Biology- Keeping Healthy


Diet and exercise

  • A balanced diet contains the right amounts of: Carbohydrates, Proteins, Fats, Vitamins, Minerals, Fibre and water.
  • Carbs proteins and fats release the energy you need to live and build new cells.
  • Vitamins and minerals are needed so as you don't suffer deficiency diseases.
  • Without a balanced mix of these things, you will be malnourished.
  • The amount of energy you need is affected by: Gender, Age, Exercise, Climate and it is called your metabolic rate. If you live in a cold climate, then your metabolic rate goes up to keep you warm.
  • Metabolic rate refers to the chemical reactions taking place inside our cells.
1 of 10

Weight problems

  • If you take in more energy than you use, the excess is stored as fat. You need fat but if you take in to much energy you may become obese. Obesity can lead to arthritus, Type 2 diabetes, high blood pressure and heart disease.
  • To lose weight you could cut back on he amount you eat- reduce the amount of energy you take in, or increase the amount of enerrgy you use by doing exercise.
  • If you don't have enough food then deficiency diseases can occur due to lack of mineral ions. This can also happen if you don't have a balanced diet.
2 of 10

Inheritance, exercise and health

  • Inherited factors from your parents affect your apperance and your metabolic rate.
  • The way your body balances cholesterol can be inherited. You need cholesterol for your cell membranes and to make vital hormones. There are two forms of cholesterol; one is healthy but the other can cause heart disease. You have to have the correct balance. It's the liver than deals with cholesterol and eating lots of high fat food raises your cholesterol levels. You can inherit factors which means you naturally have high cholesterol.
  • People who exercise regularly are generally healthier than people who don't. Exercise helps to keeep you healthy because: You are less likely to be overweight, you will have more muscle tissue- increases your metabolic rate, regulr exercise lowers your choleterol levels; which lowers the risk of heart disease.
3 of 10

Pathogens and disease

  • Infectious diseases are found all over the world. Some are fairly mild such as a cold, but some are killers like tetanus and influenza.
  • An infectious disease is caused by a microorganism entering and attaking your body. People can pass these to eachother- why they are called infectious.
  • These microorganisms are called pathogens.
  • Bacteria are single celled living organisms that are smaller than amimal and plant cells. Most bactria are quite useful, we use them to make yogurt and cheese.
  • Viruses are smaller than bacteria and have regular shapes. They cause diseases in every type of living organism.
  • Once bacteria and viruses are inside your body they reproduce rapidly. Bacteria split in two and release toxins. Viruses take over the body, destroying the cells.
  • Symptoms are High tempertaure, Headaches and Rashes- the damage of the microorganisms.
  • Ignaz Semmelweiss was a doctor who realised that doctors were going from autopsies to delivering children without washing their hands and lot of women were dying of childbed fever. Then one doctor cut his finger during an autopsy and died of symptoms identical. Semmelweiss realised the connection caused by some infectious disease and tried to get doctors to wash their hands. However he was quite aggressive about it and was unsuccessful. He died as a madman.
4 of 10

Defense mechanisms

  • There are lots of ways a pathogen can spread from one person to another. This includes:
  • 1. Droplet infection- When you cough, sneeze or talk it expels tiny droplets of pathogens from your body and other people breathe them in and get ill.
  • 2. Direct contact- some diseases are spread by direct contact of the skin, e.g. STIs
  • 3. Contaminated food and drink- Eating raw food or water containing sewage can spread diseases, such as diarrhoea and salmonella.
  • 4. Through a break in your skin- pathogens can enter your body via cuts and grazes.
  • Your body has ways of stopping pathogens getting inside you; your skin, and when you cut yourself you bleed, forming a scab, which acts as a seal. Your breathing system is a weak link. But it builds mucus which covers the linings of your lungs and tubes, trapping the pathogens.
  • Despite this, some pathogens will get in, and meet your White Blood Cells. they use three different ways:
  • 1. Ingesting microorganisms- When they take in the microorganisms they destroy them and they can't make you ill.
  • 2. Antibodies- They target particular microorganisms and destroy them. However thy are unique to each form of pathogen. Once they have been made once, they are easy to make again.
  • 3. Antitoxins- They counteract the toxins caused by pathogens.
5 of 10

Using drugs to treat disease

  • When you have a disease, you take medicines, however they don't actually cure the disease, just ease the symptoms so you feel better. They relieve the symptoms but have no effect on the viruses in your tissues.
  • Antibiotics are used to actually cure the disease- by killing the bacteria. They damage the bacterial cells without harming your cells. But, because viruses take over your cells and reproduce inside them, it's very diffucult to destroy them without destroying your cells.
  • Alexander Fleming was a scientist who discovered bacteria and waanted to find a way of killing them. He was a messy scientist and left agar plates with bacteria on in his lab when he went on holiday. When he got back, he saw that around the bacteria there was a clear ring, where the bacteria had been killed. He tried to extract it but it wouldn't survive and he gave up. But he called the medicine penicillin. 10 years later, two other scientists tried again and cured some man. It is now used on a mass scale.
6 of 10

