B1.1.2 Pathogens and Disease

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09amion
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184091
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B1.1.2 Pathogens and Disease
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2012-11-17 16:09:53
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GCSE Biology B1 Pathogens Disease
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Covers pathogens and disease topic in Biology GCSE
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  1. What causes infectious diseases?
    Pathogens, microorganisms, bacteria and viruses
  2. How do viruses differ from bacteria?
    Viruses are smaller than bacteria and are not cells
  3. How do pathogens make you feel ill?
    Pathogens reproduce rapidly inside your body; they damage your cells; they produce toxins that make you feel ill. Your body reacts to pathogens and the damage they cause/toxins they make, which also makes you feel ill
  4. Give 5 examples of things we now know we can do to reduce the spread of pathogens to lower the risk of disease, e.g. hand-washing in hospitals
    Wiping work surfaces, cleaning toilets, using tissues to blow nose, washing hands before handling food, coughing with over mouth etc.
  5. What are the 4 main ways in which infectious diseases are spread?
    Droplet infection, direct contact, contaminated food and drink and through a break in the skin
  6. What are the 3 main ways in which your body prevents pathogens from getting in?
    Skin acts as a barrier, breathing organs produce mucus to trap pathogens or acid in stomach which kills pathogens; blood uses platelets to produce clots to seal wounds
  7. Explain how diseases are spread by droplet infection
    When we cough, sneeze or talk, droplets full of pathogens pass into the air to be breathed in by someone else
  8. Explain how diseases are spread by direct contact
    Pathogens on skin are passed to someone else’s skin on contact
  9. Explain how diseases are spread by contaminated food or drink
    Pathogens can be taken in on food or in drink
  10. Explain how diseases spread through a cut in the skin
    Pathogens can get through the barrier of the skin to the tissue underneath
  11. Certain diseases mean you cannot fight infections very well. Explain why you would be less able to cope with pathogens if your blood won’t clot properly
    Pathogens cannot be stopped from getting into cuts
  12. Certain diseases mean you cannot fight infections very well. Explain why you would be less able to cope with pathogens if the number of white cells in your blood falls
    You have not got enough white blood cells to ingest pathogens or to produce antibodies/antitoxins, so pathogens are not destroyed
  13. Explain carefully how washing your hands before preparing a salad helps to prevent the spread of disease
    Prevents pathogens getting from your hands to the food
  14. Explain carefully how throwing away tissues after you have blown your nose helps to prevent the spread of disease
    Removes pathogens from where they might come into contact with other people or get on your hands
  15. Explain carefully how making sure that sewage does not get into drinking water helps to prevent the spread of disease
    Prevents pathogens from the sewage being taken in with drinking water
  16. Explain in detail how the white blood cells in your body work
    • White blood cells are part of the immune system and help our bodies fight infection. They do this by:
    • - Ingesting (taking in) pathogens, destroying them so they can’t make you ill 
    • - Producing antibodies that target particular bacteria or viruses and destroy them 
    • - Producing antitoxins. These counteract (cancel out) the toxins (poison) released by pathogens
  17. What is a pathogen?
    A microorganism that enters the body and causes disease
  18. Explain how viruses replicate inside your body
    Viruses replicate by invading your cells and using the cells machinery to produce many copies of themselves. Then they cause the cell to break open, releasing new viruses into your body

  19. What are antigens?
    Unique molecules on the surface of cells/pathogens/microorganisms
  20. What are antibodies designed to do?
    To kill/harm bacteria without killing your own body cells
  21. Why are cultures of microogranisms grown at temperatures no higher than 25 degrees in school laboratories?
    To prevent the growth of harmful pathogens
  22. What is an epidemic?
    A big outbreak of disease
  23. What is a pandemic?
    When a disease spreads all over the world
  24. Antibiotics can be used to treat certain illnesses. Why would a course of antibiotics not be suitable for treatment of flu?
