Biology - Keeping Healthy

This is for an AQA paper and there are ten sub-sub topics: 

  Diet and excercise  Weight Problems Inheritance, excersise and health Pathogens and Disease Defence Mechanisms        Using Drugs to Treat Disease Growing and Investigating Bacteria Changing Pathogens Immunity     How do we deal with disease?

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Diet and Exercise - What makes a healthy diet

A balanced diet contains the correct amount of:

Carbohydrates - used to realease energy that keep you aliveand build new cells. 

Proteins - used to realease energy that keep you aliveand build new cells.

Fats - used to realease energy that keep you aliveand build new cells.

Vitimens - Used in small dosage to keep the body working healthier, without your 

Minerals - body will suffer deficiency diseases.



Without a balnced diet you will feel malnourished. If we take in more energy than used we gain weight and if we take in less we loose weight.

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Diet and Exercise - How much energy do you need?

Three factors that tell you how much energy you need:

  • Males need to take in more than females unless the woman is pregnant.
  • Increase of exercise will mean you will need more of an intake of energy (the more exercise you do the fitter you will be).
  • If you live somewhere hot you will need less of an intake of energy.
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Diet and Exercise - Metabolic Rate

The metabolic rate is the rate of chemical reactions in your cells. 

The metabolic rate varies from person to person. The proportion of fat to muscle also affects the rate.

Men have a higher metabollic rate than women because there is a higher proportion from muscle to fat in men.

Metabolic rate is affected by the amount of exercise you do but the metabolic rate is also based on inheritance.

Metabolic rate also affects how easily you gain and lose mass.

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Weight Problems - Obesity and Lack of Food


The excess amount of intake energy is stored as fat.

The fat can be a store of energy if there is a very high amount of intake of energy then it is possible you could become overweight or obese.

Obesity causes arthritis, type 2 diabetes, high blood pressure and heart disease and leaves you malnourished.

Obese people often die at an earlier age.

Lack of Food

Eating not enough food leaves you malnourished and underweight.

Without mineral can cause deficency diseases and can also occour from an unbalanced diet.

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Weight Problems - Losing Weight

You lose weight by reducing the intake of energy, increases the amount of exercise or do both.

If you lose too much weight than necessary it will cause health problems.

There are slimming programmes, some advise you on the right amount you need to be at your optimum health and some say to cut all of the fat from your body.

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Inheritance, Exercise and Health - Inheriting Heal

Inheriting Health

Inheritance from a parent(s) affect your appearance and affect your health such as metabolic rate and partly influence on the amount of cholesterol in your blood.

Inheritance can also affect the proportion of fat to muscle.

Controlling Cholesterol

Cholesterol is need for: 1. Cell Membranes 2. Making hormones.

There are two forms of cholesterol, one is healthy, one causes problems, if the levels are unbalanced there is a greater risk of heart disease.

The way your liver makes the different types of cholesterol and the way your body deals with fat is inherited.

An example of how inherited factors can affect your health is when you eat a balanced diet and you still have high levels of harmful cholesterol when most other people don't and they have to eat lots of high-fat-foods.

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Inheritance, Exercise and Health - Exercise and He

People who exercise more are generally healthier.

These are three explanations:

  • You use more energy therefore you lose more weight and avoid problems such as arthritis, diabetes and high blood pressure. 
  • You will have more muscle tissue and increase your metabolic rate and avoid problems such as arthritis, diabetes and high blood pressure. 
  • The levels of cholesterol go down and also balances them, the  good cholesterol levels go up and the bad cholesterol levels go down.
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Pathogens and Disease - Introduction

Infectious diseases are found all over the world.

Some are mild such as colds and tonsillitis, others are killers such as tetanus, influenza and AIDS.

Infectious means the microorganisms that can be passed on.

Microorganism, if causing infectious diseases by entering and attacking the body, are called pathogens.

Common pathogens are bacteria and viruses. 

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Pathogens and Disease - Differences Between Bacter


  • Bacteria are single celled organisms.
  • They have different shapes.
  • They are smaller than plant or animal cells.
  • Many are harmless and we use them for food, to make medicines and treat sewage.


  • Viruses are smaller than bacteria.
  • They are not an organism.
  • They usually have a regular shape.
  • Viruses cause disease in every living organism.
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Pathogens and Disease - How Pathogens Cause Diseas

Once in a cell, viruses will reproduce rapidly and they soon will destroy you cell and sometimes (very rarely) produce toxins.

Bacteria excrete toxins poisonous to our bodies.

Symptoms are often; high temperature, head aches and rashes. They depend on the way the toxins or damages effect your body.

You catch diseases when you pick up a pathogen from someone else already infected.

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Pathogens and Disease - Ignaz Semmelweis

Semmelweis was a doctor n the 1950s and at that time women often dies in childbirth, but no-one knew what the cause was.

Semmelweis saw students dissecting a dead body and, without washing their hands went to treat a woman about to give birth.

A doctor then died through a cut while dissecting a dead body and died of child bed fever.

Semmelweis said to the students to wash their hands and the was a sudden decrease of child birth deaths.

This idea was mocked by other doctors because they did not know of viruses and bacteria.

They did not like this idea also because of the thought they were killing their patients rather than treating them.