Growing and investigating bacteria

  • To find out more about microorgannisms we need to culture them. This means grow very large numbers of them so we can see the colony as a whole.
  • To culture them you must provide them with everything they need, this means giving them a gel of nutrients (a culture medium). It containd carbohydrates, minerals and chemicals. They also need warmth and oxygen.
  • This usually takes place in an agar jelly in a Petri dish. You have to take care in case the bacteria you grow mutate and become a new type of pathogen. Also you must make sure the bacteria doesn't come into contact with any other microorganisms because that will contaminate the culture.
  • To grow useful bacteria cultures you must:
  • 1. Make sure the petri dish and nutrient agar is sterilised- kills off unwanted microoragnisms. You use heat to sterilise them in an oven called an autoclave, which uses high pressure steam.
  • 2. Incolulate the sterile agar, by heating the inoculating loop in the bunsen and then making zigzags on the agar. You then need to cover them to avoid contamination.
  • 3. They must be keep warm (incubated) for a few days at 25'C. This is so you don't make pathogens that could be harmfult to people (they would have to be at 37'C (body temperature))
7 of 10

Changing pathogens

  • iI you are given an antibiotic and use it properly, the pathogens that have made you ill have died off. However some bacteria develop resistance to antibiotics and mutate (natural mutation). These produce new strains of bacteria by natural selection.
  • More types of bacteria are becoming resistant to more antibiotics, therefore diseases caused by bacteria are harder to treat. This is because the medicines are being overused, incresing the rate of mutation.
  • Picture this, an antibiotic is used and it kills 95% of bacteria, however the 5%, which are resistant, reproduce and form a colony. So this is treat with Antibiotic 2 which kills 95% of those. The 5% form a new strain and it goes on and on.
  • Hospitals use lots of antibiotics to treat infections. Due to natural selection, bacteria in hospitals are now resistant to most. So this is what happened with MRSA: when doctors move from patient ot patient, the resistant bacteria are spread easily.
  • There are ways to stop MRSA such as: Antibiotics only used when needed, Specific bacteria to be treated with specific antibiotics, Medical staff and visitors should wash their hands between patients, patients with MRSA in isolation, Hospitals kept clean.
  • Another problem is that new diseases can appear, which spread quickly because there is no treatment, for example there is a new version of flu every year.
8 of 10


  • Every cell has unique proteins on its surface called antigens. The antigens on microorganisms are different to the ones on cells inside your body and the body knows this.
  • Your white blood cells then make antibodies which join up with the antigens and destroys the pathogens.
  • Your white bllod cells can recall the right antibody used to tackle a certain antigen. Therefore if you get the disease again, you don't get ill because the body knows what to do. You become immune to that disease.
  • Some pathogens make you seriously ill quickly (i.e before your body can fight it). However you can be protected by immunisation or a vaccination.
  • This involves giving you a vaccine, which contains a dead or weakened pathogen. It triggers your bodys response to fighting pathogens. Your body learns to make the right antibodies and then i you meet the live pathogens, your body knows how to fight it and you won't get ill.
  • We can use them to fight against both bacterial and viral pathogens.
9 of 10

How do we deal with disease?

  • In the 1970s, Dr John Wilson published a report saying that the whooping cough vaccine can cause brain damage in some children. This report was based on a study group of 36 patients. The story got published and parents began to panic. The number of children being vaccinated went from 80% to 30%. People were so worried about the vaccine that they forgot that whooping cough can actually be fatal in itself. In Scotland, 100 000 children died in 12 years. When they investigated, it turned out the research was a load of rubbish and not even true. The scare story meant it was 20 years before the vaccination levels returned to normal.
  • We overuse antibiotics and a lot of new strains of bacteria are resistant to even the strongest antibiotics. Ways we are looking to find new antibiotics are:
  • 1. Penicillin and other moulds. Scientists are looking all over the world for soil that has a new type of mould in it that can be used.
  • 2. Scientists noticed that although crocodiles fight each other and leave huge bites, they never get infected, which is weird because they live in dirty water. So they have extracted a chemical from their blood and trying to turn it into an antibiotic.
  • 3. Fish are covered with a slime that prevents infection. We are trying to make an antibiotic.
  • 4. Honey has been used for years to heal wounds. Scientists found that certain types have antibiotics in them.
10 of 10


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Keeping Healthy resources »