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parasitism Flashcards

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AP® Biology flashcards
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
Q

what is transmission

A

Transmission is the spread of a parasite to a host

26
Q

what is virulence

A

Virulence is the harm caused to a host species by a parasite

27
Q

how are ectoparasites generally transmitted

A

Ectoparasites are generally transmitted through direct contact

28
Q

how are endoparasites of the body tissues often transmitted

A

Endoparasites of the body tissues are often transmitted by vectors or by consumption of intermediate hosts

29
Q

how do parasites often maximise transmission

A

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
Q

The host behaviour becomes part of the extended phenotype of the parasite. true or false

A

The host behaviour becomes part of the extended phenotype of the parasite

31
Q

what do parasites often suppress

A

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
Q

what does Epithelial tissue block

A

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
Q

what are some examples of non- specific defences

A

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
Q
A

Immune response in mammals has both nonspecific and specific aspects

35
Q

what is the result of injured cells releasing signalling molecules

A

Injured cells release signalling molecules. This results in enhanced blood flow to the
site, bringing antimicrobial proteins and phagocytes.

36
Q

what is the process of phagocitosis

A

Killing of parasites using powerful enzymes contained in lysosomes, by engulfing them and storing them inside a vacuole in the process of phagocytosis.

37
Q

what can natural killer cells do

A

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

38
Q

what are examples of Specific cellular defences

A

Specific cellular defences:
A range of white blood cells constantly circulate, monitoring the tissues

39
Q

what happens if tissues become damaged or invaded

A

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
Q

Mammals contain many different lymphocytes, each possessing a receptor on
its surface, which can do what?

A

Mammals contain many different lymphocytes, each possessing a receptor on
its surface, which can potentially recognise a
parasite antigen

41
Q

what does binding of an antigen to a lymphocyte’s receptor do

A

Binding of an antigen to a lymphocyte’s receptor selects that lymphocyte to then
divide and produce a clonal population of this lymphocyte

42
Q

what will some selected lymphocytes produce

A

Some selected lymphocytes will produce antibodies, others can induce apoptosis in parasite-infected cells

43
Q

what do antibodies possess

A

Antibodies possess regions where the amino acid sequence varies greatly between different antibodies

44
Q

what does the variable region give the antibody

A

This variable region gives the antibody its specificity for binding antigen

45
Q

when the antigen binds to the variable region what is formed, and what is the result of this formation

A

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
Q

what does initial antigen exposure produce

A

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
Q

what

A

Parasites have evolved ways of evading the
immune system

48
Q

why do endoparasites mimic host antigens

A

Endoparasites mimic host antigens to evade detection and modify host immune response to reduce their chances of destruction

49
Q

what does antigenic variation in some parasites allow them to do

A

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
Q

how do some viruses escape immune surveillance

A

Some viruses escape immune surveillance by integrating their genome into host genomes, existing in an inactive state known as latency

51
Q

when does the virus become active

A

The virus becomes active again when favourable conditions arise

52
Q

what is epidemiology

A

Epidemiology is the study of the outbreak and spread of infectious disease

53
Q

what is herd immunity threshold

A

The herd immunity threshold is the density of resistant hosts in the population required to prevent an epidemic

54
Q

what do vaccines contain

A

Vaccines contain antigens that will elicit an immune response

55
Q

why does the similarities between host and parasite metabolism make things difficult

A

The similarities between host and parasite metabolism makes it difficult to find drug compounds that only target the parasite

56
Q

what does antigenic variation have to be

A

Antigenic variation has to be reflected in the design of vaccines

57
Q

why is it difficult to design vaccines

A

Some parasites are difficult to culture in the laboratory making it difficult to design
vaccines

58
Q

when do challenges arise (parasites)

A

Challenges arise where parasites spread most rapidly as a result of overcrowding or
tropical climates

59
Q

what can overcrowding result in

A

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
Q

what may often be the only practical control strategies

A

Civil engineering projects to improve sanitation combined with co-ordinated vector control may often be the only practical control strategies

61
Q

what can improvements in parasite control reduce

A

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

ah biology (12 decks)

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