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Defence Mechanisms - Introduction

There are numerous ways how a pathogen will get into your body:

  • Droplet infection: When we sneeze we expel large amounts of pathogens through droplets, the droplets are then breathed in by someone else along with the large amount of pathogens within them. The pathogens passed on like this are flu, the cold and tuberculosis. 
  • Direct Contact: Some pathogens are transmitted through the skin. Contaminated food or drinks: Eating raw food or sewage water, diarrhoea. Breaks in the Skin: Pathogens that enter the body through cut, scratches, needle punctures are HIV/AIDS or hepatitis. 
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Defence Mechanisms - First Defence of the Body

Ways in which your body stops pathogens getting in:

1. Your skin acts as a barrier.

2. If you cut yourself your blood will quickly form a clot which dries into a scab which acts like a seal.

3. If you breathe in pathogens, your mucus traps the pathogens from going into your lungs and tubes. Mucus is swallowed into your gut and the acid kills the pathogen. The acid in your stomach will kill any consumed pathogens.

How white blood cells protect you from disease:

1.White blood cells may ingest pathogens.

2. They produce unique antibodies meant for destroying a specific pathogen.

3. They may produce antitoxins which destroy toxins released by pathogens.

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Using Drugs to Treat Disease - Introduction - Anti


Drugs such as aspirin will relieve pain of symptoms but not kill the pathogen.

Many medicines that are bought at chemists will have the same effect.

You have to wait for your immune system to overcome the pathogens.


We use antiseptics and disinfectants to kill bacteria outside the body, but they are too poisonous to use inside the body.

We use antibiotics to kill pathogens inside the body.

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Using Drugs to Treat Disease - How Antibiotics Wor

Antibiotics like penicillin will kill bacteria inside your body without damaging cells.

Antibiotics can kill bacteria that have killed millions in the past.

Antibiotics, however, do not kill viruses. 

This is because viruses reproduce inside cells therefore to kill the virus without damaging the cells is extremely difficult.

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Growing and Investigating Bacteria - Introduction


To discover information about microorganisms we must culture them.

We grow bacteria in laboratories to find out more about them, what nutrients they need to grow and which chemicals kill them best.

Growing Microorganisms in Labs

To culture microorganisms we must give them a culture medium, a liquid or gel containing nutrients such as carbohydrates, warmth, oxygen and various minerals.

You usually use agar jelly.

There is also a risk of an harmless bacteria mutating into a harmful one.

You must try not to contaminate the specimen from your skin, air, soil or water.

Also you must carry out safety features.

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Growing and Investigating Bacteria - Growing Bacte

How to grow useful bacteria:

1. Sterilise an inoculation loop. 

2. Dip the loop onto a Petri dish with agar in a zigzag and place a lid over it.

3. Seal the lid but not all the way round so oxygen can get in.

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Changing Pathogens - Introduction

An antibiotic will destroy a pathogen if used correctly. 

However some bacteria will form mutations that are random, natural selection.

Over the years there has been overuse of antibiotics therefore mutations quicken.

An example of overuse of antibiotics is when people take antibiotics when their doctor say they have a viral infection which cannot be helped with antibiotics.

Another example is when a certain type of antibiotics is used for the wrong type of bacteria.

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Changing Pathogens - The MRSA story

MRSA contributes to around a thousand deaths a year.

Ways to reduce this is:

  • Do not overuse antibiotics.
  • Medical staff at hospitals should wash their hands between patients.
  • Visitors should wash their hands when entering and leaving a hospital.
  • Patients with antibiotic resistant bacteria should be under quarantine. 
  • Hospitals should be kept clean.
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Changing Pathogens - Mutations and Pandemics

Mutations may also introduce a new form of disease.

The may be a flu epidemic, in one country, or a flu pandemic, across several.

In 1918-19 a pandemic of flu killed over 40 million people.

With modern international travel, disease can spread very quickly.

Swine flu travelled fast in 2009.

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Immunity - Introduction

A white blood cell can tell between a cell antigen (proteins on the surface of a cell) from a bacteria antigen.

The white blood cell produces an antibody which joins up and kills the pathogens.

Your white blood cells remember which antibodies kill which bacteria the fastest so if ever attacked again by the pathogen it will destroy it easily.

It will be slower the first time your body meets the pathogen as the white blood cells need time to sort out the right antibody.

The next time you will not even feel ill as the white blood cells destroy it so quickly.

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Immunity - Vaccination

Sometimes it takes the body so long to create an antibody you will die.

Vaccinations make you immune.

Vaccines are made of a weak or dead pathogen. 

Your antibodies will then have time to defeat the dead or weakened pathogen without you getting ill.

Then if you ever meet the live pathogens your body will destroy them easily.

MMR is a common vaccine and is used to protect your system against, measles, mumps and rubella.

Vaccinations have wiped out small pox and will most likely wipe out polio in a couple of years time.

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How to Deal With Diseases

No vaccine is safe, the whooping cough vaccine had been claimed to cause brain damage in some.

Because people were scared by this children did not get vaccinated and in Scotland 75 people died. Now over 90% have the vaccination.

Because of overuse of antibiotics some bacteria have become immune to the strongest medicines and now many men and women may die.

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Abi Walter-Browne


Brilliant. thank you



These cards contain  a lot of useful information for the AQA specification and they deal with ten different sub topics under the 'keeping healthy'  title. Team them up with a quiz and a set of flashcards to test knowledge of the key  terms and definitions.

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