Chemical Plant Defences

Question 1

Terpenoids

Answer 1

A range of essential oils that have antibacterial and antifungal properties. They may also create a scent.

Question 2

Phenols

Answer 2

Have antibiotic and anti-fungal properties. Tannins found in bark inhibit attack by insects. They bind to salivary proteins and digestive enzymes, deactivating the enzymes.
Insects that ingest tannins do not grow and will die. Prevents transmission.

Question 3

Saponins

Answer 3

Thought to destroy the cell membrane of fungi

Question 4

Alkaloids

Answer 4

Nitrogen containing compounds such as caffeine and nicotine. Bitter taste and prevent herbivores grazing. If herbivores can be prevented from grazing this prevents damage to the plants which would allow pathogens to enter.

Question 5

Hydrolytic enzymes

Answer 5

Found in the spaces between cells.
Chitinases: break down chitin cell wall of fungi
Lysozymes: degrade bacterial cell wall

Question 6

Cell necrosis

Answer 6

Deliberate cell suicide.

A few cells sacrificed to save rest of plant. Cells surrounding infections die to stop prevent transmission across rest of cell.