will usually overcome the viral pathogens.…read more

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B1 1.7
20 May 2012
Growing and investigating bacteria
Pure cultures of non-pathogenic bacteria can be used for laboratory
A culture of microorganisms can be used to find the effect of
antibiotics on bacteria.
Investigations need uncontaminated cultures of microorganisms. Strict
health and safety procedures are used to protect yourself and others.
Contamination might come form your skin, the air, the soil or the
water around you.
If the culture is contaminated other bacteria could grow, including
pathogens.…read more

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B1 1.8
20 May 2012
Changing pathogens
Some pathogens, particularly viruses, can mutate resulting in a new
form called a mutation.
Very few people are immune to these changed pathogens so disease can
spread quickly.
Diseases that spread within a country result in an epidemic. Those
that spread across countries result in a pandemic.
The MRSA 'super bug' is a bacterium that has evolved through natural
selection. MRSA and other bacteria have become resistant to the common
antibiotics.…read more

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B1 1.9
20 May 2012
Dead or inactive forms of a pathogen are used to make a vaccine.
Vaccines can be injected into the body.
The white blood cells react by producing antibodies.
This makes the person immune. It prevents further infection because
the body responds quickly by producing more antibodies.
The antibodies recognise the antigen (protein shape) on the pathogen.
The MMR vaccination is one of several vaccines. MMR is given to
prevent mumps, measles and rubella.…read more

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B1 1.10
20 May 2012
How do we deal with disease?
Most people in a population need to be vaccinated to protect society
from very serious diseases.
Diseases such as measles can lead to long term damage to the body,
such as deafness and occasionally death.
Some vaccines cause side effects which may be mild or serious. So
there are advantages and disadvantages of vaccination.
Overuse of antibiotics can lead to the development of new strains of
bacteria.…read more


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