    Flu is caused by a virus and antibiotics are not effective against viruses
  25. Antibiotics can be used to treat certain illnesses. What might the inappropriate use of antibiotics lead to?
    Inappropriate use of antbiotics increases the chances of antibiotic-resistant strains of bacteria emerging
  26. Describe 3 ways that white blood cells fight pathogens
    White blood cella ingest/engulf pathogens, produce antibodies that kill pathogens and produce antitoxins that counteract the pathogenic toxins
  27. Explain what vaccination involves and how being vaccinated can prevent a person from cathing the disease
    When a person is vaccinated against a disease, they are injected with dead/inactive disease bacteria. The dead/inactive bacteria carry antigens, which cause the body to produce antibodies to attack them. If the live disease infect the body after this, white blood cells can rapidly produce antibodies to kill the bacteria
  28. How do viruses make you ill?
    By cell damage
  29. What is bacteria?
    They are very small living cells, which can reproduce rapidly inside your body
  30. Viruses are not...
    Cells
  31. If something makes it through to your body, what kicks in?
    Thr immune system
  32. What 3 things in your respiratory tract, helps stop pathogens getting inside your body?
    Skin, hairs and mucus
  33. Are viruses smaller or bigger then bacterium?
    Smaller
  34. What will happen if the blood contains low numbers of platelets?
    It will clot more slowly to seal wounds
  35. How does the body prevent microoganisms getting in through cuts?
    Small fragmrnts of cells (platelets) help blood clot quickly to deal with wounds
  36. What are the 2 main types of pathogen?
    Bacteria and viruses
  37. How does bacteria make you feel ill?
    By damaging your cells anf producing toxins (poisons)
  38. When white blood cells produce antibodies, are the antibodies produced specifically to the antgen?
    Yes, the antibodies won't lock on to any antigens
  39. About how long does it take your white blood cells to learn how to deal with a new microorganism?
    A few days
  40. What does the MMR vaccine protect against?
    Measles, mumps and rubella
  41. What are common disease symptoms?
    High temperature, headaches and rashes
  42. What are disease symtoms caused by?
    The toxins produced by the pathogens. The symptoms also appear as a result of the way your body responds to the damage and toxins
  43. Why is it good if white blood cells have already produced antibodies once against a particular pathogen?
    It's good as if the person is infected with the same pathogen again, the white blood cells will rapidly produce antibodies to kill it - the person is naturally immune to that pathogen and won't get ill
  44. Name 4 diseases caused by bacteria
    • Food poisoning
    • Cholera
    • Typhoid
    • Whooping cough.
  45. Name 7 diseases caused by viruses
    • Influenza (flu)
    • Colds
    • Measles
    • Mumps
    • Rubella
    • Chicken pox
    • AIDs.
  46. Pathogens are not......they cause the.......
    Disease
  47. White blood cells do not......the pathogens, they......them
    Eat, ingest
  48. Are antibodies and antitoxins living things?
    No, they are specialised proteins
  49. Pathogens contain certain chemicals that are foreign to the body. These chemicals are called......
    Antigens
  50. What are lymphocytes?
    They are a certain type of white blood cell, which can produce specific antibodies to kill a particular pathogen
  51. How does a lymphocyte kill the pathogen?
    Each lymphocyte produces a specific type of antibody - a protein that has a chemical 'fit' to a certain antigen. When a lymphocyte with the appropriate antibody meets the antigen, the lymphocyte reproduces quickly and makes many copies of the antibody to kill the pathogen
  52. What are phagocytes?
    They are a certain type of white blood cell which ingests pathogens
  53. How can an antibody neutralise a pathogen?
    • They can bind to pathogens and damage or destroy them
    • They can coat pathogens, clumping them together so that they are easily ingested by white blood cells called phagocytes
  54. Vaccines can contain...
    • Live pathogens treated to make them harmless
    • Harmless fragments of the pathogen
    • Dead pathogens
  55. Vaccines containing harmless fragments of the pathogen acts as an antigen. Why? 
    When injected into the body, harmless fragments of pathogen stimulate white blood cells to produce antibodies against the pathogen
  56. Why don’t medicines like paracetamol actually cure your illness?
    Because they do not kill the pathogens that are making you ill - they are only painkillers
