Communicable Diseases

Question 1

what’s a communicable disease?

Answer 1

caused by infective organisms known as pathogens - bacteria , viruses, fungi, proctista.

Question 2

how are communicable diseases passed on?

Answer 2

vectors- carry pathogens from one organism to another

Question 3

types of pathogen?bacteria?

Answer 3

prokaryotes - don’t have a membrane bound nucleus or organelles.
rod shaped , or spherical, comma etc.
two types of cell walls which react differently through gram staining

Question 4

viruses?

Answer 4

non living infectious agents. 0.2 nanometres.
DNA or RNA surrounded by protein.
viruses invade living cells, take over the host to generate more viruses.

Question 5

proctista?

Answer 5

eukaryotic organisms with a variety of feeding methods.
include both single celled and cells grouped into colonies.
proctista that cause disease are parasites.
need a vectorm

Question 6

fungi?

Answer 6

cause devastation in plants.
eukaryotic organisms - often multicellular although yeast is single celled and affects humans.
can’t photosynthesise and digest food extra cellularly .
many are saphropytes, feed in dead and decaying matter.
some are parasitic.

Question 7

pathogens - modes of action?

Answer 7

viruses take over cell metabolism. gets Into host cell and uses it to make more viruses, then burst and continue.

proctista - take over cells and break them open as the new generation emerge, they digest and use cell contents as they reproduce.

fungi digest living cells and destroy them

Question 8

direct transmission?

Answer 8

direct contact
inoculation - break in the skin
ingestion

Question 9

indirect transmission?

Answer 9

• fomites - inanimate objects such as socks.
• droplet infection - as you talk or sneeze , droplets are breathed in by another and infect.
• vectors, one host to another

Question 10

factors affecting disease in animals?

Answer 10

increase if :
overcrowded living/ working condition 
poor nutrition 
poor immune system - HIV
climate change

Question 11

How plants spread disease?

Answer 11

indirect transmission:
soil contamination - reproductive spores from protoctisa and fungi.

vectors - wind, spores carried by the wind
water
animals
humans

Question 12

factors affecting disease in plants?

Answer 12

overcrowding
poor mineral nutrition reduces resistance of plants.
damp, warm conditions increase the survival and spread of pathogens and spores

Question 13

defense against pathogens?plants?

Answer 13

plants aren’t passive.
receptors respond to molecules from the pathogen.
stimulates release of signalling molecules that switch on genes in the nucleus. triggers a response such as defensive chemicals or strengthening the cell wall

Question 14

physical plant defenses?

Answer 14

produce a high level of callose(polysaccharides)

• immediately callose is synthesised and deposited between the Cell wall and cell membrane next to infected cells acting as barriers

Question 15

chemical plant defenses?

Answer 15

powerful chemicals that repel the insect vectors of a disease or kill invading pathogens.

insect repellent
insecticides
general toxins - break down to form cyanide

Question 16

non specific animal defences?

Answer 16

skin,
mucus
lysosomes in tears and urine, stomach acid

Question 17

how does blood clotting occur?

Answer 17

thromboplastin - an enzyme that triggers a cascade of reaction resulting in the formation of a blood clot.
serotonin , makes smooth muscle in the walls of the blood vessels contract so they narrow and reduce the supply of blood to the area.

-seals wound, forms a hard scab , keeps pathogens out

Question 18

inflammatory response?

Answer 18

localised response.
-mast cells are activated in damaged tissue, release chemicals called histamines and cytokines.
histamines dilate blood vessels.raising temp , preventing pathogen reproducing.
cytokines attract white blood cells(phagocytes) to this site

Question 19

getting rid of pathogens? phagocytosis?

Answer 19

• pathogens produce chemicals to attract phagocytes.
• phagocytes recognise non human proteins on the pathogens.
• phagocyte engulfs the pathogen and enclosed it in a vacuole called a phagosomes.
• phagolysosome formed of phagosome and lysosome.
• enzyme from lysosome digest and destroy the pathogen

Question 20

bacterial disease in plants?

Answer 20

ring rot

Question 21

fungi in plants?

Answer 21

black sigatoka

Question 22

proctista in plants?

Answer 22

potato blight

Question 23

bacteria in animals

Answer 23

tuberculosis

Question 24

virus in humans?

Answer 24

HIV