DISEASE & IMMUNITY

Question 1

pathogen

Answer 1

microorganisms which cause disease

Question 2

bacteria examples

Answer 2

bacterial meningitis
TB
ringrot

Question 3

virus examples

Answer 3

HIV/AIDs
influenza
tobacco mosaic

Question 4

fungus examples

Answer 4

athletes foot
ringworm
black Sigatoka

Question 5

protoctista examples

Answer 5

potato blight
malaria

Question 6

direct transmission

Answer 6

• skin contact
• bodily fluid
• bites
• via placenta
• needles

Question 7

indirect transmission

Answer 7

• vector
• droplets
• touching contaminated objects

Question 8

physical plant defences

Answer 8

• bark
• waxy cuticle

Question 9

chemical plant defences

Answer 9

• production of chemicals
• deposition of calls to prevent spread in phloem sieve tubes

Question 10

skin

Answer 10

primary non specific
- tough & waterproof
- outer layer cells dead so can’t be used as a host
- outer layer constantly replaced so pathogens cannot colonise
- produces sebum which is antimicrobial

Question 11

mucous membrane

Answer 11

primary non specific
- difficult for pathogens to access cells underneath

Question 12

tears

Answer 12

primary non specific
- lysozymes kill bacteria

Question 13

blood clotting

Answer 13

secondary non specific
- protein fibres & blood cells form scab to stop pathogen entry
- prothrombin converted to thrombin
- fibrinogen converted to fibrin

Question 14

expulsion reflexes

Answer 14

primary non specific
- coughing/sneezing

Question 15

wound repair

Answer 15

secondary non specific
- cells at edge of wound rapidly divide by mitosis

Question 16

inflammation

Answer 16

secondary non specific
- tissue damaged
- mast cells release histamines which detect antigens
- histamines bind to receptors in blood vessel smooth muscle
- vessel dilates
- pressure from tissue fluid causes swelling and pain on nerve endings

Question 17

neutrophil

Answer 17

multi lobed nucleus
short lived

Question 18

macrophages

Answer 18

can display pathogen antigens on surface after phagocytosis

Question 19

monocytes

Answer 19

bean nucleus
non granular cytoplasm

Question 20

opsonins

Answer 20

small molecules eg antibodies

Question 21

cytokines

Answer 21

messengers which attract phagocytes

Question 22

describe the process of phagocytosis

Answer 22

• phagocyte recognises pathogen antigen
• opsonins bind to pathogen
• phagocyte attaches and engulfs into a vesicle forming a phagosome
• phagosome fuses with lysosome forming a phagolysosome
• lysosome enzymes digest pathogen and phagocyte becomes antigen presenting

Question 23

antibodies

Answer 23

globular proteins produced by plasma cells in response to specific complementary antigens

Question 24

agglutination as a function of antibodies

Answer 24

reduces the number of pathogenic units by clumping them together

Question 25

anti toxins as a function of antibodies

Answer 25

bind to virus / bacteria

Question 26

opsonins as a function of antibodies

Answer 26

mark pathogens to initiate phagocytosis

Question 27

what is cell signalling in specific immunity ?

Answer 27

communication between B and T cells through secretion of chemicals called cytokines

Question 28

interleukins

Answer 28

group of cytokines released to stimulate division

Question 29

describe the cells involved in the cell mediated response

Answer 29

- T cells - produced in bone marrow - mature in thymus - respond to antigens inside cells - develop into helper, memory, killer and regulatory cells

Question 30

describe the process of the cell mediated response

Answer 30

- pathogens engulfed and phagocyte is antigen presenting - clonal selection: antigens bind to receptors on T helper cells - clonal expansion: T helper cells divide rapidly by mitosis as interleukins are produced - differentiation

Question 31

T killer cells

Answer 31

destroys abnormal or infected cells by releasing perforin into cell membrane which creates pores and causes cell death

Question 32

T regulatory cells

Answer 32

suppress immune system so response only occurs when pathogen detected

Question 33

cells involved in humoral response

Answer 33

- B cells - produced and matured in bone marrow - respond to antigens outside cells - produce antibodies - develop into plasma/memory cells

Question 34

describe the process of the humoral response

Answer 34

- clonal selection: antibody on B cell binds to T helper cell - interleukins released - clonal expansion: B cell divides rapidly by mitosis - differentiation

Question 35

plasma cells

Answer 35

produce antibodies which attach to the pathogen and destroy it

Question 36

memory cells

Answer 36

remain in blood and rapidly produce antibodies if reinfected during the secondary immune response

Question 37

reasons for antibiotic resistance

Answer 37

- antibiotics given for minor infection - not completing course - unnecessary prescription

Question 38

natural active immunity

Answer 38

immune response in the body - body recognises & destroys non self substances - gained through immune system activation

Question 39

natural passive immunity

Answer 39

antibodies transferred through breast milk or placenta - body recognises & destroys non self substances - gained through external antibodies

Question 40

artificial active immunity

Answer 40

exposure to weak or dead pathogen - exposure to antibody - gained through immune system activation

Question 41

artificial passive immunity

Answer 41

vaccination - exposure to antibody - gained through external antibodies