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OCR A Biology > 4.1.1 communicable diseases and the immune system > Flashcards

4.1.1 communicable diseases and the immune system Flashcards

1
Q

what is a pathogen

A

an organism that causes disease by taking nutrition from another organism or causing it harm

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2
Q

what does parasitic mean

A

organisms that live in or on a host and take their nutrition

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3
Q

what is fungi

A

eukaryotic
non-pathogenic
parasitic
release spores and multiply via budding
grow under skin

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4
Q

what is a virus

A

akaryotic (non-living)
uses cell’s nucleus to multiply

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5
Q

what is a protoctista

A

eukaryotic
non-pathogenic
parasitic
require a host
release toxic waste

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6
Q

what is bacteria

A

prokaryotic
non-pathogenic
multiply by binary fission
release toxic waste

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7
Q

what is tuberculosis

A

bacteria
kills cells and tissues and affects respiratory system

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8
Q

what is HIV/AIDs

A

virus
attacks immune system

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9
Q

what is influenza

A

virus
attacks respiratory system and causes muscle pain/headaches

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10
Q

what is tobacco mosaic virus

A

virus
discoloured leaves

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11
Q

what is blight

A

protist
affects leaves and potatoes

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12
Q

what is black sigatoka

A

fungus
leaf spots on banana plants that reduce yield

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13
Q

what is ringworm

A

fungus
growth in skin causes rash

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14
Q

what is athlete’s foot

A

fungus
growth under skin in feet

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15
Q

what is ring rot

A

bacteria
ring of decay in vascular tissue

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16
Q

what is malaria

A

protist
parasite in blood causes fever then death

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17
Q

what is bacterial meningitis

A

bacteria
infection of meninges (membranes around brain and spinal cord)

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18
Q

what is direct transmission

A

when communicable diseases are passed along by direct contact

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19
Q

what are examples of direct transmission

A

direct physical contact
faecal-oral transmission
droplet infection
spore transmission

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20
Q

what are the passive physical plant defences

A

cellulose cell wall
lignin thickening of cell walls
waxy cuticles
bark
stomatal closure

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21
Q

what is a callose

A

polysaccharide deposited in the sieve tubes to restrict entry of pathogens

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22
Q

what is a tylose

A

a swelling that fills xylem vessels that stops passage of water

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23
Q

what necrosis

A

cells are killed to prevent the spread of infection

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24
Q

what is a canker

A

produced by death of cambium creating a sunken lesion

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25
Q

what are the chemical plant defences

A

terpenoids
alkaloids
tannins
pheromones
hydrolytic enzymes
defensins

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26
Q

what does non-specific mean

A

fast acting
same for any infection
provides a general defense against most threats

27
Q

what are the primary physical barriers

A

skin
mucous membranes
stomach acid
lysozymes
sebum
expulsive reflexes

28
Q

how does skin act as a barrier

A

epidermis contains keratinocytes so when cells dry out the cytoplasm becomes keratin

29
Q

how do mucous membranes act as a barrier

A

contain ciliated epithelium

30
Q

how does stomach acid act as a barrier

A

acidic conditions and digestive enzymes break down pathogens

31
Q

what do lysozymes do

A

break down bacteria

32
Q

what is a neutrophil

A

made in bone marrow
multi-lobed nuclei
in blood and tissue fluid short-term

33
Q

what is a macrophage

A

made in bone marrow
larger than neutrophils
in body organs or lymph nodes
travel in blood as monocytes

34
Q

what is the inflammatory response

A

mast cells detect damage and release histamines so blood flow to area increases
histamines cause capillaries to leak so phagocytes and clotting factors are released into wound
phagocytes engulf bacteria and cellular debris
platelets move out of capillary to seal wound

35
Q

what is phagocytosis

A

pathogen detected by phagocyte
pseudopodia engulf pathogen
phagosome carries pathogen into cell
lysosomes fuse with phagosome to make phagolysosome
hydrolytic enzymes break pathogen down
debris released via exocytosis
foreign antigens can be presented on cell surface - APC

36
Q

what are the three main stages of the primary immune response

A

1- phagocytosis + antigen presentation
2- cell mediated response (T-lymphocytes)
3- humoral immunity (B-lymphocytes)

37
Q

what happens in the cell mediated response

A

antigens on antigen presenting cells bind to receptors of T-lymphocytes - CLONAL SELECTION
causes T-cell to divide rapidly by mitosis - CLONAL EXPANSION
can make either T-helper, T-memory or T-killer

38
Q

what is a T-helper cell

A

release cytokines
stimulate B cell development + phagocytosis

39
Q

what is a T-killer cell

A

kill infected cells using cytotoxins

40
Q

what is a T-memory cell

A

immunological memory in secondary response

41
Q

what happens in humoral immunity

A

antigens on antigen presenting cells bind to receptors of B-lymphocytes - CLONAL SELECTION
causes B-cell to divide rapidly by mitosis - CLONAL EXPANSION
can make either plasma cells or B-memory

42
Q

what is a plasma cell

A

release antibodies

43
Q

what is B-memory cell

A

immunological memory

44
Q

what is the structure of an antibody

A

flexible hinge region
disulphide bridges
antigen binding site
light and heavy chains
variable region - specific to antigen
constant region - efficient for cloning + protein synthesis, binds to phagocytes

45
Q

what is an opsonin

A

antibody attaches to antigens on pathogen surface - helps phagocyte engulf pathogen

46
Q

what is an anti-toxin

A

neutralise toxins from pathogens

47
Q

what is an agglutinin

A

two binding sites so bind to more than one pathogen at once so cross-links pathogens - ‘agglutinates’ them

48
Q

what is the secondary response

A

B+T memory cells go through clonal selection and expansion quickly - more antibodies produced faster - immunological memory

49
Q

what is an autoimmune disease

A

when the immune system attacks itself so B+T cells specific to our antigens are destroyed

50
Q

what is active immunity

A

immune system activated - B+T mem cells

51
Q

what is passive immunity

A

antibodies from mother or injection

52
Q

what is natural immunity

A

gained when people acquire a disease normally

53
Q

what is artificial immunity

A

deliberate exposure to an antigen

54
Q

natural active

A

antigens enter naturally
produce antibodies and specialised lymphocytes

55
Q

natural passive

A

mother to foetus

56
Q

artificial active

A

vaccines
produce antibodies and specialised lymphocytes

57
Q

artificial passive

A

immune serum
body doesn’t produce its own antibodies

58
Q

what are the forms of antigens in a vaccine

A

dead pathogen
inactive toxin
antigen isolation
live microorganism
harmless pathogen

59
Q

what is an epidemic

A

wide spread communicable disease in 1 country

60
Q

what is an endemic

A

area specific disease

61
Q

what is a pandemic

A

world-wide spread

62
Q

what is herd vaccination

A

vaccinating lots of people to decrease spread in population

63
Q

what is local vaccination

A

vaccinating only most at risk people

OCR A Biology (13 decks)

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