2.5 parasitism Flashcards

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1
Q

how can endoparasites evade the immune system?

A

by mimicking host antigens to evade detection and modify the host immune responseto reduce their chances of destruction

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2
Q

what are some methods for parasite control?

A

civil engineering projects to improve sanitation (latrines, wells)
vector control (pesticides)

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3
Q

what must be reflected in the design of the vaccine?

A

antigenic variation

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4
Q

which enzymes, found in mucus, saliva and tears, and involved in the breakdown of bacterial cell walls?

A

hydrolytic enzymes

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5
Q

what does the parasite become part of by altering the host?

A

its extended phenotype

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6
Q

what can parasites do to the host to benefit its growth, reproduction and transmission?

A

suppress the host immune system and modify host size and reproduction rate

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7
Q

what can parasites alter about the host to maximise transmission?

A

host foraging, movement, sexual behaviour, habitat choice and anti-predator behaviour

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8
Q

which two factors increase transmission rates of a parasite?

A

overcrowding of hosts when they are at a high density
mechanisms such as vectors and waterborne dispersal stages (allow the parasite to spread even if infected hosts are incapacitated)

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9
Q

which two aspects of a parasite’s biology must we understand?

A

transmission - how they spread
virulence - the degree of harm they cause their host

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10
Q

what happens once a retrovirus has formed DNA?

A

it is inserted into the genome of the host cell

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11
Q

what are the stages of the viral life cycle?

A

host infected with genetic material
host cells replicate viral genome
viral genes and proteins transcribed and translated
new viral particles assembled and release

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12
Q

what can be found on the outer surface of a parasite?

A

antigens that a host cell may or may not be able to detect as foreign

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13
Q

what are some viruses surrounded by?

A

a phospholipid membrane derived from host cell materials

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14
Q

in which form do viruses contain genetic material?

A

of DNA and RNA, packaged in a protective protein coat

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15
Q

what happens second in the plasmodium life cycle?

A

red blood cells burst and gametocytes are released

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16
Q

what is fundamental niche?

A

the niche that it occupies in the absence of any interspecific competing influences

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17
Q

how can some viruses escape immune surveillance?

A

they can integrate their own genome into the genome of the host, remaining inactive until they are needed. this is called latency

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18
Q

what does antigenic variation allow?

A

the parasite to change between different antigens whilst affecting the host, which can allow for re-infection

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19
Q

what will improving parasite control help with?

A

reducing child mortality rates
improving child development and intelligence due to greater access to resources

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20
Q

what do the conditions in refugee camps mean for the coordination of treatment programmes?

A

they are difficult to achieve

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21
Q

what can refugee camps result from?

A

war, natural disasters or over-crowing cities in less economically developed countries

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22
Q

which conditions can cause parasites to spread more rapidly?

A

overcrowding and tropical conditions

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23
Q

what gives antibodies specificity to binding antigens?

A

they possess regions where the aminoacid sequence varies greatly betweendifferent antibodies

24
Q

why can it be difficult to produce a vaccine against parasites?

A

they can be difficult to culture in a lab

25
Q

why can it be difficult for drugs to solely target the parasite?

A

similar metabolisms of the host and parasite

26
Q

what are the three main control measures for infectious diseases?

A

controlling transmission, drug therapy, immunisation

27
Q

what do epidemiologists study?

A

the outbreak and pattern of infections diseases to determine the factors that affect the spread of infectious disease

28
Q

what is immune surveillance?

A

a range of different white blood cells move around the body in blood vessels, continuously monitoring the state of the tissues

29
Q

what is the role of NK cells?

A

identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis.

30
Q

what does the low pH of the stomach, vagina and sweat gland do?

A

it helps to denature proteins of a pathogen, rendering it harmless

31
Q

what are physical barriers responsible for?

A

blocking the entry of parasites

32
Q

how do retroviruses from DNA from RNA?

A

using the enzyme reverse transcriptase

33
Q

what is a retrovirus?

A

a virus that contains RNA instead of DNA

34
Q

what are viruses?

A

parasites that can only replicate inside a host cell

35
Q

what happens finally in the schistosome life cycle?

A

motile larvae now penetrates human skin and enters the blood

36
Q

what happens thirdly in the schistosome life cycle?

A

larvae then infect the snail where asexual reproduction occurs

37
Q

what happens second in the schistosome life cycle?

A

fertilised eggs are released in faeces into water

38
Q

what happens first in the schistosome life cycle?

A

schistosomes produce sexually in the human intestine

39
Q

what happens finally in the plasmodium life cycle?

A

another mosquito bites the human and the gametocytes are transferred into it where they mature into male and female gametes, allowing sexual reproduction to occur

40
Q

what occurs first in the plasmodium life cycle?

A

plasmodium enters the bloodstream and reproduces asexually in the liver and red blood cells

41
Q

what is a vector?

A

plays an active role in the transmission of the parasite and in some cases may be a host

42
Q

what is the intermediate host?

A

a host that may be required for the parasite to complete its life cycle

43
Q

what is the definitive host?

A

the host in which the parasite reaches sexual maturity

44
Q

how are ectoparasites usually transmitted?

A

by direct contact

45
Q

how are endoparasites usually transmitted?

A

by vectors/by consumption of the intermediate host

46
Q

where do endoparasites live?

A

within the body/tissue of its host

47
Q

where does an ectoparasite live?

A

on the surface of its host

48
Q

why are parasites degenerate?

A

the host provides so many of its needs

49
Q

what does it mean to say that parasites are degenerate?

A

they lack structures and organs found in other organisms?

50
Q

why do parasites have a narrow (specialised) niche?

A

they are host specific

51
Q

how is a parasitic relationship different to predator-prey?

A

the reproductive potential of the parasite is greater than that of the host

52
Q

what is a parasite?

A

a symbiont that gains nutrients at the expense of its host

53
Q

how can potential competitors co-exist if their realised niches are sufficiently different?

A

by resource partitioning

54
Q

when does competitive exclusion occur?

A

when the niches of two different species are very similar that the resulting competition between them causes the population decline and local extinction of one

55
Q

what is realised niche?

A

the narrower niche occupied in response to interspecific competition

56
Q

what is a niche?

A

the multidimensional summary of tolerances and requirements of a species