  57. What is an antibiotic?
    A drug that kills pathogenic bacteria in your body
  58. How do antibiotics work?
    They damage bacterial cells without damaging human cells
  59. Who was the first person to discover penicillin?
    Alexander Fleming
  60. What is the main difference between drugs such as paracetamol and drugs such as penicillin?
    Paracetamol relieves symptoms/makes you feel better, whereas antibiotics kill the bacteria and actually make you better
  61. How did Alexander Fleming discover penicillin?
    He noticed a clear area around mould growing on bacterial plates
  62. Why was it so difficult to make a medicine out of penicillin?
    It was difficult to get much penicillin out of the mould and it does not keep easily
  63. Who developed the industrial process which made it possible to mass-produce penicillin?
    Florey and Chain
  64. Explain why it is so much more diffi cult to develop medicines against viruses than it has been to develop antibacterial drugs
    Viral pathogens reproduce inside your cells, so it is very diffi cult to develop a drug that destroys them without destroying your cells as well
  65. Do painkillers have an effect on viruses?
    No, they will have no effect on the viruses which have entered your tissues and made you feel ill.
  66. What is agar jelly?
    A nutrient-rich medium used to culture microorganisms such as fungi and bacteria
  67. Why must everything be sterilised before you start a culture?
    To prevent contamination by microbes already on the equipment
  68. Why do we culture microorganisms in the laboratory?
    To find out more about them. To fi nd out which nutrients they need to grow and to investigate what will affect them and stop them growing
  69. When you set up a culture of bacteria in a Petri dish, you give the bacteria everything they need to grow as fast as possible. However these ideal conditions do not last forever. What might limit the growth of the bacteria in a culture on a Petri dish?
    Using up the available food and oxygen, build up of waste products such as carbon dioxide and other toxins
  70. Why is it important not to use antibiotics too frequently?
    To prevent more antibiotic-resistant strains appearing
  71. Is MRSA a bacterium or a virus?
    Bacterium
  72. (Use Figure 2) How could you explain the increase in deaths linked to MRSA?

    Increased use of antibiotics leading to more resistant bacteria, lower hygiene standards in hospitals, people failing to wash their hands between patients, visitors bringing in pathogens to hospitals
  73. (Use Figure 2) How could you explain the fall in deaths linked to MRSA, which still continues?
    Could be an improvement in cleanliness in hospital, people being more careful about hand washing or introduction and use of alcohol gels for visitors and staff in hospitals
  74. After a colony of bacteria is treated by an antibiotic, what percentage is killed and what percentage survive?
    95% of bacteria killed are by antibiotic anf 5% survive – they have a mutation which makes them resistan tto antibiotic
  75. Why can bacteria become resistant to antibiotics?
    They can mutate - sometimes the mutations can cause them to be resistant
  76. Do these mutations happen at a set time?
    No, these mutations happen by chance and they produce new strains of bacteria by natural selection.
  77. Why is it bad if some bacteria is resistant to antibiotics?
    It means that when you treat the infection, only non-resistant strains of bacteria will be killed but the resistant bacteria will survive and reproduce meaning the resistant strain will increase - which is bad. (Example of natural selection)
  78. If bacteria change or......they may become......to...... This means the medicine no longer makes you...... A......in a......or......can also lead to a new form of......
    Mutate, resistant, antibiotics, better, mutation, virus (bacterium), bacterium (virus), disease
  79. What is an antigen?
    A unique protein on the surface of a cell that identifies it
  80. What is an antibody?
    A chemical (protein) made by the white blood cells that target specific antigens
  81. Give an example of one bacterial and one viral disease which you can be immunised against
    • Bacterial - tetanus, diphtheria etc.
    • Viral - measles, mumps, rubella, polio etc.
