Disease, Defence, and Treatment

• What role do most microorganisms play in nature?

  Most are harmless and perform vital roles such as decomposition and digestion.
• What are pathogens?

  Microorganisms that cause disease.
• What types of microorganisms can be pathogens?

  Bacteria, viruses, protist, and fungi.
• What is the structure of a bacterial cell?

  Cell wall, cell membrane, cytoplasm, plasmid DNA, no nucleus.
• What is the structure of a virus?

  Genetic material (DNA or RNA) inside a protein coat.
• How can communicable diseases be spread?

  By contact, aerosol, body fluids, water, insects, and contaminated food.
• How does HIV affect the body?

  It attacks the immune system.
• How can HIV be prevented?

  Use protection, avoid sharing needles, and screen blood.
• What is Chlamydiaand how does it affect the body?

  A bacterial STI that can cause infertility.
• How is Chlamydia prevented?

  Using condoms and regular testing.
• What causes malaria and how is it spread?

  A protist (Plasmodium) spread by mosquitoes.
• How is malaria prevented?

  Mosquito nets, insecticides, and controlling mosquito population.
• What are physical body defences against pathogens?

  Skin, mucus, hairs in the nose.
• What are chemical body defences against pathogens?

  Stomach acid and enzymes in tears/saliva.
• What are the roles of phagocytes?

  Engulf and digest pathogens.
• What are the roles of lymphocytes?

  Produce antibodies and antitoxins.
• What is an antigen?

  A molecule on a pathogen that triggers an immune response.
• What do antibodies do?

  Bind to antigens and help destroy pathogens.
• What do antitoxins do?

  Neutralise toxins produced by pathogens.
• What is a vaccine?

  A substance containing antigens that stimulates antibody production.
• Why might parents be hesitant to vaccinate?

  Concerns about side effects or misinformation.
• How do vaccines protect against disease?

  They stimulate lymphocytes to produce antibodies.
• What are memory cells?

  Lymphocytes that remember an antigen and respond quickly on re-infection.
• What is immunity?

  Protection from a disease due to memory cells and rapid antibody response.
• Why don’t antibiotics work on viruses?

  Viruses do not have cell walls and live inside host cells.
• How does antibiotic resistance develop?

  Through overuse or misuse of antibiotics.
• What is MRSA?

  A strain of bacteria resistant to several antibiotics.
• How can MRSA be controlled?

  Hygiene, isolating patients, and only prescribing antibiotics when necessary.
• How can some diseases be prevented?

  With drugs or other therapies.
• Why is drug testing necessary?

  To detect side effects and ensure safety and effectiveness.
• What are the ethical issues of drug development?

  Use of animals, human safety, cost, and accessibility.
• What is the preclinical testing process?

  Testing on cells, tissues, and animals.
• What is the clinical testing process?

  Testing on healthy volunteers then small groups of patients.
• How are monoclonal antibodies produced?

  By fusing lymphocytes with tumour cells to make hybridomas.
• What are monoclonal antibodies used for?

  Diagnosis, tissue typing, tracking malaria, and targeted cancer therapy.
• What is HIV/AIDS caused byand how is it transmitted?

  A virus transmitted through body fluids