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parasitism Flashcards

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1
Q

what is an ecological niche

A

An ecological niche is a multi-dimensional summary of tolerances and requirements of a species

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2
Q

A species has a fundamental niche that occupies in the absence of what

A

A species has a fundamental niche that it occupies in the absence of any interspecific competition

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3
Q

what is a realised niche

A

A realised niche is occupied in response to interspecific competition

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4
Q

what happens as a result of interspecific competition

A

As a result of interspecific competition, competitive exclusion can occur, where the niches of two species are so similar that one declines to local extinction

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5
Q

what happens Where the realised niches are sufficiently different,

A

Where the realised niches are sufficiently different, potential competitors can co-exist by resource partitioning

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6
Q

what is parasatism

A

Parasitism is a symbiotic interaction between a parasite and its host (+/-). A parasite gains benefit in terms of nutrients at the expense of its host

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7
Q

Unlike in a predator–prey relationship, the reproductive potential of the parasite is what?

A

Unlike in a predator–prey relationship, the reproductive potential of the parasite is greater than that of the host

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8
Q

what do most parasites have

A

Most parasites have a narrow (specialised) niche as they are very host-specific

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9
Q

what does degenerate means

A

As the host provides so many of the parasite’s needs, many parasites are degenerate, lacking structures and organs
found in other organisms

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10
Q

what is the difference of ectoparasites and endoparasites

A

An ectoparasite lives on the surface of its host, whereas an endoparasite lives within the tissues of its host

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11
Q

what do parasites require to complete their life cycle

A

Some parasites require only one host to complete their life cycle. Many parasites require more than one host to
complete their life cycle

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12
Q

what is the definitive host

A

The definitive host is the organism on or in which the parasite reaches sexual maturity. Intermediate hosts may also be required for the parasite to complete its life cycle.

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13
Q

what does a vector do

A

A vector plays an active role in the transmission of the parasite and may also be
a host

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14
Q

what is the human disease malaria is caused by

A

The human disease malaria is caused by Plasmodium

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15
Q

malaria parasite lifecycle

A

An infected mosquito, acting as a vector, bites a human. Plasmodium enters the human bloodstream. Asexual reproduction occurs in the liver and then in the red blood
cells. When the red blood cells burst gametocytes are released into the bloodstream. Another mosquito bites an infected human and the gametocytes enter the mosquito, maturing into male and female
gametes, allowing sexual reproduction to now occur. The mosquito can then infect
another human host.

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16
Q

Schistosomes cause the human disease schistosomiasis, henace explain the disease

A

Schistosomes reproduce sexually in the human intestine. The fertilised eggs pass out via faeces into water where they develop into larvae. The larvae then infect water snails, where asexual reproduction occurs. This
produces another type of motile larvae, which escape the snail and penetrate the skin of a human, entering the bloodstream.

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17
Q

where can viruses and parasites replicate

A

Viruses are parasites that can only replicate inside a host cell

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18
Q

what is the form of genetic material that viruses contain

A

Viruses contain genetic material in the form of DNA or RNA, packaged in a protective protein coat

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19
Q

what are some viruses surrounded by

A

Some viruses are surrounded by a phospholipid membrane derived from host cell materials

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20
Q

what does the outer surface of a virus contain

A

The outer surface of a virus contains antigens that a host cell may or may not be
able to detect as foreign

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21
Q

viral life cycle stages

A

Viral life cycle stages: infection of host cell with genetic material, host cell enzymes replicate viral genome, transcription of viral
genes and translation of viral proteins, assembly and release of new viral particles

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22
Q

what do RNA retroviruses use to form DNA

A

RNA retroviruses use the enzyme reverse transcriptase to form DNA, which is then
inserted into the genome of the host cell

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23
Q

what can viral genes can then be expressed to form

A

Viral genes can then be expressed to form
new viral particles

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24
Q

what are the factors that increase transmission rates

A

Factors that increase transmission rates:
 the overcrowding of hosts when they are at high density
 mechanisms, such as vectors and waterborne dispersal stages, that allow
the parasite to spread even if infected hosts are incapacitated