  82. Explain how the immune system of your body works
    Every cell has unique proteins on its surface called ‘antigens’. Your immune system recognises that the antigens on the microorganisms that get into your system are different from the ones on your own cells. Your white blood cells then make antibodies to destroy the antigens/pathogens. Once your white blood cells have learnt the right antibody needed to tackle a particular pathogen, they can make that antibody very quickly if the pathogen gets into your system again, and so you are immune to that disease
  83. Explain how vaccines use your natural immune system to protect you against serious diseases
    A small quantity of dead or inactive pathogen is introduced into your body. This gives your white blood cells the chance to develop the right antibodies against the pathogen without you getting ill. Then if you meet the live pathogens, your body can respond rapidly, making the right antibodies just as if you had already had the disease
  84. Explain why vaccines can be used against both bacterial and viral diseases but antibiotics only work against bacteria
    Vaccines can be made using inactive viruses or bacteria so can stimulate antibody production against either type of pathogen thereby developing immunity. Viruses reproduce inside body cells so antibiotics cannot kill them without killing the cells of the body at the same time
  85. What is MRSA?
    A serious infection that can't be treated by antibiotics
  86. How is MRSA caused?
    Hospitals use a lot of antibiotics to treat infections. As a result of natural selection, some of the bacteria in hospitals are resistant to many antibiotics. This is what has happened with MRSA
  87. What 7 ways can we reduce the risks of mircoorganisms such as MRSA?
    • Antibiotics should only be used when they are really needed.
    • Specific bacteria should be treated with specific antibiotics
    • Medical staff should wash their hands with soap and water or alcohol gel between patients
    • They should wear disposable clothing or clothing that is regularly sterilised
    • Visitors should wash their hands as they enter and leave the hospital
    • Patients infected with antibiotic-resistant bacteria should be looked after in isolation from other patients
    • Hospitals should be kept clean – there should be high standards of hygiene
  88. Microogranisms are cultured in a...
    Culture medium
  89. What does agar jelly usually contain for the microorganisms?
    Carbohydrates, minerals, proteins and vitamins the microorganisms needs to grow
  90. Is the agar jelly hot or cold when it's poured into Petri dishes?
    Hot
  91. What are inoculating loops?
    They are wire loops that are used to transfer microogranisms to the culture medium when the agar jelly's set
  92. How are antibiotics investigated by growing microorganisms on a petri dish in agar jelly?
    Paper discs are soaked in different types of antibiotics and placed on the jelly - the antibiotic-resistant bacteria will continue to grow around them but non-resistant strains will die
  93. Why is it important to sterilise equipment when growing microorganisms in a culture medium?
    To stop unwanted microorganisms in the culture medium growing and affecting the results
  94. What 3 things must be sterilised before use to prevent contamination when growing microorganisms in a lab?
    The Petri dishes, culture medium and inoculating loops
  95. Why should the Petri dish have a lid taped on when growing microorganisms in a culture medium?
    To stop any microorganisms in the air contaminating the culture
  96. Why are cultures of microorganisms kept at 25 degrees at school and not higher?
    Cultures at a higher temperature, could allow harmful pathogens to grow
  97. In industrial conditions, why are cultures incubated at higher temperatures then 25 degrees?
    So they can grow faster
  98. Why may booster injections have to be given after period of time after the vaccine?
    Some vaccines wear off over time and so booster injections may need to be given to increase levels of antibodies again
  99. Why is it good that vaccines have been produced compared to before?
    They have helped control lots of infectious diseases that were once common in the UK (e.g polio, measles, whooping cough) Smallpox no longer exists thanks to vaccines
  100. How can epidemics be prevented with vaccines?
    They can be prevented if a large population is vaccinated as that way, even people who arn't vaccinated are unlikely to catch the disease because there are fewer people to pass it on
  101. What are the 2 disadvantages of vaccines?
    • Vaccines don't always work - sometimes they don't give you immunity
    • You can sometimes have a bad reaction to one (e.g. swelling, seizures) However, bad reactions are rare
  102. What is Ignaz Semmelweis famous for?
    Discovering that washing hands cut death rates in hospitals as huge numbers were dying from child bed fever (puerperal fever). However, he didn't know why antiseptic solution killed bacteria on doctors' hands
  103. Can viruses mutate?
    Yes
  104. Why is it bad if viruses mutate?
    It makes it hard to develop vaccines against them because the changes to their DNA can lead to different antigens
  105. What practice did Semmelweis introduce in the 1840s? Explain why this reduced death rates on the ward
    He intoduced doctors washing their hands in antiseptic solution which killed bacteria on doctors' hands and cut the death rate from 12% to 2%
  106. .......immunity involves receiving antibodies 
    Passive

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