Pathogenic Agents

Question 1

How is stem rust fungus transmitted?

Answer 1

Wind carries spores from infected plants.
Infected plant fragments in soil can infect new plants

Question 2

What is the mode of infection for Puccinia graminis ?

Answer 2

Hyphae enters the stomata of leaves.
Enzymes digest plant cells and these nutrients are absorbed into the fungus.
Hypahe forms a mycelium that feeds and grows using the plants nutrients.
Spores need water to germinate

Question 3

What are the pathogenic effects of Puccinia graminis?

Answer 3

• Stem is weakened and can collapse so not harvested efficiently.
• Pustules break through leaf surface allowing uncontrolled water loss so plant dries out
• Fungus absorbs nutrients from the plant reducing plant yield.

Question 4

How is influenza transmitted?

Answer 4

• Droplet infection (cough/sneezes)
• Direct contact with viral mucus and surfaces contaminated with the virus.

Question 5

What is the mode of infection for influenza?

Answer 5

• Infects ciliated epithelial cells of the lung
• Viral RNA enters the host cell and takes over its biochemistry to make new virus particles

Question 6

What is the pathogenic effects of influenza?

Answer 6

• Fever, sweating, vomiting, sore throats and shortness of breath.
• Secondary bacterial infection can occur

Question 7

How is malaria transmitted?

Answer 7

• Transmitted to a human host by a female mosquitoe and during a blood meal, transmission occurs in both directions

Question 8

What is the mode of infection of malaria?

Answer 8

• The parasite then invades red bood cells and reproduces asexually, then will burst and destroy the cells before infecting more red blood cells.

Question 9

What is the pathogenic effects of malaria?

Answer 9

Fever, shaking, heaaches, liver damage and anaenia (burst red blood cells)

Question 10

How can all of these diseases be treated/controlled?

Answer 10

Stem rust:
- Use GM wheat resistant to fungus
- Grow crops that mature at cooler times as spores grow best at hot temps
- Use fungicides
Spaces between plants so more distance for spores to travel

Influence:
- Antiviral medication (viruses aren’t affected by antibiotics)

Malaria:
- Drugs like chloroquinine can kil the parasite but can only be effective soon after infection
- Parasite is becoming more resistant to the drugs so malaria has to be treated by a combination of drugs to stop resistance.