communicable disease

Question 1

WHO

Answer 1

world health organisation

Question 2

How does WHO define health?

Answer 2

state of physical, mental and social wellbeing, not merely the absence of disease or infirmity

Question 3

what does disease mean?

Answer 3

where part of an organism doesn’t function properly

Question 4

what are the 2 types of disease?

Answer 4

communicable and non communicable

Question 5

what is a communicable disease?

Answer 5

a communicable disease is caused by a pathogen which can easily be spread between organisms, through different modes of transmission

Question 6

what are examples of communicable diseases?

Answer 6

cholera, chlamydia, stomach ulcers, Ebola, HIV, malaria, athlete’s foot

Question 7

what is a pathogen?

Answer 7

micro organism that causes disease

Question 8

what are the 4 types of pathogens?

Answer 8

fungi
protozoa
bacteria
virus

Question 9

name the different modes of transmission

Answer 9

sharing needles, drinking contaminated water, sex, unhygienic food preparation, air droplets, vectors

Question 10

if someone is affected by a disease already, why are they more susceptible to others?

Answer 10

• this is because the pathogen has already made their immune system weaker
• meaning that the immune system is less able to defend the organism against more/multiple pathogens

Question 11

bacteria

Answer 11

very small cells which can reproduce rapidly inside the body and produce toxins, damaging cells and making us feel unwell

Question 12

viruses

Answer 12

unlike bacteria, viruses are not cells, meaning they can’t reproduce without using a host cell’s machinery
it will replicate itself in the host cell, till the point of cell lysis, which releases all the new viruses
the cell damage is what makes us feel ill

Question 13

fungi

Answer 13

some are unicellular, and others have a body of hyphae which can grow and penetrate human skin and the surface of plants
some hyphae produce spores which can spread to other plants and animals

Question 14

protists

Answer 14

• all are eukaryotes, most are unicellular
• can be spread by vectors (organisms which spread the disease but don’t catch it themselves)
• some are parasites, which live on/inside organisms, causing them damage

Question 15

TB

Answer 15

• full name: tuberculosis
• pathogen: mycobacterium tuberculosis
• symptoms: coughing, lung damage
• MOT: air droplets, coughs, sneezes
• how to reduce cases: self isolate, social distance, wear masks, get vaccine, well ventilated home. practice good hygiene

Question 15

cholera

Answer 15

• pathogen: bacteria, vibrio cholerae
• symptoms: diarrhoea, nausea leading to severe dehydration
• MOT: contaminated water
• prevention: filtering, boiling water before use, oral rehydration solutions

Question 16

stomach ulcers

Answer 16

• pathogen: bacteria, helicobacter pylori
• symptoms: nausea, stomachache, vomiting, weight loss
• MOT: oral transmission
• prevention: clean water supplies, disinfecting food preparation surface, washing hands before meals or cooking

Question 17

ebola

Answer 17

• pathogen: virus
• MOT: bodily fluids
• symptoms: haemorrhagic fever
• prevention: medical staff should wear PPE, disinfect belongings of the infected

Question 18

chlamydia

Answer 18

• pathogen: bacteria, an STI
• MOT: sex, not really any symptoms
• prevention: condoms, screening
• effects: can cause infertility, could be passed on from an infected woman to baby during childbirth

Question 19

HIV

Answer 19

• pathogen: virus
• symptoms: initially experience flu-like symptoms, then don’t experience symptoms for many years
• MOT: bodily fluids (semen, blood)
• weakens the immune system, when almost all white blood cells are destroyed, leads to AIDS
  the person is a lot more susceptible to other diseases as their immune system fails
• prevention: condom, not sharing needles, screening, antiretrovirals (slow down HIV replication)

Question 20

Chalara ash dieback

Answer 20

• pathogen: fungus infecting ash trees
• symptoms: loss of leaves, bark lesions
• MOT: carried through the air by wind
• prevention: removing infected ash trees, and replanting a different species of tree, restricting imports/movement of ash trees

Question 20

malaria

Answer 20

• pathogen: protist
• MOT: vectors (mosquitoes)
• symptoms: repeating episodes of fever
• prevention: mosquito nets, full sleeves, insect repellent, insecticides
• long term effects: in serious cases, damages the liver as well as RBCS, so it can be fatal

Question 21

structure of a virus

Answer 21

inside contains genetic material (DNA/RNA)
surrounded by a protein coat

Question 22

what are the two pathways for virus replication?

Answer 22

• lytic
• lysogenic

Question 23

describe the lytic pathway

Answer 23

1. virus attaches itself to the receptors on a host cell, and injects its genetic material into the cell 2. the virus uses the host cell's machinery to replicate itself and produce new components of the virus 3. the new virus components assemble to produce new viruses 4. cell lysis occurs, releasing all the new viruses 5. these new viruses attack other host cells

Question 24

describe the lysogenic pathway

Answer 24

1. virus attaches to specific receptors on the host cell and injects its DNA into the host cell 2. the virus' genetic material is incorporated into the host cell's genome 3. every time the host cell divides, the viral genetic material is replicated along with the host cell's DNA 4. no new viruses are made, as the virus is dormant 5. eventually, a trigger causes the viral DNA to leave the genome of the host cell and enter the lytic pathway

Question 25

3 methods plant pathologists can use to identify plant disease

Answer 25

field identification (gardening manual, investigating distribution of infected plants) lab tests (detecting DNA/antigens of the pathogen using chosen techniques) ruling out environmental causes

Question 26

what are the chemical defences for a plant?

Answer 26

- produce poisons to deter pests trying to feed on their leaves (e.g. nicotine produced by tobacco plants) - produce chemicals called antiseptics killing fungi and bacteria - some chemicals they produce can be used to treat human diseases e.g. 1. quinine, cinchona tree, for years it was the main treatment for malaria 2. aspirin, comes from the bark and leaves of willow trees, for pain relief

Question 26

what are the physical defences for a plant?

Answer 26

- waxy cuticle is thick to stop pathogens from entering plant cells, and it is waterproof to reduce the risk of infection by pathogens carried in water - cellulose cell wall acts as a barrier against pathogens that have made it past the waxy cuticle

Question 27

what are some symptoms of plant disease?

Answer 27

galls, areas of decay, discolouration, stunted growth, spots on leaves, presence of pests, malformed stems/leaves

Question 28

what symptoms of a plant can indicate nutrient deficiency?

Answer 28

yellow leaves (chlorosis), stunted growth

Question 29

which method of identification is more accurate and why?

Answer 29

Lab based diagnostic testing allows accurate identification of specific pathogens, whereas field-testing is a bit more rough