Some biology to get you started

Biology Unit 1 : 

29/12/2011 Biology Unit 1 W Richards The Weald School (AQA)

Balanced diet : 

29/12/2011 Balanced diet A balanced diet should contain fats, proteins and carbohydrates in roughly these amounts: It should also contain water, vitamins, minerals and fibre.

Poor diets : 

29/12/2011 Poor diets If we don’t have a balanced diet we may suffer form a “deficiency symptom”. You don’t need to know all of these links but they show what can happen to your body…

Metabolic Rate and health : 

29/12/2011 Metabolic Rate and health The rate at which our bodies carry out chemical reactions is called the “metabolic rate”. This rate varies with: The amount of work we do The amount of fat in our body Inherited factors

Modern diets and health problems : 

29/12/2011 Modern diets and health problems This happens when the body is taking in more energy then it is “burning”.

Heart disease : 

29/12/2011 Heart disease The amount of cholesterol in the body can be lowered using drugs called “statins”.

Conditions caused by increased weight : 

29/12/2011 Conditions caused by increased weight Obesity is a condition caused by excess weight. This can also lead to the following diseases:

Microbes : 

29/12/2011 Microbes Microbes are micro organisms that can cause diseases. They can enter the body in a number of ways: …or other natural openings…

Disease : 

29/12/2011 Disease A disease is any condition where the body isn’t working as it should. This could be caused by a malfunction in the body (as with diabetes) or it could be caused by a type of PATHOGEN (a microbe that causes disease): Viruses Bacteria 1/1000th mm big Living cells (some are harmless) Grow very quickly Affected by antibiotics Examples: food poisoning, tetanus, sore throats 1/1,000,000th mm big Genetic info inside a protein coat Not affected by antibiotics Release poisons Examples: colds, flu, polio, chicken pox

Microbes: our defence against them : 

29/12/2011 Microbes: our defence against them Our bodies have four major defence mechanisms against invading microbes:

Fighting disease : 

29/12/2011 Fighting disease If microbes enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS: White blood cells do 3 things: They eat the microbe They produce antibodies to neutralise the microbe The produce antitoxins to neutralise the poisons produced by microbes

Producing antibodies : 

29/12/2011 Producing antibodies Step 1: The white blood cell “sees” the pathogen (microbe) Step 2: The cell produces antibodies to “fit” the pathogen Step 3: The antibodies fit onto the pathogens and cause them to “clump” Step 4: The pathogens are “eaten” by the white blood cells You’re going down

Specific antibodies : 

29/12/2011 Specific antibodies Antibodies are specific – they will neutralise the microbe they have been made for.

Fighting disease : 

29/12/2011 Fighting disease NATURAL IMMUNITY This is when antibodies are produced by a person when needed or they are passed on by the mother during pregnancy. ARTIFICIAL IMMUNITY Can be done in two ways: A vaccine with dead microbes is injected – the body is “tricked” into producing antibodies ready for the real thing. This is called PASSIVE IMMUNISATION The antibodies are injected directly into the body – this is called ACTIVE IMMUNISATION.

Using Antibiotics : 

29/12/2011 Using Antibiotics Antibiotics can be used to kill bacteria. However, there are two problems: 1) Overuse of antibiotics can lead to bacteria becoming resistant (e.g. the MRSA “superbug”). This means that antibiotics must be used sparingly. 2) Antibiotics have no effect on a virus, like the common cold. It is difficult to kill a virus without damaging body tissue. A virus is usually allowed to “run its course”.

Resistance to antibiotics : 

29/12/2011 Resistance to antibiotics Although vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new, resistant “strain”: Mutation – some strains of bacteria can develop _______ to the antibiotics. The non-resistant bacteria are _____ by the _______. The resistant bacteria _______ and pass on their mutations to their ______. Don’t use antibiotics unless you need to!! No effect!! Words – offspring, resistance, killed, antibiotics, reproduce

Using Painkillers : 

29/12/2011 Using Painkillers Painkillers are drugs used to relieve the symptoms of disease but without killing the pathogens, for example:

The spread of infection : 

29/12/2011 The spread of infection Guten tag. In the mid-19th century I realised that many deaths in hospitals could be avoided by insisting on clean hands and equipment. As a result of my work deaths in my wards fell from 12% to 1%. More people die due to infections from hospitals than on the roads in Britain. Hospitals have been trying to improve hygiene standards:

Growing micro organisms : 

29/12/2011 Growing micro organisms Method: Questions: Why are you sterilising the loop? What does the agar do? Why is the lid not sealed all the way around? Why would you not want to culture your bacteria at 37OC?