Module 4

• What are communicable diseases caused by?

  Pathogens, including bacteria, viruses, protoctista, and fungi.
• How do pathogens cause harm to the host?

  By directly damaging tissue or releasing toxins.
• What are the different shapes of prokaryotic cells?

  • Rods
  • Spherical
  • Comma
  • Spiraled
  • Corkscrew
• What determines whether a bacterium is classified as gram-positive or gram-negative?

  The two types of cell walls present in the bacteria.
• What is the causative agent of tuberculosis?

  Mycobacterium tuberculosis or Mycobacterium bovis.
• How does tuberculosis harm the host?

  By damaging lung tissue and suppressing the immune system.
• How can tuberculosis be treated and prevented?

  It can be cured with antibiotics and prevented through vaccination.
• What is bacterial meningitis caused by?

  Streptococcus pneumoniae or Neisseria meningitidis.
• What part of the body does bacterial meningitis infect?

  The brain, specifically the meninges.
• What are the potential consequences of bacterial meningitis?

  It can spread quickly, causing septicemia and potentially resulting in death.
• What is ring rot and what does it infect?

  Ring rot is caused by Clavibacter michiganensis and infects potatoes, tomatoes, and aubergines.
• How does ring rot damage plants?

  It damages the leaves, tubers, and fruit of the infected plants.
• What are viruses classified as in terms of living status?

  Viruses are non-living and acellular.
• What are the main components of a virus?

  A virus consists of genetic material (DNA or RNA), a capsid, and attachment proteins.
• How do viruses replicate?

  Viruses can only replicate inside host cells by injecting their nucleic acid.
• What is an example of a virus that infects bacteria?

  Bacteriophage.
• What virus can lead to AIDS?

  HIV (Human Immunodeficiency Virus).
• What is the structure of HIV?

  HIV has a capsid, RNA genetic material, reverse transcriptase, an envelope, and attachment proteins.
• How does HIV attach to host cells?

  HIV uses attachment proteins to bind to CD4 proteins on helper T cells.
• What happens after HIV enters a helper T cell?

  The reverse transcriptase enzyme copies the virus's RNA into DNA.
• Why is HIV classified as a retrovirus?

  Because it converts RNA into DNA using reverse transcriptase.
• What occurs when HIV DNA enters the nucleus of a helper T cell?

  The DNA is transcribed, leading to the production of viral proteins.
• What does being HIV positive indicate?

  It means a person is infected with HIV.
• How does HIV lead to AIDS?

  By destroying helper T cells, impairing the immune response to infections and cancer.
• What virus causes influenza?

  Orthomyxoviridae.
• What cells does influenza infect?

  It infects ciliated cells in gas exchange surfaces.
• What are the potential consequences of influenza infection?

  It can kill ciliated cells, leading to harmful secondary infections like pneumonia.
• What plant virus primarily infects tobacco plants?

  Tobacco mosaic virus.
• What damage does tobacco mosaic virus cause to plants?

  It causes a mosaic pattern on leaves and can damage flowers and fruits.
• How does tobacco mosaic virus affect plant growth?

  It affects photosynthesis, preventing the plant from growing.
• What is the causative agent of malaria?

  Plasmodium, a type of protoctista.
• How is malaria transmitted to humans?

  Through mosquitoes, which act as vectors.
• What are the reproductive methods of Plasmodium?

  It can reproduce both sexually and asexually within mosquitoes and humans.
• What does Plasmodium infect in humans?

  It infects red blood cells, the liver, and the brain.
• What is the causative agent of potato blight?

  Phytophthora infestans.
• What type of organism causes potato blight?

  A fungus-like protoctista.
• How does potato blight damage plants?

  It causes damage to the leaves and fruit through hyphae.
• What is the first example of a pathogenic fungus mentioned?

  Black sigatoka, caused by Mycosphaerella fijianis.
• What does black sigatoka primarily infect?

  It mainly infects bananas.
• How does black sigatoka affect banana plants?

  It causes damage to the leaves, turning them black and preventing photosynthesis.