The Spread Of Disease

Question 1

Pathogens

Answer 1

Microorganisms that cause disease
Types: bacteria, fungi, protists, viruses
Can be spread in: air, water, direct contact

Question 2

Viruses

Answer 2

Live and reproduce rapidly inside an organisms cell which damages/ destroys cell

Question 3

Virus: measles

Answer 3

Spread by: inhalation of droplets produced by infected people coughing/sneezing
Symptoms: fever, red skin rash, can be fatal
Prevention/treatment: painkillers to treat symptoms, young children vaccinated to immune them

Question 4

Virus: HIV

Answer 4

Spread by: bodily fluids (sexual contact, blood when drug users share needles)
Symptoms: flu like symptoms at first, attacks body’s immune cells leads to AIDS- body can’t fight off infections
Prevention/ treatment: antiretroviral drugs ( very damaging to body), barrier method of contraception, using clean needles

Question 5

Virus: TMV

Answer 5

spread by: direct contact of plants with infected plant material, animal and plant vectors, soil (pathogen can remain in soil for decades)
Symptoms: mosaic pattern on discolouration on leaves (chlorophyll destroyed), reduced ability to photosynthesise affecting growth
Prevention/treatment: removing infected plants

Question 6

Bacteria

Answer 6

Reproduce rapidly inside organisms and may produce toxins that damage tissue and cause illnesses

Question 7

Bacteria: Salmonella

Answer 7

Spread by: bacteria on food being ingested
Symptoms: bacteria and toxins produced cause fever, abdominal cramps, vomiting, diarrhoea
Prevention/treatment: poultry vaccination against salmonella bacteria to control spread

Question 8

Bacteria: gonorrhoea

Answer 8

Spread by: direct sexual contact, is a STD
Symptoms: thick yellow/green discharge from vagina or penis, pain urinating
Prevention/ treatment: antibiotics for treatment, barrier method of contraception

Question 9

Fungi: rose black spot

Answer 9

Spread by: water and wind
Symptoms: purple/black spots on leaves which turn yellow and drop early, reduced plants ability to photosynthesise affecting growth
Prevention/treatment: fungicides, affected leaves removed or destroyed

Question 10

Protists: malaria

Answer 10

Spread by: mosquitos feed on blood of infected people and spread protist pathogen when they feed on other person- organisms that spread disease by carrying pathogens called vectors
Symptoms: recurrent episodes of fever, can be fatal
Treatment/prevention: prevent mosquito vectors breeding, mosquito nets to prevent bites, anti malarial medicine

Question 11

Controlling spread of communicable disease

Answer 11

Hygiene: washing hands, disinfecting surfaces and machinery, keeping raw meets separate, covering mouth when sneezing coughing
Isolation: isolation of infected people
Controlling vectors: destroying or controlling populations of vectors
Vaccination: protecting large numbers of people against disease

Question 12

Vaccination

Answer 12

Inject small quantities of dead/inactive forms of pathogens into body
Stimulates lymphocytes to produce correct antibodies for pathogens
If same pathogen re enters body, correct antibodies will be produced quickly to prevent disease

Question 13

Herd immunity

Answer 13

If large proportion of population is vaccinated against a disease, disease is less likely to spread even if there are some unvaccinated individuals