General

• Antibodies are proteins that circulate around the body to detect foreign substances (antigens)
• What are symptoms of gonorrhoea?

  Pain when urinating

  Yellow discharge
• Gonorrhoea is treated with an antibiotic. HIV is another sexually transmitted disease. Explain why prescribing an antibiotic will not cure HIV.

   

  HIV is a virus and antibiotics are only effective against bacteria
• The substances made by white blood cells to kill pathogens are called antibodies.
• The substances made by white blood cells to counteract poisons produced by pathogens are called antitoxins
• Medicines which kill bacteria are called antibiotics
• What are the 3 diseases The MMR vaccine protects people against?

  Measles

  mumps

  rubella
• Name one disease thalidomide is used to treat now.

  Leprosy
• Reasons why drugs are trialled

  Side effects

  Dosage
• What are new drugs tested on in a laboratory?

  Animals
• The genetic material is arranged differently in the cells of bacteria compared with animal and plant cells. Describe two differences.

  may have plasmids

  only has one chromosome
• What does a vaccine contain?

  Dead pathogens
•  

  Explain how a vaccination prevents infection.


  White blood cells produce antibodies which produce rapidly killing pathogens
• Describe two ways the body prevents the entry of microorganisms.

  acid in the stomach kills pathogens in food

   skin forms a barrier
• Name three chemical substances transported by the plasma

  amino acids

  antibodies

  antitoxins
• Suggest how an infection with Helicobacter pylori might result in a stomach ulcer developing.

  bacteria not killed and so they damage mucus lining so acid causes an ulcer
• Helicobacter pylori can also cause stomach cancer. Describe how a person infected with Helicobacter pylori could also develop liver cancer

  if the cancer is malignant cells can spread to other organs via the blood forming a secondary tumour
• Drugs must be trialled before the drugs can be used on patients. Give three reasons why.

  Toxicity

  interaction with other drugs

  dosage
• Explain how vaccination makes a person immune to a disease

  Dead pathogens stimulate white blood cells

  To produce antibodies Made quickly on reinfection
• How does nicotine cause a person to become addicted?


  Alters body chemistry
• Suggest how the ‘nicotine vaccine’ might help wean a smoker off nicotine.

  if nicotine taken, antibodies bind to nicotine molecules

  making them too large to get to brain
•  

  There has been a large increase in the populations of many antibiotic-resistant strains of bacteria in recent years. Explain why.

  non-resistant strains killed so less competition
• Suggest how the spread of the lungworm disease can be prevented.

  destroy the snails

  isolate infected dogs

  treat infected dogs
• Describe two ways to control the spread of malaria.

  Use mosquito nets

  Take antimalaria tablets
• Give two ways that white blood cells protect us against pathogens.

  produce antitoxins

  engulf microorganisms
• What does the doctor inject into the child to make the child immune to measles?

  Dead pathogens
• Vaccination against the measles virus will not protect the child against the rubella virus. Why?

  antibodies are specific or needs different antibodies
• What is the advantage of vaccinating a large proportion of the population against measles?

  reduces spread of infection
• Explain how the nettle is adapted for defence and protection.

  stinging hairs which harm herbivores stopping animals eating them so less of the plant is removed
• Why is chlorophyll important for plants


  Absorbs light for photosynthesis
• What could farmers do to make crops grow on the cleared land for more than three years?

  Add fertiliser

  add manure
• White blood cells are part of the immune system
• Phagocytes engulf bacteria by phagocytosis, destroying it with enzymes inside the cell.
• Lymphocytes produce antibodies that bind to antigens on pathogen surfaces, marking them for destruction by other WBCs.
• White blood cells help the body to defend itself against pathogens.
• Gluten is a form of protein found in some grains. Describe the test you would use to find out if protein is present in food.

  add Biuret reagent to food sample mauve shows protein present
• Symptoms of coeliac disease include poor growth. Suggest why a person with coeliac disease might have this symptom

  damaged villi reduce surface area for absorption so less amino acids and glucose absorbed with less glucose transfer of energy from respiration is reduced and fewer amino acids available to build new proteins