4 - disease

Question 1

pathogen

Answer 1

ORGANSIM THAT CAUSES DISEASE

Question 2

bacteria

Answer 2

– tuberculosis (TB)
- bacterial meningits
- ring rot (potatoes, tomatoes)

Question 3

viruses

Answer 3

HIV/AIDS (human)
infuenza (animals),
Tobacco Mosaic Virus (plants)

Question 4

protoctista

Answer 4

malaria
potato/tomato late blight

Question 5

fungi

Answer 5

black sigatoka (bananas)
ringworm (catle)
athlete’s foot (humans)

Question 6

direct transmission examples

Answer 6

direct physical contact
faecal/oral transmission
droplet infection
transmission by spores

Question 7

indirect transmission

Answer 7

vector - another organism that may be used by pathogen to enter primary host

Question 8

outer defences plant

Answer 8

bark - physical barrier
waxy cuticle - prevents water from building up
stomatal closure - guard cells close if pathogen is present

Question 9

transport tissue defenses

Answer 9

the phloem can be blocked - callose blocks the sieve plate

xylem can be blocked - tylose are like balloons that swell up and block tube

Question 10

celllular level defenses

Answer 10

the cellulose cell wall is a physical barrier - that can be thickens and strengthened (active)

lignification - waterproofs and strengthens the cell

callose deposition in the plasmadesmata - physical barrier to defenses

Question 11

chemical plant defenses

Answer 11

terpenoids - menthol in mint
phenols - damage microorganisms
alkaloids - caffeine nic coke morphine
defensive proteins
hydrolytic enzymes - chitinase glucanases

Question 12

necrosis

Answer 12

infection occurs,
cells around pathogen die and this
decreases water avalibilty
decreases nutrition availibilty to pathogen
like cankers

Question 13

primary defence

Answer 13

prevents entry of pathogens

Question 14

secondary defences

Answer 14

counteract pathogens when they have entered

Question 15

skin

Answer 15

physical barrier

Question 16

keratinocytes

Answer 16

top layer of skin
dead skin cells

Question 17

blood clotting

Answer 17

in damaged skin vessels the platelets are exposed to collagen

triggers clotting response

fibrinogen (soluble) turned into fibres (insoluble)

mesh of fibres traps cells - stops bleeding and entry of pathogens

Question 18

trachea mucus defense

Answer 18

traps pathogens
ciliated epithelial cells waft mucus up and out of trachea

mucus is swallowed

pathogens destroyed by hcl in stomach

Question 19

coughing and sneezing

Answer 19

expulsion of pathogen with air

Question 20

inflammation

Answer 20

pathogen detected by mast cells

mast cells releases histamines

histamine causes vasodilation and make blood vessels more permeable

more tissue fluid is formed leads to swelling (oedema)

more blood flow =redness
= more phagocytes
in the area

more permeable walls =
more phagocytes into the tissue

tissue fluid containing pathogens and phagocytes drains to lymphnodes where there are lymphocytes

Question 21

describe how a neutrophil works?

Answer 21

receptors on the surface of neutrophil bind to antigens on pathogens

pseudo pods extend and surround pathogen . pathogen is engulfed

pathogen is contained in a large vessicle called a phagosome

phagosome is fused w lysosome

enzymes digest pathogen

once its done this many times it will die

shown as pus

Question 22

describe how macrophages work

Answer 22

travel in the bloodstream as monocytes - only become macrophages when reach tissues

pathogen is engulfed
contained in a phagosome. fised with with a lysosome

enzymes digest pathogen but antigens on surface of pathogen are retained

antigens are combined w proteins to form major histocompability complexes

complexes moved to cell surface of macrophage makes it an antigen presenting cell

this allows antigen to be identified by other immune cells and prevents it from being attacked by other immune cells