B1 Biology Unit1

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Diet and Exercise

  • a healthy diet hs the right balance of food types. carbohydrate, fat and protein are used by the body to release energy and to build cells.
  • mineral ions and vitamins are needed to keep the body healthy. if the diet s unbalanced a person an become malnourished.
  • if you exercise, more enrgy is used. exercise increases the metabolic rate, which means the chemicl reactions in a cell work faster.
  • metabolic rate means the rate at which the reactions in your body take place.
  • the proportion of muscle to fat in your body and your inherited factors can also affect your metabolic rate.

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 the your mass will stay the same
  • long term obesity can lead to severe health problems includin type 2 diabetes (high blood sugar)
  • some people are unhealthy because they have too little food (starvation). they find it difficult to walk about and may suffer from deficiency diseases due to lack of vitamins and minerals.

Inheritance, exercise and health

  • metabolic rate can be affected by genes which you inherit.
  • two types of cholesterol:
    • good cholesterol  - for cell membranes and to make vital substances
    • bad cholesterol - can lead to heart diseae. this is only inherited into a small number of the population
  • foods rich in saturated fat can increase blood cholesterol levels
  • exercising regularly increases the metabolic rate and lowers cholesterol levels

Pathogens and disease

  • pathogens cause infectious diseases
  • they are tiny microorganisms (bacteria or viruses)
  • bacteria and viruses reproduce rapidly when they enter the body and they produce toxins which make you feel ill
  • viruses are smaller than bacteria and reproduce inside cells meaning the damage to the cells also make you feel ill.
  • before bacteria and viruses had been discovered, a doctor called Semmelweiss realised that infection could be transferred from person to prson in a hospital
  • Semmelweiss told his staff to wash their hands between treating patients. however, oter doctors did not take him seriously.

Defence mechanisms

  • the skin prevents pathogens from getting into the body
  • pathogens are also trapped by mucus and killed by stomach acid
  • white blood cells are part of the immune system. they do three things to defend the body:
    • ingest pathogens, digest and destroy them
    • produce antobodies to help destory particular pathogens
    • produce antitoxins to counteract toxins that pathogens produce

Using drugs to treat disease

  • antibiotics kill infective bacteria in the body
  • Penecillin was discovered by Alexander Fleming in 1928
  • viruses are difficult to kill because they produce inside cells so any treatment could also damage the body cells
  • painkillers are used to relieve the symtoms of disease but do not kill the pathogen
  • your immune system will usually overcome viral pathogens

Growing and investigating bacteria

  • pure cultures of non- pathogenic (safe) bacteria can be uswed for laboratory investigations
  • a culture of microorganisms can be used to find the effect of antibiotics…


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