Plant defence system

Question 1

How does plant regconise a pathogen?

Answer 1

• Receptors in the cells respond to molecules from the pathogens, or to chemicals produced when the cell wall is attacked
• This stimulates the release of singnalling molecules that appears to switch on genes in nucleus
• This triggers cellular response, which includes producing chemicals, sending alarm signals to unaffected cells to trigger their defense, and physically strengthening the cell walls

Question 2

What is the physical defense of plant?

Answer 2

Produce callose, which contain B 1,3 linkages and B1,6 linkages between the glucose molecules

Question 3

Where does callose compose?

Answer 3

• The site of infection
• Cell wall, lignin is added to make the mechanical barrier to invasion even more thicker and stronger
• sieve plates in phloem - preventing spreading of pathogens
• Plasmodesmata between infected cells and their neighbours - preventing spreading of pathogens

Question 4

What are some chemical defense of plant?

Answer 4

• Insects repellents
• Insecticides
• Antibacterial compound including antibodies
• Antifungal compound
• General toxins - form cyanide