Biology paper 1

• What is a pathogen?

  Microorganisms that cause communicable diseases
• What are examples of pathogens?

  Bacteria

  Fungi

  Protists

  Viruses
• Why do bacteria make us feel ill?

  They release toxins that damage tissues
• How can communicable diseases be spread?

  Water

  Direct contact

  Air
• How do viruses cause cell damage?

  They live and reproduce inside cells
• What are the symptoms of measles?


  Fever

  Red skin rash
• How is measles spread?

  In droplets when an infected person coughs or sneezes
• What are the symptoms of HIV?


  Initially a flu like illness
• What does the HIV virus do?

  Attacks the bodys immune system
• What is AIDS?

  The point where the immune system becomes so badly damaged it can no longer deal with other infections or cancers
• How can HIV be controlled?

  With antiretroviral drugs
• How is HIV spread?

  Unprotected sex

  Exchanging bodily fluids ,eg, blood when drug users share needles
• What are the symptoms of the tobacco mosaic virus?


  distinctive mosaic pattern of discolouration on leaves

  less chlorophyll means less photosynthesis which leads to stunted growth
• How is Salmonella spread?

  Ingesting bacteria in food

  Ingesting food that’s been prepared in unhygienic conditions
• How does the UK control the spread of salmonella?

  Vaccinating all the poultry
• What are the symptoms of Salmonella?


  Fever

  Abdominal cramps

  Vomiting

  Diarrhoea
• How is gonorrhoea spread?

  Sexual inter course
• What are the symptoms of gonorrhoea?


  Thick yellow discharge from the penis or vagina

  Pain while urinating
• How did gonorrhoea used to be treated?


  With the antibiotic penicillin
• Why can gonorrhoea no longer be treated with antibiotics?


  Many antibiotic resistant strains appeared
• How can you prevent the spread of gonorrhoea?


  Uses barrier methods of contraception eg condom

  Get tested before having sex and be treated with antibiotics
• What are the symptoms of rose black spot?


  Purple or black spots develop on leaves which turn yellow and drop off early

  Lack of chlorophyll reduces photosynthesis so growth is also affected
• How is rose black spot spread?


  Water

  Wind
• How can rose black spot be treated?


  With fungicides

  Removing and destroying affected leaves
• What are the symptoms of malaria?


  Recurrent episodes of fever
• What is the vector for malaria?


  Mosquito
• What’s the life cycle of the malaria protist?


  The mosquito bites an infected person

  The malaria pathogen is passed into the mosquito

  The mosquito then bites a different person and transfers the malaria pathogen to them

  They will now develop malaria
• How can you prevent malaria?


  Destroy mosquito breeding sites

  Use mosquito nets
• How does the skin defend us against pathogens?

  Forms a protective layer that covers the body and is difficult for microorganisms to penetrate

  Produces an oily substance called sebum which can kill bacteria
• How does the nose protect us against pathogens?

  Contains hair and mucus which traps the pathogens
• How does the trachea and bronchi protect us against pathogens?

  Covered in cilia which traps the pathogens and wafts the mucus upwards towards the throat so it can be swallowed into the stomach
• How does the stomach protect us against pathogens?


  Contains hydrochloric acid which kills pathogens
• What is phagocytosis?


  White blood cells engulf pathogens and use enzymes to destroy them
• What are antibodies?


  Protein molecules released by white blood cells

  They stick to pathogens to trigger for them to be destroyed
• What are the features of antibodies?


  They are specific to a specific pathogen

  They remain in the blood for a long time so can be used again if the pathogen re enters the body
• What are antitoxins?


  Toxins produced by white blood cells that get rid of toxins in the body
• How do vaccinations work?


  Involves injecting a dead or inactive pathogen into the body to stimulate the white blood cells to produce antibodies
• Why are vaccinations useful in the long run?

  If the same pathogen re enters the body the white blood cells respond quickly to produce the correct antibodies which prevents infection
• What is herd immunity?

  A large proportion of the population are vaccinated and therefore immune against a particular pathogen
• How does herd immunity protect those who aren’t vaccinated?

  Vaccinated people won’t catch the disease as it will be killed by their antibodies so they can’t pass the pathogen on