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25
what is transmission
Transmission is the spread of a parasite to a host
26
what is virulence
Virulence is the harm caused to a host species by a parasite
27
how are ectoparasites generally transmitted
Ectoparasites are generally transmitted through direct contact
28
how are endoparasites of the body tissues often transmitted
Endoparasites of the body tissues are often transmitted by vectors or by consumption of intermediate hosts
29
how do parasites often maximise transmission
Host behaviour is often exploited and modified by parasites to maximise transmission. Alteration of host foraging, movement, sexual behaviour, habitat choice or anti-predator behaviour.
30
The host behaviour becomes part of the extended phenotype of the parasite. true or false
The host behaviour becomes part of the extended phenotype of the parasite
31
what do parasites often suppress
Parasites often suppress the host immune system and modify host size and reproductive rate in ways that benefit the parasite growth, reproduction or transmission
32
what does Epithelial tissue block
Epithelial tissue blocks the entry of parasites; hydrolytic enzymes in mucus, saliva and tears destroy bacterial cell walls; low pH environments of the secretions of stomach, vagina and sweat glands denatures cellular proteins of pathogens
33
what are some examples of non- specific defences
Non-specific defences Physical barriers, chemical secretions, inflammatory response, phagocytes, and natural killer cells destroying cells infected with viruses are examples of non-specific defences
34
Immune response in mammals has both nonspecific and specific aspects
35
what is the result of injured cells releasing signalling molecules
Injured cells release signalling molecules. This results in enhanced blood flow to the site, bringing antimicrobial proteins and phagocytes.
36
what is the process of phagocitosis
Killing of parasites using powerful enzymes contained in lysosomes, by engulfing them and storing them inside a vacuole in the process of phagocytosis.
37
what can natural killer cells do
Natural killer cells can identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis.
38
what are examples of Specific cellular defences
Specific cellular defences: A range of white blood cells constantly circulate, monitoring the tissues
39
what happens if tissues become damaged or invaded
If tissues become damaged or invaded, cells release cytokines that increase blood flow resulting in non-specific and specific white blood cells accumulating at the site of infection or tissue damage
40
Mammals contain many different lymphocytes, each possessing a receptor on its surface, which can do what?
Mammals contain many different lymphocytes, each possessing a receptor on its surface, which can potentially recognise a parasite antigen
41
what does binding of an antigen to a lymphocyte's receptor do
Binding of an antigen to a lymphocyte’s receptor selects that lymphocyte to then divide and produce a clonal population of this lymphocyte
42
what will some selected lymphocytes produce
Some selected lymphocytes will produce antibodies, others can induce apoptosis in parasite-infected cells
43
what do antibodies possess
Antibodies possess regions where the amino acid sequence varies greatly between different antibodies
44
what does the variable region give the antibody
This variable region gives the antibody its specificity for binding antigen
45
when the antigen binds to the variable region what is formed, and what is the result of this formation
When the antigen binds to this binding site the antigen-antibody complex formed can result in inactivation of the parasite, rendering it susceptible to a phagocyte, or can stimulate a response that results in cell lysis. Memory lymphocyte cells are also formed
46
what does initial antigen exposure produce
Initial antigen exposure produces memory lymphocyte cells specific for that antigen that can produce a secondary response when the same antigen enters the body in the future. When this occurs antibody production is enhanced in terms of speed of production, concentration in blood and duration.
47
what
Parasites have evolved ways of evading the immune system
48
why do endoparasites mimic host antigens
Endoparasites mimic host antigens to evade detection and modify host immune response to reduce their chances of destruction
49
what does antigenic variation in some parasites allow them to do
Antigenic variation in some parasites allows them to change between different antigens during the course of infection of a host. It may also allow re-infection of the same host with the new variant
50
how do some viruses escape immune surveillance
Some viruses escape immune surveillance by integrating their genome into host genomes, existing in an inactive state known as latency
51
when does the virus become active
The virus becomes active again when favourable conditions arise
52
what is epidemiology
Epidemiology is the study of the outbreak and spread of infectious disease
53
what is herd immunity threshold
The herd immunity threshold is the density of resistant hosts in the population required to prevent an epidemic
54
what do vaccines contain
Vaccines contain antigens that will elicit an immune response
55
why does the similarities between host and parasite metabolism make things difficult
The similarities between host and parasite metabolism makes it difficult to find drug compounds that only target the parasite
56
what does antigenic variation have to be
Antigenic variation has to be reflected in the design of vaccines
57
why is it difficult to design vaccines
Some parasites are difficult to culture in the laboratory making it difficult to design vaccines
58
when do challenges arise (parasites)
Challenges arise where parasites spread most rapidly as a result of overcrowding or tropical climates
59
what can overcrowding result in
Overcrowding can occur in refugee camps that result from war or natural disaster or rapidly growing cities in LEDCs. These conditions make co-ordinated treatment and control programs difficult to achieve
60
what may often be the only practical control strategies
Civil engineering projects to improve sanitation combined with co-ordinated vector control may often be the only practical control strategies
61
what can improvements in parasite control reduce
Improvements in parasite control reduce child mortality and result in population-wide improvements in child development and intelligence, as individuals have more resources for growth and development

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