Health, disease & development of medicines

• What is the definition of health according to the World Health Organisation (WHO)?

  A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.
• Why is it important to consider social and lifestyle factors in health?

  Because health encompasses multiple aspects beyond just the absence of disease.
• What are communicable diseases?

  Diseases that can be transferred between individuals.
• How can communicable diseases be transmitted?

  Through air particles, faeces, or bodily fluids.
• What are some examples of communicable diseases?

  Viral infections like flu, bacterial infections like the common cold, and parasitic infections.
• What are non-communicable diseases?

  Diseases that cannot be transferred between individuals.
• What typically causes non-communicable diseases?

  Genetic components or lifestyle factors.
• What is an example of a condition that increases susceptibility to other diseases?

  Having HIV.
• How does having HPV affect a woman's health?

  It can increase her risk of developing cervical cancer.
• What is the definition of a pathogen?

  An organism which causes disease.
• How do pathogens spread?

  Through direct contact, water, or air.
• What are the main types of pathogens?

  Viruses, bacteria, fungi, and protists.
• How do viruses replicate?

  By using the host cell's machinery to make copies of themselves.
• What happens to a host cell when it is infected by a virus?

  The cell bursts, releasing copies of the virus into the bloodstream.
• How do bacteria reproduce?


  By dividing through a process called binary fission.
• What do bacteria produce that can damage cells?

  Toxins.
• What are fungi made of?

  Hyphae, which are thread-like structures.
• How do protists cause damage?

  By being parasitic and using hosts like humans and animals.
• What are some common infections and their pathogens?

  • Cholera: Bacteria (Vibrio cholerae) - Diarrhoea, spread by water.
  • Tuberculosis: Bacteria (Mycobacterium tuberculosis) - Lung damage, airborne.
  • Chalara ash dieback: Fungi (Hymenoscyphus fraxineus) - Leaf loss, airborne.
  • Malaria: Protists (Plasmodium falciparum) - Damage to blood and liver, animal vector (mosquito).
  • HIV: Virus (Human Immunodeficiency Virus) - Destroys white blood cells, body fluids.
  • Helicobacter: Bacteria (Helicobacter pylori) - Can lead to stomach ulcers, oral transmission.
  • Ebola: Virus (B. ebolavirus) - Causes hemorrhagic fever, body fluids.
• What are the methods of pathogen spread?

  Direct contact, by water, and by air.
• How can the spread of disease be limited?

  By improving hygiene, reducing contact, removing vectors, and vaccination.
• What is the purpose of vaccination?

  To make an individual immune to a certain disease.
• What are the two pathways a virus can use to reproduce?

  Lytic pathway and lysogenic pathway.
• What are the steps in the lytic pathway of a virus?

  1. Virus replicates its DNA using host cell machinery.

  2. New virus particles are assembled.

  3. Host cell bursts (lysis), releasing virus particles.

  4. The process repeats with nearby cells.
• What are the steps in the lysogenic pathway of a virus?

  1. Virus inserts its DNA into host cell DNA or cytoplasm.

  2. Host cell replicates, copying viral DNA.

  3. The lytic cycle begins with assembly of new viral particles.
• What are sexually transmitted infections (STIs)?

  Infections spread through sexual contact.
• How can the spread of STIs be reduced?

  By using barrier methods of contraception or abstaining from sexual activity.
• What are the physical barriers plants use against disease?

  • Thick cellulose cell wall.
  • Thick waxy cuticle on leaves.
  • Layer of bark on trees.
  • Closing stomata to prevent pathogen entry.
• What are the chemical barriers plants use against disease?

  • Production of antimicrobial chemicals, proteins, and enzymes.
  • Release of compounds to attract larger insects that feed on pests.
  • Extraction of antimicrobial compounds for use in drugs.
• What are the symptoms of Chlamydia?

  Often symptomless, but can include painful urination or pelvic pain.
• What are the symptoms of HIV?


  Increased susceptibility to other infections, severe illness, and death if untreated.
• What are the visible clues for identifying plant diseases in the field?

  • Malformations and browning of leaves (Chalara dieback).
  • Discolouration of leaves (Tobacco mosaic virus).
  • Loss of leaves and pus-filled lesions on trunk (Bacterial canker).
  • Structural damage caused by aphids.
• What are the laboratory techniques for identifying plant diseases?

  1. Take cuttings from the diseased plant.

  2. Grow the pathogen on a culture medium/agar plate.

  3. Test and identify the pathogen using an ELISA kit.
• What are the physical barriers in the human body against pathogens?

  • Mucus produced by goblet cells traps pathogens.
  • Cilia waft away mucus to be killed by stomach acid.
  • Skin provides a physical barrier against pathogens.
• What are the chemical barriers in the human body against pathogens?

  • Lysozymes used by white blood cells to kill bacteria.
  • Hydrochloric acid in the stomach kills bacteria in food.
• What is the specific immune response?

  • Phagocytosis: White blood cells engulf and destroy pathogens.
  • Antibody production: Antibodies bind to pathogens, clumping them for easier engulfment.
  • Memory lymphocytes: Provide faster response upon re-infection, leading to immunity.
  • Antitoxins: Neutralize toxins released by pathogens.
• What is the purpose of immunisation?

  To make an individual immune to a certain disease.
• What is an antigen?


  An antigen is a structure on the surface of a pathogen that a specific complementary antibody can bind to.
• What happens when antibodies bind to a pathogen?

  The pathogens start to clump together, making it easier for white blood cells to find and engulf them.
• What role do memory lymphocytes play in the immune response?

  Memory lymphocytes trigger the production of specific complementary antibodies at a faster rate upon re-infection.