Pathogens and transmission of diseases

• What is the definition of health?

  Health is the state of complete physical, mental, and social wellbeing, not merely the absence of disease.
• What is disease?

  Disease is a departure from good health causing identifiable symptoms.
• What types of symptoms can diseases cause?

  Symptoms can be physical, mental, or social.
• What is the difference between acute and chronic diseases?

  • Acute diseases: Symptoms appear quickly.
  • Chronic diseases: Symptoms last for months or years.
• What are communicable diseases?

  Communicable diseases are caused by pathogens and can spread between organisms.
• What types of organisms can cause communicable diseases?

  Bacteria, viruses, fungi, and protoctists.
• What are pathogens?

  Pathogens are microorganisms that cause disease.
• How can communicable diseases affect health beyond physical symptoms?

  They may also affect mental and social health.
• How do fungi cause disease in animals?

  Fungi live in the skin, send out hyphae, and release spores.
• How do fungi cause disease in plants?

  Fungi live in vascular tissue and release enzymes causing decay.
• What are protoctists?

  Protoctists are eukaryotic single-celled organisms.
• How do protoctists cause disease?

  They enter host cells and feed on cell contents.
• Name two diseases caused by protoctists.

  1. Malaria – caused by Plasmodium spp.
  2. Tomato/potato late blight – caused by Phytophthora infestans.
• Fill in the table for Tuberculosis: disease, pathogen type, affected organism(s), and features.

  • Disease: Tuberculosis.
  • Pathogen type: Bacterium.
  • Organisms affected: Humans.
  • Features: Affects lungs, causes coughing, fever, and weight loss.
• Fill in the table for Ring rot: disease, pathogen type, affected organism(s), and features.

  • Disease: Ring rot.
  • Pathogen type: Bacterium.
  • Organisms affected: Potatoes and tomatoes.
  • Features: Causes discolouration and decay of vascular tissues.
• Fill in the table for AIDS: disease, pathogen type, affected organism(s), and features.

  • Disease: AIDS.
  • Pathogen type: Virus (HIV).
  • Organisms affected: Humans.
  • Features: Weakens the immune system by destroying T helper cells.
• Fill in the table for Tobacco mosaic virus: disease, pathogen type, affected organism(s), and features.

  • Disease: Tobacco mosaic virus.
  • Pathogen type: Virus.
  • Organisms affected: Tobacco and other plants.
  • Features: Causes mottling and discolouration of leaves, stunting growth.
• Fill in the table for Black sigatoka: disease, pathogen type, affected organism(s), and features.

  • Disease: Black sigatoka.
  • Pathogen type: Fungus.
  • Organisms affected: Bananas.
  • Features: Causes black streaks on leaves, reducing photosynthesis and yield.
• Fill in the table for Athlete’s foot: disease, pathogen type, affected organism(s), and features.

  • Disease: Athlete’s foot.
  • Pathogen type: Fungus.
  • Organisms affected: Humans.
  • Features: Causes itching, flaking, and redness on the skin of the feet.