B3-Infection and response

• What are pathogens?

  Microorganisms which cause infectious disease
• What are four types of pathogen?

  Viruses, protists, bacteria, fungi
• Put the four types of pathogen in order from smallest to largest

  (smallest) viruses → bacteria → fungi → protists (largest)
• How can pathogens be spread?

  • Through air • Through direct contact • Through water (or other ingested substances like food)
• Give three words that decsribe diseases that are easily spread

  Contagious, Communicable, Infectious
• How can the spread of disease can be reduced or prevented?

  • Hygiene e.g. washing hands before cooking/after sneezing • Destroying vectors e.g. using insecticides or destroying insects' habitats so that they can't breed • Isolating infected individuals • Vaccination
• How do bacteria make us feel ill?

  they may produce poisons (toxins) that damage tissues and make us feel ill
• How do viruses make us feel ill?

  they live and reproduce inside cells, causing cell damage
• Name three viral diseases

  • Measles • HIV • Tobacco mosaic virus
• What are the symptoms of measles?

  Fever and red skin rash
• How dangerous is measles?

  it can be fatal if there are complications For example, it can lead to pneumonia or a brain infection called encephalitis
• How is measles spread?

  when someone inhales droplets of fluid from an infected person's sneeze or cough
• How can measles be treated?

  Most people are vaccinated against it when they're young If not vaccinated, the disease cannot be treated (although symptoms may be able to be treated)
• What are the symptoms of HIV?

  • initially a flu-like illness • then, unless controlled with antiretroviral drugs, the virus attacks the body's immune cells • Late stage HIV infection, or AIDS, occurs when the body's immune system becomes so badly damaged it can no longer deal with other infections or cancers
• How is HIV spread?

  • Sexual contact • Exchanging bodily fluids, such as blood (e.g. when drug users share needles)
• HIV can't be treated; how can it be prevented?

  Barrier contraception (like condoms), or not sharing needles
• What are the symptoms of TMV (tobacco mosaic virus)?

  • Causes a mosaic pattern on leaves (which means parts become discoloured) • Discolouration means that plants can't carry out photosynthesis as well so TMV also inhibits growth
• TMV can't be treated; how can it be prevented?

  Field hygiene and pest control.
• Name two bacterial diseases

  • Salmonella • Gonorrhea
• What are the symptoms of salmonella?

  • fever • stomach cramps • vomiting • diarrhoea
• How is salmonella spread?

  It is foodborne: eating food contaminated with salmonella bacteria.
• How can salmonella be prevented?

  • Food hygeine • Most poultry in the UK is vaccinated against salmonella to control the spread
• What are the symptoms of gonorrhea?

  • Pain when urinating • Thick yellow/green discharge from the vagina or penis
• How is gonorrhoea spread?

  by sexual contact
• How is gonorrhoea treated?

  Antibiotics
• How should gonorrhea be prevented?

  Barrier contraception, e.g. condoms
• What type of pathogen causes rose black spot?

  Fungi
• What are the symptoms of rose black spot?

  • Causes purple/black spots to develop on the leaves of rose plants • The leaves can then turn yellow and drop off • Less photosynthesis can happen, so growth is also inhibited
• How is rose black spot spread?

  Through water and wind.
• How can rose black spot be treated?

  • Using fungicides • Removing the affected leaves, which should be destroyed so that the fungus can't spread to other plants
• What type of pathogen causes malaria?

  A protist
• What are the symptoms of malaria?

  Causes repeating episodes of fever
• How dangerous is malaria?

  It can be fatal
• How is malaria spread?

  • mosquitos pick up the protist when feeding on an infected animal • the mosquito infects a new animal by inserting the protist into the animal's blood vessels
• How can the spread of malaria be reduced?

  • stopping mosquitoes from breeding • using mosquito nets to avoid being bitten
• What are the non-specific defence systems of the human body?

  • skin • nose • trachea and bronchi • stomach
• How does our skin prevent disease?

  Skin acts as a barrier and secretes antimicrobial substances which kill pathogens
• How does our nose prevent disease?

  Hairs and mucus in the nose trap particles that could contain pathogens
• How do our trachea and bronchi prevent disease?

  • they secrete mucus to trap pathogens • they are lined with ciliated cells which move the mucus up to the back of the throat, where it can be swallowed
• How does our stomach prevent disease?

  hydrochloric acid in the stomach kills bacteria