module 4: pathogens and disease

Question 1

bacterial diseases

Answer 1

animals- TB
humans- bacterial meningitis
pots/toms- ring rot

Question 2

viral diseases

Answer 2

animals-influenza
human- HIV/AIDS
plants- tobacco mosaic virus

Question 3

fungal diseases

Answer 3

animals- ringworm
human- athletes foot
plants/bananas- black Sigatoka

Question 4

protoctist diseases

Answer 4

animals/humans- malaria
pots/toms-pot/tom late blight

Question 5

direct transmission

Answer 5

from one organism to another e.g. droplet, sex, touching

Question 6

indirect tranmission

Answer 6

from one to another via intermediate e.g. air, water, vector

Question 7

factors affect transmission

Answer 7

overcrowding, climate, human social factors

Question 8

inflammation

Answer 8

triggered by tissue damage, the damaged tissues release histamines which increase permeability of the blood vessels so they leak fluid into surrounding area and isolate pathogens due to swelling, histamines cause vasodilation to increase blood flow bringing white blood cells to area

Question 9

blood clotting

Answer 9

thrombin activates fibrinogen to fibrin which forms a network of fibres to form and trap platelets blood cells so platelets can form scab

Question 10

wound repair

Answer 10

outer layer of skin cells divide, tissue below wound contracts to bring edges together, repaired using collagen fibres

Question 11

primary barriers in animals

Answer 11

skin, mucous membranes, blood clotting, inflammation, wound repair, expulsive reflexes

Question 12

plant physical defences

Answer 12

waxy cuticle, cell walls, calls produced in times of stress

Question 13

plant chemical defences

Answer 13

saponins- destroy pathogen cell membranes
secrete toxic chemicals to predators

Question 14

four stages in immune response

Answer 14

1- phagocyte engulfs pathogen
2- phagocytes activate T lymphocytes
3- T lymphocytes activate B lymphocytes to produce plasma cells
4- plasma cells make more antibodies to specific antigen

Question 15

phagocytosis

Answer 15

phagocyte recognises pathogen
phagocyte engulfs pathogen so it is now in phagosome
a lysosome fuses with phagosome to break down pathogen
phagocyte presents antigens become APC

Question 16

activate T lymphocytes- clonal selection

Answer 16

surface covered in receptors which complementary antigens bind to
divides into t helper cells, t killer cells and t regulatory cells and t memory cells

Question 17

active B lymphocytes- clonal expansion

Answer 17

covered in antibodies than bind to antigen to form antigen-antibody complex, this actives B cell to form plasma cells and memory cells

Question 18

structure of anti body

Answer 18

heavy chains at bottom, light chains at top, variable regions at ends that specific to antigen, disulphide bridge holds heavy chains together

Question 19

agglutination

Answer 19

clump pathogens together as antibodies have two binding sites so phagocytes can engulf many at once

Question 20

neutralising toxins

Answer 20

have anti toxins that bind to toxins produced by pathogens which prevents them effecting human cells

Question 21

preventing pathogen binding

Answer 21

when antibodies bind to antigens, antigens can’t bind to human cells so it can’t infect host cells

Question 22

active immunity

Answer 22

immune system makes own antibodies after antigen stimulation
natural- catching disease
artificial- vaccination

Question 23

passive immunity

Answer 23

given antibodies made by different organism
natural- baby immune from breast milk as receives antibodies from mother
artificial- immune after injection of antibodies from someone else