Biology Infection & Response

• Model answer notes by @biologywitholivia
• Topic 3.1 Communicable diseases


  • 3.1.1 Communicable diseases
  • 3.1.2 Viral diseases
  • 3.1.3 Bacterial diseases
  • 3.1.4 Fungal diseases
  • 3.1.5 Protist diseases
  • 3.1.6 Human defence systems
  • 3.1.7 Vaccination
  • 3.1.8 Antibiotics & painkillers
  • 3.1.9 Discovery & development of drugs

  
• Topic 3.2 Monoclonal antibodies


  • 3.2.1 Producing monoclonal antibodies
  • 3.2.2 Uses of monoclonal antibodies
• Topic 3.3 Plant disease


  • 3.3.1 Detection & identification of plant diseases
  • 3.3.2 Plant defence responses
• Pathogens


  Microorganisms that cause infectious disease
• Pathogens


  • Bacteria
  • Viruses
  • Protists
  • Fungi
• How bacteria make us ill


  • Reproduce rapidly inside the body
  • Produce toxins (poisons) that damage cells
• How viruses make us ill


  • Live and replicate rapidly inside cells
  • Causing cell damage eg. cell bursts

  
• How pathogens can be spread


  • Direct contact
  • By water
  • By air
• Ways to reduce or prevent the spread of diseases


  • Hygiene
  • Vaccination
  • Isolation
  • Destroy vectors

  
• Not all microorganisms are pathogens / bad
• Viruses are not cells
• A pathogen is a microorganism that causes disease
• Measles


  • Fever
  • Red skin rash
• HIV


  • Initially a flu-like illness
  • Often no symptoms for years
  • If AIDS develops - recurrent infections + longer recovery

  
• Tobacco mosaic virus (TMV)


  • 'Mosaic' pattern of discolouration on leaves
  • Restricted growth due to lack of photosynthesis
• How measles is spread

  Inhalation of droplets from sneezes / coughs from infected people
• How HIV is spread


  • Sexual contact
  • Exchange of body fluids eg. blood when drug users share needles
• How TMV is spread


  Direct contact between diseased / healthy plants
• Ways to reduce or prevent the spread of measles


  • Most young children vaccinated against measles
  • Isolation

  
• Ways to reduce or prevent the spread of HIV


  • Antiretroviral drugs control HIV (to stop AIDS developing)
  • Avoid sexual intercourse / use a condom
  • Do not share needles
• Ways to reduce or prevent the spread of TMV


  • Remove infected plants / leaves
  • Wash tools in disinfectant after using on infected plant
• HIV is an infection caused by a virus whereas AIDS is the consequences in the body from HIV infection
• HIV can be controlled with antiretroviral drugs but they do not eliminate HIV completely
• Antibiotics are only effective against bacteria
• Why TMV causes restricted growth in plants


  • Less chlorophyll so less photosynthesis
  • So less glucose produced
  • So less energy released for growth as glucose is needed for respiration
  • Less proteins / cellulose for growth as glucose needed for making these
• Antibiotics are only effective against bacteria / do not kill viruses
• Reasons for the decrease in the number of new HIV cases in recent years


  • Better education (into prevention of spread of HIV)
  • Condoms more widely available / easier to source / cheaper
  • New / better drugs / antiretrovirals to prevent HIV spread
  • Better / more testing / identification of people with HIV
• Salmonella food poisoning


  • Fever, abdominal cramps, vomiting & diarrhoea
  • Due to toxins (poisons) secreted by bacteria
• Gonorrhoea


  • Thick yellow / green discharge from vagina or penis
  • Pain on urinating
• How Salmonella food poisoning is spread


  • Bacteria ingested in food (eg. chicken)
  • Or on food prepared in unhygienic conditions
• How gonorrhoea is spread


  Sexually transmitted disease (STD) so spread by sexual contact
• Ways to reduce or prevent the spread of Salmonella food poisoning


  • Poultry eg. chickens vaccinated
  • Wash hands before preparing food / disinfect surfaces
• Ways to reduce or prevent the spread of gonorrhoea


  • Antibiotics
  • Use of barrier methods of contraception eg. condoms
• Poultry are vaccinated, not humans
• Chickens can carry the Salmonella bacteria, but it only causes food poisoning (the disease) in humans
• Warmer weather


  Bacteria reproduce faster
• Other ways farmers could prevent the transmission of Salmonella from chickens to humans


  • Give chickens antibiotics
  • Don't sell infected chickens / eggs
  • Keep infected chickens isolated
  • Slaughter infected chickens
• Reasons why the number of cases of Salmonella food poisoning has decreased


  • Improved hygiene for food preparation
  • Vaccination of poultry
• Rose black spot


  • Purple / black spots on leaves
  • Leaves often turn yellow & drop early
  • Affects growth of plant as photosynthesis is reduced