4.1: Communicable diseases

Question 1

What is a pathogen?

Answer 1

A microorganism that causes disease

Question 2

How does bacteria harm?

Answer 2

Once in host cell they can multiply rapidly. Their presence can cause disease by damaging cells or by releasing waste products/toxins that are toxic to host cell

Question 3

How does fungi harm (animals)?

Answer 3

Common fungal infections occur where fungus lives in the skin of animals and where its hyphae (form a mycelium), grow under the skin surface.
Fungus sends out specialised reproductive hyphae which grows to surface of skin and releases spores which causes redness and irritation

Question 4

How does fungi harm (plants)?

Answer 4

Fungus lives in vascular tissue. Hyphae release extracellular enzymes - digests surrounding tissue which causes decay

Question 5

How does viruses harm?

Answer 5

Invade cells and take over genetic machines and other organelles. This causes cell to manufacture more copies of the virus. Host cell eventually bursts, releasing many new viruses which will infect healthy cells

Question 6

How do protists harm?

Answer 6

Cause harm by entering host cells and feeding on the contents as they grow

Question 7

What are types of bacterial infections?

Answer 7

• TB
  Kills cells and tissues, lungs are most affected
• Bacterial meningitis
  Membranes that surround brain and spinal cord become swollen and may cause damamge to the brain and nerves
• Ring rot
  Ring of decay in the vascular tissue of a potato tuber or tomato, accompanied by leaf wilting

Question 8

What are types of fungal diseases?

Answer 8

• Black sigatoka
  Causes leaf sprouts on banana plants reducing yield
• Ringoworm (cattle)
  Growth of fungus in skin with spore causes erupting through skin to cause rash
• Athlete’s foot
  Growth under skin of feet

Question 9

What are types of viral infections?

Answer 9

• HIV/AIDS
  Attacks cells in the immune system and compromises immune response
• Influenza
  Attacks respiratory system and causes muscle pains and headaches
• TMV
  Causes mottling and discolouration of leaves

Question 10

What are types of protist infections?

Answer 10

• Blight (tomatoes and potatoes)
  Affects leaves and potato tubers
• Malaria
  Parasite in blood that causes headache and fever and may progress to coma and death