Biology - B1.1 - Keeping Healthy

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B1.1.1 - Diet and Exercise

  • Healthy diet = right balance of food types
  • Carbohydrate, fat and protein are used for energy and building cells
  • Mineral ions and vitamins are needed to keep the body healthy
  • Unbalanced diet = malnourishment
  • Exercise = more energy used = increased metabolic rate - chemical reations in cells work faster
  • Muscle to fat proportion and inherited factors also affect metabolic rate
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B1.1.2 - Weight Problems

  • Important for good health to get energy balance correct
  • If energy taken in = energy used: mass will stay the same
  • Too much food leads to obesity
  • Long term obesity can lead to severe health problems, eg. type 2 diabetes
  • These can be reduced by eating less carbohydrates and doing more exercise
  • Unhealthiness can be caused by starvation
  • Walking can be difficult and deficiency diseases may occur.
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B1.1.3 - Inheritance, Exercise and Health

  • Metabolic rate can be affected by genes inherited from parents
  • There are two types of cholesterol:
      - 'Good' cholesterol is needed for cell membranes and to make vital substances
      - 'Bad' cholesterol can lead to heart disease - small numbers of the population inherit high levels of this
  • Foods rich in saturated fats can also increase blood cholesterol levels
  • Regular exercise increases metabolic rate and lowers high cholesterol levels
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B1.1.4 - Pathogens and Disease

  • Pathogens = infectious disease
  • Pathogens are tiny microorganisms - usually bacteria or viruses
  • Bacteria and viruses reproduce rapidly within the body and the toxins they produce make you feel ill
  • Viruses are smaller than bacteria and reproduce inside the cells - the damage to the cells also makes you ill
  • Because viruses are inside the cells, it is impossible to kill the virus without killing the cell
  • Before discovery, Semmelweiss realised infection could be transferred though people in a hospital - he told his staff to wash their hands but no one believed him, however, he was in fact right
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B1.1.5 - Defence Mechanisms

  • Skin prevents entry of pathogens
  • Pathogens are also trapped by mucas and killed by stomach acid
  • White blood cells are part of the immune system and do three things to defend the body:
    • Injest pathogens - digest and destroy them
    • Produce antibodies to help destroy particular pathogens
    • Produce antitoxins to counteract toxins made by the pathogens
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B1.1.6 - Using Drugs to Treat Disease

  • Antibiotics kill infective bacteria in the body
  • Penicillin is an antibiotic, discovered by Alexander Fleming in 1928
  • Viruses are difficult to kill as they reproduce within cells, so any treatment could also damage the body cells
  • Painkillers and other drugs can relieve symptoms of a disease but don't kill the pathogen
  • The immune system will usually overcome pathogens
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B1.1.7 - Growing and Investigating Bacteria

  • Cultures can be used to find the effect of antibiotics on bacteria
  • Investigations need uncontaminated cultures
  • Contamination could come from skin, the air, soil or water
  • Contaminated cultures could result in other bacteria growing
  • To grow microorganisms, a liquid/gel is needed for nutrients, containing carbohydrates, minerals and sometime chemicals - a culture medium - agar jelly is mostly used
  • Warmth and oxygen is needed, and labs keep them at 25C (school) or 35C (industry)
  • All bacteria on equipment must be killed to keep the culture pure and microorganisms in the air must be prevented from getting on the equipment
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B1.1.8 - Changing Pathogens

  • Some pathogens, especially viruses, can mutate
  • Few people are immune to mutations so the disease can spread easily
  • Epidemic - spread across a country, Pandemic - spread across countries
  • The MRSA 'super bug' is a bacterium evolved through natural selection
  • MRSA and other bacterium have become immune to common antibiotics
  • Muatations of pathogens = new strains - some resistant to antibiotics
  • Antibiotics kill individual pathogens of the non-resistant strain
  • The resistant bacteria survive, reproduce and create a whole population of a resistant strain - natural selection
  • Antibiotics shouldn't be used on mild infections in order to slow down the rate of development of resistant strains
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B1.1.9 - Immunity

  • Dead/Inactive forms of a disease are used to make vaccines
  • The white blood cells react by producing antibodies
  • The person is made immune as further infection is prevented because the body responds quickly by producing more antibodies, as they can remember the previously used antibodies that were created due to the vaccine
  • The antibodies recognise the antigen (protein shape) on the pathogen
  • The MMR vaccination/immunisation is one of several vaccines
  • MMR is used to treat Measles, Mumps and Rubella
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B1.1.10 - How Do We Deal With Disease

  • Most people in population need to be vaccinated to prevent serious diseases
  • Some diseases, such as measles, can have long term effects - such as deafness or sometimes death
  • Vaccines can occasionally have side effects, so there are advantages as well as disadvantages
  • Antibiotics being overused can lead to new strains of bacteria developing
  • You aren't given any perscription antibiotics for mild infections
  • Scientists are always trying to find new ways of curing diseases
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