plant defences against pathogens (chapter 12)

Question 1

recognizing an attack (plants)

Answer 1

• receptors in the cells respond to molecules from the pathogens/ chemicals produced when the cell wall is attacked.
• This stimulates the releases of signaling molecules which switch on genes in the nucleus.
• This triggers cellular responses, like producing defensive chemicals, sending alarm signals to unaffected cells and strengthening the cell walls.

Question 2

physical defences.(plants)

Answer 2

• callose is synthesized within minutes of the attack. It is deposited in cell walls and cell membranes , preventing the pathogens entering the plant.
• large amounts of callose continue to be deposited in the cell walls after the infection, lignin is added making the barrier even stronger.
• callose bock seave plates in phloem, sealing off infected part.