4.1.2 transmission of pathogens

Question 1

define vector

Answer 1

organism that carries pathogen from one host to another

Question 2

types of direct transmission between animals

Answer 2

• direct physical contact
• faecal-oral transmission
• droplet infection
• transmission by spores

Question 3

describe direct physical contact & factors affecting the transmission

Answer 3

eg. touching infected individual, touching contained surfaces

factors affecting transmission:
- hygiene (eg. washing hands regularly, keeping surfaces clean, cleaning/disinfecting cuts or abrasions, disinfecting surgical equipment, use condoms during sexual intercourse)

Question 4

describe faecal-oral transmission & factors affecting the transmission

Answer 4

eg. eating food/drink contaminated by pathogen

factors affecting transmission:
- using human sewage to fertilise crops
- treatment of waste water/drinking water
- wash all fresh food
- careful preparation/cooking of food

Question 5

describe droplet infection & factors affecting the transmission

Answer 5

= pathogen carried by troy water droplet through air

factors affecting transmission:
- cover mouth when coughing/sneezing
- use tissue & dispose correctly

Question 6

describe transmission by spores & factors affecting the transmission

Answer 6

= carried in air, reside on surfaces or in soil

factors affecting transmission:
- use mask
- wash skin after contact with soil

Question 7

social factors which affect transmission

Answer 7

• overcrowding
• poor ventilation
• poor health
• poor diet
• homelessness
• living/working with people who’ve migrated from areas where disease is common

Question 8

how are pathogens transmitted indirectly

Answer 8

by vector

Question 9

how are plant pathogens spread directly

Answer 9

• present in soil = infect plants by entering roots
• fungi produce spores which may be carried in wind (airborne transmission)
• when leaves shed the pathogens are distributed as return to the soil
• pathogens can enter fruit/seeds = distributed with seeds (offspring infected)

Question 10

how are plant pathogens spread indirectly

Answer 10

= insect attack
- spores/bacteria become attached to burrowing insect (eg. beetle) when it attacks infected plant
- when insect attacks another plant, pathogen transmitted
- insect acts as a vector

Question 11

why are protoctists, bacteria & fungi more common in warm/moist conditions

Answer 11

can grow/reproduce more rapidly