B6.3.6

Question 1

What are the two types of plant defences against communicable diseases

Answer 1

Physical defences - physical barriers preventing microorganisms from entering
Chemical defences - substances secreted by the plant that kills microorganisms

Question 2

Example of a physical defence

Answer 2

Cuticle

Question 3

How do waxy cuticles act as a defence against communicable diseases 1

Answer 3

It prevents pathogens from coming in direct contact with the epidermal cells. Limiting the chance of infection.

Question 4

How do waxy cuticles act as a defence against communicable diseases 2

Answer 4

It is hydrophobic nature of the cuticle prevents water from collecting on the leaf surface. This is an important defence against fungal pathogens, as most require standing water on the leaf surface for spore germination.

Question 5

How do cell wall act as a defence against communicable diseases 2

Answer 5

It provides an excellent structural barrier which is a major defence against fungal and bacterial pathogens.
Many cells have a secondary cell wall providing a further structural barrier.

Question 6

What are some examples of chemical defences.

Answer 6

Insect repellant to repel the insect vectors carrying disease
Insecticides to kill insects
Antibacterial compounds to kill bacteria
Antifungal compounds to kill fungi
Cyanide - which is toxic to most living things