4.1.1b/c) Means of transmission of animal & plant communicable pathogens

Question 1

Factors that increase the transmission of communicable diseases in animals

Answer 1

Global warming
Immunodeficiency
Crowded living areas
Hygiene
Poor nutrition
Culture
Infrastructure
Socioeconomic factors
Poor disposal of waste

Question 2

Plant protection

Answer 2

Bark
Wax layer
Cell wall

Question 3

Preventing the spread of communicable disease in plants

Answer 3

Leaving room between plants
Clear fields as thoroughly as possible
Rotate crops- spores or bacteria will eventually die
Follow strict hygiene practices
Control insect vectors

Question 4

Defence from pathogens within the body

Answer 4

Nose
Eye
Ear
Cilia
Eating
Penis
Vagina
Anus

Question 5

Plant- Physical defences

Answer 5

Callose
- Polysaccharide 1,3 & 1,6 glyosidic links
- Deposited in cell wall near site of infection to prevent spread of infection
- Blocks sieve plates in the pholem
-Deposited in the plasmodesmata

Lignin
- Added to make the barrier thicker and stronger

Question 6

Plant- Chemical defences

Answer 6

Insect repellents
- Pine resin/ citronella
Insecticides
- Pyrethrins act as insect neurotoxins
- Caffeine is toxic to insects and fungi
Antibacterial compounds
- Phenols are antiseptics from many plants
- Antibacterial gossypol produced by cotton
- Defensins are plant proteins that disrupt bacterial and fungal cell membranes
- Lysosomes contain enzymes that break down bacterial cell walls

Question 7

Plasmodesmata process

Answer 7

1. Some molecules from the pathogen are directly recognised by the plant cell
2. Signalling molecules alert nucleus to attack
3. Polysaccharides (callose & lignin) made to strengthen the cell wall